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Messages - jrista

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1051
Lenses / Re: DxO ... a little help please!
« on: February 13, 2014, 05:26:00 PM »
that is a great explanation but i will never remember it all. is there a simple way to look at it to get a quick summary? such as the black line for a general indicator and how tight the lines are together? do these mtf charts generally translate into what is found in testing of real lenses?

thanks,

You can't really narrow it down. That's the fundamental fallacy everyone falls into, and why a lot of the stuff DXO, DPR, and the whole host of other "lens testers" produce is largely useless.

If you want to eliminate anything, eliminate the set of curves that don't fit with the apertures you will most use. If you will mostly shoot wide open, then you can ignore the blue curves. If you will mostly shoot stopped down, then you can ignore the black curves. You could ignore dashed curves, and just use the solid curves, but then your not really getting the whole picture.

There is no "one number tells all". That's just a fallacy. The attempt to utterly simplify everything is really what gets you into trouble.

When it comes to the difference between an MTF and a lens test, lens tests all ultimately run into the "sensor bound" problem. Sensors have a fixed resolving power...it's the same across the entire area of the sensor. Lenses, on the other hand, have a non-linear resolving power that falls off as you stop down. At apertures wider than f/8, the potential for a lens to resolve much finer detail than the sensor becomes very real. The problem is, final "output" resolution has an asymptotic relationship with the lowest common denominator. Since the sensor usually IS that lowest common denominator, at faster apertures, where lenses have the potential to resolve a LOT of detail, may all end up looking the same in the end. Why? Well, let's say your sensor can resolve 50lp/mm, and you have four lenses capable of resolving, at f/4, 100lp/mm, 130lp/mm, 150lp/mm, and 173lp/mm (the latter is the maximum diffraction-limited resolving power of an f/4 lens.) The problem is that all of these lenses will all appear to resolve somewhere between 45-49lp/mm with a "real world" lens test, like the kind that DXO does. They are all SENSOR BOUND! The SENSOR cannot resolve more than 50lp/mm, so that is your absolute limit on final output resolution (the resolution measured in the RAW images by computer algorithms.)

So, first off, your standard lens test that tests lenses attached to cameras are largely useless for any apertures above f/8, however from f/8 and narrower, the vast majority of lenses are diffraction limited, so they will all perform the same anyway.

Second, MTFs really don't have any relationship with artificial lens test results, because they are either performed algorithmically based on fairly accurate computer models that account for overall lens construction and design, as well as material traits; or they are performed with optical lens bench testing, which uses a special apparatus to test JUST the lens. Synthetic MTFs will usually indicate just a little bit better performance than Real MTFs generated with a optical test bench, however both will be largely similar, and neither will bear any resemblance to your "standard lens+camera" tests.

If you want to keep it simple: Pick one set of solid lines, for max aperture or f/8 (depending on whichever you use most), and go with that.

1052
Animal Kingdom / Re: BIRD IN FLIGHT ONLY -- share your BIF photos here
« on: February 13, 2014, 04:47:42 PM »
Beautiful shot Jon.  I believe it is a Rough-legged Hawk.  The dark wrist feathers are my clue.

Hmm, are you sure? I thought Rough-legged hawks had darker underwings...

1053
EOS Bodies / Re: Will the next xD cameras do 4k?
« on: February 13, 2014, 04:46:49 PM »
You don't necessarily print wedding photos at 24x36", however I also wouldn't say that is unheard of, especially for wealthier couples you can't rule it out.


Quote from: lightmaster
and of course, as i wrote before, you do the big bride and groom pictures not in video modus.
did not think i have to say that again. but you can pull many of the casual images from video.


but a couple that wants all photos in 24x36inch?
hell of a job for a wedding photographer i guess.   ;D

Quote from: jrista
Plus, pulling 4k frame grabs doesn't get you the kind of aesthetic quality that a couple really EXPECTS when you shoot a wedding for them...where you have perfect focus, no camera shake at all, and just as important, the right depth of field. You aren't always in full control of these aspects of good photography when your shooting video. Getting a good wedding photo, or for that matter a good event photo or concert photo, isn't as much about resolution as it is about the other aspects of photography. Was it focused on the right thing? Was it sharp? Is the noise at an acceptable level? Is the depth of field adequate? Is boke acceptable?


Quote from: lightmaster
it´s not about shoothing the whole wedding (your project) on video.
afaik nobody in this thread wrote that. i sure did not advertise to do so.

it´s the ability to pull 4K frames from the video you shoot.
and many weeding photographer shoot video these days.... or have an assistant doing video

you seem to assume it´s not usefull to have the option?


Quote
You can call me a liar all you want

did i do so? if you had the impression i did, that was not what i meant (my english is not good).
i wrote you are WRONG.. not quite the same.
it´s not with intent... just because you don´t know better.  ;)

Well, first off, I do know better. Both with some experience, and with the necessary theoretical knowledge. I just love it how pundits deny the theory that is the BASIS for all the equipment and technology they use. ;P

As for whether having the option to pull out 4k frames is useful? As a means of avoiding catastrophe, say the wedding/event/concert/show photographer ends up frying all of the memory cards that had their still photos...sure, it could be useful. As a primary tool to get photographic images? No. Use the right tool for the job. I mean, is that not THE OLDEST ADAGE? Don't use a hammer to pound in a screw!! If there was ever a hammer in the digital imaging world, it's video. I think professionals will use the right tool for the job, every time. I think it is the mark of someone offering cheap quality work who would regularly pull out 4k frames and call it adequate for a professional gig. Sorry, but there you have it.

1054
You are comparing different results taken under entirely different circumstances. Scientifically, that is invalid. You can only compare results taken under the same circumstances. You trying to compare your credit card samples to AlanF's chart samples is invalid. You can't make any kind of reasonable comparison between those two disparate data sets.
You can only legitimately compare YOUR OWN two samples, or Alan's TWO samples, but you cannot cross-compare them. Using only your two samples, you yourself have proved that the Tamron is markedly sharper than the upsampled Canon 100-400mm. MARKEDLY. I mean, plain as day, I could probably cut my fingers on the razor-sharp text in the Tamron sample, and sooth my bleeding fingers on the Canon sample, kind of difference here. If you can't see that, then you might want to get your eyes checked, because you are either exceptionally nearsighted, or particularly farsighted.

If you want to compare the Tamron with the 300/2.8 + 2x, then you need to do that test yourself with the exact same credit card, under the same lighting conditions, with the card at the same angle, imaging the same region of the card, so the results can all be DIRECTLY compared. Since you have not done that, then we really can't know what the relative difference between all three lenses is. We don't have a single complete data set that covers all three lenses tested under identical circumstances.
We had one common setup: the canon300mm + 2xtc combo.
Alan invited me to test the same combo against the upscaled 100-400mm to show how it compared to the 300mm combo.
Just for an indication to see if they are far apart or not. Nothing more.
And have I concluded anywhere that the upscaled 100-400mm gives more details than the Tammy?
Have you the Tammy? Can you contribute for anything here at all?


Maybe you can tell me how much more magnification 7d will give than your 1dx on a subject shooting from same distance with same lens mm?
According to your theory, the 7d has 2.56x more magnification than 1dx.
Wow! So you need a 2,56x tc do compensate for the lack of reach? Do you?

Well, you seem to sort of get it now. To determine the difference in pixels per area (magnification factor for sensors) between the 1D X and the 7D, you need to factor in pixel pitch, rather than crop factor. Crop factor is a constant based on total area of each sensor. Since FF and APS-C always have the same total areas regardless of pixel pitch, using crop factor is insufficient to determine the REAL magnification difference that smaller pixels can offer.

In the case of the 1D X, you have 6.95µm pixels, or an area of 6.95^2µm: 48.3µm^2. The 7D has 4.3µm pixels, or an area of 4.3^2µm: 18.49µm^2. Again, because were working in two dimensions here, it's not a linear scale, you can fit 48.3/18.5 7D pixels into one 1D X pixel. That comes out to 2.61x 7D pixels per 1D X pixel. You would need a 2.6x TC in in order to completely normalize the crop difference between the 7D and 1D X, all else being equal.

I mean, seriously...this isn't complicated stuff. It's rather basic geometry: Two dimensions. All pixels have two dimensions. You can't compute a simple scalar linear difference between pixel pitch (a ONE dimensional measure) or focal lengths (again, a ONE dimensional measure) and assume "that's it!". Images are resolved in two dimensions, across the horizontal and vertical height of the sensor. Regardless of whether you reduce FoV or reduce pixel size, its all still in two dimensions. So, you have to square whatever scalar measure your working with in order to determine the real two-dimensional difference.

And now back original question: Is it possible that a sharp 100-400mm centercrop upscaled by 1.5x can match a confirmed soft Tamron @ 600mmf63. Im quite sure its a closer match than many people here seems to believe.
If anyone read this as bashing the Tamron, then they have a problem I think. ;)

First fact your getting wrong: The Tamron is NOT "confirmed soft". It is tested (not sure why, I need to check with Alan about those results) "softer than" a 300mm f/2.8 L II PRIME. But that does not mean it is confirmed soft in general. Relative vs. absolute. Important distinction there. RELATIVELY SPEAKING, the Tamron is softer than the 300/2.8. RELATIVELY SPEAKING, according to your own results (!!!) the Tamron is sharper than the 100-400. Your own samples of the credit card PROVE that the Tamron is relatively sharper than the Canon.

Again, you have problem withe the Reading: The Tammy is confirmed soft @ 600mmf6.3.  Also compared to any L tele from Canon including 100-400mm. Especial on a high pixel sensor. Even the cheap 55-250mm is much sharper than the Tammy at the longest end. From edge to edge.

Do you deny that? And please read again before you try to prove otherwise: Soft @600mm wide open.
Maybe not so soft that a sharp 100-400@400mmf56 center crop can be upscaled and show same details. But I GUESS its not far off.
I would love to replace my 100-400mm with a Tammy if someone could show me that it gives me valuable more details on the subject shooting at f6.3.

You could show yourself. Just rent the lens for a couple days, and compare. It is doubtful that the softness of the Tammy @ 600/6.3 is going to be enough to make it worse than the Canon @ 400/5.6. You just keep ignoring the fact that the Tammy is magnifying the subject so much more. You would have to have a SIGNIFICANT loss in resolving power at f/6.3 in order to completely obliterate that 2.25x greater resolving power.

You should really go look up a few things on optics and lenses. You keep using scalar (one dimensional) differences in lenses to compare them. A longer lens reduces the angular field of view. I assume you do know what area is (width * height). A 400mm lens has a 4.1°x2.73° AoV (relative to a FF 36x24mm sensor frame). A 600mm lens has a 2.73°x1.816° AoV (again, relative to FF frame). If we just take those angles as width and height dimensions, we have 4.1 * 2.73 and 2.73 * 1.816, or 11.193 and 4.958. If we divide 11.193 by 4.958, what do we get? We get 2.25756!! The area of a 600mm lens is 2.26 times SMALLER than the 400mm lens. In other words, the 600mm lens sees a 2.26x smaller region of your subject than the 400mm lens. However, the 600mm lens is projecting that smaller angle of view onto the exact same 36x24mm sensor area. That means its smaller region is being enlarged more...THAT is magnification.

The difference between a 600mm lens and a 400mm lens is a 2.26x magnification factor. The 600mm lens would have to be 2.27x softer in order for it to produce worse results than the upsampled 400mm frame.

Personally, I doubt that the 600mm is that soft at f/6.3. It isn't as sharp as humanly possible at f/6.3, but it would need to be pretty bad in order to be WORSE than an upsampled 400mm lens (which, BTW, is not resolving perfect detail at f/5.6 itself, which means our 600mm lens would have to be 3x worse at least at f/6.3 in order for it to be softer than an upsampled 400mm.)

1055
Jon
I see you have a 5DIII or 7DII on your buy list to replace your 7D. Your 600mm is so sharp that it doesn't take the crop hit, but the 100-400 does. I forked out on the 300mm f/2.8 because my 100-400 wasn't sharp enough on the 7D, and there was a huge leap in resolution with the 300/2.8 + 2xTC. Have you tried the 5DIII? It won't be as good for your astro-photography as the 7D but for nature photography its better IQ with colour shading and noise handling compensates for the loss of reach. I'll be using the Tammy with the 5DIII and not the 70D.

I have indeed tried the 5D III, a local wildlife photographer was kind enough to let me try his out on a few occasions when we randomly met up out in the wild. I've been very impressed with it.

I am pretty doubtful I'll be buying the 7D II, even if it hits the streets with every feature I expect. I do landscapes as well, and I also do astrophotography. The 5D III is better for both of the latter, and as you have said, it isn't quite as demanding on the optics. I am still very interested in seeing how the 7D II pans out, and I don't doubt it would kick the crap out of the 5D III in resolving power...but if it is anything like the 7D, it will definitely require more meticulous technique in order to extract the same kind of IQ.

Someone also brought up one aspect of the 7D that I have noticed and very much don't like: It has a "waxy" sheen to it's images. I honestly don't know why...AA filter? Weaker CFA? Both? Whatever it is, it is a particularly frustrating aspect of the 7D, especially at higher ISO settings. I am a little bummed to be dropping back to 6fps, but the 5D III has so much more dynamic range at higher ISO settings that there really isn't any contest. Even if the 7D II lands with 28ke- to 30ke- FWC, that is still less than HALF the FWC of the 5D III. I find myself working at ISO 1600 and up more and more often these days, even with the 600/4 II.

So yeah, I guess I should probably edit my signature and get rid of the 7D II. The 5D III is just a far more versatile, more capable camera. Plus, I can mitigate the reach difference with a 2x TC and f/8 AF if I really need it, so there really isn't any loss in the number of pixels I can put on my subjects.

1056
EOS Bodies / Re: Will the next xD cameras do 4k?
« on: February 13, 2014, 04:04:58 PM »
...you will find enough people who praise doing it on the net.
they are not all liars... of course.

Yeah, and I can go on Facebook and find blurry images with hundreds of likes.  There's also a difference between pulling a frame from video to post on FB or Flickr, downsampled significantly, and printing that frame grab on art paper at 24x36".

Plus the Internet contains only Truth, as we all know.

lol, i can find plenty of crappy 5D MK3, 1DX photos(!) on facebook too.
what kind of argumentation is that?

5D MK3 and 1DX are unable to make good photos?
or people don´t know what they are doing?

you have to pull better arguments than that.

ps: i don´t speak about facebook or 500px flickr images.
i speak about professionals who use a canon 1DC.


Quote
and printing that frame grab on art paper at 24x36".

you have done many such wedding albums?
most i see are smaller.  :P

and of course, as i wrote before, you do the big bride and groom pictures not in video modus.
i did not think i have to say that again. but you can pull many of the casual images from video.

the links above.. you think the quality is not good enough for wedding album prints?
again they are most likely not 24x36 inch.  ;)

of course not all all frames will be useable. but so are not all my 12 frames/s when i shoot BIF.
most video requires motion blur, and a lot of photography eschews it.
but it´s still very usefull to have that option.

You don't necessarily print wedding photos at 24x36", however I also wouldn't say that is unheard of, especially for wealthier couples you can't rule it out.

That said, printing high quality photos at 8x10" 600ppi is pretty standard. At that print size, in order to do it unscaled, you would need a high quality, crisp, sharp 4800x6000 pixel image. A 4k video frame grab doesn't even get you close. A 5D III, on the other hand, does get you close, and it is able to print an 8x10 @ 600ppi with a border without any scaling at all.

Plus, pulling 4k frame grabs doesn't get you the kind of aesthetic quality that a couple really EXPECTS when you shoot a wedding for them...where you have perfect focus, no camera shake at all, and just as important, the right depth of field. You aren't always in full control of these aspects of good photography when your shooting video. Getting a good wedding photo, or for that matter a good event photo or concert photo, isn't as much about resolution as it is about the other aspects of photography. Was it focused on the right thing? Was it sharp? Is the noise at an acceptable level? Is the depth of field adequate? Is boke acceptable?

You can call me a liar all you want, but when push comes to shove, I think people will still be hiring PHOTOGRAPHERS a decade and beyond from now, rather than vidographers doing makeshift photography. ;)

1057
Lenses / Re: DxO ... a little help please!
« on: February 13, 2014, 03:57:08 PM »
BTW, Rienz...I'd be happy to explain how to use an MTF. It seems complicated, all those lines, but once you get the general idea, they are actually EXTREMELY informative, and it isn't all that difficult to understand.


Hi Jon,

Please do ... I'd appreciate that very much ... and am sure others like me will also appreciate it very much.

Thanks in advance


Alright. Here goes. First, I'm just going to cover MTF charts. You don't actually need to know all the fundamental science that goes into resolving power to actually understand an MTF chart. All you really need to know is how to read the MTF chart, and that will tell you pretty much everything you need to know about the theoretical characteristics of a lens. Since most manufacturers publish MTF charts, and most use the same general standard (30lp/mm resolving power\sharpness & 10lp/mm contrast), they are pretty easy to compare brand to brand as well.

So, first off, an example MTF chart. This is the EF 24-70mm f/2.8 L II:




There are two charts here, because they represent the wide angle and narrow angle extremes of the zoom ratio. This one single chart tells you everything you need to know about a lens, and you can compare two MTF charts to each other to determine differences in each lenses performance (or, determine the differences between one extreme and the other of a zoom.)



So, first a breakdown of the chart itself. The MTF chart (absent any plot) represents the resolving power (sharpness and contrast) of a lens, from the center of the frame to the corner of the frame. The center of the frame is represented by the leftmost edge. The corner of the frame is represented by the rightmost edge. The vertical (y-axis) scale is an indication of how close to "ideal" resolving power gets. The vertical scale ranges from 0.0 to 1.0. In "historical" terms (and this really stems from the film days, so take it with the understanding that it definitely does not apply quite the same way today), MTF above 0.6 is "good/satisfactory" and MTF above 0.8 is "excellent/superior". Personally, I make the assumption, given how crisply modern digital sensors resolve detail, and the fact that people are increasingly publishing their photos online in full 1080p resolution, that MTF above 0.7 is "good/satisfactory" and above 0.9 is "excellent/superior".



Now for the plot. There are usually eight lines plotted on an MTF chart. These lines are blue and black (for Canon, other manufacturers may use other colors), thick and thin, solid and dashed. These lines represent how the lens reproduces sets of diagonal lines, the first set angled 45° and the second set 90° perpendicular to the first. These lines are called Sagittal and Meridional lines. They are angled at 45° and 135° because that is the ideal orientation to measure the behavior of optics from center to corner (vs. 0° and 90°, which would be more ideally suited to testing a lens center to edge...which is really insufficient.) The reason perpendicularly angled lines are used is because lenses do not behave the same when resolving detail at all angles...astigmatism in the lens design will often affect how lenses perform with fine detail angled differently across the lens. From the center to top right/bottom left corners, sagittal lines are angled parallel to the vector from the center to the corners of the lens. Meridional lines are angled perpendicular to the vector from center to top right/bottom left corners.

There are four sets of lines in total used in a standard MTF test. The first set are the 45° & perpendicular 10lp/mm lines. These lines are alternating white and black (technically speaking, the chart base is white, and there are thicker lines drawn at even spacing with thick white gaps between them, and thinner lines drawn at even spacing with thin white gaps between them.) The second set are 45° & perpendicular 30lp/mm lines. The 10lp/mm lines, which represent lower resolution detail, are used to measure lens contrast. The softer the transition between thick dark and thick white, the lower the contrast of the lens. The 30lp/mm lines, which represent higher resolution detail, are used to measure resolving power.



Can the black lines be resolved as fully separated with a white line in-between (resolved, high contrast)? If parallel black lines are separated, how quickly does the white line in-between become fully white (sharpness)?



So, we have an MTF chart that represents resolving power (y-axis) from center to corner of a lens (x-axis). This chart has eight curves plotted on it, that represent four sets of sagittal and meridional lines on a test chart. Why eight lines, rather than four? The MTF chart contains plots for both wide-open (max aperture) performance as well as f/8 performance. So, four sets of lines for max aperture:

  • f/2.8 sagittal thick solid (10lp/mm)
  • f/2.8 meridional thick dashed (10lp/mm)
  • f/2.8 sagittal thin solid (30lp/mm)
  • f/2.8 meridional thin dashed (30lp/mm)
  • f/8 sagittal thick solid (10lp/mm)
  • f/8 meridional thick dashed (10lp/mm)
  • f/8 sagittal thin solid (30lp/mm)
  • f/8 meridional thin dashed (30lp/mm)



Now, onto interpreting an MTF chart.

Using these eight curves plotted on an MTF chart, you can derive everything you need to know about the lens. The higher up the chart they are plotted, the better the contrast and resolution. You will normally see that as the curves move from the left edge to the right edge of the chart, they tend to "fall off", they drop lower. This is an indication of how the lens' performance chances from center to corner. You will also notice that one set of curves, either the solid curves or the dashed curves , tend to perform better than the other. This is an indication of astigmatism in the lens...sagittal curves (solid) may maintain higher performance than meridional curves (dashed).

This so happens to be exactly the case with the 24-70mm lens. At both wide (24mm) and narrow (70mm), the 24-70 resolves sagittal lines (45° angle) better than meridional lines (90° angle), and the meridional curves tend to fall off quicker in the midframe to the corners than sagittal curves do. Sometimes you may notice that some of these curves don't have a consistent falloff, they may turn "bump", resulting in slightly better resolving power just past midframe, then fall off again all the way into the corner. The nature of each curves falloff is an indication of how the various optical aberrations affect a lens' performance from center to corner. Depending on exactly what aberrations a lens may suffer from and to what degree, the nature of the curves' falloff will differ. Astigmatism and other imperfections in lens manufacture will result in falloff differing even from sagittal to meridional lines.

You will also find, once you start reading MTF charts, that wide angle lenses tend to have more chaotic late midframe and corner performance than normal and longer lenses. Telephoto/supertelephoto lenses will often have nearly flat MTF curves from center to corner (especially if they are higher end). It is not unusual to see crazy meridional performance in lenses as you approach the corners in wider angle lenses, especially ultrawide to wide angle zooms. There are simply certain compromises that must be made in order to produce a wide angle zoom lens that performs acceptably at as many focal lengths as possible.



That's pretty much it. A crash course in reading and understanding MTF charts. There is a lot more theory that builds up to WHY these kinds of tests are used to accurately measure lens resolving power, but you don't necessarily need to understand all that underlying grit in order to effectively use MTF charts themselves. All they really are is a plot of four types of detail from the center to the corner of the lens. Those plots measure contrast and resolution (sharpness & acutance) across the surface of the lens, and offer a fairly precise indication of how optical aberrations will affect your IQ in different regions of your frame.

1058
EOS Bodies / Re: Will the next xD cameras do 4k?
« on: February 13, 2014, 03:08:22 PM »
The point is I wouldn't hire any wedding photographer who was also offering to shoot video unless he had dedicated stills and video shooters with him/her.

Why, when you can theoretically shoot the whole thing in 4K video and then just pull printable stills from the video footage.

Theoretically?  We can theorize until the cows come home.  Care to share real-world examples of this being done successfully?

Aye, only in theory. This has never been proven. The thing people who believe this notion don't understand is that a camera is ALWAYS moving. Given that the standard frame rates are 24, 29, 30, and maybe 60fps (the latter is less likely unless your doing something special), even the smallest amount of camera shake will result in more than enough blur to render every single RAW 4k video frame unacceptable from a "still" photography standpoint.

The "dream" of being able to shoot video then pull out crisp, clear 4k frames as "photos" is really just that...a DREAM. The needs of video and still photography are very different. They always have been different, and with the exception of high speed filming (which is still also very different), the chances of anyone ever actually being able to pull out full sized crisp, sharp frames from 4k video is highly, highly unlikely, regardless of how good the technology gets. The entire point of 24fps is to ensure you end up with a certain amount of blur. You WANT the blur in video. You DON'T want the blur in a still photo.

i bet you never shoot 4K video in your live.

again, we do it at work and you will find enough people who praise doing it on the net.
they are all liars... of course.

You do what at work? Shoot 4k video, or pull out perfectly crisp, sharp, photographic quality stills out of your 4k video feeds?

I've done some cinematography, although at 2k. The fundamental theory, however, doesn't change with 4k. As a matter of fact, because 4k video sensors tend to be similar in physical dimensions but with smaller pixels, the camera shake issue would be even greater. Camera shake would be mitigated if you have all the necessary extra equipment to do real cinematography with a DSLR, like a proper shoulder holster, a magnified live view viewer, and even a focus puller. But that is a whole lot different than what Sella's been talking about, which basically boils down to being a super wedding photographer who just does 4k video of the entire cerimoney, then pulls out "photos" from his 4k video streams after the fact.

Sorry, but personally, if THAT is what my wedding photographer was doing, I'd fire him! You just don't get the kind of timeless WEDDING PHOTOS from a chump running around 4k video recording everything, as you do with a true professional who knows how to use the right lenses at the right times for different parts of the ceremony, how to bet the right kinds of portraits of all the guests with the right focus and creamy boke, etc. A good wedding photographer is most likely going to be using a 70-200 during the ceremony itself, and an 85 or 135 for portraiture after, and a mix of lenses during the reception depending on the time and the event of the moment.

Sorry, but your not going to produce quality wedding photos by running around recording everything in 4k video. Cinematography and stills photography are two very different things! The dream of being able to pull out professional quality still photos from a 4k video stream is purely dreamworld stuff. If I was a lawyer five years from now, I could probably make good business suing all the twits who managed to sell some poor couple on the "I do 4k video + photos all by myself for $10k" concept, because I guarantee you, not even a single one of those couples would be satisfied!!  :-*

1059
EOS Bodies / Re: Will the next xD cameras do 4k?
« on: February 13, 2014, 02:54:26 PM »
I dont need to go to a video forum...

May be I should clarify - I have worked with 4K, my $2000 system will not work unless I downscale the video... At which point... What does it matter if Im working with 4K or 1080p?


2000$ that doesn´t say much. your 2000$ system is from 2007 or 2014?  ;)
the specs would be more interesting.

and yes you need a beefy systems but you can do it for way under 10000$.

2TB harddisk cost 60 euro here.
that´s nothing compared to what i paid for film.
i can buy a few of them every month and it´s still cheaper then what i payed for film.


You cant buy cheap hard drives, it will fail on you and your clients will kill you!


now your pulling arguments out of your nose because you have no real arguments. ;)

60 euro for a seagate or hitachi 2TB disk. that´s a normal consumer drive. not a "cheap" drive
100 euro for a seagate constellation or hitachi ultrastar, if you need an enterprise drive.

but hey.. it´s a STORAGE drive.
it´s not necessary that this drive is an enterprise drive.
constellation drives are made for 24/7 workload use.
but storage drives don´t normaly run 24/7 under workload.

i rather buy consumer 60 euro drives then enterprise drives.
of course with a good backup plan, i think that needs no mentioning. you need a backup plan even with enterprise drives.

if someone does not make that kind of money to afford a few hardrives, then i agree that 4K is nothing he needs.

by the way:

http://blog.backblaze.com/2014/01/21

http://blog.backblaze.com/2013/11/12/how-long-do-disk-drives-last/



It really does not matter which hard drive you buy. The major factor for longevity is cooling..... keep them cool and they last... let them get warm and your goose is cooked.

Two years ago at work I set up a computing array. There are 80 computers, each computer has 4 1Tb WD Black hard drives and one SS hard drive. The units are WELL ventilated and kept in a 15C room. They have been running continuously for two years and I have yet to see a hard drive failure.

Last year I replaced about 40 hard drives from desktops kept on a floor, on carpet, under a desk, with restricted ventalation....


Do add to what Don has said, I use a ReadyNAS NVX device for my large scale, high speed storage. I have four 2Tb Hitachi 7200 RPM high density platter drives with 6-7ms seek times and a 180MB/s burst rate. I bought the NVX and installed the drives about four years ago. These drives run for the majority of the day, 12-16 hours, then sleep at night. The device uses a single fairly high powered fan, situated in the back, that pulls air in from the front across the drives. Every week, Sunday morning at midnight, the device does a full array scrub and reallocation, which usually takes about 20 hours (I've got about 5Tb of stuff on the array.)

These were technically "cheap" drives. I bought each one for under $100. They aren't desgined to be server-level 24/7 workhorse drives, and they have a pretty standard MTBF. But not one single drive has failed in four years. They still perform as well today as the day I bought them. I get 75-145MB/s sustained data transfer rates,  depending on whether I'm transferring large files or many small files (small files results in more overhead, so lower throughput.)

It is most assuredly NOT necessary to spend gobs of money on ultra high end drives, so long as you know how to use them, and yes, as Don said, KEEP THEM COOL! :)

1060
Lenses / Re: DxO ... a little help please!
« on: February 13, 2014, 02:47:16 PM »
I forgot to mention the-digital-picture.com in my last post.  Their tools are nice to use for comparisons as well.
When I first started out with DSLRs, the only source I used to trust for reviews was the-digital-picture.com ... also, they make it very simple to understand.

Bryan's reviews at TDP are indeed excellent. I probably have more respect for his reviews than anyones. They are just strait forward, cover the key technical aspects but also demonstrate real-world usage. Really doesn't get better than that. Just wish he would test more brands. ;)

BTW, Rienz...I'd be happy to explain how to use an MTF. It seems complicated, all those lines, but once you get the general idea, they are actually EXTREMELY informative, and it isn't all that difficult to understand.

As for using DxO, @mackguyver pretty much nailed it. Use their measures, which are comparable, and ignore the scores. The measures are pretty decent (except transmission, that one is pretty useless because they don't account for differing apertures, so it really is an aperture measure, not a transmission measure.) DxO's lens measures are handy because they can be directly compared. If you want similar detailed information about lenses that can be manually compared, DPR lens reviews have similar information. Two windows side-by-side would let you compare lenses with DPR information.

1061
Tamron soft Pit123? That is unfounded, unsubstantiated drivel. Here are the acutance tests done by DxO. The first is the Tamron at 400mm f/5.6 vs the 100-400 at 400 f/5.6. The Tamron is just as sharp in the centre of the field and its sharpness extends more to the edges. This is not just a one-off result, lensrental measurements are in exact agreement.

The second (bottom) is the Tamron at 600mm f/8 vs the 100-400 at 400 f/5.6. The Tamron is as sharp at 600mm as the Canon is at 400 at the centre, and it is much better at the edges.

This makes so much more sense. Which beggs the question, where in the world did he get the previous DxO measurement diagrams that showed the Tamron was so bad? Something really smells like rotten fish here...

1062
EOS Bodies / Re: Will the next xD cameras do 4k?
« on: February 13, 2014, 02:22:30 PM »
The point is I wouldn't hire any wedding photographer who was also offering to shoot video unless he had dedicated stills and video shooters with him/her.

Why, when you can theoretically shoot the whole thing in 4K video and then just pull printable stills from the video footage.

Theoretically?  We can theorize until the cows come home.  Care to share real-world examples of this being done successfully?

Aye, only in theory. This has never been proven. The thing people who believe this notion don't understand is that a camera is ALWAYS moving. Given that the standard frame rates are 24, 29, 30, and maybe 60fps (the latter is less likely unless your doing something special), even the smallest amount of camera shake will result in more than enough blur to render every single RAW 4k video frame unacceptable from a "still" photography standpoint.

The "dream" of being able to shoot video then pull out crisp, clear 4k frames as "photos" is really just that...a DREAM. The needs of video and still photography are very different. They always have been different, and with the exception of high speed filming (which is still also very different), the chances of anyone ever actually being able to pull out full sized crisp, sharp frames from 4k video is highly, highly unlikely, regardless of how good the technology gets. The entire point of 24fps is to ensure you end up with a certain amount of blur. You WANT the blur in video. You DON'T want the blur in a still photo.

1063
EOS Bodies - For Stills / Re: 5DIII - too grainy or not?
« on: February 13, 2014, 02:14:10 PM »
Hey. Today I went out to try shooting in "ETTR mode". I over exposed the image below by 1 2/3 EV with center weighted metering. On the camera screen review the whole sky over the castle was blinking. When I open it in LR, first thing that I have noticed was that there is quite a big difference in the sense of over exposing. I mean there was a lot less of blinking in LR compared to camera screen review. Then I made some corrections and the result is below. Actually, the sky is quite well recovered, if I thought that every part of it was blinking on the camera screen.

Do you suggest any other kind of metering mode? Maybe evaluative metering?

I always use evaluative metering myself. It seems to be the most friendly metering mode for ETTR. The problem with any of the more center-weighted modes (which is really what all the rest are, they are all weighted to the center to one degree or another) is that they don't tell you exactly how the peripheral scene content will render when you use ETTR. When you use Evaluative, it evaluates the ENTIRE scene, and with the iFCL metering system, the camera is already doing it's best to preserve highlights.

My recommendation is to use ETTR with Evaluative only. If you use a different metering mode, then your kind of indicating that your goals are different, and that you may not really are about any part of the scene outside of the center (and the camera will react accordingly.) To preserve highlights, always use Evaluative.

1064

I'm sorry, but that's completely illogical. Resolving power is resolving power. A 500mm lens resolves more detail than a 300mm lens, because it's resolving it at a higher magnification, plain and simple. It magnifies your subject 2.78x more. That is even more than the difference between a 400mm and 600mm lens. Additionally, the 2x TC introduces more of it's own optical aberrations than the 1.4x TC. There is no way that the 300mm + 2x will ever outresolve the 500mm + 1.4x. Just plain aint going to happen.
The difference in magnification between 600mm and 700mm is 1.16x.
So I have to upsample the image by 1.16x to give the same image. The same effect as putting a 1.16x TC on it. How you translate this to 2.78x more magnification is just simple stupid.
How much magnification gives a 1.4x tc?
How much more magnification gives a 18mp 1.6 crop camera vs a 18mp FF.
And how can you claim the magnification between 400 and 600 to be more than 2x?.
It is 1.5x. Nothing more, nothing less.
I just ask since you don’t seem to understand what we talk about here.

LOL! I know EXACTLY what I'm talking about! :D There is a very simple mathematical formula that proves it.

Sorry, but 1.5x is the ratio of focal lengths. The ratio of magnification is the ratio of focal lengths SQUARED!!!! You have to SQUARE the ratio of focal lengths, because lenses resolve in two dimensions!

Code: [Select]
(600mm/400mm)^2 = 1.5^2 = 2.25
The FoV is 1.5x smaller in both the horizontal and vertical...meaning 600mm FoV covers 2.25x less total area than the 400mm lens, but that 2.25x less total area is enlarged to fill the same sensor area....it has 2.25x GREATER MAGNIFICATION!

As for 2.78x, that was the ratio of area between 500mm and 300mm:

Code: [Select]
[code](500mm/300mm)^2 = 1.67^2 = 2.7889
So a 500mm lens magnifies it's subjects about 2.8x more than a 300mm lens! That's a pretty significant difference.

BTW, MAGNIFICATION is the factor we want here, rather than the simple ratio of focal lengths, because the number of pixels on subject is relevant in those same two dimensions. You enlarge the subject both horizontally and vertically relative to the sensor frame. That means you put more pixels on any given area of subject detail in both the horizontal and vertical.

I give you two examples: one from short distance (10meters), the other 948 meters from subject (according Google maps). Download and show in full size 1920x1080.
Short distance:

I'm not really sure what your saying about the distances. Were they at the exact same distance, or was the 600mm combo closer? If you normalized framing, then the comparison is invalidated, as the 600mm combo would effectively be putting the same number of pixels on subject...when the 600mm combo used at the same distance should be putting fewer pixels on subject. Either way, your own example shows the 500mm+1.4x is sharper than 300mm+2x. The 700mm combo is pretty crisp, you can clearly see the effect of the 2x TC on the 600mm combo.

Read again. The first example image was taken from approx 10 meters, The other example was taken from 943 meter (about 3000 feet). Would it make sense to change the distance depending on lens used if I try to demonstrate the effect of upscaling a very sharp lens vs a lens with more FL? No, Of course not. I said I can upscale the 300mm+2x combo to show similar (or even better details than the 500mm+1.4x combo).
I guess you had to ask because you cant believe your own eyes here. ;)

Sorry, but there is absolutely NO way that either one of those sample credit card photos was taken from 3000 feet away. That is the better part of a mile. Neither of those lenses has that kind of resolving power. Not even REMOTELY close to that kind of resolving power. LOL I don't know what your smoking, but you need to double check your facts. Like you need to double-check your understanding of what magnification is and why it matters.

Three thousand feet...and it somehow resolved just as good as something photographed from about 33 feet away? HAH! Bullsh*t!! Bull. Sh*t.

Did I say that the upscaling will add details compared to original image? Of course not.
But its much easier to compare lenses with different lens mm when the one is upsampled to the other lens mm. Or you can downsample the other. But downsampling will loose details. Upscaling will remain the details already there.

How can you clearly see the effect of the 2x? Explain? What you can see is the effect of the upscaling.
But even after upscaling, the 300mm+2x, shows at least similar details, especially in the long range image.
But also on the hair detail in the short range.

I have both lenses, and have compared them a lot.

You are comparing different results taken under entirely different circumstances. Scientifically, that is invalid. You can only compare results taken under the same circumstances. You trying to compare your credit card samples to AlanF's chart samples is invalid. You can't make any kind of reasonable comparison between those two disparate data sets.

You can only legitimately compare YOUR OWN two samples, or Alan's TWO samples, but you cannot cross-compare them. Using only your two samples, you yourself have proved that the Tamron is markedly sharper than the upsampled Canon 100-400mm. MARKEDLY. I mean, plain as day, I could probably cut my fingers on the razor-sharp text in the Tamron sample, and sooth my bleeding fingers on the Canon sample, kind of difference here. If you can't see that, then you might want to get your eyes checked, because you are either exceptionally nearsighted, or particularly farsighted.

If you want to compare the Tamron with the 300/2.8 + 2x, then you need to do that test yourself with the exact same credit card, under the same lighting conditions, with the card at the same angle, imaging the same region of the card, so the results can all be DIRECTLY compared. Since you have not done that, then we really can't know what the relative difference between all three lenses is. We don't have a single complete data set that covers all three lenses tested under identical circumstances.

And now back original question: Is it possible that a sharp 100-400mm centercrop upscaled by 1.5x can match a confirmed soft Tamron @ 600mmf63. Im quite sure its a closer match than many people here seems to believe.
If anyone read this as bashing the Tamron, then they have a problem I think. ;)

First fact your getting wrong: The Tamron is NOT "confirmed soft". It is tested (not sure why, I need to check with Alan about those results) "softer than" a 300mm f/2.8 L II PRIME. But that does not mean it is confirmed soft in general. Relative vs. absolute. Important distinction there. RELATIVELY SPEAKING, the Tamron is softer than the 300/2.8. RELATIVELY SPEAKING, according to your own results (!!!) the Tamron is sharper than the 100-400. Your own samples of the credit card PROVE that the Tamron is relatively sharper than the Canon.

Oh, and it's still a magnification ratio, i.e. a resolving power difference, of 2.25x. Your missing a VERY fundamental optical concept here that conforms to a very simple mathematical formula:

Code: [Select]
(LongerFL/ShorterFL)^2 = MagRatio

1065
EOS Bodies / Re: Will the next xD cameras do 4k?
« on: February 13, 2014, 10:55:14 AM »
Rule 2: If you can't sell enough of what you do offer, drop it and save the resources.

Interesting. For comparison, we don't think like that in our business model, unless the product causes an actual monetary loss and doesn't make up for it in marketing value.

I'm not sure that one is quite so simple...

You think that a product will be sucessful, so you perform R+D and set up production, packaging, manuals, etc...
You put it on the market and it does not sell well.... what do you do?

At this point, all the R+D dollars and the setup dollars have been spent (say $10,000,000). Even if you realize that the product will never recover those up-front costs, you have to decide if the product will sell well enough to cover continued production costs and then any return from this point (Say you now figure that over the life of the product it will return $7,000,000 profits).

You have a choice between ending the product now and taking a $10,000,000 hit or continuing production and ending up with a net hit of $3,000,000. The product will never be sucessful, but sometimes you have to make the best of a bad situation...

Right. But that is basically what Canon did with the EOS-M. They didn't drop it entirely from the GLOBAL market. They only dropped it from REGIONAL markets where it wasn't selling. They apparently sell like hotcakes in the Asian markets, particularly Japan, so they will be able to recoup their costs there. It wasn't selling in the US until the price hit like $250-$300, which is WELL below the original $800 price point. I honestly don't think Canon could cover not only the R&D costs, but also ongoing manufacturing, testing, and shipping costs, selling it at those price points. That is a MASSIVE writedown if they did, and that ultimately shows up as a huge negative to the bottom line. Instead, you pull back EOS-M to the markets where it IS selling, scale back your manufacturing targets, sell it at a good price, and you cover all your bases.

I don't think Canon spends ten million to research and develop any one single product anymore, though. Not specifically for photography, at least (they may spend that kind of money on some of their larger medical imaging devices research). I think they might spend a few million designing something like the 1D X, but for something like the EOS-M, the R&D costs had to be relatively low. They already had all the necessary electronic technology, nothing new there. The biggest differences were the lens mount and the smaller camera body package, maybe a little bit of firmware. Even if the company DID decide to drop that particular product entirely from the market before they manufactured too many of them that they end up with a massive supply surplus that only sells at nearly a third their intended price, the R&D costs would have ended up being a smaller percentage of the total writedown cost.

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