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Messages - sagittariansrock

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31
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 23, 2014, 01:33:45 AM »
jrista: Of course, sensor size does matter. Pixel size matters too, but that is not the topic of the OP's question. Now I can see how that got transformed over the few pages.
Lee Jay: You are right in considering a real world situation where an equally framed image should be the parameter of comparison, whereas I am supporting Don Haines' theoretical consideration that a larger pixel will gather more light than a smaller pixel, and that the same sized pixel will gather equal amount of light irrespective of the total area of the sensor it is a part of.

I think we all understand the physics, essentially, and also the real world fact that a larger sensor provides a ton of benefits under certain conditions, and a smaller sensor provides benefit in one specific situation. Good for us...


32
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 22, 2014, 02:01:32 PM »
@sagittariansrock: There is a difference in your explanation than the standard one: Your explanation does not utilize the full sensor area of larger sensors. Your explanation is based on the subject filling the same absolute area of the sensor, regardless of the total sensor area. That is the reach-limited argument. That is the ONE AND ONLY case where smaller sensors can achieve the same image quality as a larger sensor.

That is exactly right. Except, here we are discussing the capacity of a pixel to collect light, which is why this scenario should be used- that is, where the incident light is exactly the same in terms of intensity and quality.

The fair comparison is when your subject is framed the same, which means that for progressively larger sensors, a greater absolute area of sensor covers the subject. In that case, everything Orangutang, Lee Jay, and myself have stated is true. There is no circumstance where smaller sensors, regardless of their pixel size, can ever outperform a larger sensor.

I don't know if I will call it a fair comparison, but I can call it a real-world comparison. And as I said before I am sure everyone agrees with what you, Lee Jay and Orangutang are contending here- larger sensors have better IQ. No way can a smaller sensor collect the same amount of light. Except that is not the point here- the point is, would a smaller pixel collect less light than a larger pixel? Yes. Would a pixel collect the same amount of light whether its part of a large sensor or a small sensor? Of course!
This is why I said you all are disputing each other while everyone being right at the same time ;)

33
Lenses / Re: 100mm 2.8 vs 85mm 1.8
« on: August 22, 2014, 01:05:46 PM »

The specular highlights produced by the 85 1.8 look angular, not circular. That's part of my consideration when I sold it. Also maximum usable aperture is probably about 2.5 which is too close to my 100L's 2.8. Bokeh is not 135L quality. Nobody should expect that. But it's far better than 50 1.4. Personally like 100mm blur better though. Also it has no weather sealing.

On the good side the 85 focuses faster than the 100L. The focus seems more consistent and reliable. This is only based on my personal experience.

The 85 is a great value lens. You should definitely try it. Nothing to lose.

Don't agree with you on the usable aperture of 2.5.  It's the best lens I own and virtually never take it off 1.8 for professional portrait work - it's a belter of lens, I reckon by far the best bang for buck in the Canon line up.

85 f/1.8 is great value but I agree with the previous poster that if you need to stop it down to f/4 for a group shot the angular bokeh is ugly.  I wish Canon would update this with a 85mm f/1.8 IS design similar to the 35mm f/2 IS.

I personally would rather have the 100L of the two for its dual purpose macro/general as well as more pleasing bokeh stopped down.

Interesting that you liked the 100L bokeh stopped down? I didn't like it even wide open. Can you share some images- in case it was my technique which was the issue (and it might well be... :) )

34
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 22, 2014, 01:00:23 PM »
Here are the problems: as I said above, the comparison is irrelevant and misleading unless it's the same framing.  I will clarify that to say that it must be photographed initially at the same framing, without any cropping.  If you don't start with the same framing you are not comparing the IQ of the sensors, and the comparison is invalid.

You must start with the same frame from on each sensor, or you have no valid data on which perform comparisons.

Why is the comparison irrelevant unless it's the same framing? Last time, you used "to me" which is understandable, but to understand sensor and pixel properties, it totally makes sense to compare apples to apples where the luminance on the sensors is the same (i.e., same position of the hypothetical camera to capture the same incident light or part thereof in case of the smaller sensor).

You can compare sensors on the basis of equal sensor area. In that case, is the total light on an APS-C sized chunk located in the center of the FF sensor the same as the total light on an APS-C sensor at the exact same location. I'd say it is (it violates the laws of physics to be otherwise). Now, let's say both of these (chunk of FF vs APS-C) have the same number of pixels. Will the images on these sensors have the same noise characteristics. Yes, they will. This is easy to measure, both objectively and subjectively. What do you mean by not having data to perform comparisons!


There are certain reach-limited circumstances (which jrista has illustrated) where a high-density crop sensor can demonstrate superior IQ for a heavily cropped image.  However, that's not a comparison of the sensors themselves.

Exactly, that is completely irrelevant here. An APS-C sensor will never have the same or even close IQ to a same-generation FF sensor, while in reach-limited circumstances a higher resolution will demonstrate advantages. In this case, we are NOT talking about that. We are NOT talking about APS-C sensor being better than FF. This is a very focused argument: the size of pixel defines its light-gathering capacity. This capacity will be the same whether the same pixel resides in an FF sensor, an APS-C sensor or an MF sensor.

35
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 22, 2014, 12:49:24 PM »
You say "with identical technology, size of sensor is all that matters". I disagree. If you simply made a bigger 7D sensor, with the same technology and same pixel density, then it will have the same noise characteristics as the 7D sensor.

This is totally false.  If you make the 7D sensor bigger, you'll have more of the same pixels AND about a stop and a third better noise performance, assuming constant f-stop and constant framing.  That means, for the same image, you're going to have to either get closer or use a longer focal length.

I wish people wouldn't be so vehement in their comments, and leave some room for discussion ;P

You lose light when you magnify, so it is not an apples to apples comparison. This is why a macro lens loses half the incident light (with the same aperture) when you move from, say, 1:2 magnification to 1:1. Try using a microscope and go through the different magnifications- it will be immediately apparent.

I am not talking of the same image. I am talking of the same subject distance, therefore I am talking of a different FoV. In this situation, the total luminous flux on the center 1/2.56th of an FF sensor is the same as the total luminous flux on an APS-C sensor placed in the same location. This is why, when you select DX mode on a Nikon FF dSLR, you still get the same amount of light per unit area as before, and don't need to readjust your ISO, shutter speed or aperture, etc.

36
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 22, 2014, 06:03:49 AM »
Scenario 1: Normalize for pixel size
We have a camera that we can swap sensors on. We mount a 100mm lens to that camera.
...
The balance you select between the three is what determines the performance of your camera.

The only thing I would dispute is the regular use of "each sensor will have the exact same IQ". Hate to say it, but that is wrong...at least, so long as another required factor is not specified. :P Sensor size is the primary factor that controls "image quality", not pixel count, not pixel size. You could have twice the Q.E. on a smaller sensor, and the only one that would then only EQUAL the IQ of the larger sensor is the one that is exactly half it's size. A 4/3rds or 1/2.3 could never compare to the IQ of a FF sensor, not even with double the Q.E.

Now, the statement about equal IQ would be true...IF the aperture was specified. The 100mm lens on a FF sensor has to be using a smaller aperture than the 61.7mm lens, by a factor of the differences of the sensor diagonals. If the 61.7mm lens is f/2.8, then the 100mm lens should be f/4.5. THEN, and ONLY THEN, would "each sensor have the exact same IQ." You have to use a smaller aperture to normalize the amount of light reaching the sensor. Otherwise, one has to assume the same aperture. A 100mm lens on FF produces the same FoV as a 61.7mm lens on APS-C, however if they are both f/2.8, the FF sensor is without question gathering more light.

Equivalence. Aperture matters here.

I've said this so man times...but, I think Orangutan is the only one who actually heard it. So I'll just quote his answer:


I am sorry but neither you nor Orangutan are following Don's logic, and are traversing an entirely parallel path. It is funny, because no one is actually disputing anyone, but saying the other is wrong.

1. Forget aperture (or presume DoF to be infinity for comparison purposes)- focus on the question at hand: if the pixel size is the same, with same sensor tech, an APS-C sensor will have same noise characteristics as a FF sensor. Example: DX mode in a Nikon FF dSLR- what happens there is that a portion of the sensor is being used. Exactly the same thing will happen if you have a smaller sensor with same pixel size.

2. I don't think Don or anyone is claiming that a smaller sensor can collect more light than a larger one, if the pixel size is larger in the former. We all know that is quite impossible. The point being made is that the amount of light per pixel depends on the size of the pixel- in case of a larger sensor it is additionally multiplied by more number of pixels. However, if a FF sensor was made, using the same technology as a 7D sensor and with the same pixel size (making it 46MP I think) then it would be equally noisy.

I am not arguing that aperture affects image quality, but for this discussion let's just talk noise characteristics.



This is EXACTLY CORRECT. The only thing that really matters in the end, assuming all the sensors use the same technology, is TOTAL light gathered. More light, less noise. It's as simple as that. Pixel size doesn't really matter from a noise standpoint. Smaller pixels in the SAME sensor size mean you get more resolution, that does increase IQ...but smaller pixels in a smaller sensor DO NOT mean better IQ....they just mean more resolution, but with worse IQ.

This is equivalence. This scientific concept is documented very, very, very thouroughly here:

http://www.josephjamesphotography.com/equivalence/

If you still doubt, please, read the article on equivalence linked above. It's really not that complicated of a concept.

Sorry, but that's only partially true. The pixel size does matter. Quoting from your own link:

Given four cameras, one with...

...an mFT (4/3) sensor,
...another with a 1.6x sensor,
...another with a 1.5x sensor,
...and another with a FF sensor...

...and...

...a photo of a scene from the same position with the same focal point and the same settings (e.g. 25mm f/1.4 1/200 ISO 400) with all cameras,
...the photos cropped to the same framing as the photo from the mFT (4/3) camera,
...and the photos are displayed at the same size...

...then the resulting photos will be Equivalent.  In addition, if...

...all the sensors are equally efficient, then all the photos will also have the same noise,
...the pixels are all the same size, the AA filter the same strength, and the lens is the same sharpness, then all the photos will also have the same detail,

...the exact same lens is used and the sensors are of the exact same design with the exact same size pixels, AA filter, CFA, and processing...


It is possible to have same noise characteristics if the pixel size and sensor tech is the same, irrespective of total sensor size.


37
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 21, 2014, 11:19:31 PM »
Obviously, the FF sensor takes in more light, but it is spread over a wider field of view and the light per pixel is the same.

But the output image (print, projected image, etc) is the same size, so the light gathered by the FF sensor requires less enlargement (attenuation) to achieve that output size, and this negates your argument.

So I believe you're mistaken: with identical technology, the size of the sensor is all that matters for low-light properties.  For ample-light IQ, total MP, AA filter, etc are definitely important for resolution.

I'm sure jrista will jump in here any minute to correct us all.  :-)


Don Haines posted "the larger sensor size allows you place a similar number of pixels of greater size". This is a key sentence.

When you're comparing FF to APS-C, you are always comparing disparate pixel counts. You say "with identical technology, size of sensor is all that matters". I disagree. If you simply made a bigger 7D sensor, with the same technology and same pixel density, then it will have the same noise characteristics as the 7D sensor. The only thing different would be the field of view, and the ability to enlarge.

Going by the sentence I quoted above, on the other hand- a full frame sensor, even with the same tech as the 7D, will allow larger pixel size for the same pixel count. Here, the noise characteristics become better due to the pixel size.

So, bottom line is, you cannot improve light capturing ability without changing pixel size, given the same sensor technology. I am not sure what you mean by "enlargement of light gathered", and the output image is also subjective. The fact remains that a 46MP FF sensor can be enlarged to a greater size without pixellation than an 18MP APS-C sensor due to the larger size of the original image. It has nothing to do with reduced noise or increased light gathering in the former.

38
I think most everything that has needed to be said has been said... now there IS a way to diffuse the light more all things being equal, but it is also a sacrifice in essence...  One person said it wouldn't diffuse any more than shooting through diffusion material...  Well yes and no...  And here's the whole crux...  not all diffusion material is created equal...  You can utilize thicker diffusion material which will disperse the light even more making it appear softer, or double/triple/quadruple the diffusion to make it softer and softer...  BUT, as we all know it means we lose more light power and affect, meaning the light would have to be closer to the subject to get the same amount of light.  Now here's also another tactic, the closer the light, the softer the light... The farther the light, the harder the light... so this may very well have really thick diffusion on the "softbox" softening the light, requiring you to shoot closer, more power, and thus softening the light even more.  NOW, dont get me wrong, i'm not saying it will be an attractive light.  As professional and amateur photographers, we are conditioned that bigger the light source, in relation to the subject, the better, whereas this MAY be a small soft light-sourse close to the subject...  So it just wont have the same effect that a 16x20 or bigger softbox can produce... it physically cant.  For run and gun, grip and grins event style photographers, i can see how this MAY grab someones attention...  So i wont say this is a complete design fail... I wont even say that this is a flawed product... but if they can improve upon this in future releases (and hopefully bring down costs to a more palatable level, then maybe the inventor may be on to something)...

Don't agree, just like sensors size trumps all. Look at some of the pro modifiers now, they are 7' and bigger, why? Because size invariably trumps being closer.

A good rule of thumb with modifiers is to take their size as the optimal distance from the subject, 20" modifier 20" from the subject, 50" modifier 50" from the subject, scale that down to this useless snake oil and you need to be 3" or 4" from the subject, and if the subject is more than 3" or 4" wide you are going to get big falloff issues.

I think your confusion the quality of the light vs the softness/effect of the light...  I'm not arguing that a bigger modifier will give a better quality of light and better affect...  I am just saying it's possible with heavy diffusion to soften the light, although the quality and usefulness of the light will be in question.


Having heavy diffusion will only reduce the light intensity unless the effective lighting surface is also increased.
For example, try covering the speedlite with tightly wrapped layers of white cloth- you will only make it dimmer.

Now very low intensity light has an illusion of being soft, because there is little contrast between the well lit and poorly lit areas. This isn't truly soft light though. It's just poor lighting ;)

By definition, soft light avoids sharp shadows and harsh bright areas, with smooth transition between the two. The only way to do it is control the effective size of the light source. Reducing the illumination such that there are no bright areas and no shadows are created is hardly a step in the right direction.

39
Well, he's defending a relative.  And maybe he's a backer...   ::)

Neuro, FYI, you have a PM...

40
I didn't want to comment when I saw the post first simply because I didn't want to deprive the inventors of their su.. er, backers. If someone wants to throw away their money, it's their problem. Now that the project is funded, I suppose it is okay to speak up. Both this and the Magmod seem superfluous to me. This, because of reasons already stated. The magmod, because the modifier will not stay put if pushed around especially inside the bag.

The best gel solution I found so far comprises of buying the $ 8 swatchbook PBD mentioned (B&H etc.) and this item from ebay http://www.ebay.com/itm/321486178488.
It has a sticky velcro (put some Gaffer's tape over your Speedlite first if you want to remove the velcro cleanly afterwards), and a nice carrier for the gels with a pocket for storing extra gels (Lumiquest sells JUST the carrier for $ 10), and a set of gels for color effects.
Cost me $ 16 to set up a gel system for 3 Speedlites. 

41
EOS Bodies / Re: popup-flash - made a "pro feature"?
« on: August 14, 2014, 02:27:12 AM »
Now, to those who say pop-up flashes are terrible, there is a nice solution called the Lightscoop (you can Google it).

I think a key point can be drawn here. You have a solution, but having a solution by definition means having a problem (unless you're in government). The pop up flash is inherently a problem.

Oh, I agree it's a problem. I used it a handful of times when I had APS-C cameras, even when I didn't have Speedlites. The only time I used my 7D pop-up flash after that was to trigger the optical slave.
But, it is better than nothing. And the Lightscoop makes it actually usable.

42
Reviews / Re: Tony Northrup - D810 vs. 5D Mk3
« on: August 14, 2014, 02:22:58 AM »
I'm sorry to hear you had that experience. And I don't want to sound like I'm criticising you - but I do wonder if there's a logical link between the technology and practitioners' professionalism.

I have no experience of film photography beyond point-and-shoot family/holiday snapshots from my younger days, so maybe I'm missing a lot. But I don't think good quality digital photography is easy, nor can it be mastered (especially with a DSLR) in minutes. There are cowboys in every field - and I suspect there always have been. And it seems that most of what makes wedding photography challenging is beyond the camera - it's about scouting the location, talking to the clients and understanding their needs, getting to the venue on time, having backup equipment/assistants, and producing a package (nowadays likely in book form) that merits the occasion (thinking about it, I suppose most types of photography rely on a lot more than the camera and strict photographic technique, but anyway). Given how much people spend on weddings, and wedding photographers these days, surely (at the better end) things have improved? Maybe it's an unfair comparison, but my grandparents' expectations were very limited (they were only allowed 6 shots due to rationing, and they were just snaps, nothing fancy) - whereas a recent friend's wedding involved (after much research on the best photographer for their needs) a separate shoot on location, video, a glossy hardback book, etc.

Why would shooting on film make someone more professional? Were film cameras much more expensive? I suppose proper photographers would have a darkroom, but if you were slapdash in those days, maybe you'd get someone else to do it?

Just lots of questions arise when people compare the pre-digital era with today, I hope you don't mind :)


Not at all, I was probably not clear. I have nothing against technology, and more than half of my photography experience happened after the digital era. So I know very little of pre-digital era to be able to compare. All I am saying is that the low barrier to entry into professional photography hurts both the real pros as well as the consumers. Why does digital allow a lower barrier to entry? At least 2 reasons:

1. Availability of preview- my photographer often snapped multiple images with the same setting. It's cheap with digital to shoot multiple shots, and preview allows you to fix mistakes. A film photographer who has to give something to the clients at the end of the job, will have to know what settings work or else he might have a completely useless roll.

2. Option of multiple ISOs and post processing- can you imagine a photographer with little or no idea of lighting (as mine was, sadly) walk in with a roll of film and be confident that it will work?

As you said- good quality digital photography isn't easy. Good photography will demand the same hard work and talent but produce far better results in the digital age. However, anybody with a dSLR can now start a business and charge pennies to attract customers. Without the tools above, someone would need at least a minimal training to use film SLRs. Along the way, he would hopefully learn something about composition, the necessary shots, the necessary people who you need to take pictures of.

The solution, of course, is for the customers to be more careful of whom they hire.

43
Thanks for the information. BTW, the Clutch looks awesome. I am getting it when it's out.
There still may be time to get the discounted price as it's in the last couple of days of the Kickstarter process.
If you miss that, 1KindPhoto http://www.1kindphotography.com/2014/01/deal-peak-design-bundles-save-up-to-15-plus-additional-10-off.html has a discount code for Peak Design.
coupon code: 1kindphoto

-pw

I did get it through Kickstarter.

The Slide, though, has a few shortcomings as far as I am concerned. I agree it will be less dangly than the Blackrapid (although I use a set of Optech uni-loops to secure the camera, which makes it dangle less), but the sliding strap will make it difficult to use with a backpack over or under it. The sliding carabiner of the Blackrapids just work. A pity that they can't innovate with the connection with the camera.

Mind you, I will not be surprised of PD is bought out by BR, giving us a great all-in-one solution :)

44
EOS Bodies / Re: popup-flash - made a "pro feature"?
« on: August 13, 2014, 04:14:26 PM »
I sincerely can't accept the reasoning of those who want 'no pop up flash' as opposed to merely not wanting them.

The weather-sealing is a total marketing BS. The D810, which is 'heavily weather-sealed' has a pop-up flash. As it is, the 5DIII isn't as weather sealed as the 1D cameras, and the 6D is sealed even less.

The rigidity issue is also hard to swallow. They could just use stronger materials.

As Neuro said, it is all about marketing and selling shoe-mount flashes.

Now, to those who say pop-up flashes are terrible, there is a nice solution called the Lightscoop (you can Google it). I got it for free with my 600EX (imagine the irony, as this thing only works with pop-up flashes), but tested it with a friend's camera. Here are the results- the room was completely dark, about 12' x 12' with 9' ceiling, and the flash was the only source of light.

45
Both the Cinch 2 and the Peak design straps are great, i.e., they prevent the swing problem of the tripod-mounted straps, but they don't provide a solution to mounting directly to the lens satisfactorily when I use my 70-200.
I wonder, how safe is it to carry the 70-200 2.8 mounted to your camera with the camera connected to the strap as the ads show? I mean, the lens is at least twice the weight of the camera!
My solution for that is to attach a Peak Design Anchor to the QR plate on the lens shoe. This not only distributes the weight of the heavy 70-200, but creates a nice balance when it's at your side. I put anchors everywhere, on the two original neckstrap points, the point on the bottom plate and with heavy lenses like the 70-200, on the QR plate. The Anchor does not get in the way when mounting onto a monopod or tripod.

Anyone buying Peak Design straps, I'd suggest ticking the box for a couple of extra packs of Anchors... they're less than $10 per pack.

-pw

Thanks for the information. BTW, the Clutch looks awesome. I am getting it when it's out.

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