October 01, 2014, 09:08:43 AM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - ecka

Pages: 1 2 [3] 4 5 ... 44
31
Here is a way of calculating the effective extra reach or resolving power of a crop body versus FF, which will amuse the geeks among us...

MTF is not a measure of resolution, it is a measure of a lenses ability to transmit contrast of the original scene through a lens.  That's all it measures.

If what you really want is true image resolution, then there are two correct ways of measuring it.  The first is a measurement of the performance of the lens itself.  This measurement can be found in using something like a USAF resolution test chart and a microscope to perform aerial inspections of the image of the chart after it has passed through the lens.

Problems with this approach include difficultly in setting up a test bench (it's not easy at all).  Additionally, the final result will not include measurements of chromatic aberrations, image distortions, field curvature, etc.  The most important missing element in this kind of test is the exclusion of the imaging system itself.  However, if the question is about real optical resolution, this test will give you the right answer.

Which leads to the second way of measuring, well, actually calculating real image resolution.  This is diagnostic and very simple to perform.  Simply take the number of image points ("pixels") in your file, divide by the size of your sensor (in millimeters), and divide by two.  This number will represent the number of Line Pair per Millimeter (the measure of the ability to go from one white line to one black line) that your sensor can resolve.

This is rather interesting in that you can quickly see that a Canon 7D 18 mpixel sensor is capable of resolving 116 line pair per mm.  The Canon 5D MkII is capable of 78 lppmm.  As a comparison, Sony's 36mpixel FF sensor is capable of resolving 102 lppmm and Phase One's monster 80mpixel IQ180 returns 97lppmm.

Taking this a step further, look carefully at the physical limits (as in optical physics) of optical resolution, as measured in lppmm.  You see that at f/2, an optically correct lens will return 695lppmm in the center of the scene where the light's wavelength is 589.3mu (green).  At f/11, an optically correct lens will return 123lppmm, dropping off to 92lppmm at 25 degrees off-axis tangential.

Looking at this over the years, I have come to realize there is seldom a lens in-capable of resolving so poorly that a sensor (or old film for that matter) could out-resolve the lens.  Sure, there are other optical effects, but we are talking pure resolution here.  Nothing more.

Think about this for a moment.  MTF does _not_ measure optical resolution.  While useful, it does _not_ tell the story of resolution, no matter how much "math" you throw at it.  Secondly, and perhaps most interestingly, optical physics show diffraction limited resolution at f/11 EXCEEDS currently manufactured sensors ability to return that resolution in all cases. 

Rather shocking, don't you think?

Back to the original poster's point: Canon's 7D sensor outresolves (using the correct application of the word "resolution") the FF sensors from any manufacturer.  It does so, however, for reasons other than those that were brought up.

Correct application of rational thought and real world science can help us properly understand and identify the errors and misleading comments widely published by marketeers and critics of optical imaging systems.

You see, if Canon had made a FF camera with 7D's pixel density, then there wouldn't be any questions - FF wins, period.
Nikon did that with their D7000/D7100 vs D800/D810. You crop FF and you get almost exactly what the pre-cropped D7000/D7100 produce. In fact, you can just shoot in DX mode on D800...
So there is no global question about crop winning anything vs FF other than price.
The question is why Canon didn't make that 46mp FF camera?
Was it because consumers didn't ask for it? - Maybe.
Why didn't they ask for it? - Because they are too ignorant in How-It-Works department. They are affected by this ... More_Pixels=More_noise=Bigger_Files=My_Old_iBox_Can't_Handle_it=Crop_Is_Just_As_Good_It's_Just_Magically_Different_Because_Size_Doesn't_Matter=I_Better_Buy_An_Overkill_Lens_For_My_Crop_And_Not_Use_The_Rest_60%_Of_It=I_Don't_Need_That_Much_Pixels_But_Digital_Zoom_Is_Bad#!@ERROR*2&$ERROR...System_Reset~Hello_Micro_Four_Thirds=Must_Buy_35-100/2.8_Because_It_Is_70-200/2.8 ... virus :).

32
EOS Bodies / Re: Mirrorless vs DSLR Camera
« on: August 29, 2014, 09:09:37 AM »
I like both. Mirrorless has a big future. Once the AF gets up to speed and the EVF evolves sufficiently, what else has to happen? Based on the game-changing specs & performance & gob-smacked reviews of the mirrorless Panasonic GH-4 I bought one for my video work where it tidily beats the pants off my 5D3 in all situations with the exception of high iso shooting (over 1600 iso).

After using the GH-4 for a couple of months I'm discovering the sheer brilliance of it's very decent EVF and surprisingly good AF; much much quicker and accurate than I initially expected. Now that Adobe DNG converter v8.6 and Lightroom v5.6 can see the GH-4 RAW files, I've even been using it for stills on some commercial jobs.

Mirrorless is evolving fast. It's great to use. I'd hate to see favourite mainstream manufacturers (cough, cough..) being caught flat footed as this revolution gains pace.

-pw

GH4 is a brilliant tool for video. Have you tried the Sigma 18-35/1.8 via SpeedBooster on it? Some say it helps to overcome the high ISO disadvantage very effectively.

33
Lenses / Re: Help deciding on going full frame
« on: August 27, 2014, 01:40:33 PM »
With full frame costing less than $1,500 now (used or on sale), I can't think of any reason to stay on crop unless your budget is under $1,000.

Even if your budget is under $1000, a used 5D Classic goes for around $500 and is a much better option than pretty much any crop camera in that $500-1000 range in my opinion.

I'm not sure about the $500 5D, but no crop can beat 40/2.8STM on FF :).

34
Lenses / Re: A New Pancake Lens? [CR1]
« on: August 27, 2014, 12:47:07 PM »
I really am not concerned with how a camera looks, but the A7 just makes the 6D look like 1990's aesthetic.

Really? Isn't the A7 looking more retro?... from seventies :)

35
Lenses / Re: A New Pancake Lens? [CR1]
« on: August 27, 2014, 12:41:16 PM »
I'd like to see them also come out with a 30mm f2.8 Pancake. Great "near 50mm" equivalent for crop frames.  Would still expect it to be EF rather than EF-S--just have a slightly different utility on crop vs. full. :)

Yeap, nice 50/4.5 equivalent for crop frames :). There is really not much of size or price reduction in APS-C realm.

36
Third Party Manufacturers / Re: Samyang Teases New Lenses
« on: August 27, 2014, 12:02:45 PM »
There is no such thing as a "macro" if its below 1:1 ;)   Shame on Zeiss.

1:1 ratio is a subjective value. You get more magnification with 1:1 macro on crop, than with 1:1 macro on FF.
Something like A7R (36mp sensor) allows you to crop a lot and get the same magnification of a 16mp crop sensor. So, technically, 1:2 macro on 20mp crop provides similar magnification to 1:1 macro on 12mp FF.

1:1 has nothing to do with megapixels; it is entirely governed by optics and means the physical size of the projected image equals that of the subject, ie a 1cm tall object results in a 1cm tall projected image.

Due to the cropping factor of an aps-c sensor though, you are effectively blowing up the projected image. So this means that for a crop factor of 1.5, a 50 mm lens will become 75 mm equivalent, and at 1:2 magnification becomes 3/4 magnification.

Well, lens magnification has nothing to do with megapixels, but the amount of information you get from it depends on the number of pixels you put on each millimeter of the projection. I may be using wrong terminology here, I'm sorry for my bad english. IMHO, on different sensor sizes (FF, APSC, m4/3) 1:1 ratio has different values, as well as with different resolutions of the same sensor size, because, when it comes to the final (real macro) image, everything matters. At those magnifications I mostly care about the information I can capture with the final image in mind (on big display or print), not how big it looks on my camera LCD or in a smartphone snapshot gallery.

37
Third Party Manufacturers / Re: Samyang Teases New Lenses
« on: August 27, 2014, 09:52:55 AM »
There is no such thing as a "macro" if its below 1:1 ;)   Shame on Zeiss.

1:1 ratio is a subjective value. You get more magnification with 1:1 macro on crop, than with 1:1 macro on FF.
Something like A7R (36mp sensor) allows you to crop a lot and get the same magnification of a 16mp crop sensor. So, technically, 1:2 macro on 20mp crop provides similar magnification to 1:1 macro on 12mp FF.

38
Lenses / Re: A New Pancake Lens? [CR1]
« on: August 24, 2014, 11:03:28 AM »
I would love to have 20mm pancake on FF
I think we'd like a 20mm prime of any sort in FF.  Canon hasn't made a new once since 1992.
yeah a nice 20-21mm prime would be sweet - 21mm IS USM
pancakes at with canon's registration distance at 20mm? would have alot of compromises.
the Voigtländer 20mm 3.5 skopar is a good example. vignettes like hell, and blows the snot out at the corners.  it makes the 17-40 look good in the corners.
Not sure i would like that versus just having a regular 21mm as sharp as the other current 24,28,35 IS USM lenses - especially for under 1k.
unless this is an EF-S lens and if so, why 24mm? the same as 40mm on full frame perhaps?
for EF-S .. a more likely and needed lens would be a 30mm 1.8 EF-S IS STM  (IMO - but that's what everyone in the EF-S world usually complains about not having)
Canon 30mm F1.8 IS STM ... It would be a dream lens for me. ::) :-*

Not much different from EF 35/2 IS USM, is it? :)

39
Lenses / Re: A New Pancake Lens? [CR1]
« on: August 23, 2014, 07:11:37 PM »
I would love to have 20mm pancake on FF

I think we'd like a 20mm prime of any sort in FF.  Canon hasn't made a new once since 1992.

- A

True, I went for the Sigma, which for all the bad press still is a great and fun lens to have in my kit.

A reasonably priced ($200-$300) EF 20mm STM pancake would be nice.

40
Third Party Manufacturers / Re: Samyang Teases New Lenses
« on: August 23, 2014, 06:37:34 PM »
I'm not sure, 50mm is kind of a standard do-it-all prime, and I would like it to have AF :). My 40mm pancake with some extension tubes can do macro as well. The 1:2 mag. would require a tube too, but its working distance is unusable for hunting insects. The AF 50/2 Macro would be great though, I would trade my 40 for that.


EDIT: I know some people have like 8 different 50(ish)mm lenses in their bags for whatever reason :). I'm not that guy.

For some an F/2 50mm that can do good but not fully macro is a multi use lens, I own the Zeiss partly because it allowed to me replace a standard 50mm AND a stanardish macro. Price there though is probably an issue for a lot of people, I managed to get the Zeiss fairly cheap used but no way would I pay full wack for it.

And by cheap you mean $1000 (give or take) ? :)
I'm sure that Makro-Planar 50/2 is a nice lens (and possibly a dream lens for videography :) ), but, like you, I really can't justify buying $1300 manual focus lens, which won't even be my primary tool for macro. Zeiss Makro-Planar 100/2 is $600 more and still needs a tube for 1:1 macro. I doubt that anything can beat my Sigma 150/2.8 at the moment.

It was £450 used for an original zf version(I moved to the darkside for FF a couple of years ago) and as you say I couldnt afford to pay full price. Definitely not a lens for serious insect macro but generally I tend to shoot plants/fungi more in the closeup range so 1:2 is good enough for me and its both sharper, contrastier and has much better bokeh than my old Nikon 50mm 1.8 G.

I wonder whether Canon will ever upgrade the old 50mm 2.5 macro? a 50mm f/2 IS with 1:2 macro with Zeiss like performance would likely be popular.

EF 50/2.5 Macro has very decent optics. They could only update it with STM motor and leave the old price tag really ($299) :). 50/2 IS USM Macro would cost more than 35/2 IS, maybe $100-$150 less than the 100L Macro ($899?).

P.S.: The EF-S 60/2.8 USM Macro with extension tube works on FF too. Just saying :)

41
Lenses / Re: A New Pancake Lens? [CR1]
« on: August 23, 2014, 10:42:24 AM »
The 44mm flange distance makes a non retrofocus (ie pancake) 24mm EF or EF-S lens unlikely.

Really? 'Pancake' does not have to preclude 'retrofocus'.





http://www.voigtlaender.de/cms/voigtlaender/voigtlaender_cms.nsf/id/pa_fdih8vxb7z.html

Well, proportionally, FD 50mm f/0.95 is a pancake too :D


42
Third Party Manufacturers / Re: Samyang Teases New Lenses
« on: August 22, 2014, 05:07:45 PM »
I'm not sure, 50mm is kind of a standard do-it-all prime, and I would like it to have AF :). My 40mm pancake with some extension tubes can do macro as well. The 1:2 mag. would require a tube too, but its working distance is unusable for hunting insects. The AF 50/2 Macro would be great though, I would trade my 40 for that.


EDIT: I know some people have like 8 different 50(ish)mm lenses in their bags for whatever reason :). I'm not that guy.

For some an F/2 50mm that can do good but not fully macro is a multi use lens, I own the Zeiss partly because it allowed to me replace a standard 50mm AND a stanardish macro. Price there though is probably an issue for a lot of people, I managed to get the Zeiss fairly cheap used but no way would I pay full wack for it.

And by cheap you mean $1000 (give or take) ? :)
I'm sure that Makro-Planar 50/2 is a nice lens (and possibly a dream lens for videography :) ), but, like you, I really can't justify buying $1300 manual focus lens, which won't even be my primary tool for macro. Zeiss Makro-Planar 100/2 is $600 more and still needs a tube for 1:1 macro. I doubt that anything can beat my Sigma 150/2.8 at the moment.

43
Third Party Manufacturers / Re: Samyang Teases New Lenses
« on: August 21, 2014, 06:53:19 PM »
Quote
That's because they are VDSLR lenses and therefore made so you can pull the aperture as well as the focus.

I don't speak about the aperture-ring, of course they have one. I just speak about composing the picture at the full open aperture, but the aperture is closing automatically on taking the shot. This is controlled electronically with a chip in the lens.

And they're not all VDSLR-Lenses, mostly exist two variants... for exaple one for still cameras (35mm f1.4) and the video one (35mm t1.5)

Actually Samyang did update their 35/1.4 with electronic aperture (the Canon AE version). Let's hope that all the new lenses will come with AE by default.

44
Third Party Manufacturers / Re: Samyang Teases New Lenses
« on: August 21, 2014, 04:59:37 PM »
What Samyang should really do is designing a nice MACRO LENS or two (like 100mm and 200mm). Good manual focus ring works beautifully for macro photography and there is little need for AF, if at all.

Maybe the 50mm will be a semi macro as well? Zeiss's 50mm and 100mm f/2 2:1 macros don't really have much competision besides the Tamron 60mm f/2.

I'm not sure, 50mm is kind of a standard do-it-all prime, and I would like it to have AF :). My 40mm pancake with some extension tubes can do macro as well. The 1:2 mag. would require a tube too, but its working distance is unusable for hunting insects. The AF 50/2 Macro would be great though, I would trade my 40 for that.


EDIT: I know some people have like 8 different 50(ish)mm lenses in their bags for whatever reason :). I'm not that guy.

45
Third Party Manufacturers / Re: Samyang Teases New Lenses
« on: August 21, 2014, 11:11:16 AM »
What Samyang should really do is designing a nice MACRO LENS or two (like 100mm and 200mm). Good manual focus ring works beautifully for macro photography and there is little need for AF, if at all.

Pages: 1 2 [3] 4 5 ... 44