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Help understanding sensors & FF

Discussion in 'Sony Alpha E-Mount Cameras' started by pworden, Feb 17, 2014.

  1. pworden

    pworden TalkEmount Veteran

    325
    Aug 26, 2013
    State College, PA
    Patti
    Great reading about the A6000 here. I'm still thinking about a second camera for macro. Last summer I asked about the NEX 7 vs my 6 specifically regarding possible detail for macro and came away thinking that there wouldn't be enough of a difference between results from the two due to other features in the cameras and how the data was processed. I'm happy with most of my macro results; and I know I can do better with what I already have. That said, now we have the A7 and soon the A6000, both with 24.3 sensors (A7R is not possible for me and I guess not the choice for moving insects anyway). So I have a real basic question -
    since the maximum still shot size from both cameras is 20 megs and they use the same processor, the resulting resolution would be basically the same, right?
    If an insect, for instance, is shot so that it fills the frame on the A6000's 24.3 sensor and again on the FF A7 with its 24.3 sensor and a FF lens, is the possible detail result the same in theory, not counting differences in lenses? My two legacy macro lenses are of course full frame, but I like not worrying about distortion on the outside edges of those lenses. I'm generally satisfied with APS-C, just wondering if noticeably more detail is likely with either of these cameras and then, if the FF is a factor at all strictly regarding detail. I realize we'll get some great detail comparison shots once the A6000 is released, but I'd like to know if I'm thinking correctly about this or if I'm missing something obvious to most of you! Thanks everyone!
     
  2. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    Again, CPU does NOT affect RAW image quality. As APS-C sensors are smaller, you can get closer with a 1:1 macro lens than on ff, so a shot at 1:1 magnification with equal sensor resolution would contain much more detail when shot with an APS-C sensor camera than with an ff camera.

    If you want better quality, invest in lenses, not bodies. The Touit 2.8/50M is here in a few weeks and will be the first serious E-Mount macro lens. Other good macro lenses include the Zeiss Makro-Planar 2/100 or some of the longer Canon L macro lenses which all can be adapted quite easily.
     
  3. pworden

    pworden TalkEmount Veteran

    325
    Aug 26, 2013
    State College, PA
    Patti
    Good to know, and I'm looking forward to your opinion of the Touit. Thanks!
     
  4. jai

    jai TalkEmount Top Veteran

    589
    Feb 4, 2013
    Another thing you may want to consider, the A7 will have a shallower depth of field at an equivalent focal length.

    That's probably not a good thing for macro?
     
  5. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    Depth of field is the same among all sensor formats for equivalent terms (aperture and magnification).
     
  6. MAubrey

    MAubrey TalkEmount Top Veteran

    What it comes down to is the quality of your lenses. We often see lens resolution measured in lines per millimeters. A good lens is going to still be sharper on FF simple because the FF sensor has more millimeters to resolve detail. Neither 24MP sensor is going to truly resolve all 24MP, but the FF sensor is going to get closer to it.
     
  7. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    Rather the opposite is true. When using a smaller sensor with equal resolution, the pixel density is higher, i.e. the pixels are smaller and more of them fit on a mm of the sensor, so a lens of similar quality will always perform better on a smaller sensor with similar resolution when only measuring line pairs per mm.
     
  8. Bugleone

    Bugleone TalkEmount Veteran

    210
    Aug 21, 2011
    Interesting......

    ....So, why would anyone spend TWICE the price buying A7 to get less image quality?........presumably A7 is just a 'toy for the moneyed'......

    I have to say that my experience has been that a big chunk of film ALWAYS beats a smaller chunk of film when it comes to the quality of the image.........I can't see why digital sensors should be any different since not all pixells are born equal and image quality is not just resolution.
     
  9. José De Bardi

    José De Bardi Assistant in Virtue

    Aug 31, 2013
    Dorset, UK
    José
    There are MANY pros/cons to APS-C vs FF...

    Decent overview here... http://www.graphic-fusion.com/fullframe.htm
     
    • Like Like x 2
  10. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    You can not compare film to current technology at all (including sensors, lenses and microlenses).

    Of course image quality is not just resolution, but for color depth and dynamic range, sensor technology is much more important than sensor size. There might be a small advantage of some ff sensors over some APS-C sensors, but vice versa, the same is true on the other side when comparing different sensors.

    So where is ff actually better? High ISO. They are one to two stops better there. While you could, in theory, compensate for that by building lenses which are one stop faster for APS-C sensors with equal size, weight and price than the one stop slower equivalents for ff sensors, it's very hard to build ultra fast lenses. So there is a distinct advantage when using something like a f/1.4 lens wide open at high ISO on a ff camera over APS-C sensor cameras. At all other areas, there is not a difference big enough to justify twice the price. Of course you can buy a 36MP ff camera now while you can't buy a 36MP APS-C camera currently, but they'll come in the near future.

    As for resolution: You usually get a little bit better resolution overall (not per mm) on the ff sensor when using the same lens across a ff and an APS-C sensor with equal resolution. But that's exactly the point of building expensive lenses optimized for APS-C sensors like the Touit line - there's so much less glass needed to build them, so for the same retail price, higher quality glass can be used to achieve resolutions similar to ff cameras.

    Edit: @Josè: Thanks for the link, many valid points there. He still claims the rumor of more MP means more noise is true (which it is not when viewed at the same magnification), the depth of field part is only correct when not assuming equivalent final images and the section for APS-C sensor optimized lenses is outdated since now high quality Fuji and Zeiss lenses are available which are optimized for them, but all in all a very nice guide to get an overview of the whole APS-C vs ff debate.
     
  11. Austrokiwi

    Austrokiwi TalkEmount Regular

    63
    Feb 2, 2014
    22nd District Vienna
    Ian Fenn
    Interesting read. I actually purchased the A&r because of macro....but not for the image size. What attracted me was the lack of an anti aliasing filter. I use legacy macro lenses on the A7r and am happy with the results. For insects using APS-C a 50mm is probably going to work (because its going to perform like a 100mm on FF).....but if your camera is FF then a macro lens in the range of 150 to 200 mm might be more workable( I believe this is reinforcing the comments already made).
     
    • Like Like x 1
  12. WoodWorks

    WoodWorks Super Moderator

    Dec 12, 2012
    Ashland, OR, USA
    David
    A 50mm lens on a FF camera will actually perform like a 75mm on an APS-C camera. It'll be 100mm on a µ4/3 camera.
     
  13. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    Exactly - if you already have lenses that cover the full ff circle, there is no real reason not to buy a ff camera. But vice versa, if you already invested heavily in APS-C glass, no reason to jump ship just because of a bigger sensor. As for macro lenses - it really depends on what you want to shoot. For many macro subjects, shorter macro lenses are more practical. For insects, of course, the longer, the better. That said, I've seen some awesome insect macros shot with 50mm lenses on ff.
     
  14. pworden

    pworden TalkEmount Veteran

    325
    Aug 26, 2013
    State College, PA
    Patti
    I've read this with interest in all the comments. I hadn't considered lens resolution. However, I know that this is true: Physical size increases, resolution decreases. Still thinking back to my original understanding, that one little bug fitting edge-to-edge on either sensor size would effectively result in similar detail, since the pixels would get bigger (resolution decrease) on the APS-C image as soon as it was enlarged to the same physical size as the FF image. It's an interesting subject, and that last link and posts address it very well. The initial question came from comparing this subject to the effect of IQ when resizing images for printing. Without interpolation, enlarging always results in lower resolution. Great responses; really informative.
     
  15. pworden

    pworden TalkEmount Veteran

    325
    Aug 26, 2013
    State College, PA
    Patti
    I'd like to see some of your macros with this setup. I have to get through winter before trying again; wall-to-wall snow right now.
     
  16. jai

    jai TalkEmount Top Veteran

    589
    Feb 4, 2013
    If you are trying to take a photo with the same composition, a full frame photo definitely does have a shallower depth of field than APSC taken with the same aperture value. That's the issue.

    So if you are limited to F8 or wider to get a shutter speed that is fast enough, less of your little bug will be in focus.

    I am not sure why you are saying depth of field is the same in equivalent terms. Does that mean the "equivalent" aperture is different from FF to APSC?
     
  17. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    Let me explain: When shooting at "equivalent" terms, you need to stop down the ff camera by one stop (and eventually increase ISO to compensate) to get the same depth of field as on APS-C sensors. As the diffraction limit is also "reached" about one stop later on ff sensors, you'll get the same working depth of field range at the same maximum resolution. This makes the difference between ff and APS-C sensors in macro work negligible, and ff sensors don't have any disadvantage there.
     
  18. jai

    jai TalkEmount Top Veteran

    589
    Feb 4, 2013
    I see.

    I had only ever heard "ff equivalent" used to describe equivalent focal lengths.

    Another question, slightly off topic but it sounds like you will know Poki. If I use a speed booster and a 50mm lens on an APSC camera (and "gain" a stop), does that then have the same depth of field as a 50mm on Full Frame?
     
  19. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    There is an equivalence for everything in terms of camera sensors. ;)

    If you mount a 50mm f/2 lens with a speed booster on an APS-C camera, you'll get a 33,33mm f/1.4 APS-C lens, or differently put, a 50mm f/2 equivalent lens. This not only gives you the same depth of field as when using the lens on a ff camera, but also equivalent low light capabilities due to the lens being "faster" on the APS-C sensor.

    If that's a definitive solution or not, that I'm not sure. Honestly never looked too deep into the different speed boosters offered today, and I don't know nothing about possible quality drops because of the optics used in them.
     
  20. jai

    jai TalkEmount Top Veteran

    589
    Feb 4, 2013
    I have a speed booster I use with Minolta glass.

    I find the quality actually increases when compared to using a dumb adaptor, especially in terms of contrast. Which is apparently what the lens designer predicted.

    It's real heavy though! So you don't get something for nothing. A 50mm F1.4 rokkor with a speed booster is probably equivalent in size and weight to a lens designed for APSC that was F1.0. A lot of glass.