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08-14-2015, 02:48 AM   #1
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APS-C lenses

Using aps-c lenses on full frame will reduce the amount of megapixel, but in how far will dynamic range be affected as well?

08-14-2015, 03:08 AM   #2
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That's a property of the sensor, Dili.
08-14-2015, 03:27 AM   #3
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Hey, welcome!
QuoteOriginally posted by dili Quote
Using aps-c lenses on full frame will reduce the amount of megapixel, but in how far will dynamic range be affected as well?
I am not sure what you are talking about.

Total megapixels of the sensor will not be changed. But there is a chance that APSC lens will not cover the edges of the sensor. So you might have to crop the frame to APSC (or slightly bigger). But this doesn't mean the lens loses MP, its resolution does not change. Most lenses will still outresolve the FF camera or an APSC camera. And many DA lenses actually cover the FF normally, so you don't lose anything: https://www.pentaxforums.com/forums/54-pentax-lens-articles/31629-da-lenses-f...ts-thread.html
Actually rather few K-mount lenses are truly only for APSC.

QuoteOriginally posted by dili Quote
but in how far will dynamic range be affected as well?
Not at all. Why would this be affected? The lens will project the same colours and contrasts and brightness regardless of the camera it is mounted on. What happens after that depends completely on the camera. Generally speaking, newer cameras have better DR than older ones.. And higher end, more expensive cameras, have better DR than cheaper ones. So we can expect the Pentax FF to be quite good in that department, probably better than the K-5IIs.
But as stated, the total recorded DR depends on the sensor and camera technology. The lens itself of course has an effect on the image, but it is independent of the camera and will not change if you put it on a different sensor.

Just keep in mind the lens and sensor are two independent things. They only come together because the output of the lens is the input of the camera. And if the camera's sensor is bigger than the lens' projected image circle, the edges of the frame will be dark or low quality. But that is rarely a problem.
08-14-2015, 06:20 AM   #4
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QuoteOriginally posted by Na Horuk Quote
Total megapixels of the sensor will not be changed. But there is a chance that APSC lens will not cover the edges of the sensor. So you might have to crop the frame to APSC (or slightly bigger). But this doesn't mean the lens loses MP, its resolution does not change.
Don't Nikon Fx bodies have a Dx mode which basically crops the full-frame image to APS-C? I think that's what you're talking about, OP, but we don't know if Pentax has anything like that, as the FF body is not here yet. But as Na Horuk mentioned, most "DA" lenses actually cover FF, so I doubt that would be an available "feature."

08-14-2015, 06:27 AM   #5
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A few of the DA primes works well without vignetting (DA 35, 55, 200 and 300) on 24x36 format, but the only DA zoom that seems to work is the DA 60-250...
08-14-2015, 06:41 AM   #6
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QuoteOriginally posted by lavascript Quote
Don't Nikon Fx bodies have a Dx mode which basically crops the full-frame image to APS-C? I think that's what you're talking about, OP, but we don't know if Pentax has anything like that, as the FF body is not here yet. But as Na Horuk mentioned, most "DA" lenses actually cover FF, so I doubt that would be an available "feature."
In the pre-release announcements, the APS-C crop mode was mentioned as a feature of the FF. Makes sense for Pentax who have a large selection of APS lenses and until now haven't had a FF body.
08-14-2015, 06:43 AM   #7
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QuoteOriginally posted by MikePerham Quote
In the pre-release announcements, the APS-C crop mode was mentioned as a feature of the FF. Makes sense for Pentax who have a large selection of APS lenses and until now haven't had a FF body.
Ah, good to know! I haven't been following.
08-14-2015, 07:07 AM   #8
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The question will be, will the crop come from lens info read an interpreted by the camera? Probably yes, can you over ride an auto crop? We will see. And, will it have a different auto crop dependent on the lens used? More difficult, but doable I would think.

08-14-2015, 08:11 AM   #9
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QuoteOriginally posted by dili Quote
Using aps-c lenses on full frame will reduce the amount of megapixel, but in how far will dynamic range be affected as well?
Megapixels and dynamic range are both properties of the sensor not the lens. As noted above IF a crop mode is implemented and made mandatory then some reduction in MP is to be expected. Without a crop mode the MP stays the same but the lens may not cover the FF image circle so the edges may be poor or even black. Dynamic range would not be affected regardless.
08-14-2015, 09:44 AM   #10
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QuoteOriginally posted by ramseybuckeye Quote
More difficult, but doable I would think.
Yeah, but this would bring in so much confusion. A zoom lens might no longer have a linear zoom progression lol
I agree, though. Camera should have a) auto-crop to APSC based on lens ID, b) always FF, c) always crop, and d) auto-crop based on lens ID to biggest size lens' image circle allows (APSC, APSH, whatever). Two automatic, two overrides. Bonus points if you can choose raw+, where raw would use one option and the jpeg another option. But so many options can get confusing for many users, so Pentax might simplify things
08-14-2015, 11:38 AM   #11
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With Sony, you can autocrop according to lens ID or no crop at all. One of either Canon or Nikon (can't remember) offers two crop sizes.
08-18-2015, 08:07 AM   #12
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QuoteOriginally posted by dili Quote
Using aps-c lenses on full frame will reduce the amount of megapixel,
It probably will based on some pixels not being used to form the image (when compared to a full frame lens of the same focal length), but we'll have to wait and see. Depending on the pixel density across the sensor, the absolute number of pixels used to form the image from an APS-C lens may not change at all from the K-3.
08-18-2015, 08:27 AM   #13
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I think it would be smart for Pentax/Ricoh to adopt the approach in 2 ways as in Sony or Nikon FF models, crop according to lens ID or ignore that (ie. no cropping). This would make sense, say, if you mount a Pentax lens it would be cropped accordingly unless you turn it off. And if you mount a third party lens (ie. Sigma or Tamron) it would not be cropped.
08-18-2015, 09:27 AM   #14
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QuoteOriginally posted by aleonx3 Quote
And if you mount a third party lens (ie. Sigma or Tamron) it would not be cropped.
Better then to have three options - auto, forced, or none. If we find that legacy glass is indeed "not up to the rigors of the full-frame sensor" as some doom-prophets are saying, it would be nice to force a devolution back into APS-C mode and continue to enjoy the sweet spot, as well as being able to use third-party lenses that for whatever reason can't tell the camera to crop.
08-18-2015, 02:20 PM   #15
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Yes, DR is affected by cropping

QuoteOriginally posted by jatrax Quote
Megapixels and dynamic range are both properties of the sensor not the lens. As noted above IF a crop mode is implemented and made mandatory then some reduction in MP is to be expected. Without a crop mode the MP stays the same but the lens may not cover the FF image circle so the edges may be poor or even black. Dynamic range would not be affected regardless.
DR is affected, as is noise when you crop and enlarge the crop to the same display dimensions.

In the case of the D800 (FF), aps-c 'crop mode' gives almost the exact same image the D7000 (aps-c) would natively using the same lens - in noise, DR, FOV, DOF.

As others have pointed out there are a lot of DA lenses that do or *almost* cover the FF image circle, so hopefully Pentax will offer a selectable crop amount - like 2:3 aspect ratio, square, or something like 1.2x crop (in addition to 1.5x, which is aps-c.)

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