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02-07-2015, 06:46 PM   #1
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APS-C crop on a FF camera

I know this is probably simple but for some reason I have a problem getting my brain wrapped around it.

So on APS-C we enjoy a 1.5x boost on the long end so that 300mm "looks like" 450mm. And since I've only shot APS-C recently I am used to that FOV. Now we have a FF camera coming and if we move to that the 300mm will now "look like" a 300mm again, or much shorter than I am used to.

But, if the FF camera has an APS-C crop mode that can be turned on will that make the 300mm look the same as it did on APS-C? Seems that would be the best of both worlds, use the FF 'mode' on the wide end and if you need that reach on the long end just turn on the crop mode?

Am I confused or is that how this would work? And is there any difference between using APS-C crop mode and just cropping the center out of the 36mp FF image?

02-07-2015, 06:48 PM   #2
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QuoteOriginally posted by jatrax Quote
I know this is probably simple but for some reason I have a problem getting my brain wrapped around it.

So on APS-C we enjoy a 1.5x boost on the long end so that 300mm "looks like" 450mm. And since I've only shot APS-C recently I am used to that FOV. Now we have a FF camera coming and if we move to that the 300mm will now "look like" a 300mm again, or much shorter than I am used to.

But, if the FF camera has an APS-C crop mode that can be turned on will that make the 300mm look the same as it did on APS-C? Seems that would be the best of both worlds, use the FF 'mode' on the wide end and if you need that reach on the long end just turn on the crop mode?

Am I confused or is that how this would work? And is there any difference between using APS-C crop mode and just cropping the center out of the 36mp FF image?
Boy I'm glad you asked this question because I was just about going to do that too !
Waiting for responses!
Good post!
02-07-2015, 06:50 PM   #3
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Am I the only one who is going to think the FF stuff looks really wide to me? A 300mm lens on FF will look like a 200mm lens on a normal DSLR to me.
02-07-2015, 06:55 PM   #4
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If you crop the FF picture to APS-C size you'll get the same result as if you had been shooting with an APS-C camera. So the answer is yes. If the camera doesn't provide such a crop from an FF lens you can crop in post-processing, the result is the same. But - you also lose 50% of the pixel count, i.e. you lose resolution. If the FF camera has a 24MP sensor, then your "APS-C crop" will be 12 MP. I'm not saying the the new Pentax FF will have a 24 MP sensor since I don't know, it's just an example.

02-07-2015, 06:56 PM   #5
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QuoteOriginally posted by VoiceOfReason Quote
Am I the only one who is going to think the FF stuff looks really wide to me? A 300mm lens on FF will look like a 200mm lens on a normal DSLR to me.
I'm quite sure some knowledgeable member(s) will soon come in and offer detailed explanations to our questions !
02-07-2015, 07:36 PM   #6
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Think of it this way. When you mount a FF lens on a crop camera, you lose angle of view. When you mount a crop lens on a FF camera, you lose pixels from a smaller sensor area in use.
02-07-2015, 07:50 PM - 1 Like   #7
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QuoteOriginally posted by VoiceOfReason Quote
Am I the only one who is going to think the FF stuff looks really wide to me? A 300mm lens on FF will look like a 200mm lens on a normal DSLR to me.
"Normal" is such a judgmental word…

Anyway, the two posts above have answered the OP's question. The really interesting question is not about an APS-C crop on a 35mm sensor, but whether other sub-35 crops will be allowed, like a square format that fits in an APS-C image circle.
02-07-2015, 07:58 PM   #8
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So we hear all about the "reach" of the Q. How does that relate? If you use a k-mount lens on the Q we are using a lens designed for a much larger image circle so we get a FOV that appears to be magnified, right?

How about pixel density? How does that relate?

---------- Post added 02-07-15 at 07:00 PM ----------

QuoteOriginally posted by VoiceOfReason Quote
Am I the only one who is going to think the FF stuff looks really wide to me? A 300mm lens on FF will look like a 200mm lens on a normal DSLR to me.
Yes that is what I am afraid of. Normal to me right now is APS-C, will all my glass look weird on FF? (To me of course)

02-07-2015, 08:05 PM   #9
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QuoteOriginally posted by jatrax Quote


Yes that is what I am afraid of. Normal to me right now is APS-C, will all my glass look weird on FF? (To me of course)
I know it looks strange to me on my SF1.
02-07-2015, 08:23 PM   #10
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All these years we have been struggling with the equivalent focal length going from film to APC. Now we have to struggle it the other way. How about making it nice and simple. It will look the same as it did on film! The equivalent focal length will be exactly what it says on the lens.
02-07-2015, 08:28 PM   #11
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The 1.5 crop option on a 24 megapixel FF camera is going to yield smaller file size than on an 24 megapixel APS-C camera . Far example, the 1.5 crop option drops the file size to 10.9 megapixels on a 24 megapixel Nikon D600 . This is because the pixels are larger on a FF sensor and are less dense than on an APS-C sensor.
02-07-2015, 08:28 PM   #12
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QuoteOriginally posted by jatrax Quote
And is there any difference between using APS-C crop mode and just cropping the center out of the 36mp FF image?
No, there's no difference. That's all "crop mode" will do. It'll look the same as if it was on the smaller sensor... because it's only using part of the sensor.
02-07-2015, 08:34 PM   #13
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You'd also be able to shoot that 300mm on the full 35mm frame and be pretty sloppy about your framing if you were planning to crop to aps-c afterwards in post. Spray, sort of aim in that general direction, and pray! (I'd expect lower fps than a k3 though)
02-07-2015, 09:20 PM   #14
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QuoteOriginally posted by clicksworth Quote
How about making it nice and simple. It will look the same as it did on film! The equivalent focal length will be exactly what it says on the lens.
But I have not shot film in 25 years. So APS-C is "normal" to me. But if we can crop a 16mp out of a 36mp frame and get the same look I don't think it will be a problem. You have the same number of pixels on the subject and that is all that counts right?
02-07-2015, 09:31 PM   #15
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The crop mode on FF camera means that the camera itself will crop the photo for you!
so in the end, there's no difference if you crop the photo in post process, or camera do it for you! is it really that hard?

So to answer your question: NO, you won't get the best of the both worlds! except if the FF camera has 50MP, which in turn the resulting crop will give you around 24MP which is K-3's photo! But still I think if it's 36MP as rumors saying, you'll have plenty of room for crop!
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