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02-16-2015, 05:35 PM   #76
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We might be overanalysing things. An APS-C crop of a FF image means a proportional loss of photographic information in the periphery of the FF image and thus loss of resolution. The lens doesn't suddenly multiply its FL by 1.5 by shooting in crop mode.
There is no advantage to shooting in crop mode on a FF camera with a FF lens. The same result would be achieved in PP with cropping - getting rid of the peripheral photo detail and thereby reducing the resolution.
Clearly, to get the same scene on the VF, a FF photographer has to be closer to the subject compared to an APS-C photographer, but if this occurs, the FF image will be of better quality (better DR, resolution etc, assuming capable lenses and similar sensor technology between the FF and APS-C cameras). But technology keeps improving so much that the advantage of having a 2 or 3 generation old FF camera is being eclipsed by that of a current generation APS-C (ONLY for IQ, obviously the OVF experience is undeniably better in a FF camera).

02-17-2015, 10:06 PM   #77
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QuoteOriginally posted by jsherman999 Quote
You speak of 'downsampling' and 'normalizing' as if they also are special cases. They are not - they are the default case.
They are an argument's dead end - again, they're not about taking the picture, they're about post processing, and they're all about the algorithm, not about the camera.

If we go with that, you should always buy a D7100 instead of a D4S because there are more pixels to sample.
02-17-2015, 10:30 PM   #78
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QuoteOriginally posted by Michaelina2 Quote
What's the impact of pairing the HD 1.4TC with APS-C crop DA lenses (other than loss of an f-stop)? Does it NOT expand the DA's image circle to fit the FF frame so there's no loss of sensor pixel density/count?


Just curious... M
It's close. As you might imagine, the area of the image circle needed to cover a FF sensor is....1.5x larger than that for the APS-C sensor. Of course, the image circle of an APS-C lens may be a bit larger than the sensor itself (it certainly won't be exact). It may cover the entire FF sensor or be a bit short. It will be close.

Now, whether the result will be any better than just cropping...that will depend on the quality of the TC and the lens.
02-17-2015, 10:39 PM   #79
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QuoteOriginally posted by MadMathMind Quote
It's close. As you might imagine, the area of the image circle needed to cover a FF sensor is....1.5x larger than that for the APS-C sensor. .
More than double, actually, MMM.

02-18-2015, 06:38 AM   #80
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QuoteOriginally posted by clackers Quote
More than double, actually, MMM.
Yeah. It was late and I was tried. Change "area" to diameter or 1.5 to 2.25 and it becomes right.
02-18-2015, 06:45 AM   #81
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QuoteOriginally posted by Ash Quote
An APS-C crop of a FF image means a proportional loss of photographic information in the periphery of the FF image and thus loss of resolution.
Why a loss of resolution unless you are trying to keep the image the same size as the pre-crop version?
02-18-2015, 08:52 AM   #82
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QuoteOriginally posted by clackers Quote
- again, they're not about taking the picture, they're about post processing, and they're all about the algorithm, not about the camera.
I'd like to know how you manage to produce digital images without raw processing and algorithms. Methinks the camera and Lightroom would protest.

Anyway, this whole cropping/enlarging argument applies to film as well.

QuoteQuote:

If we go with that, you should always buy a D7100 instead of a D4S because there are more pixels to sample.
But less sensor area to gather total light. I would personally certainly choose a D7100 (or K3) over a same-gen, lesser-MP aps-c camera with the same required features.

.

Last edited by jsherman999; 02-18-2015 at 09:03 AM.
02-18-2015, 01:14 PM   #83
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QuoteOriginally posted by jsherman999 Quote
I would personally certainly choose a D7100 (or K3) over a same-gen, lesser-MP aps-c camera with the same required features.

.
Sure.

Sports shooters might prefer their D4 to a D810 because of the frame rates possible with less Mp, but they have that specific need.


Last edited by clackers; 02-18-2015 at 01:56 PM.
02-18-2015, 01:21 PM   #84
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I shoot my 36MP DSLR in 1.2 crop mode occasionally for a boost in FPS when I shoot sports. It's all the same to me except about 24MP instead of 36MP. I don't know how close I'd have to look to notice a difference. More than I'm willing to do for sure. And you guys not comfortable with FF focal lengths shows you've most likely learned photography on APS-C which has not be around long at all. We've had FF on small format for, well, forever it seems as apposed to the comparatively few short years of a 1.5 cropped version.
02-18-2015, 03:58 PM   #85
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QuoteOriginally posted by mohb Quote
Why a loss of resolution unless you are trying to keep the image the same size as the pre-crop version?
The 'loss' is from the innate effect of the 'crop'.
Cropping means discarding (loss) of information cropped off.
02-18-2015, 04:24 PM   #86
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QuoteOriginally posted by Ash Quote
The 'loss' is from the innate effect of the 'crop'.
Cropping means discarding (loss) of information cropped off.
If I cut a printed photograph in half that doesn't affect the quality of the halves except make them smaller so why does cropping a digital picture affect the quality Ie resolution?
02-18-2015, 05:35 PM   #87
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I might be expressing it incorrectly, excuse my terminology.
What I mean is, the cutting of the photograph decreases the total information of the photograph (i.e. there is less of it and thus, there is a decrease in the total resolution).
In digital terms, a crop reduces the image size, and thus how many pixels it has in total (what I was calling resolution).
So if a 36Mp FF image is cropped to 16Mp, the total image size goes down as well as how many pixels it resolves. Upscaling a 16Mp image back to 36Mp does not add detail and as such it would degrade the IQ of the image, as you mentioned. But at 100%, there is more to the 36Mp image than the 16Mp one can reproduce.
02-19-2015, 05:40 PM   #88
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This Tony Northrup is a slippery character. I watched his videos on crop factor and started a thread which got really quite noisy. He repeats the same glib crop factor remarks on this video. At no point does he say on this one either that an f2.8 lens (for example) is an f2.8 lens what ever the size of the sensor of the camera. It is true that less light overall is being utilised on the crop factor camera, but that's not what counts as far as exposure is concerned - the light intensity is what counts. For more detailed explanation see relevant dpreview page.

I have test pics taken with my DA 18-135mm and with a tamron adaptall SP 28-135mm on my K5. At 50mm the pics from the tamron are equal. At 135mm the tamron IMO is if anything ahead. Fullframe lens vs apsc lens. Tony says the apsc lens is sharper right? So whats going on? Just Tony being devious.

I think what he is saying is this. Put a sheet of newspaper on the wall. Lets use 50mm lenses as example.
Now frame the page with your full frame camera and take the pic. Swap to the apsc camera and take the pic. Now Tony's calculations and point are true. In reframing the pic on apsc you have moved 50% further away. This is obvious: is that page easier to read from (say) 4m away or from 6m away? The perceptual data (or pixels as he calculates) will be superior in case 1.

Just as the f-stop of the lens doesn't change because of the size of the sensor, so the real resolving power of a lens doesn't change either. My 50mm smc-a remains one of my sharpest lenses, it is not degraded by being used on a apsc body (however the apsc sensor is more demanding of it). In terms of real comparative results the whole package needs to be considered: lens, camera, sensor..

UPDATE: this is the dpreview page:

http://www.dpreview.com/articles/2666934640/what-is-equivalence-and-why-should-i-care

Last edited by marcusBMG; 02-20-2015 at 07:34 AM.
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