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D800-FX and crop vs DX

kallisti

kallisti

macrumors 68000
Original poster
Apr 22, 2003
1,751
6,670
Theoretical question.

The D800 has an insane sensor that can capture a huge amount of information in FX mode. When used in DX mode it can also capture a large amount of information (more than the D700).

My question: if you know from the outset that the lens you are using isn't long enough to capture what you desire, is it better to shoot in FX mode and then crop or shoot in DX mode?

Shooting in DX mode should put *most* lenses closer to their "sweet spot" regarding MTF curves. But not sure if there are other factors that need to be considered (and also acknowledging that MTF curves aren't everything when using a given lens).

This is really an academic question on my part: the D800 is the first body that pushes FX into the medium format category (at least regarding file size) and can at the same time capture DX images that are large enough to tolerate significant cropping and manipulation when needed.

So FX and crop or shoot in DX?
 
kallisti said:
...
So FX and crop or shoot in DX?
Click to expand...
That's in some ways personal choice. If you shoot in full frame, you have more latitude on where your central object of the image is in relation the background when you go to crop it. If you shoot in DX, you save disk space and possibly have less work to do later.
 
But any theoretical or real differences in IQ between the two methods?
 
kallisti said:
But any theoretical or real differences in IQ between the two methods?
Click to expand...

Probably none that you would notice. This is one of the problems that I have been reading about. People are getting more and more hung up on the technical (not completely bad) rather than getting out and creating artistically. Sure the technical aspects will be of benefit but they are no substitute for creative ability.
 
kallisti said:
But any theoretical or real differences in IQ between the two methods?
Click to expand...

Some lenses take a hit to image quality away from center even on a crop frame. To achieve maximum sharpness/etc on a subject, it would have to be placed towards the center of the composition. Shooting at full resolution, the subject could be shot at the center to maintain sharpness, but the extra image data to the sides would allow for the final image to be cropped so that the subject is placed off-center.

Haven't tried out the comparison for myself, but now I'm tempted to try ;)
 
El Cabong said:
Some lenses take a hit to image quality away from center even on a crop frame. To achieve maximum sharpness/etc on a subject, it would have to be placed towards the center of the composition. Shooting at full resolution, the subject could be shot at the center to maintain sharpness, but the extra image data to the sides would allow for the final image to be cropped so that the subject is placed off-center.

Haven't tried out the comparison for myself, but now I'm tempted to try ;)
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Good call but I think it would also depend on the glass used. Using pro glass would make a big difference over a kit lens I would say. I could be wrong and those in the know can weigh in, but I would say that the Nikon 24-70mm, f2.8 on a D800 would have as good if not not better when shot on FX as opposed to DX.
 
kallisti said:
My question: if you know from the outset that the lens you are using isn't long enough to capture what you desire, is it better to shoot in FX mode and then crop or shoot in DX mode?
Click to expand...

No. It will make no difference since the image data you capture will be identical, it would just be missing some portion of the data (on the edge of the sensor) that is discarded when using DX crop mode.

That's why they call it a crop mode and not zoom mode. Shooting in DX crop mode does not give you more "reach". The only reason DX cameras are thought to give more reach is because they typically feature sensors with finer pixel pitch than their FX counterparts. In the case of the D800, this may not necessarily be hold true, and thus the real concept of "crop sensor" needs to be understood.

Arguments about the lens performing better in the center are useless when comparing FX mode and DX crop mode because you're still using the same lens. The better choice is always going to be to shoot in FX mode because you're gathering more data, which you can always voluntarily discard later on, but you can never go back and make an "FX frame" out of a "DX crop".

The only caveat to this would be, as mentioned, if data volume constraints are in place, or if you need extra shooting speed (because I think the DX crop mode can shoot a little faster than the FX mode).
 
Ruahrc said:
No. It will make no difference since the image data you capture will be identical, it would just be missing some portion of the data (on the edge of the sensor) that is discarded when using DX crop mode.

That's why they call it a crop mode and not zoom mode. Shooting in DX crop mode does not give you more "reach". The only reason DX cameras are thought to give more reach is because they typically feature sensors with finer pixel pitch than their FX counterparts. In the case of the D800, this may not necessarily be hold true, and thus the real concept of "crop sensor" needs to be understood.

Arguments about the lens performing better in the center are useless when comparing FX mode and DX crop mode because you're still using the same lens. The better choice is always going to be to shoot in FX mode because you're gathering more data, which you can always voluntarily discard later on, but you can never go back and make an "FX frame" out of a "DX crop".

The only caveat to this would be, as mentioned, if data volume constraints are in place, or if you need extra shooting speed (because I think the DX crop mode can shoot a little faster than the FX mode).
Click to expand...

Thanks Ruahrc (and all the other posters). This was actually my assumption when I first thought about it, but there are sometimes elements in play that defy common sense (wasn't positive that FX --> DX was a straight crop in camera or if there might be differences in how the sensor captures the image data between the two modes).
 
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Use Dx only when required

mulo said:
nope, using dx mode just crops the image in camera, thats all
Click to expand...

I would use the Dx only with a Dx lens, and the Fx mode for all other situations. Then you could crop any part of your picture instead of letting the camera crop center only
 
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