Anyone tried setting their D700's image area to "DX", for use with FX lenses?

Naboo32

Naboo32

Suspended / Banned
Messages
3,278
Name
Andy
Edit My Images
Yes
I've just been reading through Uncle Ken's D700 Guide (Link ...), for the first time (must remember to send him his $5 when I get home ;)) and I discovered something which may just help me improve my wildlife shots .

The issue is that I (only) have a 70-300mm lens and am looking to find a better way to get bigger, better close-up images, other than simply cropping the hell out of the images that I currently get in FX mode.

After reading the guide, another option has occured to me, but I'm not at home to try it out right now, so I thought that I'd consult the TP Oracle first :D. Here's the question:

"If I set the "Image Area" option in my D700 to "DX" (instead of the default "FX") and shoot using my FX lenses;

a.) Will the image in the viewfinder be masked around the edges and (more importantly)

b.) Will the camera meter everything correctly for the "cropped" image and find it easier to focus on the bigger and more obvious subject"?

Also, can the "DX" setting be stored in one of the "Custom Shooting Profiles", or will it affect every shot I take in every other mode :thinking:?

To clarify, I do realise that only about 7MP of the D700 sensor will be used and that "resolution" and "focal length" will not be altered, but I suspect that, due to (probable) better focus and better exposure of the "larger" image on the active portion of the sensor, the images themselves will be of better quality. If nothing else, the images will certainly be easier to review on the LCD screen :|.

Can anyone else see the potential advantages of what I'm suggesting, or do you think that the results will be no different/worse than shooting at full frame with an FX lens and just cropping it down to (say) 30% :|? Of course, I'll try it and see at some point, but some of you may already have done so, hence the post.

Thanks in advance for your input :).
 
Yes to A and B (partially)

It won't change focusing.

I can't really see any advantage to what you are proposing, although if you do intend to crop I guess the DX mask might help....?

The real answer is to get closer or buy a longer lens :)
 
I don't think they'd be a any advantage doing this vs cropping later. Just to clarify you'll only use 5.1 mp and not 7mp if you do this. All the focus points in the D700 are in the crop sensor area (I know thats not technically correct but you know what I mean) so autofocus would have no advantages either way. The only one I'm not sure about is what happens when you matrix meter. Nikon don't say anything about this changing so I assume it meters using the same frame as in FX.

All in all I think you don't gain anything from using DX so you may as well use FX and crop

Hugh
 
puddleduck said:
Yes to A and B (partially)

It won't change focusing.

I can't really see any advantage to what you are proposing, although if you do intend to crop I guess the DX mask might help....?

The real answer is to get closer or buy a longer lens :)
Click to expand...

Indeed, Andy, that is the longer term plan ;).

In the meantime I was simply hoping to find some new ways of squeezing every last gram (I've gone all metric :p) of performance out of my current set-up :). Some other counter-intuitave things that I've tried, like pulling back the focal length and shooting a 240mm (as opposed to 300mm) and bumping up the ISO to allow smaller-than-max apertures for the same shutter speeds, have helped to improve the sharpness and contrast of my wildlife subjects (although I have to crop a little more and suffer a tiny bit more grain than before).

The real question here is whether or not the metering will behave any differently in DX mode :thinking:. It should, I think. This would really help with high speed continuous shooting too, where I often get a high percentage of over/underexposed frames, when trying to track flying birds against a broken tree/sky line :|.

boyfalldown said:
I don't think they'd be a any advantage doing this vs cropping later. Just to clarify you'll only use 5.1 mp and not 7mp if you do this. All the focus points in the D700 are in the crop sensor area (I know thats not technically correct but you know what I mean) so autofocus would have no advantages either way. The only one I'm not sure about is what happens when you matrix meter. Nikon don't say anything about this changing so I assume it meters using the same frame as in FX.

All in all I think you don't gain anything from using DX so you may as well use FX and crop

Hugh
Click to expand...

Thanks Hugh :)!

Yes, of course you're right, it's only 5.1MP - I remember reading that somewhere, now ;).

My thinking with the autofocus was that if the object was "larger" in terms of occupying more of the "active" sensor, it might be easier for the camera to recognize contrast, depth, distance and all of the other things that it uses for establishing a focus lock :thinking:. But, as stated above, if the camera does not consider only the central, active portion of the sensor, then it's not going to make any difference.

If I get any conclusive A/B results from my tests, I'll come back here and post them. Otherwise, let's just assume that it was simply a pipe dream gone wrong :D.

Thanks again for your input, chaps.
 
puddleduck said:
Its not larger, just cropped.
Click to expand...

:| Well, what I meant to convey was the idea of the camera's processor looking at a flying bird against a background of sky (for example) and saying to itself;

"OK, this bird occupies 55% of the image that I am seeing, so I'll expose longer in favour of this big, dark object". As opposed to it thinking;

"OK, I'm seeing 75% light blue sky and there's an insignificant brown blob in the middle - I think I'll just go for a quick shutter speed".

In summary, in percentage (of the active portion of the sensor) terms, the subject is larger.

As already stated, if the sensor/processor doesn't work this way (i.e. if it still looks at the full frame image and bases all exposure settings on that, then my theory is wrong and I won't gain anything this way). But, as far as I can see, nobody has really answered that question here, yet :thinking:.
 
The metering is based on crop mode, however this will not influence metering as much as you think.

In summary, in percentage (of the active portion of the sensor) terms, the subject is larger.

No it isn't - the same part of the sensor is active in both cases, and you subject is not larger. You are simply cropping.

DX mode will change metering.. but nothing is larger here, its simply not reading exposure information outside of the DX frame. Which is very different.

Think of the difference between center weighted and matrix, DX crop mode will expose a bit more like Center Weighted.
 
Thanks for the further info, Andy.

I'll stop using the term "larger" then, because it only applies in a relative sense (i.e. the percentage of subject vs. background), but it's good to hear you say that the camera will meter differently in DX mode :).

Particularly with fast moving objects, it's often tricky to use centre-weighted metering, although it would often give better results than the full matrix metering mode in this situation. Now, I can continue in matrix metering mode and just have a better chance of getting a balanced subject exposure, than when the subject was just a tiny speck in the frame (as opposed to being a 40% bigger, tiny speck in the frame :lol:).

So, it seems like I might get some small benefits from using DX mode for certain applications, afterall :).
 
You must log in or register to reply here.
Back
Top