What is the MP area using a DX lens (crop mode) on the D3.

1> Please explain the math...;
2> how does the large FF mirror avoid the rear element on a DX lens??
(wonder if Canon will follow suit on this wonderful technology!

THX!

It crops... so my 17-55 works fine in DX mode or 5x4 mode with higher resolution. But there is vignetting

And your talking to someone who just sold his 1dmk3 for D3.

1. The math has to do with the FX sensor area divided by the DX sensor area. Which you then multiply by 12.1 MP, and you get 5.2MP in DX mode and BTW that 17-55 should work on FX from about 26mm out to 55.

2. It.Just.Works.

w2hef wrote: And your talking to someone who just sold his 1dmk3 for D3.

Was that a good move? YES or NO and.....WHY?

Avi B wrote: 1. The math has to do with the FX sensor area divided by the DX sensor area. Which you then multiply by 12.1 MP, and you get 5.2MP in DX mode .....

what is the mathematical equation?? (please show your work)

EOSMIKE wrote:
2> how does the large FF mirror avoid the rear element on a DX lens??
(wonder if Canon will follow suit on this wonderful technology!

THX!

DX lenses have the same lens mount as non-DX lenses. It's just a smaller diameter so you don't have to worry about it hitting the mirror.

Canon's EF-S uses a Short Backfocus for their APS-C lenses which the lens pertrudes further and is in danger of hitting the mirror on FF cameras.

sounds like Im back in math class, lol

EOSMIKE wrote:
w2hef wrote: And your talking to someone who just sold his 1dmk3 for D3.

Was that a good move? YES or NO and.....WHY?


Well i had a history of nikon and a lot of AIS glass along with the D300. So it just was the right thing to do instead of having two camps. Don't get me wrong, i love the Canon 1dmk3 but i'm more partial to the nikon setup.

The D3 uses 3 modes: FX for full from lenses with no crop factor. If you use the DX lenses you have a choice of really two modes: DX drop or 5x4 with vignettes on the sides which is higher resolution than the 5mp DX mode... It's not bad, but whatever?

Show my work? What is this? Grade 9 or something? Please.
But I'll tell you how to do it
Take the dimensions of the FX sensor and the DX sensor, compute the areas, and then the ratio between the two areas. This aint rocket science.
How about you show me the work For extra credit, how about you find the dimensions of the 5x4 mode too, and then figure out how many MPs you get out of that?

Pixel dimensions across the full sensor:
4256 x 2832 = 12.1 MP

When only capturing data from the cropped area of the sensor, the pixel dimensions are as follows:
2784 x 1848 = 5.1 MP

And if you want to see the math that shows why the smaller high-speed crop area in the D2X yields more resolution than the D3 cropped, let me know. It's all about pixels per unit area.

~Ted

Image sizes:

FX: Large 4256x2832 12.053 megapixel does not accommodate DX
DX: Large 2784x1848 5.144 megapixel does vignette on DX (all over)
5:4: Large 3552x2832 10.059 megapixel does vignette on DX (sides)

Well, let's do the math the right way:
According to Nikon canada website here, the dims are as follows:

FX -> 36mm x 24mm
DX -> 24mm x 16mm
5:4 -> 30mm x 24mm

Ratios of areas are as follows:

DX to FX = (24*16) / (36*24) = 0.44
5:4 to FX = (30*24) / (36*24) = 0.833

So, a 12.05 MP image would work out to 12.05 * 0.44 ~ 5.3 MP for DX crop, and 12.05 * 0.833 ~ 10 MP for 5:4 crop.

The theoretical 24.4 MP D3X would work out to 24.4 * 0.44 ~ 10.7 MP for DX crop, and 24.4 * 0.833 ~ 20.3 MP for 5:4 crop.

See, it's all about the ratios.... Pretty straightforward.


Now, about vignetting on FX for DX lenses, it depends on the lens. The 17-55 does not vignette past 26mm or so (I've put it on my film camera and tried to look through it while zooming). I've also read that the Nikkor 12-24 does not vignette from 18mm onwards.

some of these DX lenses "work" from xxmm to xxmm on a D3 in FX, but by all means are not sharp in the corners, i can say this for the 17-55 for sure, unless used in DX mode.

does the following "mathematical formula" work.....?
If so, it's much easier & faster to compute than what people have described above,
which is painfully complicated and slow!

To get the native resolution of the crop....
take the crop factor (which in this case is 1.5x)
take 1.5 and multiply buy 1.5 - which equals 2.25!
now take the native MP of the FF sensor: 12.1 and divide by 2.25.

does this work? and is this correct?? 5.37777777MP

Since the crop is in both dims, then that works too. Or since each dim on DX is 2/3 of FX, you could even do 2/3x * 2/3y = 4/9 xy ~ 0.44 xy. Similarly for 5:4 crop, you get 5/6x * 4/4 y = 5/6 xy ~ 0.833 xy. Both of which correspond to the long-winded stuff, and this method works for *any* crop factor you may want to figure out. Like say for a 4:4 crop factor, final ratio works out to 2/3 so you'd get 0.666 * 12.05 = 8 MP.

But I find that people deal much better with numbers

just an example of the effect:
http://users.skynet.be/van.hooveld/Reviews/nikond3.htm#dx
or with a fisheye:
http://users.skynet.be/van.hooveld/tips/fishond3.htm

Guy

You are throwing away 60% of your sensor's image to get a 5Mp picture?