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DX on FX bodies.

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779HOB
779HOB  2985 forum posts United Kingdom
1 Jun 2012 - 9:41 AM

I’m not sure I can even ask this question clearly – but here goes.

If you put a DX lens on an FX body I know you don’t get the full use of the FX sensor. That’s fine, I get that, and the D700 very kindly shows you what you are missing by having the DX lens mounted.

But, does the format of the image revert back to DX sensor, i.e. is the photo a letterbox shape as with a DX sensor or does it retain the FX shape. Logic to me would say that it retains the FX shape, just cropped. It must retain the FX sensor shape just at a different focal length, surely?

I think I have answered my own question by writing it! But would be happier is someone who knows more about this sort of thing either confirmed or laughed at my logic!

Thanks.

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1 Jun 2012 - 9:41 AM

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User_Removed
1 Jun 2012 - 9:57 AM

Hmmm.

I had D80 and D300 DX cameras and D3s and D800 FX cameras, and the "letterbox" format you mention is new to me.

As far as I am aware, the image proportions of DX and FX (at least on Nikon dSLRs) are pretty much the same. (approx 3:2)

Edit: Just checked and they are

Last Modified By User_Removed at 1 Jun 2012 - 10:00 AM
Nick_w
Nick_w e2 Member 63723 forum postsNick_w vcard England98 Constructive Critique Points
1 Jun 2012 - 10:01 AM

If you use a DX lens on an FX camera, you basically get extreme vignetting on the corners/ edges are black. Even if there was any image info it would be very soft as the lens is only designed to capture the smaller sensor size.

But why would you want to use DX lenses on a full frame? You lose so much information, you would be better sticking to a DX body

Last Modified By Nick_w at 1 Jun 2012 - 10:02 AM
779HOB
779HOB  2985 forum posts United Kingdom
1 Jun 2012 - 10:05 AM

Thanks Nick - It doesn't show the vignetting in the viewfinder, it shows an area that is captured - but I haven't looked at the results on a PC yet to the fair. The only reason is I have a DX lens that I don't use any more because I have a FX body. But out of having nothing better to do at the moment I stuck it on and it seemed to be ok. It's the Nikon 17-55mm which I always liked using on my D300.

779HOB
779HOB  2985 forum posts United Kingdom
1 Jun 2012 - 10:09 AM


Quote: As far as I am aware, the image proportions of DX and FX (at least on Nikon dSLRs) are pretty much the same. (approx 3:2)


Not sure - but I know my D300 images are a different "shape" to the D700 ones. The 300 seem more letterbox - not as extreme as that maybe but definitely different - on a landscape composed shot the vertical edge is shorter than it is on the D700. Or is it just my eyes playing tricks!

snapbandit
1 Jun 2012 - 10:29 AM

according to specs:-
D300 = 4288x2848 (approx 3x2)
D700 (Fx) 4256x2832 (approx 3x2), (interpolated up to D300 long side = 4288x2853)
D700 (Dx) 2784x1848 (approx 3x2), (interpolated up to D300 long side = 4288x2846)

so only 5 pix 'taller' with D700 Fx & 2pix 'shorter' with D700 Dx


effectively no difference

(can you tell I've a bit of time on my hands this morning!! SmileWink )

HTH

Joe B

779HOB
779HOB  2985 forum posts United Kingdom
1 Jun 2012 - 10:35 AM

Thanks Joe - very helpful.

User_Removed
1 Jun 2012 - 10:51 AM


Quote: If you use a DX lens on an FX camera, you basically get extreme vignetting on the corners/ edges are black. Even if there was any image info it would be very soft as the lens is only designed to capture the smaller sensor size.

But why would you want to use DX lenses on a full frame? You lose so much information, you would be better sticking to a DX body

Nick,

The Nikon FX cameras automatically detect of a DX lens is mounted and (by default) reduce the capture to the DX format, thus avoiding any vignetting. Effectively it means that, with a 12 Mp FX sensor, you get a 6 Mp crop. (or thereabouts).

Why would you do it? I guess a lot of new FX users do it until they can afford to replace all their DX lenses with the FX equivalents.

Nick_w
Nick_w e2 Member 63723 forum postsNick_w vcard England98 Constructive Critique Points
1 Jun 2012 - 11:00 AM


Quote: The Nikon FX cameras automatically detect of a DX lens is mounted and (by default) reduce the capture to the DX format, thus avoiding any vignetting. Effectively it means that, with a 12 Mp FX sensor, you get a 6 Mp crop. (or thereabouts).

True for Nikkor lenses, but not all 3rd party lenses (or older Nikkors). What I was trying to show is what you would see if you looked at the full image captured on the FX sensor, academic really.

Graysta
Graysta  91119 forum posts England
1 Jun 2012 - 6:40 PM

From reading the OP i feel a sense of reverse thinking . A lens designed for Full frame film or digi will on a crop sensor DX format will give a full sensor of image but the angle of veiw will mean that the edge of the image passes the sensor edges,hence crop.A lens designed to be used with an DX sensor will not fill the area of an FX the sensor ,Hence vignetting.Classic example tog gets 10.5mm Fisheye lens for FX puts on D5100 crop sensor and wonders why 16mm fisheye on D3s has more effect.DOH.

Last Modified By Graysta at 1 Jun 2012 - 6:41 PM
photofrenzy
2 Jun 2012 - 1:04 PM

Dx & FX are similar ratios in size approx 3/2 ratio . Nikon designed its FX cameras to support most of the f mount lenses even dating back to the 60,s.
They're also designed to accept dx lenses at a cost ,By cropping the full frame sensor down to a dx size format thus changing the appearance of the image by a factor of 1.5 x the original sensor size of 1:1

The only issue is it takes the original 12mp in case of D700 and crops it to 5mp giving the appearance of a longer lens used compared to the original 12mp FX image . As far as vignetting I haven't experienced this on.the Nikon system ,However this would almost happen on the canon system as it doesn't autmatically crop the sensor Wink

thewilliam
2 Jun 2012 - 1:49 PM

One colleague uses DX lenses with her D800 when she doesn't need the full 36Meg resolution because the area of the DX frame is exactly half of the FX.

For many vulgar professionals, there aren't many jobs that demand the full resolution of the D800.

photofrenzy
2 Jun 2012 - 6:45 PM

The Nikon fx sensored cameras can be manually cropped to dx format also , Even whilst the Fx lenses are attatched , What i like about the D800 is you can carry a few lenses around with one camera body shooting between full frame & Dx format ie 36 mp or 15 mp.

Several Canon users who use both systems have to carry two camera bodies around each with thier own range of lenses , I know several people who do this but its a lot of equipment to carry around, Shooting between full frame and aps can be a pain having the D800 system makes it that much easier and lighter.

Last Modified By photofrenzy at 2 Jun 2012 - 6:46 PM
779HOB
779HOB  2985 forum posts United Kingdom
3 Jun 2012 - 7:58 AM

Thanks everyone - interesting. You know I hadn't put two and two together and figured that the MPs would be reduced, obvious now you say so.

ray1
ray1  9511 forum posts England1 Constructive Critique Points
3 Jun 2012 - 8:35 AM

Interesting stuff and a subject area that has been driving me nuts at the moment - DX or FX. Its a major expense to go FX and re invest in new lenses - whats the cost of a new 70 - 200 2.8 when my dx version is still as new - yeh I could probably get the best part of a grand for the old one but I would still need to find another £600 for its replacement, plus the ever growing cost of the camera. I have even considered selling all my kit and just getting something like the J1, however, my next upgrade will probably be the d300s replacement or even a secondhand d300s. This photgraphy lark is becoming a very very expensive game.

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