BebuLamar

No they don't. The 18mm lens on the FF camera give you wider field of view if it's built for FF camera. It would vignette if it's built for crop camera.

Brucej67 Loc: Cary, NC

Wrong you will see a larger view as a 18mm for a crop frame camera produces the same field of view as an 18mm for a full frame camera produces.

Notorious T.O.D. Loc: Harrisburg, North Carolina

I tried to be clear that if the same FF or FX lens was used on both a FF and a crop Nikon then you would need to move closer with the FF to get the same FOV. If you are talking 2 different lenses one for FF and one built for DX or crop then the view and steins should be the same. DX lens on the FX body would be vignetting. At least that is what I was trying to say..

Happy Thanksgiving Everyone...off to have some turkey now...

Best,
Todd Ferguson

rehess Loc: South Bend, Indiana, USA

No, I won’t argue with you, but this is not correct. I have a Pentax 35mm camera. I also have an APS-C Pentax K-30. I have a K-mount Sigma 10-20mm lens. I get the same view with the lens set @ 15mm on the film camera that I get with the lens set @ 10mm on the APS camera. Nikon is the same.

Bobspez Loc: Southern NJ, USA

I don't see how that is possible. The same focal length lens on a larger sensor (or negative) gives a larger field of view. On a smaller sensor it gives a smaller (or cropped) field of view.

From experience, using a 40mm lens on my 120 film Mamiya camera gives approximately the same field of view as a 19mm lens on my D3100 APS-C dslr.

Doing the math verifies this observation.

A 120 MF film camera has a 0.7 crop factor compared to a 35mm or FF dslr. So the 35 mm equivalent of the 40 mm lens on the Mamiya is 40 x 0.7 = 28mm.

The APS-C dslr has a 1.5 crop factor. So the 35mm equivalent focal length of the 19mm lens on the APS-C camera is 19 x 1.5 = 28.5mm.

rehess Loc: South Bend, Indiana, USA

You are exactly correct.
1.5 x 10 on K-30 = 15mm on 35mm

blackest Loc: Ireland

Ok here is what you could do, take the 2 shots at the same vantage point using the same full frame lens. with identical settings Enlarge the 2 photo's by exactly the same amount (for the full frame you would require a larger sheet of paper).

Lets use 2 sheets for the crop sensor with a 24mm by 16mm sensor lets enlarge to 24cm by 16cm and for the full frame with a 36mm by 24mm sensor lets enlarge to 36cm by 24cm. place the crop sensor enlargement exactly on the centre of the full frame enlargement and draw round it and cut it out.

now holding the cropped full frame photo and the full enlargement of the crop frame camera the 2 photographs are as close as possible identical.

Do any of you lads disagree?

Brucej67 Loc: Cary, NC

I can only answer to Nikon cameras and lenses since I own 5 full frame Nikon cameras and 3 crop frame cameras and have high quality glass for each. If I put an 18mm lens designed for a crop frame camera on a crop frame camera and an 18mm lens designed for a full frame camera on a full frame camera the result will be the same, if however I put the 18mm lens designed for a full frame on a crop frame camera the crop size would be the same as a 27mm lens on a full frame camera. Keeping the lenses designed for their specific cameras does not alter the field of view, but switching the lenses between cameras would.

Brucej67 Loc: Cary, NC

What???????????????????????????????????? 😯

rehess Loc: South Bend, Indiana, USA

I have never seen a 18mm lens designed for a crop-sensor camera mounted on a crop-sensor camera give same results as a 18mm lens designed for a FF-sensor camera mounted on a FF-sensor camera.

Brucej67 Loc: Cary, NC

I have the Sigma 18-35mm f1.8 art lens for a crop sensor and a Nikon 18-35mm f3.5-4.5 G lens designed for a full frame camera.

blackest Loc: Ireland

ok this lines from a table on https://www.nikonians.org/reviews/fov-tables

h= horizontal v= vertical d= diagonal for an 18mm lens on full frame fx, crop sensor dx
18mm fx h90.0 v67.4 d100.5 dx h66.0 v46.9 d76.0

28mm fx h65.5 v46.4 d075.4 dx h45.4 v31.1 d53.3



(1) 36x24mm 35mm film frame/FX sensor size - Field of View Crop Factor = 1

(2) 23.6x15.7mm APS-C/DX sensor size - Crop factor = 1.5

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ok my little diagram isnt much cop but if you imagine 2 cones of light joined at their points the cone on the right is the outside world and the much smaller cone is the circle projected on the back of the lens. The size of that circle is dependent on the distance between the back wall where the sensor is and the back of the lens. how much of that image cone that is recorded depends on the physical size of the sensor.

The image circle size doesn't change but the part thats recorded by the sensor does, the crop sensor only records the central area.

maybe its easier to think of a projector lets say its projecting on to an 8 by 4 screen. The whole of the screen is covered by the image. now lets swap that screen for a 6 by 3 screen placed at exactly the same distance from the projector. The image you see is still in focus on the screen but the outer parts are not shown because that light misses the screen entirely.

you can think of the 8 by 4 screen as fx and the 6 by 3 screen as dx.

Thats why i was saying if you apply exactly the same magnification to the images from both sensors if you cut away the outer part of the fx image what you are left with is the dx image.

Lets return to our projector and screen everything is in focus but because the screen is smaller we are missing everything thats going on at the sides and top and bottom of the frame. ok Normally you would just move the screen forward and refocus but this is a camera simulation so we can't do that.

So instead we change the lens for one which projects a narrower beam of light and now all of the image is on the smaller screen. Everythings a bit smaller but we can live with that. Ok finally we bring back our 8 by 4 screen and put it back where the 6 by 3 screen is but the image is the same size the outer part of the bigger screen isnt being lit. This is like a crop sensor lens used on a fx sensor camera.

jumping back to my table at the beginning we can see that for an 18mm lens the field of view on full frame is horizontally 90 degrees on the full frame and 66 degrees on the dx so to record the same view as on the dx camera with the fx camera you need a lens with the same field of view on the fx as on the dx. the 28mm lens on the fx camera has a horizontal field of view of 65.5 degrees close to the 66 degrees of the 18mm of dx camera. slightly too long 27mm would be closer.

if you were to print the 2 images from the 27mm on the fx and the 18mm on the dx to fill a 6 by 4 print, the 2 images would look similar (and the dx print will have been enlarged more to fit the paper). One thing you might notice (if the aperture used was identical) is that the depth of field is a little different between the 2 photos.

So what we can say is that the image projected through a given lens doesn't change just because you changed sensor sizes just the smaller sensor records less of the image projected than the larger one. if you want to record just the field of view from the dx sensor on the fx sensor then a longer lens must be used all though the images recorded now show the same slice of the world if nothing else was altered the depth of field would be different. The only way to record an identical photo (as the dx camera with the fx camera) would be to use the same lens and crop the image down.

With the nikon fx camera you can choose to record in dx mode and have the camera do the crop. Hope this is clear enough.

Brucej67 Loc: Cary, NC

So what you are trying to tell me is that an 18mm lens built for a DX camera and placed on a DX camera gives a different field of view than a 18mm lens built for an FX camera and placed on a FX camera, am I right?

BebuLamar

The Sigma lens on a DX camera gives the diagonal angle of view of 76.5 to 44.2 degrees.
The Nikon lens on an FX camera gives the diagonal angle of view of 100 to 63 degrees. On the DX camera it's 76 to 44 degrees which is the same as the Sigma.

These are manufacturer specifications.

Brucej67 Loc: Cary, NC

Discounting all other mm are you telling me that each lens on their appropriate cameras (DX lens on DX camera and FX lens on FX camera) at 18mm have different field of view? I do understand the DOF difference, however 18mm would be 18mm field of view with the lens on their appropriate camera bodies.