D7000 Owners
- Thread starter 06Honda
- Start date
I had planned to upgrade to the D7100, but more recently I've been thinking that I want to have the same lens set for all my cameras, namely FX. Having to switch between DX and FX ultimately won't serve me well if I get to the point where I shoot pro stuff. If I got the D7100, I would want to upgrade the DX lenses I have, but it would make more sense to put that money into FX lenses. So I'll be going later on with the D600 as a second camera. I could always get cheaper FX lenses (or a single mid-range zoom) as well for those times I or my wife just go out to shoot casual stuff as I had planned initially to stay DX for that.
Fred Kingston
Senior Member
You do understand that the FX lenses work fine on DX cameras, right?
Cowboybillybob1
Senior Member
Gotta have it.
Yes but then there are the differences in focal length and depth of focus. I'd rather be able to switch to a second camera and not have to go with a different lens to compensate for that difference.
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There are no differences in focal length between DX and FX using the same lens. As for DoF, it's subjective on how you define the comparisons.
Depth of focus is greater with the smaller DX sensor than with the larger FX sensor (assuming things like f stop, distance to subject, and final image size are the same).
Yes you are right about focal length in terms of distance to the sensor, I was actually referring to FLM (focal length modifier) due to the difference in crop factor. The 50 mm FX lens on the DX camera will provide the same FOV as a 75 mm DX lens because the angle of divergence is steeper with an FX lens. So I meant to say effective focal length.
Not to continue beating an already dead horse but the DoF is the same under the conditions you have listed. If, however, you move the FX so as to equal the same coverage as the DX will then the DoF will be different. But keeping all things constant as you have described DoF is the same. The reason is that DoF is an optical property of the lens and has nothing to do with the sensor.
BackdoorArts
Senior Member
I thought about it but jumped ships and am now fully on the FX boat. The D7100 was very tempting, but ultimately came up just a bit short for me. Not knocking the camera, it's just that I'm better off investing the money into a second FX.
I have the D7000 and it's a great camera but the next logical step is the D600 or D800. The D7100 doesn't offer me enough to justify an upgrade. I'll keep my 7000 as a travel camera and as a backup until I get the second FX body. But I can't see more DX bodies in my future.
Sorry, I meant to say subject distance in terms of providing the same FOV, then DOF will be greater with the DX. However, if distance to subject, f stop, focal length, and the final images are the same size, the DX will have less DOF.
Also, if you change sensor size, you would need a different angle of light to fill the sensor, and therefore a different focal length. DOF ratio is in direct proportion to format size when using the same focal length, same subject distance, and the same f-stop, and inversely proportional to format size when focal length is adjusted at same subject distances to give the same size final image. So DOF is intimately associated with format size, because it is derived from not only what the light is being projected FROM, but also where the light is being projected TO.
This is simply not correct. The sensor on both DX and FX is in the same place. The only difference is how much of the light coming through the lens is being recorded. They do not change up the focal length to account for the smaller sensor. If they did adjust the sensor placement to accommodate the different sized sensors then there would be no crop factor.
In fact, the reason you know the focal lengths do not change between FX to DX is that the lens has a very specific place in which the light rays all converge. And it is at that exact point that you must place the sensor. If you move the sensor forward or backward relative to that single focal point your images will be out of focus. The lens is designed to focus all the light rays at that single point irrespective of the camera body. And it is this focus point that creates the measurement of focal length. Therefore focal length is dependent upon the lens and has nothing to do with the camera or sensor.
pistnbroke
Banned
Well so far 100% of D7000 owners dont know the exact specs of the D7100 as no one has tested it ( DXO etc) so too soon to deceide..Just because its 24 mp does not mean a better picture