BIG ROB Loc: Princeton, NJ 08540

What "they say" isn't correct...it only SEEMS to make sense, yet it's not valid. Study FX lens sharpness ratings when they're mounted on DX body's on the www.dxomark.com website. Select the FX lens and see what it's sharpness rating is on the default FX camera, then manually select a DX camera from the drop down list, and see how low, the sharpness rating has dropped, with that same FX lens, now mounted on a DX camera. It will take a tremendous hit
in sharpness. FX lenses are best for use on FX camera's, DX lenses are best for DX camera's. Spend time studying
the ratings and you will learn this fact yourself. (I have a Canon EF 70-200 f/4L lens that's rated at 24 on a Full Frame
and only 14 on an APS-C camera.) This is the case for all full frame lenses when they're used on crop sensor body's;
sometimes they fall much lower than this! Check out your FX lenses, on your actual, DX bodies, to get your actual, sharpness ratings. DO NOT TAKE THE "OVERALL NUMBERS" WHICH ARE HIGHER! LOOK FOR THE "SHARPNESS" #'s.

TriX Loc: Raleigh, NC

I'm not sure whether the FX lens itself is less sharp on a DX camera (which does seem hard to explain) or the COMBINATION/system (which is what DXOmark is measuring) is less sharp (the body being the limiting factor) Anyone know the answer?

burkphoto Loc: High Point, NC

This is a case where the cause is less important than the effects.

BIG ROB Loc: Princeton, NJ 08540

[quote=TriX]I'm not sure whether the FX lens itself is less sharp on a DX camera (which does seem hard to explain) or the COMBINATION/system (which is what DXOmark is measuring) is less sharp (the body being the limiting factor) Anyone know the answer?[/quote

The question is, is the sharpness of the FX lens significantly reduced when it is used on a DX body. (DXOMARK has performed these measurements and displays the results of them.) The answer is that yes the sharpness of an FX lens
is significantly reduced when it is used on a DX body. (Explaining why this is so is a different question which i don't know for certain; but FX lenses work best on FX cameras as DX lenses work best on DX cameras.)

cjc2 Loc: Hellertown PA

Just a quick question?! Do any of you actually make images with your equipment or do you just argue theory? Do you actually own any of this equipment that you argue about? Please -- go out and do some photography, learn and have fun!

TriX Loc: Raleigh, NC

[quote=BIG ROB][quote=TriX]... but FX lenses work best on FX cameras as DX lenses work best on DX cameras.)[/quote

Sorry, but with respect, I do not agree. The fact that FX lenses show lower sharpness on DxOMark tests on crop bodies does not imply that DX lenses work better, only that full frame lenses do not deliver the same sharpness on crop bodies as FF bodies (duh?), in fact, FX (or EF lenses in the Canon world) work fine on crop frame (DX) cameras. If you have verification that DX lenses work "best" on DX cameras, please post it. That will be difficult, since there are no DX equivalent lenses to many FX lenses. In fact, if you want lenses like the 70-200 f2.8, which was the original subject of the discussion and has several advantages including speed and thin DOF/ bokeh, your only choice from the manufacturer is a FF lens, and there are many thousands of pro-level photographers using them on crop frame bodies. I'm a Canon shooter, so cannot comment in detail on Nikon offerings, only Canon, but if you want high performance (low f-stop) lenses, then they are only available in FF rom the manufacturer.

BIG ROB Loc: Princeton, NJ 08540

Defense post...

BIG ROB Loc: Princeton, NJ 08540

[quote=TriX][quote=BIG ROB][quote=TriX]... but FX lenses work best on FX cameras as DX lenses work best on DX cameras.)[/quote

Sorry, but with respect, I do not agree. The fact that FX lenses show lower sharpness on DxOMark tests on crop bodies does not imply that DX lenses work better, only that full frame lenses do not deliver the same sharpness on crop bodies as FF bodies (duh?), in fact, FX (or EF lenses in the Canon world) work fine on crop frame (DX) cameras. If you have verification that DX lenses work "best" on DX cameras, please post it. That will be difficult, since there are no DX equivalent lenses to many FX lenses. In fact, if you want lenses like the 70-200 f2.8, which was the original subject of the discussion and has several advantages including speed and thin DOF/ bokeh, your only choice from the manufacturer is a FF lens, and there are many thousands of pro-level photographers using them on crop frame bodies. I'm a Canon shooter, so cannot comment in detail on Nikon offerings, only Canon, but if you want high performance (low f-stop) lenses, then they are only available in FF rom the manufacturer.[/quote]

...and that full frame lens is sharper when it is mounted on a full frame camera than on a crop sensor camera.

burkphoto Loc: High Point, NC

[quote=TriX]
I can tell you that my full frame Nikkor AI primes, when adapted to my LUMIX GH4, with its 2X crop factor, are not nearly as good as my LUMIX G X- Vario pro zooms.

Used with a Metabones SpeedBooster, the Nikkors perform better, but the main advantage there is the extra stop of light concentration. That reduces the quality disparity to something close to FX lens on DX body.

TriX Loc: Raleigh, NC

Sure Big Rob, we agree on that - here is the statement that I disagree with: "... as DX lenses work best on DX cameras". If you mean that DX lenses only work satisfactorily on crop cameras (viginetting or mounting being the issue), I agree. But if you mean that DX lenses work BETTER on a crop camera than FX lenses, then I disagree with that.

TriX Loc: Raleigh, NC

Bill, I believe you, but what I don't (yet) believe is that you can extrapolate your experience with one lens on one body (+ an adapter) to the idea that an an FX lens on a DX body is inferior to a DX lens on a DX body, assuming there was an equivalent DX lens, which there isn't (which is an important point). I do believe that a 70-200 f2.8 FX produces better results on a FF body than a crop body, and that a 70-200 f2.8 FX produces excellent results on a DX body, which I believe was the gist of the original question.

Cheers

tooltinker

I shoot with a Sigma 70-200 F/2.8 DG (ff desination) on a canon 7D and love the image quality and the price was fantastic compared to the canon version. I also have the Sigma 24-70 f/2.8 very satisfied with both. these are the older models that are not the new art series their prices will drop to clear inventory making way for the new, this just means bargan!

tooltinker

I shoot with a Sigma 70-200 F/2.8 DG (ff desination) on a canon 7D and love the image quality and the price was fantastic compared to the canon version. I also have the Sigma 24-70 f/2.8 very satisfied with both. these are the older models that are not the new art series their prices will drop to clear inventory making way for the new, this just means bargan!

GrandmaG Loc: Flat Rock, MI

I've often wondered about this same situation. After selling my 70-200/2.8 because it was too heavy, every where I turn, I read that it is THE lens to own. I have pretty much decided to stay with crop sensor. I just cannot justify the cost of a full frame camera and the lenses to go with them. If I were planning to become a professional photographer, I would go full frame. However, I like photography as a hobby and it might take the joy out of it if it were a JOB!

I found this video on YouTube by Tony Northrup interesting: "Should you use full frame lenses on crop bodies - Yes and No"

https://www.youtube.com/watch?v=YDbUIfB5YUc