Brucej67 Loc: Cary, NC

Steve, I always talked about the image produced not looking through the camera or live view, my topic has always been about the image, and on the image (photo untouched by post processing) there would be a difference.

rehess Loc: South Bend, Indiana, USA

Difference between what and what??

Brucej67 Loc: Cary, NC

It should be obvious what I meant but to spell it out the difference is the size of the image between the full frame lens on the DX camera versus the size of the image taken with the DX lens on the DX camera. Please I don't want to discuss this anymore. There was a new thread today and a similar discussion.

oldtigger Loc: Roanoke Virginia-USA

they looked the same to me.

rehess Loc: South Bend, Indiana, USA

The problem with this discussion is that you keep seeming to agree, but then it turns out you have a non-existent difference in mind.

The viewfinder, LiveView, and final sensor image all show essentially the same view; there is no meaningful difference between them

Other than possible difference in quality,

There is no difference between what you see in viewfinder when a DX lens is mounted on DX camera and when an FX lens of same focal length is mounted on that same camera

There is no difference between what you see in LV when a DX lens is mounted on DX camera and when an FX lens of same focal length is mounted on that same camera.

There is no difference between what is captured by the sensor when a DX lens is mounted on DX camera and when an FX lens of same focal length is mounted on that same camera

The only potential differences between DX lens and FX lens of same focal length mounted on same DX camera are quality and cost

When talking about DX camera, other than potential differences in quality and cost, no difference is caused by replacing DX lens by FX lens of same focal length, so there is no reason to mention lens when talking about the difference.

Brucej67 Loc: Cary, NC

I take it that you are not a TROLL so I will answer you. Your statement "There is no difference between what you see in viewfinder when a DX lens is mounted on DX camera and when an FX lens of same focal length is mounted on that same camera" is wrong from the final image produced by the crop frame camera. You don't need me to confirm this do your own research on the internet and if you find out that an image produced (view able on a CRT or printed without post processing) between a full frame lens on a crop frame camera is in every way equal to a crop frame lens on a crop frame camera (especially the field of view on the visible image) I will concede to your point of view, but remember I say image (picture either view able on a CRT or printed without post processing cropping).

rehess Loc: South Bend, Indiana, USA

I will do no Internet research on this subject; I don't need to, because I have done the lab many times.

As I indicated yesterday, I did this regularly when I had a Canon Rebel {which you would characterize as a DX camera}.
Somedays I would use the EF {FX to you} lens which had been kitted with my previous 35mm camera and somedays I would use the EF-S {DX to you} lens which was kitted with my Rebel. If I set the lenses to the same focal length (*), I got images which were equal in every respect. {and, no, I normally do not do any PP; normally I use the JPG Straight Out Of Camera}.

As I indicated yesterday, I do this regularly today with my Pentax K-30 {which you would characterize as a DX camera}. I have several old KA lenses dating back to when I had a 35mm Pentax camera, and like many other Pentax owners, I have purchased several more old KA lenses recently.
Somedays I will use one of those old KA lenses {FX to you} and somedays I will use a modern DA lens {DX to you}. If I set the lenses to the same focal length (*), I get images which are equal in every respect {reminder that no PP is involved because I use SOCC}.

Nothing I have said on this thread was a result of Internet research. Everything I have said on this thread has been a result of my own experience. I know from experience that if I put a 50mm lens, or a lens of any particular focal length, on my K-30 camera, the result I get depends entirely on the focal length of the lens, it is entirely independent of the sensor it was designed for.

(*) I use the "set to" terminology because some of these lenses are zoom lenses. Zoom or prime doesn't matter - what matters is that lenses are providing same focal length

SteveR Loc: Michigan

That's just it, Bruce, a house that would be the center subject of both lenses would be projected onto the sensors at the same size.

Leitz Loc: Solms

stillducky, I beg your forgiveness for calling your comment condescending.

Brucej67 Loc: Cary, NC

Yes but the area surrounding the house (edge to edge) would be different (or to put it another way one cropped the other UN-cropped).

SteveR Loc: Michigan

That's why they call it them "crop" cameras, Bruce.

rehess Loc: South Bend, Indiana, USA

This subject has had entirely too much talk, so I don't plan to say any more unless something new comes up. I'm guessing you don't have any FX lenses so you can't try this for yourself - but actually doing things, rather than talking about them, is how you gain real understanding.

I had been thinking of going out into my yard and doing a demonstration ... but that would be Pentax equipment, and then I discovered an already existing demonstration here using Nikon equipment.

http://www.uglyhedgehog.com/t-136625-1.html

Compare the first two images. The first one is 50mm DX lens on DX camera; the second one is 50mm FX lens on DX camera. They are identical within measurement uncertainty.

Brucej67 Loc: Cary, NC

And that is all I meant by putting my 300mm f.28 full frame lens on my crop camera D7200 instead of a full frame camera like my D610, D800, D810 or D4. I do the same with the Sigma 150-600mm Sport and the Nikon 80-400mm G putting them on either my D2x, D7200, D500 or D7100.

SteveR Loc: Michigan

Here is a good discussion of the crop factor from B&H. Notice the illustrations.

http://www.bhphotovideo.com/explora/photography/tips-and-solutions/understanding-crop-factor

SteveR Loc: Michigan

But what is projected onto the crop sensor is projected at the same size as what is projected onto the full frame sensor (see the illustrations in the link I posted). It doesn't matter, either, whether it is projected by an fx or dx lens. A 300mm lens is a 300mm lens.