Why don't photographers ever rate lenses with FF cameras set to crop image: I always see evals with TC's, longer lenses, etc. But why not do the eval with a 500mm FF set to crop size.

SonyBug

I always see evals with TC's, longer lenses, etc. But why not do the eval with a 500mm FF set to crop size. That would be an effective 800mm or so, and would to me be the same thing as a 1.4 TC. And it would be cheaper and faster.

Bill_de Loc: US

You don't need to shoot in crop mode to show what a cropped image would look like. All that's necessary is to show the FF image cropped. The image, I believe, would still have the same pixels per inch. If so, all you need is to do a crop yourself.

Unless I am totally off base, which is very possible.

But, I would expect DX lenses to be tested on DX cameras and FX on FX cameras.

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imagemeister Loc: mid east Florida

Bill_de wrote:

You don't need to shoot in crop mode to show what a cropped image would look like. All that's necessary is to show the FF image cropped. The image, I believe, would still have the same pixels per inch. If so, all you need is to do a crop yourself.

Unless I am totally off base, which is very possible.

But, I would expect DX lenses to be tested on DX cameras and FX on FX cameras.

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This is true - but it does help for composition to know where the boundaries are in the viewfinder while shooting !

imagemeister Loc: mid east Florida

nikonbug wrote:

I always see evals with TC's, longer lenses, etc. But why not do the eval with a 500mm FF set to crop size. That would be an effective 800mm or so, and would to me be the same thing as a 1.4 TC. And it would be cheaper and faster.

700mm to be exact .............

And it would be cheaper and faster.[/quote]

This is why I use Sony cameras with Clear Image Zoom ......

orrie smith Loc: Kansas

when you shoot an ff camera in dx mode, you lose pixels. on the nikon d750 you would go from 24 megapixels to about 18 megapixels. you would be better off to crop the photo in post processing. when you shoot in crop mode, you are not actually getting a larger image, it is just cropping the photo on the camera sensor instead of cropping the photo in software. the only time you would need to use the dx mode is if you are having a hard time positioning the image while taking a photo. a dx setting on an fx camera with a 300mm lens does not physically make the 300mm a 450mm lens. it just seems like it does.

wingclui44 Loc: CT USA

nikonbug wrote:

I always see evals with TC's, longer lenses, etc. But why not do the eval with a 500mm FF set to crop size. That would be an effective 800mm or so, and would to me be the same thing as a 1.4 TC. And it would be cheaper and faster.

That's completely different, when cropping, it will lost almost half the pixel of the sensor. when using TC, you are using the whole Pixel area of the sensor. The actual focal length of the lens will be 700mm with TC1.4, not equivalent 700mm!
By the way, cropping after taking the image with FF in PP is the same as setting the FF to crop mode to shoot. You crop before or crop after is the same. So why bother using crop mode, except when you have only a DX lens and you what to use it on a FX body, but the camera will automatic set it self on crop mode when it detects a DX lens is mounted.

imagemeister Loc: mid east Florida

wingclui44 wrote:

That's completely different, when cropping, it wil... (show quote)

you missed the wording - effective IS the actual - equivalent is the focal length needed for full frame same field of view ......

[quote=wingclui44]That's completely different, when cropping, it will lost almost half the pixel of the sensor. when using TC, you are using the whole Pixel area of the sensor. [quote]

This why they make pixel enlargement software ! - and so you do not loose f-stops of light from the TC !

wingclui44 Loc: CT USA

[quote=imagemeister]you missed the wording - effective IS the actual - equivalent is the focal length needed for full frame same field of view ......

[quote=wingclui44]That's completely different, when cropping, it will lost almost half the pixel of the sensor. when using TC, you are using the whole Pixel area of the sensor.

Quote:

This why they make pixel enlargement software ! - and so you do not loose f-stops of light from the TC !

Thank you for your correction!

Nelson.I Loc: Monument, Colorado, USA

Bill_de wrote:

You don't need to shoot in crop mode to show what a cropped image would look like. All that's necessary is to show the FF image cropped. The image, I believe, would still have the same pixels per inch. If so, all you need is to do a crop yourself.

Unless I am totally off base, which is very possible.

You are dead-on correct.

pmackd Loc: Alameda CA

orrie smith wrote:

when you shoot an ff camera in dx mode, you lose p... (show quote)

Actually you go to about 10 megapixels not 18. You have to divide 24 by 1.5 x 1.5 since area is involved.

bull drink water Loc: pontiac mi.

best to buy a aps-c body for the lens. my fx flips to dx but looses half the pixels. i'd do better cropping the fx image. I have both formats, and I choose which to use and when.