Industry News: Nikon Announces Development of Next Generation Full-Frame Mirrorless Camera and Nikko

[neuroanatomist]

Re: Industry News: Nikon Announces Development of Next Generation Full-Frame Mirrorless Camera and N

All this talk about how hard it is to make a good adapter and how it will degrade the image off centre.

I have never seen anybody complaining about Canon teleconverters, after all, an adapter is just a teleconverter without glass.

Umm No....

A teleconverter magnifies the image.

Whereas an adapter connects a lens to a body at the correct distance for the lens to work.

But how does the TC do that? It moves the lens forward by a prescribed distance and then magnifies a portion of the image circle, focusing it to the sensor plane. Like an adapter it has to maintain alignment between lens and the sensor, otherwise it would be magnifying a tilted image circle.

Teleconverters aren’t perfect. They lose sharpness and necessarily lose light. I’ve never experienced alignment problems (but again that’s in my own anecdotal usage, not from lab testing).

But the point is TC's are only using the bit of the image circle that even Roger's testing shows minimal degradation.

Part of the reason they lose sharpness could well be due to alignment.

Exactly. The effect of a misalignment is most evident at the periphery of the image circle. A TC is similar to using an adapter with a lens for a larger format (e.g. FF lens adapted to APS-C body), you're effectively cropping away the problematic area of the image circle.

In the context of adapting a FF lens to a FF camera, the issue becomes relevant.

 

[takesome1]

Re: Industry News: Nikon Announces Development of Next Generation Full-Frame Mirrorless Camera and N

All this talk about how hard it is to make a good adapter and how it will degrade the image off centre.

I have never seen anybody complaining about Canon teleconverters, after all, an adapter is just a teleconverter without glass.

Umm No....

A teleconverter magnifies the image.

Whereas an adapter connects a lens to a body at the correct distance for the lens to work.

But how does the TC do that? It moves the lens forward by a prescribed distance and then magnifies a portion of the image circle, focusing it to the sensor plane. Like an adapter it has to maintain alignment between lens and the sensor, otherwise it would be magnifying a tilted image circle.

Teleconverters aren’t perfect. They lose sharpness and necessarily lose light. I’ve never experienced alignment problems (but again that’s in my own anecdotal usage, not from lab testing).

But the point is TC's are only using the bit of the image circle that even Roger's testing shows minimal degradation.

Part of the reason they lose sharpness could well be due to alignment.

Exactly. The effect of a misalignment is most evident at the periphery of the image circle. A TC is similar to using an adapter with a lens for a larger format (e.g. FF lens adapted to APS-C body), you're effectively cropping away the problematic area of the image circle.

In the context of adapting a FF lens to a FF camera, the issue becomes relevant.

So adding an extender can introduce a loss of IQ because of alignment issues.
The discussion was directed toward different manufactures and adapters.
But would it be relevant with Canon lenses and Canon bodies.
A curiosity would be to compare the 200-400 L using internal and external.

https://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=764&Camera=979&Sample=0&FLI=5&API=1&LensComp=764&CameraComp=979&SampleComp=0&FLIComp=6&APIComp=1

 

[3kramd5]

Re: Industry News: Nikon Announces Development of Next Generation Full-Frame Mirrorless Camera and N

All this talk about how hard it is to make a good adapter and how it will degrade the image off centre.

I have never seen anybody complaining about Canon teleconverters, after all, an adapter is just a teleconverter without glass.

Umm No....

A teleconverter magnifies the image.

Whereas an adapter connects a lens to a body at the correct distance for the lens to work.

But how does the TC do that? It moves the lens forward by a prescribed distance and then magnifies a portion of the image circle, focusing it to the sensor plane. Like an adapter it has to maintain alignment between lens and the sensor, otherwise it would be magnifying a tilted image circle.

Teleconverters aren’t perfect. They lose sharpness and necessarily lose light. I’ve never experienced alignment problems (but again that’s in my own anecdotal usage, not from lab testing).

But the point is TC's are only using the bit of the image circle that even Roger's testing shows minimal degradation.

Part of the reason they lose sharpness could well be due to alignment.

Perhaps so

 

[neuroanatomist]

Re: Industry News: Nikon Announces Development of Next Generation Full-Frame Mirrorless Camera and N

So adding an extender can introduce a loss of IQ because of alignment issues.
The discussion was directed toward different manufactures and adapters.
But would it be relevant with Canon lenses and Canon bodies.

No, you've missed the point. The point was that misalignment affects the periphery of the image circle, and an extender magnifies the center of the image but the periphery is cropped away. An extender is similar to adapting a FF lens to a crop body. The issue manifests when adapting a FF lens to a FF body.

(As a side note, telephoto designs generally aren't limited by the image circle, so they're also less likely to be affected by a misaligned adapter.)

 

[3kramd5]

Re: Industry News: Nikon Announces Development of Next Generation Full-Frame Mirrorless Camera and N

It should be possible to actuate a sensor and use test charts to bring things into alignment, much like AMFA.

Nikon's camera is rumored to have IBIS. I haven't see one yet which moves in an out of plane or pivots, but doing so would not be revolutionary.