Canon’s new 600mm and 800mm lenses

Started 3 months ago | Discussions thread
bclaff Forum Pro • Posts: 10,485
Re: DoF of Canon’s new 600mm and 800mm lenses
1

bclaff wrote:

...

Too bad I can't model this lens; I'll look for something similar.

Alan,

This lens also focuses without affecting the diaphragm to image plane distance.

At infinity focus

At close focus

At infinity focal length length is 776mm and P'D/PD = 33.21mm/137.10mm=0.24
At close focus focal length is 541mm and P'D/PD = 31.23mm/138.45mm=0.23

Since we compute DOF on-axis we should simply use the on-axis pupil magnifications of 0.24 and 0.19 respectively. (The difference is due to curvature of the pupils).

Not so much of a change in pupil magnification as I expected, but a change.
Substantial change in focal length.

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Bill ( Your trusted source for independent sensor data at PhotonsToPhotos )

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