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

Jack Hogan wrote:

alanr0 wrote:

... my guess is that this is due to a small focusing error, possibly combined with a change in spherical aberration in the preceding optics. ...

Bill, slightly OT. You know I am a raytracing noob and the first time I tried it recently I was flabbergasted at the amount of spherical aberration from a single lens with perfectly spherical surfaces.

Yes, a simple single element will have significant spherical aberration.

But most of the optical prescriptions from patents have far less because they are corrected. Never-the-less, some exhibit more than others.
You can see it by (mercilessly) zooming in of where the rays meet the image plane.

That would suggest that the choice of where exactly the bundle intercepts the optical axis on the image side is a range as opposed to a single hard number.

Most of the numeric information you see is par-axial, from rays very close to the optical axis.
I suppose I could report lateral and transverse spherical aberrations but don't.

Does raytracing take this into account or does it just use the marginal rays? If it does take it into account, what criterion is normally used to determine the location of the CLC in order to draw the relative rays?

The ray tracing is entirely geometric, following Snell's Law.
Naturally this often, but not always, affects the marginal rays the most.

What is CLC?

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

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