Why no mirror telephotos for DSLR Canon?

Started Jan 25, 2010 | Discussions
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jpr2 Forum Pro • Posts: 14,957
re: it would be quite a revolution

RobertSigmund wrote:

Wow - time to get one and either reactivate my minolta film slrs
or buy a sony dslr.

no doubt in-body IS must play a role here, but above all if we consider
how it is possible to AF a f/8 lens using standard PD sensors... it would
mean quite a revolution should Canon decide to build such a f/8 CAT.
There are f/5.6 500mm Rubinars but they are loosing all benefits of
being light and small (Minolta-Sony 600/8 is quite tiny).

I've old 500/8 mirror, bought over 20 yrs. ago - it is a typical no brand,
el-cheapo lens, and yet... when focused carefully it can hold it's own,
even with 2x and 1.4x teleconverters:

all shots taken with 40D, ISO 400 (focused with LV, 550EX sync.at
1/250 sec was used to freeze any motion)

top row (from the left):

  • 1) at the native 500mm f/8,

  • 2) for comparison purposes - EF 300/4L IS + 2x mkII TC (painted black, see just below),

  • 3) cat 500/8 + 1.4x pro300dg of Kenko.

bottom row (from the left):

  • 4) 100% crop of the native 500 f/8,

  • 5) how does 1000mm look like: 500/8 CAT with the 2x mkII and lens hood on 400D, (there is a 12mm ET together with M42 to EF-mount adapter equipped with a confirm chip between the cat, and 2x TC) - notice how small the cat is in comparison to this 2x TC,

  • 6) cat 500/8 + 2x mkII TC;

panels 1-3) and 6) are resized in the same way; so, they can be
compared between all four;
panel 4) is the actual 100% crop of the panel 1) - before resizing
of course

street candids (non-interactive):
music and dance:
wildlife & macro:
interactive street:

Comments and critique are always welcome!

Lee Jay Forum Pro • Posts: 51,686
Re: I have a $700 1900mm f15

Bill MacBeth wrote:

Here's what I mean by 'eyepiece projection'. I've used the technique many times on my on reflector, and on a larger refractor at a university. An eyepiece (normally used for visual observation) is moved away from the visual focal location, so that it profects a focused image about four inches outside itself. The film plane or sensor plane of the camera is placed at that location. No lens is used on the camera.

Oh. This was used with eyepiece projection through my little Canon S3IS compact, which obviously had a lens on it, with the lens set at maximum wide angle (36mm-equivalent).

This was through the same eyepiece, at maximum telephoto (432mm-equivalent):

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Lee Jay
(see profile for equipment)

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samWebster123 Senior Member • Posts: 1,153
I'm referring to camera lenses

not telescopes!

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Bill MacBeth Senior Member • Posts: 1,631
Re: I have a $700 1900mm f15

Lee Jay,
The upper photo is especially nice. I bet few would guess how it was taken.

I think we're on the same page now.

Thanks and regards, Bill

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