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Larry C

Sigma EX 17-35 F2.8-4.0 for full frame?

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These lenses are cheap and plentiful and have a fairly close focus. Anyone tried it? I haven't seen any zoom gears, so I assume there's a problem?

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Hi,

I did use the HSM Version in the good old times with my F80 and I was pretty happy with this lens.
You can avoid a diopter even with a small dome because of the close focus capabilities.
But the zoom gear is a problem. You will not get anything from stock but you need a custom solution.
My solution was this one: http://www.uwpix.org/viewtopic.php?f=56&t=2890
Today you will more look for someone who offers custom made solutions with a 3D printer. (like this one: http://www.uwpix.org/viewtopic.php?f=53&t=6184&start=34 )
But the diameter of this lens is pretty big, so you have to make sure that there is enough room for the zoom gear in your housing.

Juergen

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Thanks Juergen. Just got a good deal on one on E-Bay, and I plan to try it on my D300 and my F100. What extension length do you use with your smaller dome?

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That's not easy to answer since I did not use any extension but a dome with specific length.
I did try to measure the distance from the bayonet of the camera to the tip of the dome glass and got 145mm.
The dome should have a radius of 80mm. So if the dome is exactly adjusted for the lens (no guaranty for that, but the results have been ok) the pupil point of the lens should be at 65mm from the bayonet of the camera.
With this information your housing manufacturer should be able to provide a solution.

In general you can say:
R = Radius of the dome glass
E = distance of the pupil point from the bayonet of the camera

G = Distance bayonet of the camera to the bayonet of the housing
L = Length of the port from bayonet of the housing till the the tip of the dome glass
V = Length of the extension

You have
R + E = G + V + L and V = R + E - G - L

Hope my English is good enough to describe it in an understandable way.

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Terrific. Thanks for the help. I got the non HSM version, which is a bit smaller and fits fine in my dome. It looks like the Sigma 10-20 gear might be close. Otherwise, I have a spare Sea & Sea 60mm gear that I could alter or make a mold and build one out of resin. I'm looking forward to trying it on my F100 as the widest lens I had for full frame was my 35mm f2.0. One thing I really like about the lens is that it zooms inward for both ends of the range and the center area is only about 1/4" different. In reading reviews, people complained a bit about sharpness and contrast so we'll have to see.

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Due to my knowledge the non HSM version is a much older model with a closed focus distance of 50cm.
So you need a diopter which will reduce your angle of view. This lens might have been cheep but it would not have been my choice (except here is another better non HSM version which I do not know).

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