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Old 24-08-2009, 03:07 PM
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Sigma lens to Canon body?

I have looked and looked but will ask here.
I can borrow a nice Sigma 200mm f2.8 lens (sigma mount).
Is there an adaptor I can get to fit it to a 350D etc?
It would be for wide field sky work so if I loose elec focus & apature it doesn't matter.
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Old 24-08-2009, 04:22 PM
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Hi David,
according to what I was able to find about this on the net, not possible task especially because the lens is not yours, so you can not fiddle with it.
I propose you get a similar lens with M42 thread mount, then there are adaptors on Ebay for canon for up to $10 (and there are even models available with focus confirmation chip, however a bit more expensive).
I have one such lens spare (Sun), but no adaptor unfortunately. If you are desperate, I can give it to you to play with it until you find something better :-)
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Old 24-08-2009, 04:32 PM
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Quote:
Originally Posted by bojan View Post
Hi David,
according to what I was able to find about this on the net, not possible task especially because the lens is not yours, so you can not fiddle with it.
I propose you get a similar lens with M42 thread mount, then there are adaptors on Ebay for canon for up to $10 (and there are even models available with focus confirmation chip, however a bit more expensive).
I have one such lens spare (Sun), but no adaptor unfortunately. If you are desperate, I can give it to you to play with it until you find something better :-)
Well here is the deal, I can buy it for a steal , then I could fiddle with it. Can you change the mount on the lens itself?
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Old 24-08-2009, 04:40 PM
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I will have a look.. and will let you know.
It is probably possible, but it may include irreversible modifications..
Are you prepared for this?

EDIT:
One more question: is it worth it?
It may be good if you have test images of star fields. so you can decide you really want this lens modified.
I did this mod ( -> EOS) on two lenses: Canon FD 50mm F1.4 (it was absolutely worth the trouble) and one Tamron 200mm F2.8 (was Minolta mount.. the lens is so-so, but my Tair11-A 135mm is much sharper in the centre.. so I am not using it much).

Last edited by bojan; 24-08-2009 at 04:55 PM.
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Old 24-08-2009, 05:03 PM
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OK, if it is Sigma SA mount, it has the same flange to focal plane distance as EOS cameras (44mm).
Theoretically, it should be possible to remove the Sigma flange and install one of those cheap M42->EOS adapters (from ebay).
However, I would still need to investigate some more, or to see the actual lens to let you know if is possible and what would it take to do it :-)

More about it here on Wikipedia:
http://en.wikipedia.org/wiki/index.html?curid=6773242
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Old 24-08-2009, 07:02 PM
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mmmmmm, the same electrionic protocall as Canon.Just the flange is the issue.
Thanks mate
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Old 24-08-2009, 07:11 PM
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Originally Posted by DavidU View Post
mmmmmm, the same electrionic protocall as Canon.Just the flange is the issue.
Thanks mate
The same protocol, meaning Motorola SPI serial bus.. but not necessarily the same functionality/inter-changeability..
Anyway, that does not mean a lot for astro-photography, you do not really need autofocus and/or iris control for that.

As for the flange, as below or just type "M42" in search bar at ebay:
http://cgi.ebay.com.au/M42-Pentax-Ze...d=p3286.c0.m14
The only thing needed to be done is to machine the internal hole, and to modify it such that it can fit to the lens after Sigma flange is removed (it is probably mounted with 3 small screws)

Last edited by bojan; 24-08-2009 at 07:26 PM.
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Old 24-08-2009, 08:20 PM
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Yes there is an adapter .

Sorry , I've not got any Sigma lenses I'm prepared to lend to anyone. You might be lucky and find someone more generous at your local club.
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Old 24-08-2009, 11:23 PM
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David,

Have a look for Steve Mogg's web site. If he doesn't have what you need already, you should be able to email him and ask him what he can do for you. It might work?

Regards,
Humayun
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Old 25-08-2009, 06:45 AM
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I had look at what Steve Mogg has..
It seems he is re-selling the same adapters available on ebay, with his price margin. They are all coming from various manufactures in China, anyway..
He does not have Sigma -> EOS adapter, though.

Because Sigma produces lenses for various cameras (including Canon), I do not think there will be adapter available from third-party vendors, since it is easier to go to Sigma service and ask for conversion.
Perhaps this is what you should try first.
If they can not or do not want to do it for reasonable price (which is quite likely if lens is older), then the modification is certainly an option.
That is, if this particular lens is really that good (which may be the case, but I do not know for sure.. I tried only Sigma 35-70 Zoom lens once, and it proved to be quite sharp, even in corners of the frame - of course, I had to step it down to f4).

Last edited by bojan; 25-08-2009 at 07:36 AM.
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Old 27-08-2009, 06:53 PM
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Hi David, what is your decision re modification of that lens? Go or no go ? :-)
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Old 27-08-2009, 07:47 PM
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Originally Posted by bojan View Post
Hi David, what is your decision re modification of that lens? Go or no go ? :-)
I will get hold of it as soon as I can.I will then see if I can do a re-mount job or try ringing the Sigma service center for a quote on doing it.
Thanks for your help & time
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Old 27-08-2009, 08:25 PM
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No worries, David.
If al lhat fails, I can do it with the help of my friend, who has a very decent workshop (where I did mods on my lenses)
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Old 27-08-2009, 08:54 PM
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No worries, David.
If al lhat fails, I can do it with the help of my friend, who has a very decent workshop (where I did mods on my lenses)
Ah ! Thankyou.
I had a friend Glen David who had a photographic shop in chappel st, I was going to track him down.
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