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shadowlies May 9, 2006 11:33 AM

I have been looking at different lens to put a new kit together?

The Canon 300mm f2.8 is just too much money for me?

So I looked at the Sigma APO f2.8 EX DG/HSM lens. Is this lens compatible with the Canon 1.4x II extender? I have read I think of somewhere of someonehaving problems with a Sigma lens and a Canon extender.

I would really appreciate your comments.


GM2006 May 9, 2006 1:01 PM

If you paying almost $1000 for Sigma 2.8 you can add 100 more and buy Sigma extender. I do not understand why extender can be a problem? It is just a piece of glass with couple of contacts in it. I am using Tamron 1.4 with Canon lenses and never had a problem. It is more likely that contacts are just dirty. There is no any electronic circuits in extender as far as I know.

NHL May 9, 2006 2:05 PM

1. The Canon teleconverters are longer than the Sigma's TC (i.e. the internal portion that extends past the lens mount is thicker) - They might work on the longer Sigma tele, but not on others like the 70-200 f/2.8 for example because the back of the lens collide into the front of the teleconverter ;)

2. If you're thinking about getting the Sigma 300mm f/2.8, the Sigma 120-300 f/2.8 EX zoom with HSM is actually a better buy: a) less expensive and b) sharper! (just check the MTF's for digital cameras) They are both APO lenses... and the 120-300 f/2.8 works with the Canon's TC
3. The teleconverters 'translate' the aperture data from the lens to their equivalent value :idea:
-> without the electronics the aperture info is not transfered allowing the camera to be fooled into AF @ smaller than f/5.6 :cool:

shadowlies May 9, 2006 10:57 PM

With the Sigma extender will it allow full function of Canon lenses and also offer the same weather seals as the Canon counterpart?

I also thought that the Canon extender would work on the 70-200. I need to be able to get to a shop to see things for myself. This is the problem I face living 5-6 hours away from the nearest store stocking Canon.

So I thank you greatly for your advice. Please keep them coming.

NHL May 9, 2006 11:32 PM

shadowlies wrote:

With the Sigma extender will it allow full function of Canon lenses and also offer the same weather seals as the Canon counterpart?
Yes the Sigma TC's are shorter and will work on the same compatible Canon lenses (i.e. mostly tele lenses); However they do not have the weather seal... :(

-> I have the Sigma 70-200 f/2.8 as well and I know for a fact that it won't work with the Canon extenders! ;)

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