Another Teleconverter question...

I'm trying hard to curtail the LBA whilst waiting on the new body announcement but have been looking at telephotos as my kit is lacking in that dept.

I'm leaning toward getting a 70-200mm f2.8 & a 2x TC so that I can have a stab at street candids & fit the TC for some wildlife shots. Now, although the Sigma 70-200mm looks somewhat softer & has more CA at the longer end than the Tamron, the HSM would prove very valuable I would think (draw less attention in street & not scare wildlife in the field). I'm a little confused as to its compatibility with TC's though. - a few questions if you will:

Will only a Sigma 2X TC retain the HSM AF & give accurate metering, or will any other currently available TC do the job ?
If it is only Sigma, is there a special model no. or denomination I need to look out for ?
Will a TC (Sigma or otherwise), when used with my Sigma 70mm 1:1 Macro, convert it to an effectively 140mm 2:1 Macro or will it be a 140mm 1:1 ?

Anyone have the answers please ?

Cheers, Bob

The only teleconverter that will work with HSM and SDM is the Tamron MC4 and possibly certain Kenko 1.5's. The current Sigma teleconverters will not work with Sigma HSM lenses.

Ah.. thought you must of got that wrong Mike but I've just found the small print on SIgmas site: (Sony and Pentax fittings will not allow AF when the optional 1.4x or 2x teleconverter is attached.) which is more than a little crappy.

I have a promaster 1.7x teleconverter which gives good results and retains AF for screw and SDM/HSM - metering also seems fairly accurate. Picked it up new from ebay usa last year.

I use it mainly with my Sigma 50-150mm.

Hi Bob,

I went through the same dilemma a couple of months ago and went for the Tamron and used it with a Tamron 1.4x TC and a Kenko 2x TC. AF worked well with the 1.4x but it did hunt pretty badly in poor contrast situations with the 2x.

I used it on a trip to Rwanda recently and the weather was pretty wet - in the bad weather the 2x TC struggled with the poor contrast of a mountain gorilla in the jungle. Interestingly the Pentax/Tamron combination saw off the more expensive Canon and Nikon equivalents used by my friends - both of which saw failures in the wet climate.

Edit: I should also say that I was within 20ft of wild gorillas and whilst the lens isn't the quietest it didn't cause me any problems at all - I got no adverse reactions at all.

All in all, I think the Tamron is a cracking lens.

Hope that helps!

Cheers,

Annette

PS I believe that my other half bought me your Tamron 28-75 and it is great - a really good companion to the 70-200. It was in mint condition.

The TC only doubles the focal length but you will keep your focus range, the subject will be 2 times as big at the same focus distance so you're right.

Thanks all for your replies. Has given me more to consider. I think the new body announcement may complicate things further though.

Glad you're enjoying it, I hope it IS mint rather than WAS mint

Yes. It is still in mint condition!

I suspect that you are right with regard to the K7 making things complicated! Shame my birthday is so close to Christmas!