teleconverter for sigma lens?

[jensgt]

I have been thinking about getting a teleconverter to be able to get a little closer to birds and such...but it seems that sigma does not make one that goes with the 70-300 APO DG Macro lens that I have for my Sony Alpha. Looking around it seems like I would need a new lens...none in the affordable range for me right now. Anybody know if another company makes teleconverters that work with Sigma lenses? Or a combo comparable lens/teleconverter combo that would not combine to be like way over a thousand bucks? Its not something I have to have right now...but would like to in the future. Right now I just started going to school...so it could be a while!! lol

 

[PhotoXopher]

Maybe Kenko?

 

[Overread]

Kenko is your best and only chance I would exepect for a good quality teleconverter that would fit. However there are two possible problems with this. The first is that even the kenko teleconverters might not fit the lens itself (test in shop if you can't find someone to confirm this).

The other problem is that adding a teleconverter takes away one stop of light from the setup and will also affect the image quality of the final shot. That means you lose one stop making it an f8 lens at the long end which will most likley slow your auto focus speeds and the accuracy of the AF.
A 2*teleconverter I would not use - 2 stops of light lost would make it far too slow a len and the image quality would take a very significant image quality drop (even top range 70-200mm lenses have trouble with the 2*TC).

Overall if you want more zoom I think your best bet is a different lens. Perhaps consider the Sigma superzooms - 50-500mm, 150-500mm as cheaper options

 

[LeoLady]

Do NOT get a Kenko - I just found out they are known to screw up Sigma Lenses - this info came too late for me - I have had 2 Sigma lenses repaired and 2 more in for repair - as a result of using as Kenko teleconverter with them - I THOUGHT it was my camera and bought a new one (no choice, I was in India) and the Kenko teleconverter screwed up the SONY kit lens too. Yep - I had to buy another camera. Very expensive trip.

NO KENKO!!!

 

[gsgary]

That lens is not good enough to handle a tele converter

 

[Overread]

Leolady - what specific lenses and teleconverters were you using and what problem did you experience with them? Its the first time I read of kenko teleconverters messing up sigma lenses.

 

[myfotoguy]

My Tamron 1.4x Pro (supposedly the same thing as Kenko, one makes the other, but that's just rumor, have not verified it).

Anyway, that didn't screw up the Sigma 50-150 2.8 I had, but auto-focus was behaving very erratically. When I got a Sigma TC, all worked great. I have read this from other users too (dpreview forums). Other folks have experienced sigma lenses not playing nice (my experience was focusing) with other TC's.

This is Nikon mount by the way.

 

[icassell]

It is not just the loss of light that makes a TC inappropriate for some lenses. A TC always will degrade image quality to some degree (some more than others) because you are adding additional glass elements between your lens and your camera. This may not be very noticable if your main lens is very high quality, but it will magnify the flaws of a lower quality optic. TC's tend to work better with primes than zooms, but I use a 1.4X with my zooms (the sigma matched EX series) with decent results. The 2X is terrible with my zooms (I haven't gotten rid of it yet because I am waiting to see how it does when I buy a long prime).

 

[gsgary]

My Kenko 2x works flawlessly but i only use it on primes
http://gsgary.smugmug.com/Sports/Sports-Portfolio/Image00004/188042218_XuHN3-L.jpg

 

[jensgt]

I realized that nothing would work with my 70-300 so I just got the 150-500 instead. Might add a 1.4 to that one day...but for now its awesome.

 

[gopiqpp]

You must be mistaken. In the past two years I've used Kenko 1.4 and 2x TC's extensively with my Sony kit lenses as well as the Sigma 150-500mm lens. No problems like the one you describe. Where did you hear about this problem with Kenko? Can you name the source? I did extensive web scouring to find similar instances of lens damage after using Kenko TC but your post is the only one in the world wide web to mention it. Hard to believe.If Kenko was that bad there should be many forums talking about it.

 

[SCraig]

This topic has not been posted to in over two years. I sincerely doubt that you are going to get an answer.

 

[Overread]

*thread locked*

two years old and the member making the claim hasn't appeared on site since they gave their singly flyby post. I doubt you'll get an answer from them at all and with no further evidence on the net I'd treat it as a one off incident without any supporting evidence - ergo a non-issue.