Thinking about adding a TC


TPF Noob!
Jul 27, 2006
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Mesa, AZ - ASU Polytecnic
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So at the moment I have a Tamron AF 75-300mm F/4-5.6 lens, and its all right but its defiantly a budget lens. Ive found that its fairly sharp at f/9 - f/11 and about 250mm zoom. However, I would like to extend that range and don't have much of a budget so I'm thinking about getting a teleconverter.

Would the image still be sharp if the lens is at 250mm but with a 1.4 teleconverter attached?

I've heard that TC's can negatively effect AF with certain apertures, I'm wondering if that will effect my lens. Also I've read that they can degrade quality but I have seen test shots with a 1.4 and I didn't see much of a difference personally.

Finally, are the Tamron TC's any good? The test shots I've seen were with a Canon TC and havn't had a chance to see any examples from a Tamron.

So do you guys think a TC is worth the purchase?
TC's are handy to have in a pinch and under the right conditions..

They are not a substitute for a longer lens.

You will lose a stop or more of light so your lenses will be darker to view through, and you will need lots of light outside with the lens you have.

The quality of the photograph is only as good as all the glass it has to go through to reach the film plane, so adding an additional piece of optics will almost always cost you in IQ; the question is is that loss if quality acceptable to you.

The very excellent Canon 1.4 II TC is well made and has L quality optics.... It only fits on a few Canon high-end lenses and may not fit your Tamron...
I wouldn't fit one on that lens, the canon won't fit but kenko should but i only use converters on primes, you can get away with 1.4x on L quality zooms
As mentioned, a TC will eat some light, which is why they often cause the loss of AF when used with slower lenses. Most cameras need F5.6, so if you used a 1.4X TC with that lens, you might be able to AF on the sort end but maybe not on the long end.
You can still manually focus though.

Either way, you would have a heck of a time getting hand holdable shutter speeds in anything by good light...and if you wanted to use the optimal apertures F9-F11...then you might need a tripod or something similar.

I'm not saying don't get a TC...but if you do, don't expect outstanding results.

I've got an old Tamron 2X's OK. Not outstanding but not too bad either.
Thats what I was expecting, I think my best bet is to see if I can find one to try on my own. I would generally only use it outdoors for aviation photography so light wouldn't be much of an issue.

But for now I guess the best way to go is to just wait since I don't think I want to lose any more quality out of this lens.

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