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08-20-2013, 07:56 AM   #1
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Inconsistent exposure with a 2x TC

I've never been a fan of teleconverters, but when I recently spotted a Tamron-F PK-A (KR with the Ricoh pin removed) 2x MC4 TC for $4, I had to pick it up. I thought if nothing else, I'd de-glass it & use it as an "A" extension tube. I tried it out on a couple of lenses & it's actually not bad. Surprisingly sharp & relatively free of PF. Better than I expected.

Anyway - I've noticed that it exposes differently with different lenses. On the Pentax A 50/1.7, it consistently underexposes by about 1.5 stops. On the Tamron SP 60-300 model 23A, it consistently overexposes by a stop.

Anyone else used a TC that exhibited this behavior? Just curious...

Bob :-)


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