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11-13-2008, 10:58 PM   #1
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Attention Tamron 70-200 f/2.8 and Pentax 300/f4 SDM users- need urgent help

Hello,

Can anyone tell me if the Tamron 70-200 f/2.8 AFs with Pentax bodies? I'm being forced to think of this option as I'm not finding any long lenses within my budget that will go with my K 10D. I'll have to order today and need to find out fast. Also, have you noticed substantial degradation in sharpness and increase in CA after using the 2X TC? Will the Sigma 50-500 be a better option than the Tammy+2X when it comes to IQ? I don't mind losing 100mm for better IQ.

Another question, does the Pentax 300 f/4 SDM AF with Tamron/Sigma 1.4X TCs?

Thanks in advance.

Regards,
Aditya

11-13-2008, 11:11 PM   #2
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I have the 70-200 and I love the lens. It is my main walkaround lens and almost never leaves my camera. The 2.8 is great for low light work and if you sharpen to f/4 it is as sharp as a knife. And it does autofocus on the K10D.

I don't know anything about the Pentax lens or the Bigma so I can't comment on those.

Between the 3 it's going to depend on what type of shooting you plan on doing. I went for the Tamron 'cause for my type of shooting I wanted the 2.8 all through the focal range.

The Sigma 1.4x is only compatible with the Sigma lenses while the Tamron reportedly works on both the Sigma and the Tamron, and probably the Pentax lens also.

Look at this thread for a bit of info on the converter.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/41463-tamron-1...er-f2-8-a.html

Hope that helps,

-Yale
11-13-2008, 11:57 PM   #3
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Thanks Yale. My shooting is mostly wildlife and birds. And I need to have at least 400mm at the long end. Thats why I'm keen on 70-200 2.8 for large mammals and 70-200+2X for birds and smaller/distant mammals. I want to know if the Tammy will AF with the 2X on the K 10D.
11-14-2008, 12:02 AM   #4
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I found this on bhindia.com:

Pentax | SMCP-FA 645N 400mm f/5.6 ED (IF) | 26555 | B&H Photo

Are these 645N lenses compatible with Pentax K DSLRs?

11-14-2008, 12:22 AM   #5
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QuoteOriginally posted by Aditya Panda Quote
I found this on bhindia.com:

Pentax | SMCP-FA 645N 400mm f/5.6 ED (IF) | 26555 | B&H Photo

Are these 645N lenses compatible with Pentax K DSLRs?
Yes, you can use these 645 lenses on Pentax K dSLR cameras w/ an adapter, but you'd lose AF and auto metering. It's like you are using a M42 lens (someone correct me if I'm wrong).

For this 400mm lens alone, I think you'd better get the SMC A 400/5.6 in PK mount, it'd much cheaper and smaller/lighter.
11-14-2008, 12:27 AM   #6
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Thanks Frank. I deleted my 645N query because I realised that the FL is halved on SLRs. So it doesn't make sense. I'm looking for a lens that is in production and quickly available. I have been waiting since 3 months and have been len-less for over a month now
11-14-2008, 01:07 AM   #7
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QuoteOriginally posted by Aditya Panda Quote
Thanks Frank. I deleted my 645N query because I realised that the FL is halved on SLRs. So it doesn't make sense. I'm looking for a lens that is in production and quickly available. I have been waiting since 3 months and have been len-less for over a month now
Why not get a DA*300? It's available new, and it takes wonderful pictures And I'm sure it'd work w/ Tamron 1.4x AF TC.
11-14-2008, 01:31 AM   #8
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Yeah Frank, considering the DA* 300 f/4. But the problem is, some say that the new Tamron 1.4 SP AF TC wont work with it.

11-14-2008, 06:47 AM   #9
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Just checked out the Tamron website and found that there are no 2X TCs for Pentax However, Kenko does make them and I wonder if the Sigma EX 2X TC works with the Tamron 70-200 f/2.8. Any help about that?
11-14-2008, 06:48 AM   #10
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Kenko 2X MC7 DG TC looks like it has the necessary contacts for SDM support. Anyone tried it?

Check it out here:

Kenko 2x DG AF Tele-Converter for Pentax AF
11-14-2008, 08:40 AM   #11
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QuoteOriginally posted by Aditya Panda Quote
Just checked out the Tamron website and found that there are no 2X TCs for Pentax However, Kenko does make them and I wonder if the Sigma EX 2X TC works with the Tamron 70-200 f/2.8. Any help about that?
2x TC is just too much for a lens like DA*300/4. I'd rather using a 1.4x TC and crop if needed.

Sigma EX TCs are known to have problem using w/ some lenses due to their design (one side will protrude into the matching lens' rear end). Better know if the lens you are buying is compatible w/ it before you buy the lens or TC.
11-14-2008, 09:08 AM   #12
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I think you should consider the sigma 50-500 more. It is a heavy lens but sure has a great range for wildlife and versitile for other shooting too. It will be heavier than the other options you've considered though.
11-14-2008, 10:30 AM   #13
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QuoteOriginally posted by frank Quote
2x TC is just too much for a lens like DA*300/4. I'd rather using a 1.4x TC and crop if needed.

Sigma EX TCs are known to have problem using w/ some lenses due to their design (one side will protrude into the matching lens' rear end). Better know if the lens you are buying is compatible w/ it before you buy the lens or TC.

Frank, the 2X is intended for use with the Tamron 70-200 f/2.8. That was my original question- does the Tamron 70-200 f/2.8 AF with a 2X on?

Could you refer some stores to me in Singapore? My dealer sources his stuff from Singapore and Hong Kong and I was wondering if I could inquire with some stores there to see if they have any of the lenses I want in ready stock- especially the Sigma 100-300 f/4 and the Pentax DA* 300 f/4.

Thanks in advance
11-14-2008, 10:37 AM   #14
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QuoteOriginally posted by LaRee Quote
I think you should consider the sigma 50-500 more. It is a heavy lens but sure has a great range for wildlife and versitile for other shooting too. It will be heavier than the other options you've considered though.
Thanks LaRee. I have thought of the Bigma several times and given it up for the following reasons:

1. It is nowhere near the Tamron 70-200 f/2.8, Pentax DA* 300 f/4 or Sigma 100-300 f/4 when it comes to sharpness and IQ.
2. It is priced just as much as the above three lenses.
3. Its a superzoom and that makes me believe peoples' claims that its actually not a 500mm at all, achieving only about 460mm and that too around infinity.
4. I will never even think of using the 50mm-200mm end of it.

All said and done, if nothing works out, Bigma will have to be a last resort. For even though my dealer and my head urge me to change religion to Canon or Nikon, my heart refuses to let go of my beautiful K 10D.

I hope someone at Pentax is listening to this. There are such organisms called Pentax wildlife photographers too.

Cheers,
Aditya

Last edited by Aditya Panda; 11-14-2008 at 10:58 AM.
11-14-2008, 10:37 AM   #15
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Have you considered the Sigma 70-200 f/2.8 + Sigma 2x teleconverter? B&H shows they're compatible and allow autofocus.

Sigma - Lenses - Teleconverters
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