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05-09-2009, 09:49 AM   #1
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2X teleconverters

Hi

I recently bought an older Vivitar 2x tele converter, which seems to work (read: metering and aperture adjustment) with some lenses, but does not work with my Sigma 100-300. It oddly show every aperture values, starting from 1.2, and does not really do the aperture adjustment properly.

I am starting to look for better 2X model out there (already have a 1.4x Tamron). Any suggestions?

One specific question: is there any essential difference between the MC4 and MC7 types of models, in IQ, that is?

05-09-2009, 11:23 AM   #2
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QuoteOriginally posted by gawan Quote
...

One specific question: is there any essential difference between the MC4 and MC7 types of models, in IQ, that is?
Yes, the 7 element converters are much superior.
05-09-2009, 12:53 PM   #3
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QuoteOriginally posted by Canada_Rockies Quote
Yes, the 7 element converters are much superior.
Thanks I though there has to be some benefit for the higher price!

Which one you use, does it support the auto-aperture and metering?
05-09-2009, 05:58 PM   #4
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I got decent results from 2XTC Bower MC Pz/AF which is an 'A' TC so will give correct aperture info, and will auto focus as well.

Good for uncropped images, but cropping with it compromises IQ. As always the TC affects sharpness and contrast, but this definitely does better than the Vivitar and pentax 1.7 AFA, both of which i have tested on this lens. It is actually only marginally inferior to the 1.4 sigma TC.

I paid $50 for this in the marketplace, and all the images are post processed for sharpness and contrast.

Uncropped images of the birds that sat on my yard last wknd.







Indoor testing uncropped



Cropped





I am new to shooting birds. I will have to take the combo to the Zoo and see what it can do.

05-09-2009, 07:42 PM   #5
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I have the Kenko TelePlus 2X MC7 TeleConverter and used it on my f*300mm. Very good results and it will autofocus. I suspect it will work with your Sigma also. Heres 2 uncropped pics. The Kenkos are routinely on ebay:

Kenko TelePlus 2X MC7 TeleConverter for Pentax AF Lens - eBay (item 130288825211 end time May-20-09 08:20:39 PDT)

Last edited by ivoire; 10-04-2010 at 03:59 PM.
05-09-2009, 09:36 PM   #6
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QuoteOriginally posted by gawan Quote
Thanks I though there has to be some benefit for the higher price!

Which one you use, does it support the auto-aperture and metering?
I don't currently own a 2X. I do have the Pentax AF 1.7X converter and the Pentax A 1.4X-S. Both work well. I am in the process of serious testing of the 1.7X on my M 400/5.6. Now that I have my accurately metering focus screen, I hope to get a bit better shots to analyze. Tomorrow our favourite wildlife refuge (wetlands near Creston BC) is predicting sunny weather. That should give me enough light to put it through its paces. Last time I was out there, the best exposure I could get was 1/320 wide open at f/9.5, ISO 800, When it comes to birds, that is no where near enough speed, and the old 400 is not at its best wide open.

They both support A level metering with an A level lens mounted and are equipped with aperture levers. On the M lenses, they only work in manual exposure, of course, on the k10, but really work nicely on the MZ-S.
05-10-2009, 10:01 AM   #7
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Gawan, as I said I am new to shooting birds. This is my second wknd. with the combo. I shot this today and now I think I finally found the TC for this Sigma 100-300,

05-10-2009, 10:22 AM   #8
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I'm not sure whether it will work with this lens but check out the Sigma 2X TC.

it works very well with the sigma 70-200 F2.8 (first generation)

05-10-2009, 11:27 AM   #9
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try to find a Kenko TelePlus 2X MC7 TeleConverter ....maybe the "Macro" version is also more interesting!
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