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06-08-2007, 12:16 PM   #16
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QuoteOriginally posted by Lowell Goudge Quote
I have 3 teleconverters, one sigma to go with my autofocus 70-200 F2.8, one pentax 1.7x autoficus adaptor, and one 2x Pentax A TC
Does your Pentax-A 2x TC + some KA-bayonet lens + K10D combo meter properly without any +/- EV adjustments?

Your other TC:s are different story because they are KAF-compatible.....

06-08-2007, 02:31 PM   #17
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QuoteOriginally posted by Harald Quote
Does your Pentax-A 2x TC + some KA-bayonet lens + K10D combo meter properly without any +/- EV adjustments?

Your other TC:s are different story because they are KAF-compatible.....
My lens selection is limited.

I have either new modern AF zooms or K mount primes. No KA mount lenses

Sorry
06-08-2007, 04:50 PM   #18
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QuoteOriginally posted by Harald Quote
Does your Pentax-A 2x TC + some KA-bayonet lens + K10D combo meter properly without any +/- EV adjustments?

Your other TC:s are different story because they are KAF-compatible.....
Mine sure do- I've tested the setup with my A* 200mm and the A-2xS converter. TTL metering even works with manual lenses, but you'll have to stop down to meter first.

So, in conclusion, only the F teleconverter shows the aperture change in the viewfinder, but the A teleconverters are still able to meter correctly through TTL and compensate for the loss of the two stops.

Speaking in general, the K10D has substantial metering issues with wide-angle manual-aperture lenses. This should't be the case with auto-aperture lenses, though...

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06-09-2007, 12:16 AM   #19
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QuoteOriginally posted by Mo Quote
Mine sure do- I've tested the setup with my A* 200mm and the A-2xS converter. TTL metering even works with manual lenses, but you'll have to stop down to meter first.

So, in conclusion, only the F teleconverter shows the aperture change in the viewfinder, but the A teleconverters are still able to meter correctly through TTL and compensate for the loss of the two stops.

Speaking in general, the K10D has substantial metering issues with wide-angle manual-aperture lenses. This should't be the case with auto-aperture lenses, though...
I was wondering... can this be due to a too weak shutter mechanism in the body? if the shutter actuator is too weak to handle the load of the converter and the lens together....

Could this also be behind the some reported problems with K and M-lenses too; older, little stiff mechanism could be similar higher load to the too weak actuator than newer A-series lens + TC......

I sold this spring an Tamron 80-210/2.8 adaptall-2 lens I had not used much with the K10. Buyer complained that aperture didnt close properly but closes less than it should do. We tried other adaptall KA adapters and found one which worked reasonably well. If the actuator is too weak, it could explain this episode too......


Last edited by Harald; 06-09-2007 at 01:00 AM.
06-09-2007, 12:24 AM   #20
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The lever in the converter doesn't add much load to the camera mechanism, so that shouldn't be a problem. There might be something wrong with the camera, but what could it be?

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06-09-2007, 01:09 AM   #21
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QuoteOriginally posted by Mo Quote
The lever in the converter doesn't add much load to the camera mechanism, so that shouldn't be a problem. There might be something wrong with the camera, but what could it be?
Actually all additional mechanisms adds the load, it is evident. I do not have proper equipmets to measure this other than my finger, but even it can give me feeling of stiffer movement of the lever.

If the actuator is too weak, capable only handle the lens aperture mechanism only just, this could happen.

I do not have problems with any single lens, without the TC.

Could this be one of those places where the very reasonable price (->desperate need to keep the manufacturing expences low) shows its concequences. (engineers chose one too cheap part )
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