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03-11-2012, 10:42 AM   #1
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2X Conveter

Hello,
Can anyone tell me if a 2X tele converter that came with a Pentax K1000 will work with my IST DS ? If so, are there any restrictions or problems ?
Thanks...Charles

03-11-2012, 11:17 AM   #2
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Hi Charles,
Funny you ask right now when I am checking same thing on my istds.
I am going to Sweden tomorrow carry on and i will take the istds with the SMC Pentax M 1:2.8 40mm and might take the Vivitar MC TeleConverter 2X 22.
I just tried them and the histogram is good outside in bright sun at iso 200 and indoors at iso1600.
And the image is sharp at iso200 at 5.6 which is actually 11 now:

https://www.box.com/s/t8g85otu6ds2ekiz3my4
03-11-2012, 12:08 PM   #3
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Hello Charles,

Not sure what you mean by "any" restrictions, but your TC from the K1000 era will most likely be a purely manual TC (without electrical contacts). If so, any lens used together with that will essentially be an "M" lens and should be operated as such on your *ist DL. See more here:

https://www.pentaxforums.com/forums/pentax-beginners-corner-q/110658-using-ma...x-dslrs-f.html

And then, not all lenses work equally well with TCs. You will have to try out yourself, but in general I should say that you have a better chance to get acceptable results with primes than with zooms. What lenses do you have?

Good luck!
03-11-2012, 12:14 PM   #4
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Depends on several things but essentially all K mount adapters will work, the question is what information will be transferred to the camera and what functions will work beyond manual everything. I have two 2x adapters - one is an old manual one that has a transfer lever for the A setting and the other is a more modern one that will transfer aperture and implement the auto focus if the scene is bright enough. Bottom line is that since its a K mount adapter the worst case is that you'll have to do all the settings manually including focusing.

03-11-2012, 03:14 PM   #5
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I bought the Vivitar 2X-22 new in 1982, and used it quite a lot with my ME Super and a SMC-M 2/50. With my K200D, I only tried it out to see whether it will work in case of an emergency. As Stone.G wrote, it was built for K- and M-lenses, and any newer lens will act as if it were such a lens.

Of course IQ of your lens is degraded a bit - it is one of the simpler designs with 4 elements in 2 groups, which was standard in its time. I replaced it by a Kenko 2X KAX TELEPLUS MC7, which is a 7 element design, and has the contacts for A-lenses - so everything but AF will work as usual.

In respect to IQ, I recommend to

- use it with normal or tele lenses
- stop down the lens by 1-2 stops
- expect slightly reduced sharpness
- expect strongly reduced contrast
- expect increased tendency to show flare
- expect added CA in high contrasty situations.

All that said, there may be situations when using it is still better than cropping afterwards, specially for me, with the 10MP K200D. With a 16MP K5 probably only a high class (= high price) TC would deliver better results than cropping. With APS-C, avoiding shots with fully opened aperture may not be needed as much as with FF.

EDIT: With the 6MP of the IstDS, reduced sharpness may not be an issue at all. But all the other things apply.

Last edited by RKKS08; 03-11-2012 at 03:19 PM.
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