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08-03-2013, 01:16 PM   #1
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Pentax-A* 600mm/f5.6 with Pentax-F 1.7 AF

Does anyone have experience using the Pentax-F 1.7 AF with the Pentax-A* 600mm/f5.6- Thanks

08-03-2013, 01:20 PM   #2
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Someone send me their A*600 and I'll try it out..... I'll even pay return postage...
08-03-2013, 02:36 PM   #3
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You will be on f/9.5 and I doubt that will work very well.
08-03-2013, 02:38 PM   #4
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Do you have specific questions?

I have the F 1.7x AF adapter, but only with 200mm and 300mm lenses, so I may not be able to help you.


But I guess your questions would be along the lines of:

- Will AF work? How well?
- How is the IQ?


I'm sure you're aware the IQ will be better with either the Rear Converter-A 1.4x-L or 2x-L. There are even a couple of example photos taken with this lens in the review here for the 1.4x version.


I can assure you you'll see IQ degradation using the 1.7x AF adapter, whereas folks claim they see little or none using a Rear Converter L (and their photos bear this out). Unfortunately, those don't fit my longer lenses - otherwise I'd get one.


Last edited by DSims; 08-03-2013 at 02:46 PM.
08-03-2013, 03:32 PM   #5
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I regularly uses a 1,4 XL converter on a 600f4, there is noticeable image degradation, unfortunately, but this remains acceptable when lens is stopped down. Note also that the IQ of the FA*600 is on a very high level.
I doubt the autofocus will work with the A*600f5.6 + 1,7 X converter, I think that f6.3 is the upper limit for AF to work, and as said by StigVidar the combo will be on f9.5.
Go for the 1,4 XL converter and buy and OM-53 magnifier to achieve a precise focus.
Note also that image stabilisation is limited to 800 mm.
Example with 1?4XL converter
08-03-2013, 03:35 PM   #6
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QuoteOriginally posted by goubejp Quote
I regularly uses a 1,4 XL converter on a 600f4, there is noticeable image degradation, unfortunately, but this remains acceptable when lens is stopped down. Note also that the IQ of the FA*600 is on a very high level.
I doubt the autofocus will work with the A*600f5.6 + 1,7 X converter, I think that f6.3 is the upper limit for AF to work, and as said by StigVidar the combo will be on f9.5.
Go for the 1,4 XL converter and buy and OM-53 magnifier to achieve a precise focus.
Note also that image stabilisation is limited to 800 mm.
AH so that's why the AF is so hit and miss on my A-400 with the 1.7. Unless the light is perfect I just turn it off and focus manually most of the time. The AF will actually take my perfect manual focussed image and mess up the focus if I leave it on. It does work in really good light and at a close distance though.
08-03-2013, 04:13 PM   #7
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QuoteOriginally posted by goubejp Quote
I regularly uses a 1,4 XL converter on a 600f4, there is noticeable image degradation, unfortunately, but this remains acceptable when lens is stopped down.
I'm glad to hear someone say this, because it's clearly impossible for it to have no affect on IQ. Some people speak as if certain optics are magical. Enchanting perhaps, but never magical.
08-03-2013, 04:22 PM   #8
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QuoteOriginally posted by DSims Quote
I'm glad to hear someone say this, because it's clearly impossible for it to have no affect on IQ.
The issue for me isn't about image degradation.... the image isn't as good... the question is, do you get a better image with the TC than you would blowing up an image taken without the TC if you're cropping half your image. I still think for images the same size, the TC gives you a better image.Spreading the desired info out over more pixels can't hurt. The large TC image won't be as sharp as the smaller non-TC image, but if you downsize the image to the same size, how could it be worse? That's the only way I would consider the image to be degraded would be if you actually lost detail.

08-03-2013, 04:26 PM   #9
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QuoteOriginally posted by RockvilleBob Quote
Does anyone have experience using the Pentax-F 1.7 AF with the Pentax-A* 600mm/f5.6- Thanks
I have used that combo once. It won't autofocus, and the results won't stand up to any cropping or pixel peeping, but uncropped it's fair to middling. As has been stated elsewhere, the XL converters are preferred. Here's an uncropped shot, for illustrative purposes only.

08-04-2013, 10:15 AM   #10
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Thanks for all the comments. I am still looking to an alternative to the SIGMA 500 for wildlife and BIF but just haven't come up with any. There seems to be a nice A*600 ON EBAY but I really need auto focus.
08-04-2013, 05:39 PM   #11
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I tried the 500mm f4.5 pentax with the 1.7x, but it just hunted and the lens wasn't sharp with it, so I doubt a f5.6 lens would work at all. There are a lot more choices in another mount.
08-04-2013, 05:46 PM   #12
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I have tried with several F5.6 lenses all the way back to when I bought it for my PZ1. Even using my K5 it hunts and only locks in bright sunlight on my 200-500/5.6 zoom. Focuses flawlessly on my 300/4 which I consider to be a limit(F4 that is)
08-05-2013, 04:05 AM   #13
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Good to know about the 300/f4 Lowell, thanks. Perhaps if I knew two years ago about my interest in wildlife and BIF another mount would be a good option back then. However a good 500mm or 600mm solution is costly in any mount and Sigma offers a 500 solution today that is very good and costs less than a Nikon or Canon solution. That is the case even without considering the hit I would take on selling what I have. Since Pentax must be fully aware of the long lens issue and the relative poor acceptance of the 560 and Ricoh wants to be successful with Pentax I feel confident this shortcoming along with the FF issue will be resolved in time. so for me I have three choices: wait and use my 150-500 Sigma zoom; buy a new/used Sigma 500 now or buy a used Canon long lens solution (I think Canon used prices are cheaper.)
So far I've been in the wait 150-500 mode and very happy with the K-5 and dozen lenses I have.
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