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08-20-2013, 06:10 AM   #1
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Help on Teleconverter for Pentax A* 600mm f/5.6

I bought a good copy of Pentax A* 600mm f/5.6. but 600mm is not good enough to reach those wild birds and Pentax F 1.7X AF adapter produce soft image. I am searching for possible options to extend the capability of this lens. One option, would like to trade my Pentax F 1.7X AF to Pentax rear converter a 1.4x-l.

Since rear converter a 1.4x-l is hard to find andto purchase with economical price tag , thinking to purchase sigma 1.4X DG teleconverter. Is this teleconverter works with Pentax A* 600mm f/5.6? Is the quality of image is soft? I need you input fellow forum members.

Thanks a lot.

08-20-2013, 06:20 AM   #2
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pentax 1,4xL i 2x L that are pro converters
08-20-2013, 06:36 AM   #3
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I use both Pentax 1,4 XL converter and Sigma 1,4X converter on a FA*600f4 (not the F5.6 as yours).
Both produce correct image quality, there is some degradation in sharpness and contrast, but really side by side it is difficult to distinguish which converter was used. The interest of the sigma is that it is compatible with AF on this lens. Using a converter on a manual focus lens, will also make the focus tricky as your 600 is only f5.6, so the combo will be an F8 lens.
The interesting point is that with a 600 mm on APS-C I have enough reach for 95 % of my bird pictures, use of the converter is rather uncommon. May be you should also improve your skill to get closer from the birds.
08-20-2013, 06:44 AM   #4
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I'd recommend you take some time to find a 1.4xl at a reasonable price. I've tried a few converters on my A* lenses and don't find any drop in image quality with the 1.4xl. I also have the 2.0xl but unfortunately find some drop in IQ with it.

I understand what you mean when you say 600mm isn't long enough at times. I find the 1200 too short at times as well.

08-20-2013, 06:45 AM   #5
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Why not just get a Q and use it with your DA*300?
08-20-2013, 07:02 AM   #6
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With a perfectly matched lens/TC combo you may not see decreased resolution ("softness") and contrast in real life shots, but by the law of Physics they are always there. After all, the TC is magnifying what the lens delivers.

The Pentax 1.4x(L) and 2x(L) are the only TCs which are really designed to get everything possible out of the Pentax >=300mm lenses.

But keep in mind that, the farer away from the object you are, the more additional other problems increase. There are possibly areas of different air temperature on the light path (acting themselves as lenses), a longer way through humidity/dust, and with any increase of focus length very tiny vibrations of the tripod will also increase softness.

I remember from the 1980s, only 1 of 3 of my shots with a 8/500+TC were correctly focused.
This was with the very bright VF of the ME Super and Super A, and a lot of practice with MF on such conditions.
And I also have some doubts about the precision of any AF on such conditions (because of tiny DOF).
08-20-2013, 07:45 AM   #7
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QuoteOriginally posted by Barbarosa Quote
pentax 1,4xL i 2x L that are pro converters
Thanks to your input.
08-20-2013, 07:47 AM   #8
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QuoteOriginally posted by goubejp Quote
I use both Pentax 1,4 XL converter and Sigma 1,4X converter on a FA*600f4 (not the F5.6 as yours).
Both produce correct image quality, there is some degradation in sharpness and contrast, but really side by side it is difficult to distinguish which converter was used. The interest of the sigma is that it is compatible with AF on this lens. Using a converter on a manual focus lens, will also make the focus tricky as your 600 is only f5.6, so the combo will be an F8 lens.
The interesting point is that with a 600 mm on APS-C I have enough reach for 95 % of my bird pictures, use of the converter is rather uncommon. May be you should also improve your skill to get closer from the birds.
I do appreciate your input and opinions. Thanks a lot. You have a good one.

08-20-2013, 07:47 AM   #9
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QuoteOriginally posted by SteveM Quote
I'd recommend you take some time to find a 1.4xl at a reasonable price. I've tried a few converters on my A* lenses and don't find any drop in image quality with the 1.4xl. I also have the 2.0xl but unfortunately find some drop in IQ with it.

I understand what you mean when you say 600mm isn't long enough at times. I find the 1200 too short at times as well.
I do appreciate your input and opinions. Thanks a lot. You have a good one.
08-20-2013, 07:48 AM   #10
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QuoteOriginally posted by boriscleto Quote
Why not just get a Q and use it with your DA*300?
Thanks a lot. You have a good one.
08-20-2013, 07:48 AM   #11
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QuoteOriginally posted by RKKS08 Quote
With a perfectly matched lens/TC combo you may not see decreased resolution ("softness") and contrast in real life shots, but by the law of Physics they are always there. After all, the TC is magnifying what the lens delivers.

The Pentax 1.4x(L) and 2x(L) are the only TCs which are really designed to get everything possible out of the Pentax >=300mm lenses.

But keep in mind that, the farer away from the object you are, the more additional other problems increase. There are possibly areas of different air temperature on the light path (acting themselves as lenses), a longer way through humidity/dust, and with any increase of focus length very tiny vibrations of the tripod will also increase softness.

I remember from the 1980s, only 1 of 3 of my shots with a 8/500+TC were correctly focused.
This was with the very bright VF of the ME Super and Super A, and a lot of practice with MF on such conditions.
And I also have some doubts about the precision of any AF on such conditions (because of tiny DOF).
I do appreciate your input and opinions. Thanks a lot. You have a good one.
08-20-2013, 08:50 AM   #12
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I just recently managed to source an un-used Tamron AF 1.4x Teleconverter (they are very tough to find) for my K-5 and have had a great experience with it. I have not seen any real degradation and the photos are crisp. I did have to adjust the AF of the lens slightly though, but once dialed in it is great, though sometimes it wont lock, but I will usually fine tune anyways - it just gets me there quicker. I mainly use it with my Pentax SMC-DA* 60-250mm f/4 ED [IF] SDM when I need to get a closer shot. I am looking at moving up to the DA 560mm F5.6ED AW eventually though. Please let us know how the teleconverter works for you ... good shooting!
08-20-2013, 10:41 AM   #13
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QuoteOriginally posted by jpstanisic Quote
I just recently managed to source an un-used Tamron AF 1.4x Teleconverter (they are very tough to find) for my K-5 and have had a great experience with it. I have not seen any real degradation and the photos are crisp. I did have to adjust the AF of the lens slightly though, but once dialed in it is great, though sometimes it wont lock, but I will usually fine tune anyways - it just gets me there quicker. I mainly use it with my Pentax SMC-DA* 60-250mm f/4 ED [IF] SDM when I need to get a closer shot. I am looking at moving up to the DA 560mm F5.6ED AW eventually though. Please let us know how the teleconverter works for you ... good shooting!
Thanks a lot to your opinion.

I always be in search for F600mm f4 beyond reasonable price and recently purchased A* 600mm f5.6, I owned 500mm f4.5 and DA* 300mm and coupled with 1.7X AF adapter, but the results are unsatisfactory, less contrast and less sharpness. The copy of A* 600mm I owned is very promising and good. I am contributor in Shutterstock and have earnings in landscape and night photography (google “cvrestan” will give the links). My bald eagle image in Shutterstock made a lot of hits. Maybe I could make an extra pennies in birds and other wildlife exposures. That is the reason why I am search for a decent teleconverter to marry my A*600mm f5.6.

Once again, I value and do appreciate your opinion. Have a good one.
08-20-2013, 12:20 PM   #14
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Maybe a Q or Q10 with the K-mount adapter? But with the 5.65x crop factor the 600mm would be about equivalent to a 3390mm, probably too much reach for you. A 300mm would be about equivalent to a 1695mm lens.
08-20-2013, 02:42 PM   #15
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Have you considered taking a "ninja stealth mode" class, this will allow you to creep up closer on your subjects and let you use the 600 mm without converters.
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