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03-07-2010, 11:19 PM   #1
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F 1.7X AF adapter and DA* 50-135

Today, I used my recently repaired DA* 50-135/2.8 and the SMC-P F 1.7X AF Adapter together at Elizabeth Lake (which is still frozen over) on a pair of Canada Geese, walking on water. I really don't see anything wrong with the combination. There was a bit of red CA, but it was fixed easily. Here are the details, followed by the image and crop.

[Edit] The adapter did the focusing with the lens at infinity, centre point only selected.
  • K10d
  • Effective focal length, 230 mm (1.7*135)
  • Effective aperture, 6.7 (f/4 on lens)
  • 1/750 second at ISO 400
  • +1 EV to compensate for the ice and lighting
  • Hand held, Shake Reduction at 200mm (choice of 200 and 250)
Lightroom import from card, Chromatic Aberration correction +60. 100% crop below full image, not cropped.

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PENTAX K10D  Photo 

Last edited by Canada_Rockies; 03-07-2010 at 11:25 PM. Reason: Left out adapter was in AF mode.
03-07-2010, 11:47 PM   #2
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I really like the idea of a DA* 50-135mm mated to a 1.7X teleconverter, but that image doesn't sell me on it. Maybe it's just the dreary, colourless setting, but that picture doesn't seem to show off the DA*'s qualities very well (in my very humble opinion). I've grown accustomed to seeing a DA* picture and thinking "Wow! Now THAT's a sharp, colourful picture!", and I'm not getting that reaction right now.
03-08-2010, 08:42 AM   #3
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It Is kind of hard to make colors pop when there is no color. Using the converter takes a little practice I think. I'm not quite there yet but it also works nicely with the da*300. The best way to use the converter is to manually focus the lens until you're Close and then let the converter AF take over.

03-08-2010, 09:10 AM   #4
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QuoteOriginally posted by GoremanX Quote
I really like the idea of a DA* 50-135mm mated to a 1.7X teleconverter, but that image doesn't sell me on it. Maybe it's just the dreary, colourless setting, but that picture doesn't seem to show off the DA*'s qualities very well (in my very humble opinion). I've grown accustomed to seeing a DA* picture and thinking "Wow! Now THAT's a sharp, colourful picture!", and I'm not getting that reaction right now.
I will have to find a colourful setting, and use it there for you. We were there, the geese were there, I did not have my beloved M 400. The day was partly cloudy, as you can see from the shadows, and Canada geese are shades of brown, white and black. I'll add a shot or two to this thread when we get some decent lighting. I am still playing with the F 1.7 AF, having bought it only a few months ago.

03-09-2010, 09:28 PM   #5
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How is the auto focus when the DA* is mounted on the teleconverter?
03-10-2010, 12:24 AM   #6
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QuoteOriginally posted by cgoudie Quote
How is the auto focus when the DA* is mounted on the teleconverter?
The Pentax AFA 1.7X treats any lens as manual focus. The auto focus is done by the AFA. Its auto focus range is limited so you have to bring the lens to "kind of" focus. When you half press the shutter release, the AFA will take over.

I'm not sure if this is what you're asking, but I'd like to state that there are no TCs that work reliably (autofocus-wise) with Pentax SDM lenses in SDM mode.
03-10-2010, 04:34 AM   #7
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when you say F4 on the lens, did you set aperture to manual also, or was it F4 as indicated on the display.

my 1.7x correctly compensates for the change in aperture with auto exposure, and shows an F2.8 lens as an F4.5 lens.
03-10-2010, 09:07 AM   #8
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QuoteOriginally posted by cgoudie Quote
How is the auto focus when the DA* is mounted on the teleconverter?
My shots were taken in a high contrast situation, and the converter would focus within 1/2 second. The lens was set to infinity. I have yet to finish all my tests. Personally, I am more interested in the optical results.

QuoteOriginally posted by SOldBear Quote
The Pentax AFA 1.7X treats any lens as manual focus. The auto focus is done by the AFA. Its auto focus range is limited so you have to bring the lens to "kind of" focus. When you half press the shutter release, the AFA will take over.

I'm not sure if this is what you're asking, but I'd like to state that there are no TCs that work reliably (autofocus-wise) with Pentax SDM lenses in SDM mode.
This is correct. For the birding incident, infinity focus was fine.

QuoteOriginally posted by Lowell Goudge Quote
when you say F4 on the lens, did you set aperture to manual also, or was it F4 as indicated on the display.

my 1.7x correctly compensates for the change in aperture with auto exposure, and shows an F2.8 lens as an F4.5 lens.
The converter was showing f/6.7. I have my program mode set to MTF, and this gave me f/4 on the lens, one stop down from wide open.

03-17-2010, 05:45 PM   #9
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An update to the combination

This shot was taken through my kitchen window, directly across the street to my neighbour's front garden. K10D + 1.7X AF + DA* 50-135 exposure 1/500" @ f/4.5 (wide open at 2.8) ISO 400, Shake Reduction at 200mm. A 100% crop of the mule deer's head in the centre of the image is below. The converter was on AF, centre point.



100% crop

03-17-2010, 05:55 PM   #10
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Actually there is a TC that will AF with SDM. The Tamron MC4 1.4. SDM works fine and it's a very sharp TC. Not bad shots CR. The lack of contrast on both days doesn't help. I have the above Tamron, and nearly the same combo you have (FA*300mm). it works great and is quite sharp.
03-17-2010, 06:44 PM   #11
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QuoteOriginally posted by Peter Zack Quote
Actually there is a TC that will AF with SDM. The Tamron MC4 1.4. SDM works fine and it's a very sharp TC. Not bad shots CR. The lack of contrast on both days doesn't help. I have the above Tamron, and nearly the same combo you have (FA*300mm). it works great and is quite sharp.
I am waiting for a sunny day to do a bit better. We don't have such nice weather right now.
03-17-2010, 06:55 PM   #12
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QuoteOriginally posted by Peter Zack Quote
Actually there is a TC that will AF with SDM. The Tamron MC4 1.4. SDM works fine and it's a very sharp TC.
I can never get the Tamron 1.4X TC to work reliably with my Pentax DA* 50-135mm and my Pentax DA* 60-250mm at their respective long end of the FL. The combos kind of work but autofocus keeps hunting until I lift my finger from the shutter release button and half press again.

It is not because of the particular Tamron TC. I had more than one copy before I sold all but one.
03-17-2010, 09:18 PM   #13
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I was going to get a Tamron 1.4x w/ Pz contacts to extend the reach of my DA* 50-135 f/2.8 when needed, however I've heard horrible stories of this teleconverter downgrading the IQ too greatly. How does the Tamron 1.4x compare to the Pentax F 1.7x in terms of IQ with the DA* 50-135? Some pictures would be great with the Tamron 1.4x
03-20-2010, 03:15 PM   #14
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Sunlit tests with the DA* 50-135 and F 1.7X AF TC

Out and about with my wife this afternoon on a local back road. I took the K10D, with 1.7X and 50-135 for a spin. There are three shots here:

F 1.7X AF + DA* 50-135 f/2.8 - a set on Flickr

They are full size, if you wander through the [All Sizes] to [Original Size]. Pixel peep all you want. The one that I found really interesting was the Canada Goose taken in flight. The TC was in AF, and it focused on the bird. I'll keep the TC. I get a very nice 85 - 230 AF lens out of it.
03-20-2010, 03:29 PM   #15
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Those are much nicer examples of this combination. The detail on that goose is impressive.
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