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09-04-2013, 03:47 AM   #1
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Teleconverters - again! (Pentax Rear Converter A 2X-S on DA* 200mm f/2.8))

I know.

This topic is about as worn-out as "Do you shoot raw?" or "Are filters any good?". Still, I want to share the following with you:

Many DA* 200mm owners have probably experienced that this lens doesn't behave too well with generic teconverters - in particular 2X converters -designed for use with a bit of "each and everything". So have I.

But the A 2X-S (manufactured during 1984-2005) is, according to Pentax designed to work with (most of) their longer lenses up to 300mm F.L. And the DA* 200mm is, optically speaking, a desing from 1993 so, maybe, just maybe......?

So, admittedly somewhat gambling, I ordered one of these rear converters to find out myself, and here are a few, first samples.

My target is a powerline a few scores of meters away:


(DA 18-135 mm lens)

and a 100% crop shot with the DA* 200 looks like this:


(DA* 200 mm f/2.8 lens)

and now to a similar crop with this lens plus rear converter:


(DA* 200 mm f/2.8 lens plus Rear Converter A 2X-S)

Apart from cropping or resizing and labelling, these images are unprocessed JPEG straigt out of the camera and the images were shot handheld on a cloudy day with light showers. Still, there is no doubt in my mind that the image taken with teleconverter reveals fine detail that you cannot reach merely by cropping, (and no - I don't mean the bird).

It is unquestionably true that teleconverters MAY degrade image quality in certain situations. But, to me, it is unquestionably equally incorrect to state that this will ALWAYS be the case. There are teleconverters and then there are matching teleconverters.


(DA* 200 mm f/2.8 lens plus Rear Converter A 2X-S)

09-04-2013, 03:54 AM   #2
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I have the same opinion of the sigma 1.4x and 2x APO - EX converters when used in long sigma lenses
09-04-2013, 04:30 AM   #3
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I have long been a fan of both the A-2xS and A-1.4xS converters - I've used then both with Pentax primes between 100mm and 300mm and have had some very good results. Most of the non-pentax converters have been quite dissapointing in comparison.
09-04-2013, 04:59 AM   #4
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The DA* 200 also works with the A-2x-L converter. I have all the A converters so perhaps I should do some comparisons. I've found the 2x-S to be a good match with the DA* 300:




09-07-2013, 04:27 PM   #5
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QuoteOriginally posted by baro-nite Quote
The DA* 200 also works with the A-2x-L converter. I have all the A converters so perhaps I should do some comparisons. I've found the 2x-S to be a good match with the DA* 300:


Black-crowned Night Heron (juvenile) by baro-nite, on Flickr
Now that would be great if you could do so and share the results with us. Before I bought my A 2X-S, I did a fairly thorough search to see if it would fir my DA* 200mm f/2.8 - and found rather little useful information on how these converters work with the newer Pentax telephoto lenses.

- Wonderful heron picture, by the way!

Quite generally, in the forum reviews of the various teleconverters, it would have been nice if one could see, what lenses all of the individual reviewers tested their teleconverters on.
09-09-2013, 03:47 AM   #6
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I'll see what I can come up with. The 1.4x-L has a sterling reputation so it will be interesting to compare it to the 1.4x-S. I have a suspicion that part of the 1.4x-L's reputation is based not so much on the TC itself as on the lenses it can be used with -- mostly the * super-teles. The DA*300 does so well on a TC (or on the Q) because it is extraordinarily sharp, with extraordinarily well controlled CA. Here's another DA*300 + 2x-S shot, from last night's conjunction of the Moon and Venus (cropped, of course):


09-09-2013, 06:45 AM   #7
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QuoteOriginally posted by baro-nite Quote
(cropped, of course):
Well, if that's a single, non-stacked image it is VERY convincing nonetheless!
01-23-2014, 07:51 PM   #8
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Talked to a Pentax source these days. Looks like a (the) "HD DA 1.4x AW AF Rear Converter" is on it's way. It seems to be more than a rumor. He showed me a picture of the new converter. It has the new HD design. I have no further specs or release date though.

01-24-2014, 01:05 AM   #9
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QuoteOriginally posted by Pentaxoe Quote
Talked to a Pentax source these days. Looks like a (the) "HD DA 1.4x AW AF Rear Converter" is on it's way. It seems to be more than a rumor. He showed me a picture of the new converter. It has the new HD design. I have no further specs or release date though.
I would love to know two things about the converter.

First, does it modify the aperture coding, so the true aperture is reported to the camera?
Second, does it modify the focal length reported. This is important for shake reduction, and also for following the program curves that use focal length derived shutter speed as one criteria
01-24-2014, 03:09 AM - 1 Like   #10
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I would be interested in that too. Unfortunately I have no further information. I have a picture though.

Name:  HD_1.4x AW AF Rear Converter-web.jpg
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01-24-2014, 08:33 AM   #11
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QuoteOriginally posted by Lowell Goudge Quote
First, does it modify the aperture coding, so the true aperture is reported to the camera?
Second, does it modify the focal length reported. This is important for shake reduction, and also for following the program curves that use focal length derived shutter speed as one criteria
I'd be amazed if the unit itself were capable of either, but perhaps with a firmware upgrade a camera body could do the necessary conversions when it recognizes the TC. I don't really expect that either, but my naive guess is that this would be a lot easier than working this capability into the TC. Doesn't seem to have much room for electronics, based on the picture above.
01-24-2014, 11:32 AM   #12
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I used a Pentax A 2X-S 1.4X with an A*300 f4 and DA*300. It wasn't pixel sharp on either, and I sold it. I am very happy with the sharpness and low aberrations of my Kenko SHQ PZ 1.5X, but auto-focus on the DA*300 is pathetic.

QuoteOriginally posted by Pentaxoe Quote
I would be interested in that too. Unfortunately I have no further information. I have a picture though.

Attachment 203442
This is very encouraging, thanks for posting. Any guess on how far away it is from release? I'm hoping for CP+ in February. I am most definitely buying one.

Last edited by audiobomber; 01-24-2014 at 11:42 AM.
01-24-2014, 12:06 PM   #13
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QuoteOriginally posted by Pentaxoe Quote
I would be interested in that too. Unfortunately I have no further information. I have a picture though.
Wow, is this legit or a photoshop job? Looks great if it's real.
01-24-2014, 12:27 PM - 1 Like   #14
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QuoteOriginally posted by baro-nite Quote
I'd be amazed if the unit itself were capable of either, but perhaps with a firmware upgrade a camera body could do the necessary conversions when it recognizes the TC. I don't really expect that either, but my naive guess is that this would be a lot easier than working this capability into the TC. Doesn't seem to have much room for electronics, based on the picture above.
Actually since the SMC-F 1.7x AF converter modifies the aperture, why would the noe TC also not do so.

They have the technology
01-24-2014, 12:44 PM   #15
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Looks like - in theory that this will also support K-AF3 from the image posted. This would be good for some of the more modern SDM/DC lenses.
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