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01-19-2012, 01:49 PM   #1
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auto extension tube question

So after some searching I think what im looking for is Vivitar AT-23 set but they seem to be rare. Is there any other brand that has the "A" pin? Thanks

01-19-2012, 02:21 PM   #2
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I've got a set of 3 Kenko Auto tubes all have the contacts for Auto aperature, and Lens info, No autofocus tho.
01-19-2012, 02:36 PM   #3
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The least expensive way I know of to get A-type extension is to buy old A-type TCs and remove their glass. My 2x TCs are each about 25mm thick and cost an average of US$15 on eBay.
01-19-2012, 03:04 PM   #4
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QuoteOriginally posted by RioRico Quote
My 2x TCs are each about 25mm thick and cost an average of US$15 on eBay.
I've been getting frustrated by this. I see you and other suggest this a lot, but I'll be damned if I can find them at that kind of price on Ebay. I've been thinking about posting in the wanted forum here looking for some, even scratched or fungused would be fine, since they're going to be deglassed. Am I just unlucky, or are they a lot more uncommon at that kind of price than it sounds?

01-19-2012, 03:36 PM   #5
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QuoteOriginally posted by Philoslothical Quote
I've been getting frustrated by this. I see you and other suggest this a lot, but I'll be damned if I can find them at that kind of price on Ebay. I've been thinking about posting in the wanted forum here looking for some, even scratched or fungused would be fine, since they're going to be deglassed. Am I just unlucky, or are they a lot more uncommon at that kind of price than it sounds?
I think Rio's average isn't an average but the exception (well, maybe not for Rio). On the average, I've paid 25-30 locally which I thought was pretty good. Maybe you should just snipe whatever PK/A TC's you find on eBay at around 25-30 range and see what happens.
01-19-2012, 04:00 PM   #6
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RioRico has found some bargains.

It looks like around $40 delivered is ebay's going price for PK/A teleconverters - there are a few Takumar-A teleconverters being sold now and the bids are currently low.
See: takumar-A teleconverter | eBay

What is it that you are trying to do?

If all you want to do is to make p-ttl flash work while you use a manual lens then all you need do is to fool the camera into thinking an A type lens is mounted. There are a few ways to do that, one of which involves removing glass from a TC and another makes a minor, easily reversible change to the camera's lens mount to make the camera think that all lenses are A type lenses.

If you want to use a no-aperture ring lens and set the f-stop using the camera's e-wheel then you'll need true A type tubes. Two PK/A teleconverters at $40 each isn't much to pay for A type extension tubes and in my experience removing the TC's lens stack is easy and reversible.
01-19-2012, 04:38 PM   #7
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QuoteOriginally posted by newarts Quote
If you want to use a no-aperture ring lens and set the f-stop using the camera's e-wheel then you'll need true A type tubes.
This is one eventuality I'd like to plan for, yeah.

I'm using AT-22 tubes right now, and they work fine for most things. I'd just like more flexibility, as well as more extension.
01-19-2012, 05:17 PM - 1 Like   #8
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QuoteOriginally posted by Philoslothical Quote
I've been getting frustrated by this. I see you and other suggest this a lot, but I'll be damned if I can find them at that kind of price on Ebay. I've been thinking about posting in the wanted forum here looking for some, even scratched or fungused would be fine, since they're going to be deglassed. Am I just unlucky, or are they a lot more uncommon at that kind of price than it sounds?


2x Tele-Converter Lens for Pentax K mount --- 45-Day Limited Warranty | eBay

01-19-2012, 05:52 PM   #9
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+1. If somebody doesn't grab these in the next hour, I will. Get moving!
01-19-2012, 05:54 PM   #10
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Thanks. Saw that listing the other day, but the two with contacts were already gone. I'll keep looking though. There's no mad rush, as long as I get set up with some new stuff before the bugs emerge in the spring.

QuoteOriginally posted by RioRico Quote
+1. If somebody doesn't grab these in the next hour, I will. Get moving!
Confirm my understanding of these, but the two remaining are no use for my purposes without the contacts, correct? They would function just like AT-22 tubes, rather than AT-23?
01-19-2012, 06:02 PM   #11
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Someone indeed grabbed all the KA units in a hurry.

Just looked over that seller's other items. Golly gosh, that seller deals in quantity!

Back to the general topic of de-glassing a TC, I took apart my Pro-Optic AF TC. While an interesting learning exercise, it was more difficult to put back together than I had expected; furthermore, the glass elements seemed cemented in to a metal casing and offered no easy means of removal. So I'm keeping it as a TC for now. Any guidelines on which KA-mount TCs are easiest to de-glass?
01-19-2012, 08:12 PM   #12
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QuoteOriginally posted by Philoslothical Quote
Thanks. Saw that listing the other day, but the two with contacts were already gone. I'll keep looking though. There's no mad rush, as long as I get set up with some new stuff before the bugs emerge in the spring.



Confirm my understanding of these, but the two remaining are no use for my purposes without the contacts, correct? They would function just like AT-22 tubes, rather than AT-23?
That's right.

To clarify my previous statement; a PK/A TC with lens removed is completely equivalent to a segment of a PK/A extension tube.

You might consider placing low bids on some low bid pk/a tc's currently listed on ebay. You may get lucky.
01-19-2012, 08:18 PM   #13
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QuoteOriginally posted by baro-nite Quote
Someone indeed grabbed all the KA units in a hurry.

Just looked over that seller's other items. Golly gosh, that seller deals in quantity!

Back to the general topic of de-glassing a TC, I took apart my Pro-Optic AF TC. While an interesting learning exercise, it was more difficult to put back together than I had expected; furthermore, the glass elements seemed cemented in to a metal casing and offered no easy means of removal. So I'm keeping it as a TC for now. Any guidelines on which KA-mount TCs are easiest to de-glass?

I've done a vivitar and a quantaray. Both were easy. Just removed one spanner ring, and the glass fell out into my hand with a couple of flat metal rings and a metal tube.
01-19-2012, 08:26 PM   #14
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QuoteOriginally posted by bluestringer Quote
I've done a vivitar and a quantaray. Both were easy. Just removed one spanner ring, and the glass fell out into my hand with a couple of flat metal rings and a metal tube.
Ditto for vivitar MC 2x
01-20-2012, 06:00 AM   #15
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Thanks, is that the AF Vivitar, the one that is still in production?
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