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04-02-2012, 03:38 PM   #16
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QuoteOriginally posted by newarts Quote
Keh is listing a 3x -A tc in excellent condition for $13.
Right, but that almost certainly won't be a macro-focusing TC. I'd say you can hardly go right with an ordinary 3x TC.

04-02-2012, 03:43 PM   #17
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I think I'll go the extension tube route. Thanks for the tips, guys!
04-02-2012, 04:20 PM   #18
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QuoteOriginally posted by baro-nite Quote
Right, but that almost certainly won't be a macro-focusing TC. I'd say you can hardly go right with an ordinary 3x TC.
What difference does the focusing aspect make when it is behind a macro lens that already has a long focus throw?

I guess I don't understand what's going on here.

There's a big magnification difference between empty extension tubes on a 100mm lens (as the OP now intends to purchase) and a 3x TC with an added 50mm helicoid.

According to the description of the Vivitar 2x macro focusing TC, in such a tc the optical component effectively doubles the focal length of the lens to which it is attached and the TC also adds further focusing tube capability. http://www.nicobastone.com/Vivitar_2x_Macro-Focusing_Teleconverter.htm

OP's already got a 100mm 1:1 focusing capability, adding a 3X TC in itself should give a large difference in magnification. Fifty mm of empty tubes won't do much in comparison.

see also https://www.pentaxforums.com/userreviews/vivitar-2x-macro-focusing-teleconvertor.html

On the other hand the optical problems introduced by a 3x TC might be severe.

Please enlighten me!

Last edited by newarts; 04-02-2012 at 04:40 PM.
04-02-2012, 04:26 PM   #19
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QuoteOriginally posted by GibbyTheMole Quote
I think I'll go the extension tube route. Thanks for the tips, guys!
The cheap PK macro tubes I've seen are all metal, quite sturdy, but lack any aperture interface.
If you can find any M-type tubes, at least you'll be able to do stop-down metering & exposing.
If you can find A-type tubes, you'll have stop-down shooting and pTTL flash at your disposal.
If you can't find M-type tubes, cheap M-type TCs are available and can be de-glassed easily.
And cheap A-type TCs, easily deglassed (with a lens spanner), are a price-performance win.
The only problem with deglassed TCs is that you don't get the flexibility of macro-tube sets.
But now you have your ultra-cheap DA10-17. Shoot macro with that! It's an experience!

04-02-2012, 04:44 PM   #20
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QuoteOriginally posted by RioRico Quote
The cheap PK macro tubes I've seen are all metal, quite sturdy, but lack any aperture interface.
If you can find any M-type tubes, at least you'll be able to do stop-down metering & exposing.
If you can find A-type tubes, you'll have stop-down shooting and pTTL flash at your disposal.
If you can't find M-type tubes, cheap M-type TCs are available and can be de-glassed easily.
And cheap A-type TCs, easily deglassed (with a lens spanner), are a price-performance win.
The only problem with deglassed TCs is that you don't get the flexibility of macro-tube sets.
But now you have your ultra-cheap DA10-17. Shoot macro with that! It's an experience!
How 'bout removing the glass from a type A 3x macro focusing TC? - that should give almost a rigid but adjustable bellows!
04-02-2012, 05:19 PM   #21
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QuoteOriginally posted by newarts Quote
How 'bout removing the glass from a type A 3x macro focusing TC? - that should give almost a rigid but adjustable bellows!
That should work too. I didn't mention it because I haven't tried it because 1) I haven't owned or even seen A-type vari-macro TCs and 2) I tried that with a front-loading 3x vari-macro which only had room for enlarger lenses. Maybe I should look for more TCs.
04-02-2012, 06:26 PM   #22
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QuoteOriginally posted by RioRico Quote
The cheap PK macro tubes I've seen are all metal, quite sturdy, but lack any aperture interface.
I've heard horror stories about the lens becoming stuck to the cheap tubes because of badly machined mounts. Is there a super cheap tube you can recommend that won't get stuck?
04-02-2012, 06:51 PM   #23
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QuoteOriginally posted by GibbyTheMole Quote
I've heard horror stories about the lens becoming stuck to the cheap tubes because of badly machined mounts. Is there a super cheap tube you can recommend that won't get stuck?
I've never had a PK lens jam on my ultra-cheap PK mounts. Maybe I'm just lucky.

04-02-2012, 08:05 PM   #24
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QuoteOriginally posted by RioRico Quote
If you can find any M-type tubes, at least you'll be able to do stop-down metering & exposing.
If you can find A-type tubes, you'll have stop-down shooting and pTTL flash at your disposal.
This could be confusing to some people. The Vivitar tubes I mentioned are marketed as "A type tubes" which simply means they have aperture linkage, no contacts. Your post above is the first time I've ever seen "M type tubes" used to describe an extension tube.

QuoteOriginally posted by GibbyTheMole Quote
I've heard horror stories about the lens becoming stuck to the cheap tubes because of badly machined mounts. Is there a super cheap tube you can recommend that won't get stuck?
Never heard of this either. I've heard of lenses getting trapped on damaged bellows, but never on tubes for K mount lenses. Did you hear about this regarding a Pentax K mount lens, or could it have been another mount?
04-02-2012, 08:38 PM   #25
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QuoteOriginally posted by Philoslothical Quote
Did you hear about this regarding a Pentax K mount lens, or could it have been another mount?
No, it was a K-mount. So what would be a good, super-cheap set of tubes that would be safe to use with no flare caused by inadequate light damping/paint on the inside of the tube?
04-02-2012, 08:45 PM   #26
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QuoteOriginally posted by Philoslothical Quote
This could be confusing to some people. The Vivitar tubes I mentioned are marketed as "A type tubes" which simply means they have aperture linkage, no contacts. Your post above is the first time I've ever seen "M type tubes" used to describe an extension tube.
Yeah, makers don't call them A- or M-type, just Auto (in various incarnations) or nothing. I'm using these terms as they apply to lenses. M-type have a mechanical linkage. I've heard of these (I think) but haven't owned any. A-type have electrical contacts and mechanical linkage. Of the two A-type TCs I've had (and de-glassed), one (Promaster) said Auto and the other (Focal) didn't.

As for non-defective PK-zero macro tubes, I just ordered various cheap sets from eBay sellers and have had no problems. PK-zero: that's my own name for mounts with zero automation or linkage. Cheap tubes and bellows; thin- or wide-flange M42-PK adapters; T and T2 and mount-reversal adapters; Lens-In-A-Cap toys -- these are all PK-zero. If anyone here has a better name, whip it out.

Last edited by RioRico; 04-02-2012 at 08:51 PM.
04-03-2012, 04:52 AM   #27
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I've managed to get a lens stuck to a TC, by getting the aperture coupling levers crossed up. Had nothing to do with cheap. Seems to be an issue with one particular lens of mine, not that I put many other lenses on tubes. I stuck a note on the rear lens cap to remind me to always stop this lens down before connecting it to something with an aperture coupling, and so far I haven't had the problem again.

QuoteOriginally posted by Philoslothical Quote
The Vivitar tubes I mentioned are marketed as "A type tubes" which simply means they have aperture linkage, no contacts.
"Auto" or "automatic" is how these are usually labeled; I hadn't noticed any such marketed as A type (although if we're talking about eBay, I only trust the photos anyway, and then only if they match the description reasonably well and aren't obviously stock photos). Best reasonably cheap source of A-type tubes I've come across yet is the KA/KR (Ricoh mount) 2x converters. Pretty easy to remove the Ricoh pin and the glass on these; they are marketed under various names. About 25mm long.

Not all TCs have easily removable glass.
04-03-2012, 05:00 AM   #28
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You know, something else just occurred to me about making my own tubes out of junk TCs vs. buying a cheap set:

Making one out of TCs would also preserve the automatic diaphragm, while the cheap eBay sets don't. I'm not talking about auto exposure, I'm talking about not needing to focus wide open, then manually stop down to shooting aperture.

Am I correct on this?
04-03-2012, 05:09 AM   #29
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QuoteOriginally posted by GibbyTheMole Quote
I'm talking about not needing to focus wide open, then manually stop down to shooting aperture.
That's the "auto" feature, which lots of cheap tubes do have.
04-03-2012, 05:53 AM   #30
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QuoteOriginally posted by baro-nite Quote
That's the "auto" feature, which lots of cheap tubes do have.

Most of the cheap tubes I've seen are like these. According to the ad: "This Macro Extension Tube set does not have electrical contacts and does not preserve the automatic diaphragm." Wouldn't there be an aperture stop-down pin on the rear mount of the tubes if it had that feature?
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