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04-12-2009, 01:35 PM   #1
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Macro Extension Tubes

I want to use some of my existing lenses for macro work -- I have a DA 35, but that's not much good for anything that moves. Anyway, I wondered if someone can explain the differences in extension tubes. There seem to be all kinds from dirt cheap, to quite expensive. Can meter with them? I assume I would manual focus, but anything else I need to know?

04-12-2009, 06:49 PM   #2
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I don't think any extension tubes are made that support either AF mechanism. It's not a big limitation because you usually must use MF to get the correct focus point anyway.

The cheapest ones are just tubes, with a K bayonet at one end and a K camera mount at the other. They have no linkage for the aperture mechanism. You can use these with a lens that has an aperture ring. You will have to set the aperture ring yourself before metering.

Next is ones with just a mechanical aperture mechanism. Your lens still needs an aperture ring. You use the green/AE-L button to meter. I have some labeled Chinon that are fine. The genuine Asahi ones are too expensive IMO for what you get.

The last type has electrical contacts to transmit aperture information from the lens to the camera. They are somewhat expensive but if you have a KA-type lens the extra functions are useful. The lens doesn't need an aperture ring for this type since the body can control the aperture. I think they are out of production which also drives the price up, kind of annoying for something with no lens elements or focus mechanism. A set can cost more than a full manual macro lens.
04-12-2009, 10:36 PM   #3
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You can buy 2X teleconverters. Cheap ones are, well, cheap

Then you remove the optics and use them as extension tubes.

I sold my genuine Pentax K auto extension tubes and are using gutted 2X teleconverters instead.
04-13-2009, 01:36 AM   #4
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I use a set of very simple tubes from about 1960 and they work just fine. Paid about $25 bucks for them. They are nothing more than simple rings of various depth, blackened on the inside. Here are some samples of what they can do with a $10 lens from the 1970s:








All Pentax K20D
SMC Takumar 55/1.8
M42 Extension tubes[/i]

Like so many other aspects of photography, you can spend big bucks if you want to...but you don't have to.

04-13-2009, 07:53 AM   #5
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I have see many posts suggesting teleconverters with optics removed as extension tube. So does that mean that such a modified teleconverter can be used as an extension tube with DA lenses? If so, then this is a great news for me

Just one more question - what teleconverters (models) are capable of doing this function?

Thanks in advance.
04-13-2009, 09:21 AM   #6
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Mike Cash:

Those are excellent results. I just bought three no-name third party extension tubes with a K bayonet online. I have a couple of M42 lenses and a M42 converter ring, I hope it will work with my set up.

Like many others, I would love to be able to experiment with makro. I already do so much photography close focus, so this would be the next step.
04-13-2009, 09:23 AM   #7
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I don't understand why one would want to cannibalise a TC. For one thing, it wouldn't give you much of an extension and for another, extension tubes are cheap enough.
04-13-2009, 09:33 AM   #8
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Gary, one of the reasons might be to find a 2x with contacts that will pass through the exposure data. So you have a macro adapter that only requires manual focus. Otherwise an M style TC isn't much advantage over regular tubes.

Here's a couple other links to macro stuff that might help the conversation:
https://www.pentaxforums.com/forums/photography-articles/24622-macro-tutorial-bellows.html

https://www.pentaxforums.com/forums/pentax-beginners-corner-q/11161-answer-macro-question.html

Shooting Macros Section 1 - Equipment Enticing the Light


.

04-13-2009, 09:40 AM   #9
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QuoteOriginally posted by Damn Brit Quote
I don't understand why one would want to cannibalise a TC.
I have 4 TCs with cheap optics (and 3 with good optics). They come as parts of packages bought used from local sales. It'd be more difficult not to get them.

Among the 4 with cheap optics, 2 have PKA mount . Have you checked prices of extension tubes with PKA mount recently?

QuoteOriginally posted by Damn Brit Quote
it wouldn't give you much of an extension
Each of them is anywhere from 1" to 1 3/4" long. Put 2 or 3 together and you can easily get to better than 1:1 with a 50mm lens.

As I remember, the Pentax-K auto extension tubes I had were from 1/2" to 1" long.

QuoteOriginally posted by Damn Brit Quote
extension tubes are cheap enough.
Cheaper than free?
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