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I was looking for extension tubes and found this one being sold by a surplus liquidation company in Brampton, Ontario, Canada. It was a bit pricy but was brand new in an unopened box. It is the same as stacking the three tubes from an auto extension tube set, but is three times more convenient.

[Pentax Auto Extension Tube K 50mm With Case Model 30551 100 NEW IN BOX | eBay

They had ten and four have been sold. It is very unusual to find a brand new, discontinued, Pentax accessory, but the really good thing about it is that it came with a pristine thirty page (3”x6”) manual which is the most complete one I have seen. It includes the Auto Extension Set K, the Extension Set K, the Auto Extension tube K 50mm, the Auto Extension tube 100mm, as well as the Mount Adapter K and the Reverse Adapter K. It also has the magnification tables for all lenses up to 1992.

The original listing expired, but it was re-listed with two available. I edited the URL above.

Have a good one!

Murray

[milewis]

All gone now.

[oneill]

All gone now.

Sorry, must have screwed up the URL ..... I fixed it and there are some left

Murray

---------- Post added 01-03-2015 at 02:46 PM ----------

All gone now.

I corrected the URL. There are still some left

[oxidized]

Sorry, must have screwed up the URL ..... I fixed it and there are some left

Murray

So does this mean that you can set aperture from within the camera?

Edit:
Nvm. Checked in the database. It does not transmit aperture information to the camera.

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Last edited by oxidized; 01-03-2015 at 04:33 PM.

[vonBaloney]

So does this mean that you can set aperture from within the camera?

No, it has no contacts. It looks like it does have a mechanical aperture linkage though, which would allow allow the aperture to stay open until the shutter is fired. But on DSLRs with their crippled mount, that will be annoying in some situations...

[Scorpio71GR]

You would need to set the aperture on the lens manually. Then you would have to use the green button to stop down and take an exposure reading.

[slowhands95128]

This auto extension tube is for pre A mount lenses. It lacks A contacts, so digital cameras will treat the attached lens like any pre A lens, that is, manual only, no auto exposure, no PTTL flash. The documentation with it, however, is very valuable for knowing how extenders magnify, so that by itself is worth something. You could add the A contacts to it with some effort, but it would not give accurate auto exposure information due to the extension. It would function, but not be accurate about the exposure.

You are better off to get a cheap A mount 2x teleconverter, modify it by unscrewing the optics, and use that as an extension ring. You can stack two or more if you want longer extension. It will pass A info from the lens to the digital camera, and the camera will allow auto exposure and use of PTTL flash. The A info about the lens will be wrong because it is on an extender and hence much slower aperture, but you can put in exposure compensation and work around that, particularly if the attached lens is really an A lens with the right aperture calibration curve.

[yucatanPentax]

It includes the Auto Extension Set K, the Extension Set K, the Auto Extension tube K 50mm, the Auto Extension tube 100mm, as well as the Mount Adapter K and the Reverse Adapter K. It also has the magnification tables for all lenses up to 1992.

The link now goes not to a set of tubes or items, but to one single tube, 50mm.

[aoeu]

The link now goes not to a set of tubes or items, but to one single tube, 50mm.

It always did. The manual describes the rest.

[aoeu]

If I buy one of these and use it with my FA 100 what would the magnification ratio be?

[oneill]

I was looking for extension tubes and found this one being sold by a surplus liquidation company in Brampton, Ontario, Canada. It was a bit pricy but was brand new in an unopened box. It is the same as stacking the three tubes from an auto extension tube set, but is three times more convenient.

[Pentax Auto Extension Tube K 50mm With Case Model 30551 100 NEW IN BOX | eBay

They had ten and four have been sold. It is very unusual to find a brand new, discontinued, Pentax accessory, but the really good thing about it is that it came with a pristine thirty page (3”x6”) manual which is the most complete one I have seen. It includes the Auto Extension Set K, the Extension Set K, the Auto Extension tube K 50mm, the Auto Extension tube 100mm, as well as the Mount Adapter K and the Reverse Adapter K. It also has the magnification tables for all lenses up to 1992.

Have a good one!

Murray
PENTAX : PENTAX Photo Gallery artist page

Original listing expired. Listed again with 2 left. I edited the URL

[Prakticant]

1:2 (50/100) plus magnification of your 100mm lens (I do not know the magnification of FA 100).

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If I buy one of these and use it with my FA 100 what would the magnification ratio be?

[Scorpio71GR]

I purchased one came brand new unopened. Included the booklet which describes all the extension tubes and their magnifications on various lens. Very rare to find a brand new unopened Pentax accessory.