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06-02-2012, 04:17 PM   #1
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Jessops Extension Tubes

I've been hunting and hunting and hunting for a sub $100 USD set of full auto extension tubes with at least 60mm of range on the PK mount.

I seem to have found someone selling the Jessop Extension Tubes and inquired about them since in the photo I see no contacts but the photo is at an angle. They claim "No they are manual - but do have mechanical aperture couple" but I'm am unsure if is he correct in his response to me.

QUESTION: Wondering if anyone knows if Jessops made Extension Tubes for PK that were manual (much like the cheap, chinese plastic ones on ebay for 10 dollars) ??

06-02-2012, 06:25 PM - 1 Like   #2
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Every mention I've seen of Jessops tubes refers to ones with the aperture contacts. They'll give you equivalent functionality to an A series lens. If they made a manual type with just the aperture linkage, I haven't seen it.

Vivitar makes both, actually three variants. Their AT-21 was fully manual, AT-22 (which I have) have the mechanical aperture linkage, and the AT-23 set has the six contacts for aperture info, like the Jessops tubes.

For what they are, my Vivitar AT-22 set works great. That linkage allows for proper stop down metering, so while they're still limited to M mode, they're much more convenient than fully manual tubes.
06-02-2012, 08:20 PM   #3
mee
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Original Poster
Thank you for the info.. I am inquiring further to see if they have more info on exactly what they are selling.

I think the Vivitar AT-23 might be the most difficult of the 3 to find. So far I've seen a couple of the Kenko sets and one of the Jessops (well jury is out still) but yet to see the AT-22 or AT-23 anywhere.

I figure I'm in no major rush.. so I'll see what shows up on ebay in the next couple of weeks. frustrating I just cant go to adorama or a bh and buy them new off of the 'shelf' though.

If something doesn't change for the better in Pentaxland, we are going to become similar to Cubans under Communist rule.. piece-mealing 1960s era automobiles together... :c (
10-12-2017, 09:02 AM   #4
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I know this is an old tread but maybe someone is still around.
Are you sure the At-21 is manual?
I am looking at a picture and it looks like there is a lever and the manual says automatic.
TIA

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10-12-2017, 03:01 PM   #5
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Re the original question - Jessop and Vivitar sold equipment for many years, and sold auto tubes for Pentax back in the days when it was all mechanical linkages. If you look at the lengths of those Vivitar tubes they're most appropriate to a full 35mm frame, even the shortest is a fairly large extension for the smaller frame, so they're probably from the nineties or earlier - go back even a few years and you're talking about KA bayonet, which is pre-autofocus and pre electrical contacts in lenses. So if the seller is saying that that I'd be inclined to believe it.

later - why not just buy a modern set of tubes and pick up an extra tube somewhere to get the length you want?
10-13-2017, 07:17 PM   #6
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QuoteOriginally posted by Marcus Rowland Quote
Re the original question - Jessop and Vivitar sold equipment for many years, and sold auto tubes for Pentax back in the days when it was all mechanical linkages. If you look at the lengths of those Vivitar tubes they're most appropriate to a full 35mm frame, even the shortest is a fairly large extension for the smaller frame, so they're probably from the nineties or earlier - go back even a few years and you're talking about KA bayonet, which is pre-autofocus and pre electrical contacts in lenses. So if the seller is saying that that I'd be inclined to believe it.

later - why not just buy a modern set of tubes and pick up an extra tube somewhere to get the length you want?

Thanks for the input.
As for this set after correspondence with the eBay seller and him sensing me a picture of the mount turns out that this set is for Olympus OM mount and not PK.

What “modern set of tubes” are available for K mount?
10-14-2017, 08:55 PM   #7
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I was thinking in terms of the no-name Chinese sets etc., having bought them for Nikon and (recently) Canon, but there do seem to be remarkably few compared to Nikon (which is a similarly complex mechanical and electrical design).

Apart from that the leading manufacturers seem to be Vivitar, Kenco, and Jessop, all discontinued, so apologies, it does look like second hand is going to be your best bet.

10-15-2017, 12:57 PM   #8
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Further to this, I was looking at some other sites and one of them mentioned that the motor in Pentaxes isn't usually powerful enough to overcome the friction of more than a couple of tubes, so this may not be a good idea from the AF viewpoint.
10-16-2017, 11:37 AM   #9
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I appreciate your input. AF is not very useful for Macro (I think).
The aperture lever is important. Pentax or third party sets with this lever even used, look to be expensive. Maybe because they are not common.
I came across this set on AliExpres.
There seems to be mounting problem on the camera with this set and some modification needs to be done. Removing the AF and aperture simulator that is not used on DSLR.
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10-16-2017, 06:04 PM   #10
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No, it's usually easier to move the camera and stick to manual focus. The things I would have expected to find even on older tubes are the stop-down and aperture sensor components etc., they've been part of the K mount since 1983.

Rather than modifying the tube, why not just switch the camera to manual focus when you use it?
10-17-2017, 12:25 PM   #11
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That would be the logical thing to do but you have to remember that it is a no name brand with probably little to no quality control. From what I understand that even with the AF disengaged on the camera manual focus is possible only with quick shift lenses. With lenses that do not have quick shift one will hear grinding noise that might indicate damage being done to camera or lens.
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