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07-25-2015, 11:55 PM   #1
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Extension tube help

Hey team macro, I'm having trouble finding k mount extension tubes in North America for a decent price. I just had to return the ones I bought from Amazon because the k mount on the tubes was far too tight and wouldn't properly mount onto my camera. I couldn't even get it to turn more than a centimeter, and when I did that it took me twenty minutes to pry them back off my camera. I almost resorted to using channel locks. Upon closer inspection it appears that almost all of the k-mount tubes sold on Ebay, Adorama, Amazon, B&H, KEH, etc are all the exact same tubes. These tubes are listed under different manufacturers for wildly different prices but if you look closely you'll notice that they are all the same set of tubes. They all have 5 parts, poor reviews (if any), are numbered 1,2,3 (or by their mm in the case of fotodiox) and have a little silver pin to release the lens.

Upon reading the reviews it seems that some people have gotten lucky and their tubes didn't try to forever marry to their camera or to each other, but just as many others have had serious issues with these poorly machined, cheap tubes. On Ebay I've found several decent vintage tube sets in Europe and Japan, and even some for a decent price! But that price is negated after shipping. So what's your experience? Is it just a fact that I'll have to pay over $100 for 60 mm worth of hollow k mounted metal tubing? For those of you who use tubes, where did you get yours?

Your help is much appreciated.

-Mike in North Carolina.

07-26-2015, 02:03 AM   #2
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I've found a Kenko 25 AF . it's plasticky but suits perfectly in my k5 and has elctr. contacts for info trasmission to the body. That's for 90 used.
07-26-2015, 03:00 AM   #3
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Try looking for used....much better quality and fit...something like this...
Pentax K PK Mount Vivitar Automatic Extension Tube Set 12mm 20mm 36mm Tubes | eBay

I use these and can recommend them... mine were about the same cost as those others you have found new so far Ymmv.
07-26-2015, 06:48 AM   #4
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About a year ago I ordered the Pentax auto K tube set from KEH twice--both time they sent the non-auto set, so I then got a set from ebay. They were not rare at the time. I would suggest you check B&H, KEH, and ebay, and one should come up.

And when it comes to tubes proper blacking/baffling is also important to avoid flare, and I would think it best to get the Pentax brand--just be sure it is the auto (aperture) version.

And as I recall they were in the $50-70 range.

I just looked at KEH and they want now $144. for an EX+ set. Maybe mine were listed as BGN, which BTW has (in the past) been excellent (optically and mechanically) in on the order of 90% of the lenses I purchased from them.


Last edited by dms; 07-26-2015 at 07:04 AM. Reason: added KEH current listing info.
07-27-2015, 05:10 AM   #5
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There are many options, so what's best will depend on what you need. Are you wanting to use extension to reduce MFD with a long lens, or for macro work? In the first case you will certainly want the "auto" feature and may even need the electrical contacts, depending on the lens. In the second case, you might be happy with fully manual tubes, e.g. if you are planning to reverse-mount the lens.

I tend to prefer buying genuine Pentax gear for this kind of thing, but have also had good results removing the glass from 2x teleconverters, by way of getting extension tubes with A-type contacts.
07-27-2015, 08:26 AM   #6
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If you are content to use manual tubes you could look out for these Ricoh ones, well made and metal throughout. The cheapo plastic ones from Ebay are horrible, these though have proper K mounts so the lens is the right way up, with the controls on top! I can't remember how much I paid but it wouldn't have been more than 40 or 50.

David in England

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07-27-2015, 08:37 PM   #7
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Thanks team! After serious scouring of the internet, I've gone ahead and purchased some metal tubes on Ebay for $50 with the option to return them. I was wary at first but after asking a few questions from the seller I think it'll be alright. I am only using them to reverse mount a 28mm lens so they don't need to be perfect. If I do get a macro lens it will be the fully manual
from the hobbyist lens makers at Laowa. So hopefully I won't be needing any automatic tubes any time soon. If I do though I think it'll be a waiting game because after looking I've discovered the auto ones for k mount are pretty tough to find unless you want to pay top dollar from Japan.
07-27-2015, 08:52 PM   #8
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With the newer cameras (k5/K20/K3) Can you use extension tubes with a lens doesn't allow manual aperture adjustments ?

Or do you need to go with one of those Raynox deals that goes on the end of your lens? I have extension tubes..... am hoping to use them on a Tamron 70-200 i just had repaired and will get back tomorrow.


Last edited by photolady95; 07-27-2015 at 09:45 PM.
07-28-2015, 03:04 AM   #9
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Extension tubes without any electrical contact don't allow you to control aperture on AF lenses ( mean DA without aperture ring). So you're forced to use MF lenses (theorically you can use AF lenses at their max aperture - but that's completely unuseful in macro photo). But if you're goingto use some F or FA lenses, they have aperture ring and you're OK.
07-28-2015, 06:04 AM   #10
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QuoteOriginally posted by McCoyoioi Quote
I am only using them to reverse mount a 28mm lens so they don't need to be perfect.
Enjoy! Obviously you're after high magnification, so also consider lens stacking. Despite what many think, lens stacking can give results as good or better than plain reversal on extension (I've tested this extensively).
07-28-2015, 08:43 AM   #11
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Thanks Baro-nite.

I haven't gotten into lens stacking yet but I plan on giving it a go once I have some good insect photos to try it out on. I'll be giving it a go in photoshop and probably buying Zerene Stacker when I get the money for it. It's supposed to be pretty awesome for this purpose.
07-28-2015, 05:05 PM   #12
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Zerene Stacker is indeed great stuff for focus stacking. By "lens stacking" I meant reverse-mounting a lens onto another lens, an alternative to reverse-mounting onto plain extension. Either method can give great results, but there's an idea floating around that plain extension is best because you aren't adding extra optical elements, and my own testing has tended to refute this.
07-28-2015, 06:54 PM   #13
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QuoteOriginally posted by baro-nite Quote
By "lens stacking" I meant reverse-mounting a lens onto another lens, an alternative to reverse-mounting onto plain extension.
Oh sorry, I read that sentence far too quickly. I've just come across that idea via this forum. I'm certainly intrigued. I had actually just googled how to calculate the magnification of arrangements like that and came across this article which claims that lens stacking can actually yield higher quality images because lens stacking doesn't produce soft edges whereas apparently a single reversed lens can. Definitely something I'll have to try out!
07-28-2015, 09:01 PM   #14
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I've played around with a lot of this.. including my mega setup of a full set of vivitar tubes attached to a 105mm macro lens attached to a 50mm M series lens reversed. Massive macro ability but extremely unwieldy. Plus, the more glass in front of your sensor, the more image degradation.. theoretically.
07-29-2015, 05:36 AM   #15
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QuoteOriginally posted by mee Quote
Plus, the more glass in front of your sensor, the more image degradation.. theoretically.
If that were true we'd be using single-element lenses. Or pinholes. More air-to-glass surfaces do give more opportunity for internal reflections and loss of contrast, but that's what coatings are for. I'm no expert on optics, just speaking from my own experience testing a lot of combinations of lenses and extension on a high-resolution test target. As you have, I've experimented with extension with stacked lenses, but I haven't found it to answer well; as I recall, all the combinations I tested would vignette.

QuoteOriginally posted by McCoyoioi Quote
I had actually just googled how to calculate the magnification of arrangements like that and came across this article which claims that lens stacking can actually yield higher quality images because lens stacking doesn't produce soft edges whereas apparently a single reversed lens can.
That accords with what I've observed in my tests. I think the issue with reversed lenses is field curvature. I don't know why this is reduced by stacking lenses, but it certainly is, in my experience. But, again, you can still get excellent results without stacking. Unless you are photographing stamps or some other flat subject, corners don't usually matter.
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