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06-14-2012, 03:13 PM   #1
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Are macro rings all the same?

I'd like to get some cheap extension tubes to started doing some macro work. I believe I've seen some more expensive extension tube sets that allow you to keep autofocus, but I don't think I will need autofocus. So I was planning to just get the cheapest set of extension tubes that I can find. But is this going to come back to haunt me? For instance, do cheaper extension tubes have problems securely mounting to the camera and lens? Any recommendations for inexpensive macro ring sets would be appreciated.

06-14-2012, 04:57 PM   #2
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I can't be for sure but to my knowledge I would get an extension tube that has at least contacts for auto aperture. As for autofocus I wouldn't recommend it as I find that since the working distance is so thin that your AF will be hunting too often. As for securing properly I would make that a priority as if the lens falls your out a whole lot of money which cheap out to save a buck or two.
06-14-2012, 05:22 PM   #3
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The cheap Chinese ebay-type tubes are just simple metal and screw together. No aperture control lever, so the lens would presumably behave as if it wasn't connected to anything, which if I remember correctly means aperture closed for lenses with no aperture ring. This may be fine if you want a high DOF, but makes it pretty hard to see while composing, and limits you to shutter speed and ISO only for exposure control. As you can probably see, these cheap tubes probably aren't worth getting.
I think all the "real" tubes which have K-mount connections on all the parts rather than screw threads have aperture levers. Someone correct me if not? Newer/better ones will have pins for lens detection etc, and I don't really remember but I think this may be necessary if you want to use "new" lenses with no aperture ring at anything other than fully open?
I don't think I've ever seen any tubes with autofocus screw drive, even ones marked as "AF" or similar. Do any have it? Not that you really need autofocus for macro anyway...
06-14-2012, 07:02 PM   #4
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I have bought at least a half-dozen sets each of M42 and cheap PK tubes and have had no problems. Why so many? Because I use some PK sets to adapt lenses with weird mounts; and because I keep some enlarger lenses on enough M42 extension that I can just plop them onto the camera quickly without piecing-together the right combination.

None of my PK tubes have any aperture contacts nor linkage. AF is totally unneeded for macro shooting. Aperture control would be nice in many situations, but I haven't yet bought M-type (mechanical linkage only) nor A-type (automatic contacts) tubes. However, I have improvised such tubes, by removing the glass from cheap teleconverters. These tend to be of certain thicknesses -- 2x tubes are about 25mm thick.

Don't worry about those US$8 PK sets nor US$6 M42 sets. I've seen complaints of flakey paint on some but I've not experienced that. If I found such a problem, a bit of matte-black spray paint would fix it. Don't bother buying expensive AF tube sets, they're just impractical for macro work. Where the AF system wants to focus may not be where YOU want to focus. If you have the budget, you won't regret getting one or two sets of M- or A-type tubes. If you're a cheap bastard like me, deglassing TCs may be just right for you. Good luck!

06-15-2012, 06:39 AM   #5
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So what I am taking away is:
1) Autofocus isn't necessary.
2) No aperture control on the super cheap extension tubes means you'll be stuck with the smallest aperture when using new lenses.
3) It could be a big problem if the mount failed, but it doesn't happen often.

Lenses: I've got the DA L 18-55, DA L 55-300, M 50/2, and Tak 135/2.5. I think I can live without aperture control on my new lenses. From what I have heard you usually are trying to maximize DOF in macro shots. And the manual focus isn't very good on those lenses anyway. I suspect I would end up mainly using my manual focus lenses, especially the 135mm lens.
06-15-2012, 07:55 AM   #6
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QuoteOriginally posted by stainsor Quote
So what I am taking away is:
1) Autofocus isn't necessary.
2) No aperture control on the super cheap extension tubes means you'll be stuck with the smallest aperture when using new lenses.
3) It could be a big problem if the mount failed, but it doesn't happen often.
1: Yes.
2: No. Yes.
3: Sorta.

1) Yes. Autofocus is NOT your friend when shooting very close. At 1:2 or greater magnification, hay even at 1:4 with some lenses, focus is critical and MUST be done manually. One common procedure is to secure the camera and slowly move the subject till it's in focus.

2) No. Yes. AF lenses lacking aperture rings stay closed to the tightest aperture. With AF lenses lacking aperture rings, or auto-only M42 lenses, the iris is held open to the widest aperture. On any other PK lens, or an M42 lens with an M/A switch or preset aperture, you have manual control of the aperture. That's with cheap tubes. If you get A-type tubes, or deglass A-type TCs, you have in-camera aperture control. EDIT: Corrected.

3) Sorta. I'm not sure what "if the mount failed here" means. Cheap PK tubes aren't the sturdiest metal and *could* be bent, but then they wouldn't mount. And they could also be bent back into shape. I don't worry about the mounts.

One concern from some (which I haven't experienced) is that the cheapest tubes may be badly painted, so paint fragments could fall into the mirrorbox. I haven't seen such tubes, but if I did, I'd just run a wire brush around inside, then spray some matte-black paint in.

Last edited by RioRico; 06-15-2012 at 03:16 PM.
06-15-2012, 10:01 AM   #7
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Auto extension tubes?

Please be aware that not all extension tube sets with the K bayonet on each piece enable auto-diaphragm, although most do. I learned this the hard way some years ago when I bought a used set which didn't have auto diaphragm. The seller took them back, so I was only out postage.

You really don't want non-auto tubes, unless you have a pre-set diaphragm lens to use. Pre set lenses have two diaphragm rings; one is click-stopped for f stop setting, the other moves the diaphragm between the "pre-set" stop set with the click-stop ring, and full aperture. Not too bad for leisurely close-up work, but a pain in the fundament for most other shooting. The venerable AsahiFlex cameras had this set up, as did a lot of the pioneering SLRs.
06-15-2012, 02:18 PM   #8
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QuoteOriginally posted by stainsor Quote
I'd like to get some cheap extension tubes to started doing some macro work. I believe I've seen some more expensive extension tube sets that allow you to keep autofocus, but I don't think I will need autofocus. So I was planning to just get the cheapest set of extension tubes that I can find. But is this going to come back to haunt me? For instance, do cheaper extension tubes have problems securely mounting to the camera and lens? Any recommendations for inexpensive macro ring sets would be appreciated.
Hunt these:

PENTAX Auto Extension Tube Set K reviews - Pentax Camera Accessory Review Database

I have those and found it relatively inexpensive (equivalent to US$25). The build quality is really good, as is the macro if you use all 3 tubes. Pair with lenses containing an aperture ring, and meter with green button, as usual.

06-18-2012, 04:14 PM   #9
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I got a cheap Chinese set of extension tubes recently, they seem to work ok but as you close the aperture it gets too dark to see. No aperture lever. That's the only thing I don't like, everything elkse seems to be ok, and for under 10 bucks I'm not unhappy.

I'm also using a K mount teleconverter with the lens elements removed, it has the aperture lever and works well with 50 and 28mm lenses, should work well with a 135mm but the old Makinon I have is not that great. did get a couple of decent shots with it though.

With M42 I have 3 sets, for a total of something like 147mm extension, I usually only use the Vivitar set which is 58mm, sometimes I add a 10mm ring from another one. The only M42 lens I have that's usable with it is the Lentar 135mm, and it works very well. It has the double aperture ring, which is nice to have with this setup. One sets a stop, the other actually changes the aperture. That lets me open it up where I can see to focus, then stop it down and shoot. I can do the same thing with the Chinese K mount set but I have to count aperture ring clicks to get the one I want. I'll be looking for some other k mount teleconverters to use, the one I have is 26mm and I'd like to be able to put together around 75mm or so.

The teleconverter route may be worth considering, sometimes you can find them cheaper than extension tubes but check them first, you don't want to gut one that works well. I gutted mine because I was never happy with it, degraded image quality no matter what I did so I finally cannabalized it and it's an extension tube now.

I use all manual focus lenses, so the auto focus question is not an issue for me, but I would avoid it. I shoot fully manual, nothing on auto, but I've been doing that for 30 years, so I'm comfortable with it.

One thing I don't think has been mentioned, or maybe I missed it, any time you start talking macro, no matter what the method, your depth of field goes out the window. With my 135mm Lentar and 68mm of extension tubes, I can shoot at f8 and a daisy the size of a dime is not all in focus. So plan on using the smallest aperture you can get by with, I often use a flash and go with f11 or f16 just to get some depth of field. Any macro setup will have this same limitation. The closer you are to your subject, the thinner the depth of field gets. This can be seen on older manual lenses by looking at the depth of field scale. f8 at 10 feet has maybe a foot of depth, infinity has loads. With macro you're talking inches, so depth will be a fraction of an inch even at f16.

That was my biggest issue when I started getting into macro, once I got accustomed to it, and learned to be really picky about focus, I love it.

Welcome to your new addiction.
06-22-2012, 10:36 AM   #10
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I bought a super cheap set of M42 extension tubes for under $5 from Amazon. The tubes thread together fine. My Pentax screw-mount lens screw in with no binding. However the tubes will only thread in about 1 to 3/4 of a turn into my OEM Pentax M42 to K mount adapter. I don't trust that to be secure enough to support my lenses. Oddly enough the tubes thread perfectly into a T/T2 mount adapter so they are usable that way even though the T/2 adapter adds some additional extension. Very poor tolerances on the threads.
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