11-15-2013 04:56 AM
Hallo, I am looking for an extension tube set for my Canon 6D. I Found some different brand that offer a set 13, 21 and 31mm sets. They don't specify if they support autofocus. I would prefer a set that support autofocus.
Do you have a suggestion ? Thanks
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11-15-2013 10:40 AM
If you really want AF then I'd recommend not trying to save a few bucks going with a generic, there's a reasonable chance of it just not working. Kenko is the "name brand" when it comes to third party extension tubes. These should work with any EF or EF-S lenses.
Canon makes some too, but I don't know if they sell a three set. The Kenko's have a good reputation.
11-15-2013 12:21 PM
11-15-2013 01:12 PM - edited 11-15-2013 01:33 PM
The macro tube set that includes the rather odd sizes 13mm, 21mm and 31mm is made by Zeikos and sells under a whole bunch of different brand names (Bower, Vivitar, Jessops, ProOptic and many more). There are two grades of these tubes... one with metal bayonet mounts and a cheaper version with plastic bayonet mounts (like some kit lenses have). The bodies of these tubes are plastic and they support AF and aperture control. All of them made for Canon will fit fine on the EF mount of your 6D (someone with a crop/EF-S Canon camera will need to take care to buy the later versions of these that support that mount if they want to use with EF-S lenses, some earlier ones didn't). These tubes sell for under $100 US (the plastic bayonet are often closer to $50 US). Three things worry me about them: They don't seem very durable, I've heard some reports of them cracking over time. The release latch button protrudes quite a bit and might be accidentally pressed. And I have seen a few reports of them "frying" the circuitry of Canon 5D models. This last seemed to be quite isolated cases and the 31mm tube seemed the culprit. I haven't seen any reports of issues with other Canon models.
Opteka is now making a tube set that's similar in construction - plastic bodies with metal bayonet mounts - that also sells for under $100 US, but includes the more traditional sizes of 12mm, 20mm and 36mm tubes. These also support AF and aperture control. The release button is slightly recessed, but I haven't used these and can't say if it's appreciably better than the Ziekos (etc.) tubes. They are a relatively new item, so only time will tell how durable they might be.
The Kenko tube set is metal bodied and metal bayonet mounts, more comparable to the tubes that Canon themselves offer (but only individually). The Kenko set included 12mm, 20mm and 36mm and sells for roughly $200 US. Older versions of this set (marked "CA/AF") are for EF mount lenses only. Current version marked "CA/AFs" (note the small "s") is usable with both EF and EF-S lenses. Of course either will work on 6D and EF lenses. The Kenko tubes also support AF and aperture control.
Canon offers individual tubes only: 12mm and 25mm. The older original type are EF only. The current "Mark II" are EF an EF-S compatible. The construction is very similar to the Kenko and fully supports both AF and aperture control. In fact, Kenko also offers individual tubes in the same size. Both the Canon and the Kenko use a fairly recessed release button that's hard to accidentally bump. The Canon tubes currently sell for about $85 for the 12mm and $140 for the 25mm.
Finally, there are really inexpensive macro extension tubes that lack the electronic contacts to provide AF and aperture control. These are usually all metal construction, use various latching mechanisms and sell for under $25 US (sometimes even under $10). The sizes included in a set usually are 12mm, 20mm and 36mm.
To be honest, not having AF when shooting macro really isn't all that big a deal. It's often easier to focus high magnification shots manually. I often turn AF off and several of my macro lenses are manual focus only. You focus by moving the entire camera and lens closer to or further from the subject. The focus ring of the lens sort of serves more as a zoom, setting the degree of magnification. The fine tuning of focus is done with the movement of the entire rig. This can be done by hand, or there are tools such as macro focusing stages avail. that allow this with a high degree of precision... or with a lens that's got a tripod mounting ring, if you use Arca-Swiss quick release system it's possible to use an extra long lens plate as a focusing "slider".
More of concern is being able to directly control the aperture, which is done electronically with Canon lenses and cameras, via controls on the camera body and the electronic contacts connecting the two. High magnification means shallow depth of field, so stopping down is often necessary. There are ways to vary the aperture with the really cheap tubes that lack the electronic contacts, even with the modern camera and lens. But it's a pain in the arse. Personally I would only use and recommend the really cheap tubes for use on adapted, vintage lenses that have an aperture control ring right on the lens itself.
But most of the tubes being discussed (Canon, Kenko, Zeikos/etc. and Opteka) provide the electronic contacts, so both AF and aperture control are fully supported.
What lens do you plan to use with the camera and extension tubes? The longer the focal length, the more extension you need to significantly increase magnification. But, too short a focal length can put you way too close to the subject. Most often for use on a FF camera a lens in the 70mm to 135mm range is a good compromise of adequate working distance, yet handholdable and not requiring too much extension. You can stack multiple tubes for a whole lot of extension, but this can get risky with too many tubes. Best to use as few as possible.
I'm a big fan of extension tubes.... have been using them with various systems for 25+ years and always have some on hand just in case they are needed. They also can improve the close focusing ability of a big telephoto. They are easy to use and, having no optics inside, have little negative effect on image quality.
With my Canon kit I currently use Canon 12mm (2X), 25mm and an older Kenko set. Over the years I've used them with lenses from 20mm to 500mm, as well as 24-70, 70-200 and 28-135mm zooms. I sometimes use them with macro lenses, too... boosting their magnification higher than the 1:2 or 1:1 the lens alone offers.
My recommendation.... Buy a good set and you'll only buy them once. There is little to wear out and macro extension tubes are versatile, helpful, and easy to tuck into the corner of your camera bag to have with you all the time. IMO the Kenko set offers the best value (but I haven't seen or used the new set Opteka just introduced, so can't really compare).
11-16-2013 12:03 PM
"... having no optics inside, have little negative effect on image quality."
Alan this is true theoretically but not actually. It is akin to enlarging a photo to the same magnification as it would be with the extension tube in Photoshop. A poor lens is going to show it's weaknesses more in either case.
Even though there is no glass involved there is a f-stop penalty involved using them.
I have also used them and have a couple sets right now. I even have a bellows, don't know if they still make them?
11-16-2013 04:10 PM
Yes, there can be some loss of image quality. Any time you ask a lens to focus closer than it's designed, you can get into field curvature problems and there is some light fall-off effect as well.
For example, an EF 50/1.4 lens tends to get soft in the corners and show some vignetting when used with extension tubes, most noticably at apertures larger than f2.8. Not that this is necessarily a bad thing. I've used the lens with tubes deliberately, because of this effect. That's one reason I recommend somewhat longer, but not too long, focal lengths... in the range of 70mm to 135mm. Short teles typically show less of this effect (while not needing too much extension). True macro lenses are "flat field", designed to focus more evenly across the entire frame at really short working distances. But, of course, they are also much more expensive than a set of extension tubes, plus another lens to carry around.
Light-falloff (aside from optical vignetting) isn't really a problem so long as the camera's TTL metering is being used. That compensates for it nicely. It might be an issue if using manual exposure settings and/or manual flash.
Yes, I believe Novoflex still makes a macro bellows (sort of an adjustable extension tube for really high magnifications) for use with Canon EF/EOS. It was quite expensive, last time I looked. There are also "generic" bellows and bellows in mounts that are easily adpated for use on Canon (Nikon F, Leica R, Oly OM, Pentax screwmount, etc.). But those would not support AF or direct aperture control.
Am alternative to a bellows in the Canon system is the MP-E 65mm macro lens.... which gives much higher magnification than the typical macro lens (1:1 to 5:1), in the range a bellows might give, but is manual focus only and unable to focus to infinity. It's a pretty impressive lens, I've just started experimenting with one... But it's not easy to use so I really wouldn't recommend it to someone who is just starting to shoot macro, who probably doesn't need magnifcations that are nearly so high (really are beyond what we normally see with our bare eyes).
I've also still got a couple bellows in other, vintage film systems (Nikon and Konica).
Another thing I've seen advertised recently is a macro helicoid being offered in EF/EOS mount. This is also sort of an adjustable macro extension tube, though not with as much range offered by a bellows. It's basically a pair of solid tubes with a helicaladjustment thread in-between. If memory serves, it offers about 45mm to 65mm of extension. Supposedly it fully supports AF and aperture control and is being offered in several different mounts. I suspect it's a Meike, Zeikos or Opteka product, but have seen it rebranded under a couple other names too. I haven't had one in hand or used one yet, so can't say anything one way or another about it's quality.