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Hi All,
Only today, I mentioned that I'd ordered a couple of tripod rings from China to try with the Pentax K2Q adapter, and as luck would have it, they both arrived in today's mail. Both were shipped on the same day ordered (12/12) and arrived in my Chicago suburb 12/18, so they came pretty fast, especially considering that this is only a week before Xmas.
Here are the listings for the two adapters:
The Plastic one -- $5.39 with Free Shipping
Tripod Ring Mount Collar for Canon EF 100mm F 2 8L Macro Is USM | eBay
The Metal one -- $22.95 with Free Shipping
iShoot Tripod Mount Ring Lens Collar Support for Canon EF 100 2 8 L Is USM Macro | eBay
The metal one is more nicely made, and includes felt tape inserts in the ring to prevent scratching. There are no such inserts in the plastic one, but that might actually be something of an advantage. . .
Both of them are a bit loose on the adapter when fitted so the aperture control ring is in front of the ring, so it still can be turned. Despite the descriptions that indicate that the plastic one has a 0.5mm larger inside diameter, it's actually a touch tighter, and can be more easily user modified to fit securely. Neither is rattle around loose, they're both just loose enough that the adapter can slip out, one a little more easily than the other.
The metal one has considerably better build quality besides the materials used. The catch uses a captive spring loaded pin that catches into a D shaped depression in the other side, then when tightened extends down a slight ramped surface to tighten the ring further. The Plastic one just has a captured screw that tightens the ring as it's screwed in further.
There are a few options to make these work. I've used the "electricians tape" method, which only took me a couple of minutes each, only needs a scissors, and costs next to nothing. I use 3M brand electricians tape because it's the best I've found -- thin and stretchy so it' easy to apply to non flat surfaces, stays very pliable over time, and uses adhesive that seems to be pretty water resistant, so it stays where it's supposed to under adverse conditions.
The Plastic one was easy -- only two pieces of tape, one on the inside of each of the ring halves. The only reason it took more than a minute was that the tape was a tiny bit wider than the ring, and I didn't want any of it sticking out. ..
Another, more permanent fix would be to take some of the material off of the face of the surface where the threaded hole is -- This would allow the ring to be tightened down smaller. I'd take it off of the surface with the hole as opposed to the surface where the screw sticks out because the latter would become too thin. A disk or belt sander would be best for this, but a sanding block would also work -- I'll probably do this some time in the future.
The Metal one was also easy, but took a couple of minutes more. I used three pieces of tape, 3 turns each on the "top" half and 4 turns on th bottom. I think with this design, spacing is the only way to do it effectively. Maybe one or two thicknesses of friction tape on the inside surfaces of the ring might be a better solution.
These are pretty much the minimum amount to secure the adapter. You may feel that you need to take up more thickness to make them tighter. I think that these will suffice for my use as there are only a few lenses that I'll use these with -- the heaviest are the Tamron SP 180 f2.5 and A* 200 f2.8, neither of which has any area that's wide enough to place a tripod ring on the lens. The heavier lenses that I'd use have their own tripod rings/collars, or I've found or adapted one. With either of these modded like this, I can slip the adapter into the loosened, but started ring, then just tighten it down. It's easier with a lens attached -- there's more to hang on to. . .
I used orange tape to make what I did more visible -- I'll replace these with black tape before I start using them outside -- or maybe not -- I have a habit of putting things down and then losing them. . . the orange will make them a lot more visible in the field
when I put them down on the ground.
Here are some pics after the mods -- the iShoot is the metal one with the longer foot and the three pieces of tape. Please excuse the photography -- just snaps with the Q and popup -- I also used my not very photogenic A 50 f2.8 Macro -- not a looker, just a shooter. . .
Bottom line, I'd trust my lenses in either one of these, but if I were using heavier lenses, then I'd go with the metal one as I'd have more faith in the tripod socket screw in the metal foot over the plastic one -- with the ring located so far back, there's going to be more torque on the foot using longer, more front-heavy lenses. Using very heavy lenses, I'd always use a tripod ring on the lens rather than one mounted on the adapter.
Scott