QR plate help (retrofitting for RRS or Kirk)

Hi all, i recently picked up a RRS L-Bracket for my 5D, so now i need a matching QR plate for my tripod. this is my first time with QR plates so i need some help figuring out which plate to get for my tripod head.

For the tripod head i have an amvona cf881 and a head that looks like this. http://www.flickr.com/​photos/minhi/450355442​8/ you can see that this has a key which matches a slot on the current plate http://www.flickr.com/​photos/minhi/450292495​1/ and what looks like a 1/4 inch whole for a bolt. I guess the slot+key is to keep the plate from rotating.

I would like to get a QR plate and the two i'm looking at a kirk one http://www.kirkphoto.c​om …_Quick_Release_​Clamp.html

and an RRS one http://reallyrightstuf​f.com …sp?kc=B2-Pro-II-1%2F4&eq=

The Kirk one has no slot, is this a risk for the plate rotating on the head? The RRS one has a slot, but not sure if it would actually fit my head. If it doesn't fit could i still make it work with a longer bolt? A bigger issue with rotation of the plate?

Will this work or should i look at buying an RRS head for my amvona legs? Thanks for any help, this is one of the cases where i would be happy to go to a store for help but no-one sells Kirk or RRS around me!

You mean a QR clamp It appears that the head you have is keyed Arca-Swiss style, and yes, you are correct about the function of the key. The Kirk you are looking at is a generic fit, and I would be concerned about the raised key on your ball stem, which means a fairly small and narrow contacting area to the clamp, which may affect stability.

Here's something you might not have considered: Kirk does make a clamp with an Arca-Swiss key slot, the "SQRC-Arca." The key slot measures exactly 7/32" wide, 3/32" deep, and the screw hole is 1/4". Since the RRS you're looking at is claimed to fit "current model Arca-Swiss ballheads," I believe you can safely assume that the key dimensions are the same. The only thing you need to do then is measure the key on your ball head to see if it matches.

http://www.kirkphoto.c​om …_Quick_Release_​Clamp.html

Edit: If you're suddenly interested in the Kirk SQRC-Arca, look on the big auction site before buying it brand new.

Edit #2: If you can swing it, I'd definitely look into a new head altogether. I've never tried Amvona, RRS or Kirk heads, but I can definitely attest to the quality of my Markins and Arca-Swiss heads (I own Q3 and Z1, respectively) which are miles ahead of the Manfrottos I used to own. The Markins screw clamps are excellent, and people really seem to like the new lever ones. My Z1 needed a better clamp (which I replaced with the Kirk I mentioned above) but that elliptical ball works as advertised for preventing flop.

The image of the post on you ball head isn't very clear but it appears that the post has a female thread on it. If this is the case, the Kirk clamp you linked to isn't going to work. That clamp is designed to be attached to a 1/4X20 male thread. I think your best bet is going to be the one suggested by hyt...

My Arca Swiss style clamps from RRS and Markins, and ballheads from Manfrotto and Markins, all have simple unkeyed bases. I've not had a problem with twisting once everythings fully tightened down with locktite.

But provided the threaded drilling in the ballhead is deep enough I don't see a major problem, the rectangular key could be simply cut off and carefully filed flat. Threads tend to be a standard 3/8th UNC. RRS will supply a plate either drilled and threaded for spinning onto a stud or with a countersunk clearance hole for a simple machine screw. I suspect other manufacturers would do the same.

JWright wrote in post #9958404
The image of the post on you ball head isn't very clear but it appears that the post has a female thread on it. If this is the case, the Kirk clamp you linked to isn't going to work. That clamp is designed to be attached to a 1/4X20 male thread. I think your best bet is going to be the one suggested by hyt...

thanks all, yes the kirk one i linked to, i think it's meant to be threaded onto a male stud, i think i need a clamp with an unthread hole that i could bolt into the female hole on my head. i think the sqrc one is the correct match for what i want to do.

so i need to figure out if the key on my head will fit the slot on either of the clamps. wow, thanks guys, helps out a bunch.

one last question, there's no issue mixing RRS plates with Kirk clamps? I know they are both arca-swiss styles but i see mixed messages about the compatibility (particularly with the quickrelease ones)

There's no issue as long as you use a screw clamp, which is exactly what the Kirk SQRC-Arca is. Screw clamps by their nature are more forgiving of the slightly different tolerances across different brands of plates. Markins' new lever clamps aim to somewhat alleviate the issue but you still need to dial in a new adjustment for each different brand of plate you want to put on there (and Markins even advises customers of their new lever system to stick with one brand of plates).

I use a Markins plate on either my 70-200 or 100-400, cannot remember which one off-hand. On my tripod I use the RRS lever clamp and as supplied the markins plate slid straight through, as if the lever clamp was not even closed.

But the solution is simple. I added a single layer of self adhesive sail repair cloth to the underside of the plate. This was originally intended as a temporary fix, but it worked so well I've left it there. It works by raising the bevelled edge that crucial fraction of a millimetre, the tolerances really are that small! It now clamps just as well as my RRS plates.

But in future I will make sure that I use clamps and plates from the same manufacturer. The one exception is Wimberley, because RRS and Wimberley have co-operated to ensure that their kit is fully compatible.