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05-10-2019, 10:49 PM   #1
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Advice requeseted for concerns with my Acratech Ball Head QR Clamp

I'm a big fan of the Acratech line of ball heads. I have the Ultimate Ball head and the GP Ball Head. What I'm not a big fan of is the Acratech QR Clamp. I'm noticing that the "bite" of the clamp isn't great with many of the QR plates that I own. I did a little sleuthing about the Arca-Swiss "standard," which appears to be anything but standard. So I am left with more questions than answers.

I'm looking for a better QR clamp solution to install on my Acratech ball heads. Or maybe a better line of QR plates that work well with the existing QR clamp. Hoping folks here might have some good advice for me.


Below are less that stellar cell phone photos of my various QR plates mounted on the Acratech ball head clamp. But I think they get the point across. The Arcratech Universal QR Plate and the iShoot IS-MA L-Bracket seem to have the best amount of bite. The Induro, Kirk and the Wimberley P-20 (which lives on my D-FA 150-450 lens) are the worst offenders of the group, with minimal bite. I do have a Wimberley Sidekick (not shown in the photos), which fits quite comfortably in the Arcatech ball head QR clamp.

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05-11-2019, 04:35 AM - 1 Like   #2
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I have experienced this issue. QR clamp that comes with Ultimate ballhead is not that good. I replaced the QR-clamp with RRS Circular clamp.
PC-PRO Quick-Release Clamp
05-11-2019, 07:42 AM - 1 Like   #3
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Great catch. I have several different make plates and just assumed all were the same dimension. Now I will check them all and any out of size will get cut to spec. Your post might prevent some dropped equipment, Thanks.
05-11-2019, 11:50 AM   #4
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QuoteOriginally posted by catfishjohn Quote
Great catch. I have several different make plates and just assumed all were the same dimension. Now I will check them all and any out of size will get cut to spec. Your post might prevent some dropped equipment, Thanks.

Fortunately I've never had a dropped camera because of this QR plate discrepancy. On the other hand, the variation of standards, for QR plates and QR clamps, between manufacturers is a little disconcerting.

---------- Post added 05-11-19 at 11:53 AM ----------

QuoteOriginally posted by pentaxfall Quote
I have experienced this issue. QR clamp that comes with Ultimate ballhead is not that good. I replaced the QR-clamp with RRS Circular clamp.
PC-PRO Quick-Release Clamp
Thanks for the link. I'll take a look. What's the dovetail fit like for non-RSS QR plates? Seems that the thickness at the bottom of the plates is what's really causing the discrepancy between manufactures.

05-11-2019, 01:09 PM - 1 Like   #5
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Yikes!!! Your findings have been noted!
05-11-2019, 04:26 PM   #6
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I have the Arcatech GP ballhead. From what I understand, out of the original first batch - since it's going on 14 years old now. I would also think that it's pretty similar (if not the same) to the Ultimate. For plates, I currently have...
  • Arcatech plate for the K100D (this came with the ballhead)
  • Krik L-Bracket for the K5
  • RRS L-Bracket for the K1
  • Sunwayfoto flat generic plate PU50 that I have on the bottom of my Nodal Ninja 3
  • HejnarPhoto 14mm rail with a Y that is also AS compatible - support for my A-300mm/f4 lens
You have gotten my attention. After mounting all of these and taking a look, I see a reasonable bite across the length of the clamp. I have never had the clamp fail to engage. That said, I've always checked the stability before letting go of my camera body. Some plates have a larger surface area interface across the length of the clamp than others. The Arcatech and Hejar are probably the best. I can see a slight additional thickness across some of the others, but not to an excess.

Based on this, I do wish that there would be a better defined Arca-Swiss interface standard. What all of this comes down to is the acceptable engineering tolerances that the various manufacturers use.

05-11-2019, 09:18 PM   #7
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QuoteOriginally posted by interested_observer Quote
Based on this, I do wish that there would be a better defined Arca-Swiss interface standard.
Agreed.


Since originally posting this thread, I realized I have a RRS macro focus rail with a RRS QR clamp buried in a box. Pulling it out, and adding the RRS rail & QR clamp to my QR plate test, I find the RSS dovetail fits nicely into the Acratech QR clamp, easily as good as the Acratech QR plate. And the 3-Legged thing fits the RRS QR clamp pretty much the same way as it fits the Acratech QR clamp. Doing some quick comparison, the Acratech and RRS QR clamps are almost identical in their dovetail bite depth.
05-11-2019, 09:36 PM   #8
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QuoteOriginally posted by david94903 Quote
Fortunately I've never had a dropped camera because of this QR plate discrepancy. On the other hand, the variation of standards, for QR plates and QR clamps, between manufacturers is a little disconcerting.

---------- Post added 05-11-19 at 11:53 AM ----------




Thanks for the link. I'll take a look. What's the dovetail fit like for non-RSS QR plates? Seems that the thickness at the bottom of the plates is what's really causing the discrepancy between manufactures.
This is how it fits. This picture is taken with RRS QR plate but I have used it with non-RRS plates without any problem. RRS clamp is expensive but it gives long life. Mine is 10-12years old. RRS clamp is 6 inch long and that makes contact-area long.



Going back to Arcatech clamp. There is a spring attached to knob(knob is used for tightening). There was some problem with spring and knob, and it prevented clamp from going closer to QR plate. .

05-11-2019, 10:27 PM   #9
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QuoteOriginally posted by pentaxfall Quote
This is how it fits. This picture is taken with RRS QR plate but I have used it with non-RRS plates without any problem.
Nice picture of the QR clamp and QR plate, really shows how engaged the plate is with the clamp (good peace of mind there). Also, you can really see that bottom edge of the dovetail. The RRS, like the Acratech brand and my iShoot L-Bracket, have a pretty narrow edge at the bottom of the dovetail, while some of my other QR plates/brackets, have a much thicker bottom on their dovetail. I used to have a micrometer in my toolbox. I'll have to dig it out and see about taking some measurements.


That's interesting to hear about your issue with the Acratech QR clamp. I haven't run into that issue (yet, ha!).
05-12-2019, 05:49 AM - 1 Like   #10
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I learned about variability in "standard Arca-Swiss" style base plates from different manufacturers when I tried using a lever-lock clamp unit. Set it to clamp just right on one base plate, other plates slip, yet others I can barely get the lever closed (at the moment, the lever lock clamps are all shelved). BTW I DO NOT LIKE the Arca-Swiss system. Before I was more-or-less forced to it (new ball head with permanently attached A-S clamp) I used a system with 42mm square dovetails (dimensions specified by a DIN standard). It was truly QUICK = MUCH faster that any A-S so-called "quick release - the A-S system is still twist a knob to tighten, be sure to tighten securely = is A-S really "quicker" than the traditional tripod head screw?? However, the manufacturers of 42mm base plates were never sufficiently inventive at making anti-twist prongs, either universal or camera-body specific. The best base plates of that system are still made by Velbon, the most compact/light clamps were made by Kaiser, but a truly QUICK clamp was made by Bilora. MUCH, MUCH quicker than A-S for switching from camera with normal lens on tripod to telephoto mounted via tripod foot.

Last edited by WPRESTO; 05-12-2019 at 03:31 PM.
05-12-2019, 08:52 PM   #11
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QuoteOriginally posted by WPRESTO Quote
system with 42mm square dovetails
Interesting. I wasn't familiar with that system.
05-15-2019, 09:34 PM   #12
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So an update on my A-S QR clamp/QR plate issue. As previously noted, not all A-S QR plates are created equal, nor are all A-S QR clamps. So I bought a Wimberley QR clamp directly from Wimberley (they have "blemished" section with discounted prices, which saved me $20) and tested it out on the same QR plates I tested earlier on my Acratach QR clamp. I'm happy to report the Wimberley is a better fit for my mishmash of QR plates. And the quality of the Wimberley C-12 QR clamp is fantastic. More photos below. I didn't do a side by side comparison, but you can still see the obviously better clamp bite.
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