I recieved my LP 39 plate from kirk,it has two "safety stops" two tiny screws and places two screw them into. I called Kirk to inquire about the purpose of these screws or "saftey stops" . I have not received a response. The LP 39 is a long plate for long lens. I bought it for my Bigma. Anyone know the purpose for these? thanx jim
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#2. "RE: Safety stops on Kirk plates" | In response to Reply # 0J_Harris Nikonian since 29th Mar 2011Wed 30-May-12 10:00 AM
I have also emailed Kirk with a question and never received a reply. However, for future reference/questions they do have a toll-free phone number and the customer support person is knowledgeable and friendly.
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#3. "RE: Safety stops on Kirk plates" | In response to Reply # 0MEMcD Nikonian since 24th Dec 2007Thu 31-May-12 02:56 AM
Phil hit the nail on the head.
A plate can slide in a clamp that is not fullt tightened. The screws are in the ends of the plate will hit the clamp preventing the plate from sliding through the clamp.
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#4. "RE: Safety stops on Kirk plates" | In response to Reply # 3jrp Charter MemberThu 31-May-12 03:42 AM | edited Thu 31-May-12 03:48 AM by jrp
They are commonly installed on long lens plates, because users may be sliding the plate (with lens and camera mounted) from one side to the other without loking at it, but into the viewfinder. Yes, we do have one report of a photographer balancing the setup over the clamp and then a rare subject came into view and ....
Others may forget to tighten the clamp. I really don't know how but it has happened.
It serves the same purpose as the pin stop on the Markins clamps. When using hollow bottom plates it works the same. Even if the pin doesn't fall into a cavity when first mounted, the pin will slide into a cavity when the plate starts sliding out and will stop it from falling.
Some call it "a fool proof measure" Not me, of course, as a I may soon be reaching a somewhat critical age.
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#5. "RE: Safety stops on Kirk plates" | In response to Reply # 0
Just to add another reason, for gimbal users. And gimbals are typically used with lenses that use long plates.
When installing a long lens on a ball head, I don't typically balance the load and I find it difficult to even attempt it. And there is generally no reason for it unless I want to get a perfect sweet spot set that provides equal travel up and down.
On the other hand, gimbals require precise balance and that is often an iterative process. I typically tighten the clamp just enough to allow me to push the lens back and forth as I test the balance, but tight enough that it should retain my current position. Should is the operative word.
It is possible that I lose control of the lens as I tilt it at extreme angles to test balance, should the clamp tension not be exactly right.
Once I get the lens perfectly balanced, the clamp is tight enough for me to think it is tight but loose enough for further tweaking.
Then I see something (like an Eagle hit a pigeon in midair) and I forget all about that last important step- a final tightening of the clamp. The lens might fall out an hour later, or maybe only when I throw the rig over my shoulder. It is easy to forget that last critical step of fully tightening the clamp.
What I'm trying to say here is that I think stop pins are CRITICAL for gimbal use, maybe more so than when used in a ball head, depending on your diligence. Before I got my gimbal I was on the fence as to using the stop pins because they eliminate the convenience of sliding a plate in and out of the clamp without fully opening the jaws. As a heavy gimbal user, I would never buy a lens plate without stop pins.
Aside from all that, and gimbal or not, if you are going to throw your rig over your shoulder the least you should do is eliminate all possible sources of accidents, especially easy things like using stop pins. And the heavier the payload, the more likely are strange accidents due to minor lapses of attention. Stop pins are just one part of my plan to defeat that inattentive side of me.
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