Review: Gitzo 1541T Tripod, Markins Q3T Ballhead w/ RRS B2 LR II Clamp

seb87 wrote in post #11270636
the gitzo GC1201T or others ?

https://photography-on-the.net …read.php?t=5382​98&page=46

Just taken delivery of 1541T and Q3T. Thank you Ben, and others, for all your in-depth observations.

There is just one issue that surprised me a little. The threads involved in the connection between the stud on the 1541T and the base of the Q3T appear to be quite a loose fit. It is as if the thread on the stud is UNC and the Q3T is Whitworth. Can anyone shed light on this?

Andy

Any of you using the RRS L brackets happen to have one on a 5D mark II? I've got an off-brand cable release and I have a VERY hard time getting it into portrait orientation. I'm wondering if this is a problem with the canon-brand cable release as well or if the connector on my off-brand cable is just too big.

theague wrote in post #11296537
Any of you using the RRS L brackets happen to have one on a 5D mark II? I've got an off-brand cable release and I have a VERY hard time getting it into portrait orientation. I'm wondering if this is a problem with the canon-brand cable release as well or if the connector on my off-brand cable is just too big.

According to the users, you have to loosen the screw and physically slide the L-bracket away from the body to make room for the cables.

klr.b wrote in post #11297232
According to the users, you have to loosen the screw and physically slide the L-bracket away from the body to make room for the cables.

Thx, I'll have to find the tool and try that!

Andyh77 wrote in post #11293126
There is just one issue that surprised me a little. The threads involved in the connection between the stud on the 1541T and the base of the Q3T appear to be quite a loose fit. It is as if the thread on the stud is UNC and the Q3T is Whitworth. Can anyone shed light on this?

Andy it's only initially that you're experiencing this right? Once you screw the ballhead on a few turns the stud fits the threaded hole properly? As I recall that's how mine worked, but it's been awhile since I put the ballhead on.

Peter, it’s more than a looseness on the initial mating of the threads. It is loose until the platform of the 1541T begins to bear on the underside face of the Q3T. At this point you can achieve a rigid connection with a little more rotation and applying reasonable torque. Even though you can readily achieve a rigid connection I am concerned what is happening at the thread profile level (ie. Transfer of the load from the 1541T thread to the Q3T thread)

In another context I have experienced a failed threaded connection where UNC and Whitworth are mixed. In this case the nominal diameters and thread pitch were identical. However, because of the difference in thread angles between the two thread specifications there is the potential of high stress concentrations on the very tip of the threads. Let me say that I have no evidence that a mixed thread situation exists here. But I am concerned that the two components I have received have such a loose thread connection. Hence my canvassing the experience of others.

I agree that you probably don't have mixed threads. I just tried to get my Q3T off the 1541T but I tightened it with a strap wrench and now it won't come off! Two things: 1- It's entirely possible you're suffering from tolerance, a teeny bit small on the stud, a teeny bit large on the ballhead. Just one of those things with the pieces you have. 2 - If you're really happy with both the tripod and the ballhead, dab a touch of blue Loctite onto the middle part of the stud and tighten the ballhead on quickly. That'll give you peace of mind.

Well Andy I did get the Q3T off the Gitzo tonight and it's very loose to screw on. Not as loose on the Benro, but not by much. I have a second Q3T and that is definitely tighter on the Gitzo. So it looks like it's a tolerance issue on the inside thread of the ballhead base. I use a little Sears strap wrench on the panning base and it was really tough to unscrew, they seem to get tighter over time or something. If you use a strap wrench no need to over-tighten it...

Huh, well that would explain why some people felt they had to Loctite the head onto the tripod while mine has never even come loose... Interesting. I wouldnt have expected a variance in tolerance there of all places.

peter_n wrote in post #11336734
Well Andy I did get the Q3T off the Gitzo tonight and it's very loose to screw on. Not as loose on the Benro, but not by much. I have a second Q3T and that is definitely tighter on the Gitzo. So it looks like it's a tolerance issue on the inside thread of the ballhead base. I use a little Sears strap wrench on the panning base and it was really tough to unscrew, they seem to get tighter over time or something. If you use a strap wrench no need to over-tighten it...

That is very interesting Peter. Now that I am back in my workshop I have made a few measurements. I have measured the longitudinal float of the Gitzo stud part-way engaged in the Q3T base. I have made a similar measurement on a generic 3/8 inch – 16 TPI bolt and nut. The longitudinal float on the Q3T is 0.38 mm while on the generic bolt / nut engagement it is 0.10 mm. So there is nearly 4 times the float / play in the longitudinal direction when comparing the Q3T with a generic bolt / nut. Subjectively the bolt /nut has a reassuring feel to the fit, where-as the Gitzo stud / Q3T just feels sloppy and raises my concerns regarding strength.

Just to clarify a point I would like to stress that Loctite does not contribute to the tensile strength of the thread connection. It merely resists the undoing of the connection due to rotation. The tensile strength is largely a factor of the penetration of the thread crests into the valleys of the mating thread. If they do not penetrate too far then there is a risk that loading the connection, by tightening or by normal service loads, will just shear off the tips of the thread crests, with a catastrophic failure of the connection, (i.e. camera on the rocks). Loctite will not help in this situation.

I have put my observations to markins@gmail.com and hope to hear their considered opinion soon. I’ll report back here when that happens.

Andy

HOSTED PHOTO
please log in to view hosted photos in full size.

Excellent work Andy! Very informative! Im anxious to see how they respond!

Andy I bow to your mechanical ingenuity! You are right about the Loctite too, it's merely a seal on the connection and has nothing to do with the strength of it. Let's see what Markins have to say...

if i buy the q3t and the rrs clamp , the screw comes with the clamp o i can use the one is just installed ? or i must buy another one ?

The clamp screws into the stud that's on the ballhead. Markins use red Loctite to seal their clamp onto the stud, so when you order make sure you send them an instruction to remove the Markins clamp and they will do it for you using heat. It sounds bad but it's fine; they did it for me with no ill effects. If you want to use Loctite yourself to seal the RRS clamp onto the Q3T use the blue Loctite, the red is totally unnecessary IMHO. Enjoy the Q3T, it's a fantastic ballhead!