The Physics of Putting a Pan Base at the Top of Your Tripod Headgreenspun.com : LUSENET : Large format photography : One Thread
This question is actually a continuation of previous questions asked by me and others. Previous questions have established that placing a pan head between your tripod head and camera is an effective way of not only leveling your camera, but doing it in a way where it stays level even if you pan. The alternatives previously described are to either level your tripod, or place a leveling base between your tripod and head.
I was recently talking with the folks at Really Right Stuff about this approach, and they *strongly* discouraged it unless the tripod head manufacturer had factored it into their design. They argue that placing a pan base above the tripod head raises the height above the head where the load is supported, and is thus more unstable. Common sense would say their argument is correct, but in reality is the extra stack height enough to make any reasonalbe difference? In my case, the players involved are an Arca Swiss B2 head and a 6.5 to 9.5 lb camera and lens. In most cases, the load can be centered. The pan adapter I was considering is made by Foba. The additional stack height of using this part including the needed plates and adapters on the top and bottom of it would be about 1.9 inches. RRS advocates using the Gitzo leveling base instead (I don't always use a center column, but the Gitzo leveling base precludes the use of a column entirely).
I am aware that Arca Swiss is consider making such a part as I describe for their tripod heads. I am discounting using their potential product for two reasons: (1) availability (it will be released *sometime* next year) and (2) it is not certain it will work with older B2s (more than about a year old).
-- Larry Huppert (Larry.Huppert@mail.com), November 05, 1999
I think the loss of stability of this setup will depend very much on the tripod you use. If, for instance you are putting this on top of a Gitzo 3 series tripod, roughly 60" tall and 7lbs, the center of mass of your original setup, tripod + B2 head + 9.5 lb camera will already be close to the top of the tripod at ~56". Adding two inches between the head and tripod will raise the center of mass by over an inch. This could have a noticeably comprising affect on the stability, vis-a-vis the force required to topple the whole thing. If you use a heftier tripod, the difference will be considerably less.
-- Richard Ross (firstname.lastname@example.org), November 05, 1999.
Larry, I am not sure how you are planning on using the resulting photographs but if you are planning on making smooth transitions between frames when the film or prints are mounted together, you need to take into account the location of the nodal point of the lens and have that nodal point centered precisely as you can over the vertical axis. As I recall the test for aligning the nodal point with the axis involves setting up a fixed vertical rod in point of the lens, noting it's position against a distant point (you also have to be focused at the distance you'll be shooting to) and rotating the camera. You'll have the nodal point and axis aligned when the rod stays in place with regards to your landmark. I consulted for a company doing QTVR movies a couple of years ago and the RRS suggestion of using a leveling base rather leveling on top of a head, especially with a heavy camera is a sound one. You might even consider removing the head from the system. Hope all of this helps and good luck.
-- Ellis Vener (email@example.com), November 05, 1999.
The tripod in use most of the time is a Gitzo 504. I like big heavy stable tripods.
Ellis: Although I do an occasional stitched panoramic (and here your comments are well taken), my more common use for panning will usually be for aligning the film plane parallel with some architectural feature. Will non-level panning, your camera goes out of level fairly quickly, and you end-up chasing your tail so to speak.
-- Larry Huppert (Larry.Huppert@mail.com), November 05, 1999.
Yes Larry, I agree about tail chasing. I still think thevsimpler you can make your support system the better off you will be.
-- Ellis Vener (firstname.lastname@example.org), November 05, 1999.
My concern for the panoramic adapter atop the ballhead is when you tilt the whole camera by the ballhead. The adapter gets pressure and torque. I'm not sure if a normal panoramic adapter is designed to hold them. I believe most panoramic adapters are designed to be supplements for a tripod head without panning capability (i.e. the normal adapters can hold the vertical pressure but not necessarily for horizontal pressure or torque where the axis of rotation is on the plane parallel to the plane of the adapter's surface and they are meant to be in between the tripod and tripod head). However, in our case, we mount the adapter on the ballhead when we want to pan the camera parallel to the horizon. So when you are not going to use this feature, you can prevent this problem simply removing the adapter from the ballhead before you mount the camera. I think this is feasible for large format. But then, the adapter must be removable. Bottom line: Only a real experiment can tell how rigid a panoramic adapter is for this problem. If it's ok, then the problem is solved!
Most adapters connect to a tripod and tripod head simply by screws. So we now have two or three possible inadvertent rotations between 1)tripod and ballhead (pan head) 2) ballhead and the adapter and 3) adapter and camera base. This problem may occur more than often especially if you use a ballhead because you tend to grab the rear standard of the camera, try to level and generate torque on the screw connection when you rotate the camera along the vertical axis, assuming all locks are tight (this is a reasonable assumption because if the locks of the adapter and the panning base of the ballhead are loose, then you can't level the camera easily. I guess this problem can be solved by some kind of quick release ratchet mechanism (gluing things together would not solve the first problem I mentioned earlier unless the adapter is designed accordingly). But I can't find any feature like that in current products I know. Hopefully Arca would make a panoramic adapter that passes these two possible problems (please! I guess we should keep saying this because they are trying to see if they could do without it).
As for the center of gravity (~mass) problem, I can always lower the center of mass by hanging some mass from the center column. So that shouldn't be a problem.
By the way Larry, there are two Foba panoramic adapters if you didn't know. You might want to ask Sinar Bron if either of the adapters are designed for the configuration we're talking about (i.e. for the first problem). The adapters might attach to the Foba super monoball or miniball without causing the second problem.
As for Gitzo leveling base, I returned it because the tightening handle is sticking too long so I can't get my Gitzo 345? lowest possible (as I said in a related thread). There is also the problem Larry mentions. If you go this approach, I'd rather recommend Bogen camera leveler 3115 (fairly unknown because it's not on the Bogen catalog); you can still use the center column with this leveler.
I still think the panoramic adapter atop the ballhead is better.
-- Masayoshi Hayashi (email@example.com), November 05, 1999.
You make a good point about the forces on the adapter causing problems because this proposed use is different than the designer intended.
The Foba part I was looking at is the Panorama Adapter (#33-0514). In the Sinar Bron catalog it says, "Allows rotation of the camera plate at any angle in addition to the base rotation." It sounds like this part was designed for the purpose proposed here.
Because the Arca Swiss B2 has a quick release clamp on top, this panorama adapter would have to be fitting with a quick release plate on the bottom, and another quick release head on top. The adapter could then only be used when needed. The whole affair gets pricey (~ $400). A previous reply said that you really couldn't tell how well it would work until you put it together. This would end-up being a very expensive non-returnable experiment. Considering a leveling base is 1/4 to 1/2 this price, I'm not sure it is worth it even if the problems could be solved.
There is another issue with this setup which the Foba part appears to help solve. Since the Arca Swiss B2 has independent axial controls (similar to a pan-tilt head), and my camera has levels which correspond to these axes, you would want to assure that the adapter assembly proposed doesn't muck this up. Anotherwords, for the initial leveling, you would want the panorama adapter to be locked at the zero setting. Because quick release plates and adapters are also being used, they also must be set to align with the axes. The Foba Quick Release Head (#33-0513) appears to mount on top of the Panorama Adapter with two screws which would keep it in perfect alignment. A quick release plate on the bottom of the Panorama adapter would have to be precision aligned to the correct axis, and screwed to the adapter. This appears to be solvable, just very expensive and maybe too complex in the end.
-- Larry Huppert (Larry.Huppert@mail.com), November 05, 1999.
Larry, I think Cambo makes a large geared rational head that has a rotating camera platform built in. Let me get the cat off of the Calumet catalog and see if my memory is accurate... Yep: Cambo 3-D Gearhead, cat # CB2725, side to side tilt is manual (not geared), forward and back tilt is geared and self locking. USA$409.95 at www.calumet.com I looked at and handled one of these once. it is plenty big enough for the load you describe.
-- Ellis Vener (firstname.lastname@example.org), November 08, 1999.
I've been pondering this question and the answers, and I really think a base leveller between the legs and the head is the only sturdy solution. I use the Gitzo leveller with my Gitzo legs and it is wonderful. The Bogen is a fine piece also, and I intend to get one of these too for my Bogen tripod. I do architecture too, and level the leveller off when I first position the tripod for the right view, and then can pan to correct for distortion wobble-free once the head and camera are also levelled. I lost the center column when I installed the leveller but by choice never use the column anyway. Extending the height above the apex of the legs with a column is as inherently unsteady and prone to bad stresses as the quick-release/leveller/quick release just below the camera would be. I wouldn't bother with all of the connections and extra hardware on top of a 'pod that doesn't do it for you, but would invest in the proper tools for the situation, including a leveller designed for the 'pod you are using and possibly longer legs if you are worried about needing the extra height (rather than use of a center column). I've used but never liked ball heads with large format monorails, but this is purely personal. I have as many tripods as I have cameras (six) because one is never right for all of it.
-- Rob Tucher (email@example.com), November 10, 1999.
Rob, you should try the Arca Swiss B2. It is the best rational (pan + double tilt head) I have ever used, will support everything except a full blown Panavision 35mm motion picture camera, with no creep. It isn't a ballhead at all despite the name.
-- Ellis Vener (firstname.lastname@example.org), November 10, 1999.
Thanks for all the responses. I've decided to punt, and go the traditional route. I've ordered the Gitzo leveler. At $135, the Gitzo leveler is 1/3 the cost of the Foba experimental solution. I still think it will be interesting to see the Arca Swiss adapter once they bring it to market. They tend to do everything rock solid.
I second Ellis's recommendation for the B2. Although it's large compared the the B1, it's still much smaller, lighter and more stable than other heads with similar load bearing capability.
-- Larry Huppert (Larry.Huppert@mail.com), November 11, 1999.
I should check out the B2, because I've never even seen one. I have a very old Arca Swiss Monoball, which is rock solid but was designed long ago and doesn't even have a vertical position or pan. It's purely a ball with a tripod screw. But it is the only thing to use in certain situations, as with a field camera clamped inderneath a bridge.
-- Rob Tucher (email@example.com), November 16, 1999.