Fifteen minutes with a Vision Blue at DVinfo.net

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Old December 12th, 2011, 06:40 PM   #1
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Fifteen minutes with a Vision Blue

As the Vinten Vision Blue has been very favourably reviewed here I was keen to have a look at one. I have an EX3 for which I hasten to add Vinten recommend the 3AS. However my agent said that they could balance their EX3 on the VB so I investigated. In particular I wanted to see how the VB would handle an EX3 fitted with a 300 mm lens.

My yardstick was to be my ancient home-made tripod and fluid head built initially for under-water work using a large 16 mm film camera. Why did I build my own? For a start I could select materials better able to withstand regular dunkings in sea-water. Also instead of using intricate castings or mouldings as used in mass production the various components were labouriously bolted together. Over the years the components have been unbolted and rearranged as my needs changed. However the main components are original. In this head I tried a way of controlling drag by varying the thickness of the silicone fluid film. This worked well then and still works well now. Also I used bearings that can take far greater loads than needed.

What works well underwater does not necessarily work well on land. I can lock the legs in any position - great underwater but a nuisance on land. It is also several kilograms heavier as well being bulkier than the VB. Also undesirable.

The VB on offer had two-section aluminium legs and a mid-level spreader. I left the balancing to the sales person and I experimented with the drag settings. Setting 4 on both tilt and drag seemed optimal. The 300 mm lens on a 1/2 chip (as in the EX3) represents a side to side coverage of ~ 1.25 degrees or ~ 1 degree within safe area markings. At this focal length wind-up was quite noticeable. That is, the inevitable twisting of the whole assembly under the applied operator torque was visible. It was more apparent than in my own set-up. Also it was harder to achieve a smooth slow pan. I call a pan slow if it takes 10 - 20 to cross the width of the picture. Had I had the opportunity I would have experimented with the pan handle. I use a flexible handle that reduces vibrations transmitted by the operator. At the end of the handle I use a protruding tension spring that gives yet more damping. It is like a rubber band but with the advantage that you exert less and less torque the further out you grip it. To be useable the drag has to be reduced to match. The VB had lower drag settings available but without my pan handle I found them to be harder to control than setting 4.

I would be interested to know how much the wind-up would be with carbon fibre legs, as carbon fibre is stiffer than aluminium it should be less. Also as the VB is not the first choice for the EX3 how much better would the recommended 3AS be for longer lenses?
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Old December 12th, 2011, 11:03 PM   #2
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Re: Fifteen minutes with a Vision Blue

Very interesting, Alastair.

Your comments regarding wind up on the VB sticks are particularly intruiging, as none of my tests took lens focal length into account, so I cannot draw any real empirical conclusions from your brief play.

However, as the VB sticks as offered standard are obviously not man enough for the task, it would probably be appropriate to look at a more substantial set of 2:2:2 sticks instead of the 2:2:1's supplied.

Making the move to CF may or may not make a difference to the wind up quotient, depending on whether they have been designed to mimic the aluminium alternatives in rigidity, at the gain of some weight saving OR have been designed to have the same weight but provide greater rigidity.

Using either the VB or 3AS head with such a long lens at a drag setting of 4 would, to my mind, be a complete no - no.

My yard stick with Vinten heads is "longer focal length = HIGHER DRAG". Winding either up to 8 or 9 with full zoom on an XH - A1 stock 20X zoom lens would not be uncommon.

I have my doubts that you would find any significant difference between the VB and 3AS heads in practical terms, as long as they can handle the payload, their handling characteristics are very similar, if not identical.

Bottom line, I guess a set of 2:2:2 sticks seems to be almost a given (ask Peter Harman about that: Peter.Harman@VitecGroup.com ) and probably the 3AS if your rig fits in the weight range (it does have the side load head, which is a real plus).

Very interesting post, thank you.


CS
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Old December 13th, 2011, 07:56 PM   #3
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Re: Fifteen minutes with a Vision Blue

Hi Chris,

The drag setting question is an interesting one. Increasing the drag should increase the fluid drag component of the total resistance thereby further masking any roughness produced by the bearings and seals etc. However the torque necessary to pan and/or tilt then has to be increased and it is this torque that causes wind-up problems. If the tripod can withstand the extra torque then increasing the drag may be the way to go. My old Miller LP with wooden legs is the most rigid tripod that I own. It is also better damped, i.e. if it is knocked the ensuing vibrations stop quicker than is the case for my aluminium tripod. Even so my wind-up control of the EX3 and 300 mm lens with either of these tripods improves if I reduce the drag. My best control as mentioned comes with a flexible handle and low drag. Also, as mentioned, I have used good bearings and I try to minimise seal friction - both necessary requirements if low drag is to be used. This strategy causes problems of its own because static friction is so minimal. Greater care must be taken in leveling the head and balancing the camera if creep is to be avoided.

Because of the crop factor using a 300 mm lens on an EX3 is the equivalent of 1550 mm on an 35 mm FX camera. As a subtended angle this represents a safe picture width of about one degree. In this case a wind-up of one degree would be the full picture width and obviously unacceptable. What amount of wind-up is acceptable to the critical eye looking out for something to criticize? I would guess a very few percent of the picture width at most. So, in the case of a 300 mm lens this would be a very few percent of one degree. The camera operator expects a 20 handle with which to apply torque and also expects to have a light weight structure that can be repeatedly closed and extended. Quite an engineering feat.
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Old December 15th, 2011, 01:49 AM   #4
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Re: Fifteen minutes with a Vision Blue

Quote:
Originally Posted by Alastair Traill View Post
Quite an engineering feat.
You've said it, in spades.

My weapon of choice if using long FL lenses is my Vinten FiberTec's, which is how I got into this whole subject originally.

They're CF nested I - beams with a leg locking mechanism of fiendishly clever engineering, which locks every single millimetre of overlapping leg to it's mate, I still to this day haven't worked out how it's done, but done it they did.

Much to my absolute horror (and boy, did I go ballistic over it), Vinten pulled the entire production of said sticks, as they simply weren't selling enough to make them viable, just as HD was taking off and they were needed more than ever.

Yep, they're heavy, but boy, are they rigid.

If they were to take another shot at the market now, I think a "re - thought" version would do a VB all over again.

Would they be suitable for your particular situation, can't say, that's one heck of a long lens and you're really getting to the point where a tripod, any tripod that's carryable anyway, bless their cotton socks, just ain't going to cut it.

Good luck in your search.


CS
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