Specialist tripod chairs

[DobDobDob]

Does anyone make for sale, chairs that are suitable for using when wedged under a tripod and trying to view somewhere near the zenith?

[erick]

I bought a couple of compact plastic stools ($6 in an el cheapo shop) - searched for a while to find something suitable. They weren't too bad to practice balancing on your tailbone.

I've also bought another stronger, but lower and with a back, chair. It's a kids chair from Freedom - cannot remember the name but it was $12.95 or $14.95. I had planned to, but haven't tried it, yet. I planned to use if for high altitude viewing only - with legs stretched out in front of me and leaning against the low back.

Whatever you get, I think you need something that can get in close to the tripod - and allow you to stretch your legs out under the tripod - which helps with balance.

Of course, for lower altitude viewing, my old office gas lift chair is fine.

[DobDobDob]

I agree with what say above, last night I had the sorest neck because I never got out till late/early and everything was straight up. I found myself almost horizontal swinging off the sturdy new mount, sort of driving the tripod like a racing car with a hand on each of two tripod legs, naturally this can't continue. My search for a reasonable, small, seat will begin tomorrow.

[erick]

Somewhere in one of those binocular reviews by Ed Zarenski, he said something I found interesting:- "I don't spend a lot of my time viewing above 75-80 altitude. Just wait an hour, it won't be at zenith anymore and it will be within range of just about any mount."

[DobDobDob]

It may be that I need to find a new location then, imagine a typical square backyard, with the odd light on a couple of sides, a tree on another and the remaining side, my East is fairly clear of obstructions, but also barren of stars. The action for me is straight up, smack bang in the middle of the Milky Way, this is sore-neck territory but it is also, where the theatre of the heavens is acted out, night after night. I can't change the universe, however I can change my orientation and go from the vertical to the horizontal, if I only had a chair. :P

[Dennis]

Here’s my solution, a home made wooden tripod, wooden parallelogram arm and recliner – not ideal but workable in the short term until I can think of something better.

Cheers

Dennis

[DobDobDob]

Yes I have the tripod, and of course the binos, it's the parallelogram that I am going to have to get. I think it would be easier for me to simply purchase one rather than try to build one, a carpenter I am not. Is there any company out there that actually manufactures them, or are you meant to hack it yourself regardless of how hopeless you are at making stuff?

[snowyskiesau]

Don't know about manufacturers of timber mounts but there are a couple of metal ones available - Bintel has one advertised as do Telescopes-astronomy .
I've almost finished building a timber mount. My woodworking skills are far from expert but all it took was some basic tools and a bit of care.

[Miaplacidus]

Bintel sell the "Heavy Duty Bino mount" (for $479!)

https://www.bintelshop.com.au/Product.aspx?ID=6624

Cheers,

Brian.

[DobDobDob]

I appreciate what you're saying but I have sat in front of a computer screen for 30 odd years, all I know are keyboards. Trust me, when it comes to making real stuff with real tools, I am an Olympian at doing it poorly. :work:

[DobDobDob]

I wonder if they will sell the parts separately, because last week I purchased a really heavy duty tripod that is a beauty. I'll contact them and find out. Thanks for the link :thumbsup:

[okiscopey]

Interesting to see folks with parallelogram (pgm) mounts all saying "its not perfect but it'll do." I've used a pgm device in a photo studio and all this did was to make sure there was no lateral movement when changing the camera's height. I assume this is true of the astro versions.

Presumably that's why 'they're not perfect', as this motion solves only a part of the problem.

I'm also a bit concerned about the pgm's counterweight extension - if someone walks into it in the dark, it could be mega-oops!

It seems to me that another approach might be worthwhile, although I wouldn't have a clue how to make it happen, and the device would probably be less-than-portable.

Surely the observer and the binocular needs to move together both in az and alt. to any desired extent. To achieve this, you could start with a cheap reclinable, swivelling chair, low enough (or made low enough) so you can control these movements with your feet on the ground. It needn't be high-back ... you'd get this advantage by clamping on (?) a head support to the back of the chair which also holds the binocular support arm (or presumaby two arms for bigger binos). It would be a sort of Dobsonian mount for humans.

The binoculars would never have to be moved relative to the observer (except for a small adjustment for different people) - all the movement would be in the chair.

I realise this isn't an original idea (viewed a link once to a US observer who had the whole thing motorised - may have been a commercial device).

The thing is, is it possible to make something like this with a similar amount of work to making a pgm mount, would it be better, has anyone here constructed such a thing?

[erick]

Head for South Australia?

http://www.arkaroola.com.au/images/star_chair_web.jpg

"Three Star Chairs, each fitted with powerful 20x80 astronomical binoculars - computer or manually controlled (located at the Reginald Sprigg Observatory)"

[DobDobDob]

There it is, we go in under cover of bright sunlight, steal the chairs and problem solved, one for me one for erick and one for okiscopey :thumbsup:

Actually, they look great, even though the boy in the foreground is not actually pointing at the zenith, he is close to it, close enough for me anyway. Needless to say these would have cost a small fortune to manufacture and would be outside the budget of most private citizens. It does however highlight the fact that the chair is the focus and not the binoculars, which is the point okiscopey was making.

[Dennis]

Here’s one seen at the Qld Astrofest in 2003 with the owner’s 25x100 bino’s pointing at the zenith.

Cheers

Dennis

[DobDobDob]

Yes Dennis, you are 100% correct, it is definitely pointing at the zenith, I must get one of these. Can you tell me why the binoculars he is using, has what looks like a cardboard extension on the front, is this to block out light from the sides at ground level?

Also, any rough estimate how much a chair like this would cost, or is strictly a build them yourself type thing that is too hard to cost.

[Dennis]

What the person has is a dew shield, or pair of them. The protective dew shield slows down the formation of dew on the front optics. This is a passive system, as the dew shield (a circular tube, a bit like a very long lens shade on a camera lens) literally “shields” the objective lens (or SCT corrector plate) from the rapidly cooling ambient air.

An active system would be the fitting of a dew heater. These are low powered electrical strips made from resistance wire which you wrap around the objective lens cell. The low power slightly warms the cell and air around the objective, to maybe just ½° C above ambient, and this is sufficient to prevent dew from condensing on the optics.

Heat from your eyeball can also contribute to condensation forming on eyepieces on those very humid nights.

I’m not sure of the price of these motorised chairs – it was a manufactured unit rather than home made. If I can find a price, I’ll let you know.

Cheers

Dennis

[DobDobDob]

There you go, something else I learned today, Dew Shields, I had no idea they existed, thanks Dennis. The binoculars in that image look no larger than mine, or not substantially anyway, I have 20x80 triplets, so would a dew shield be available for me, would I benefit from having them, given the rapidly cooling conditions I might expect, particularly as cooler weather is approaching?

One again looking at that image, the dew shield appears to be some sort of flexible material, thick cardboard perhaps and held in shape by electrical tape or similar. Would a device if I built one (two, one for each eye), have any real practical benefit? In other words do they really work? Or do you have to have a battery powered one as you have described to be effective?

[Dennis]

Passive dew shields do a remarkably good job, but I have had them "fail" on those humid nights after say, 2 hours. Generally, the optics are more vulnerable to dewing up when pointed at the zenith, as the cross section of glass exposed is larger compared to pointing at say, 30 degrees.

I used closed cell foam camping mat to make mine. Some people use those thin plastic sheets used to bind computer paper. I think the recommended formula is to make them at least 1½ times longer than the tube diameter.

Basically, long is good provided they do not cut into the field of view, or become too heavy or act as a wind sail.

Cheers

Dennis

PS – closed cell or chemically blown foam is tough, does not absorb moisture and is easier to cut than the cheaper, sponge like foam.

[DobDobDob]

Thanks Dennis, I am definitely going to make some, this is just within my handyman capabilities which are legendary in the negative. I do believe I can find some suitable material somewhere around the house and cut them, shape them and clamp them on. The tip regarding the 1.5 times the tube diameter is a winner, I needed to know that, plus if I do encroach on the FOV, I could simply trim the length of the shield back slightly. I am 'really' going to do this!!!

[Dennis]

That’s great news - nothing like having a go and learning from the process. Make a template using stiff paper or thin card first, as a practice run. Don’t forget that the 1.5x dimension is the length clear of the objective, i.e. protruding proud of the lens and not the total length, which would include the section that slides over the bino body.

Stiff cardboard will do, but it does tend to get soggy after a few uses.

Cheers

Dennis

[DobDobDob]

Thanks again Dennis, I'm on it and will report back after I have created my first one and field tested it. Judging by looking out the window won't be for a week or so :(

[okiscopey]

Tailwag, youve inspired me, I'm really going to do things too!

:thumbsup: :party: :painting: :computer: :cool: :astron: :violin:


Now, where's that lawnmower ...?

[DobDobDob]

Now I know your tricking, no one within 50 miles of Sydney will be mowing today! ;)

[DobDobDob]

I based the above theory on the image below ;)

[LX200]

Hee Hee :D
Here's a novel deck chair option

http://www.cloudynights.com/item.php?item_id=609

[okiscopey]

Now this is approximately, almost exactly just about more-or-less what I had in mind!

This is the bit I like:

“… the Couch Potato Telescope. It's not really a telescope at all, but rather a full motion, fully adjustable binocular viewing chair. ... For the total couch potato experience, you could mount a drink holder to the arm of the chair, which I plan on doing very soon." :thumbsup:

As usual, nothing is perfect:

" ... there is still some VERY slight vibration from my heartbeat, but it is not at all objectionable in 10 power binos. The heartbeat vibration might be more of an issue in 20 power binoculars. In addition, the image in the binos shakes quite a bit in windy conditions ... " :(

Also the folks who would have walked into the parallelogram extension will now sneak up and give you a big push, so you end up rapidly orbiting around your own eyeballs. :lol:

[DobDobDob]

Yes it looks a little flimsy for my 100kg plus frame, plus the actual bino mount looks weak. I know that some PVC advocates will say it's strong, but I need the look and feel of metal to reassure me that my 2kg+ binos will be firmly fixed. :P

[erick]

tailwag, check this article:-

http://www.iceinspace.com.au/index.php?id=63,321,0,0,1,0

I made something like these - they are relatively heavy, but work fine - though I haven't been through a heavy dew night yet.

I have dew guards for all my binoculars. I just went shopping in the supermarket with a set of vernier calipers and bought bottles etc. that were the right diameter. Must have looked funny on the security video!

[DobDobDob]

Thank you very much for this link erick, it is exactly what I need, the article is brilliantly written and accompanied by images, the author Alan Sheehan has done a Stirling job indeed. I can't wait till next weekend, when I'll go purchase the PVC pipe and paint and go at it.

[okiscopey]

I use it indoors.

[DobDobDob]

Hmnnnn :whistle: