sparrow
Pooh-Bah
Reged: 02/10/06
Posts: 1002
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Finally - a tripod that can hold my Orion 120mm steady.
The only problem is it gets awfully stiff in winter with all those grease fittings.
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ronruiz44
sage
Reged: 08/29/07
Posts: 289
Loc: West Texas
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Not to mention the size of the tripod bag required!
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Ron
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upsguy
Uff da
Reged: 10/01/05
Posts: 3149
Loc: Schaumburg, il.
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Nice grab-n-go!
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Jim
Scopes, Bins, Cameras and Guns
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Jon Isaacs
Postmaster
Reged: 06/16/04
Posts: 32442
Loc: San Diego, California
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Probably OK for Astrowork but a bit clumsy for birding. I think this would definitely be a mount for "observational bird watching" and not climbing through the brush. While it with some effort one might "backpack it", the rain and dust would likely cause problems later on. 
(Not to hijack this thread but.. On a more serious note, an Eagle Optics Denali showed up on Astromart and after considering Sparrows thoughts on spotting scopes vs astroscopes, I went for it. Obviously not the high quality optics of the WO ZS 66SD but it only weighs 28 ounces and could be a fun scope to have, all is not optics.)
Back on track... This is what serves as the Ultimate Tripod in my house. It's an old Houston-Fearless tripod from the 1950's that a friend found at a garage sale. It has the Hollywood standard Mitchell base for mounting the big movie cameras and TV station cameras of the 50's. Currently it is available as the Quickset Gilbratar is rated at 400 lbs (and costs $3300)
Not really designed for a spotting scope but could be used to mount a blind + the scope + the birder. 
Jon
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sparrow
Pooh-Bah
Reged: 02/10/06
Posts: 1002
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Jon,
That tripod looks like serious stuff. My Bogen looks like a light
version of the same basic design - split legs with spreaders only with a
crank up center post.
Since getting the 120mm I have been thinking a lot about stability. I
don't think the Bogen and the fork mount have any problem with the sheer
weight of the scope or at least that that's the main problem.
Sometimes I can sight down the scope and release the shutter with the
remote and watch the end vibrate from mirror slap. More and more I'm
beginning to think that the camera mechanism sets up harmonics in that
long thin metal scope tube.
The scope is very long and is only made out of light weight sheet metal.
For instance the 80mm Astro Tech's tube, at less than half the length,
is made out of heavier gauge tubing than the 120mm Orion. I beginning to
think that there is just not enough mass in the scope tube to properly
dampen the kind of vibrations setup by a SLR camera mechanism. I suppose
for 300 bucks Orion only sees this scope as a bright wide field low
power visual scope and works fine for that purpose.
I think this winter I'll fuss around with it. I thought of fabricating
some wide thick shims and put them under the rings and see if that would
help. I wonder if you astro people run into such problems with some of
your very long scopes? That is where the problem is not supporting
weight but where the tube is so long it starts to ring like a bell?
Take care out there in Lotus Land,
Sparrow
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mooreorless
Just worried
Reged: 07/05/05
Posts: 2248
Loc: Cornpropst Mills,Huntingdon,Pa
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Post deleted by mooreorless
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Regards,Steve M
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Jon Isaacs
Postmaster
Reged: 06/16/04
Posts: 32442
Loc: San Diego, California
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Sparrow:
This is my thinking/experience...
I had an Orion 120mm F/8.3, it came on an Astroview/EQ-3 mount and it was not solid enough, each tick of the motor would set up a vibration so that at 100x it blurred the image, to split a 2 arc-second double like the double-double or an evern tighter one like Porrima (1.3 arc-seconds at that time) I had to turn off the drives. I replaced the tripod with that Houston-Fearless in the photo and the mount was rock-solid at 500x.
The size and length of the 120mm F/8.3 OTA are most likely overwhelming you mount. I use a Bogen 3040 which is quite similar to a 3046 with my 80mm but I don't think it would handle the 120mm F/8.3 for photography.
I don't know what effective focal lengh you are using but a blurr is only one pixel of motion. Roughly guessing your camera to have 25mm chip size at 6 megapixels, this puts the pixel at about 8 microns or about 0.0003" of in, 1/10 the thickness of a human hair. This means if the scope moves 1/10th the thickness of a hair, you will have blurr of 1 pixel...
My point is simply how stiff and rigid things need to be to use long focal lengths effectively.
Here's what the Orion 120mm F/8.3 looked like on the Houston-Fearless.
Jon
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sparrow
Pooh-Bah
Reged: 02/10/06
Posts: 1002
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Quote:
Post deleted by mooreorless
mooreorless,
I don't know why you deleted your post. I think your idea of using some kind of wrap was a good idea.
Your post reminded me that I have some heavy rubber material that was made to be put under large industrial electric motors to reduce vibration. Instead of an ace bandage I'm going to try some of this stuff and see what happens.
Thanks for the heads up.
Sparrow.
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sparrow
Pooh-Bah
Reged: 02/10/06
Posts: 1002
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Jon,
If, as you say, the problem is one of mount and not of the scope it's self I have a good test of this idea.
I have a very heavy (about 500 pound) maple work bench that's bolted to the floor out in the shop. On this bench is mounted a huge industrial vise. As a test I'm going to mount the dovetail of the scope in the vise and take some test pictures and see what kind of vibration I get set up this way. I would think set up this way it would factor out any vibration due to an unstable mount.
As a further test of this I will set the camera to the lowest ISO setting and turn down lighting forcing the camera to take extra long time exposures. That should bring out any vibrations in the mount.
I'll give it a try and let you know what has happened.
Sparrow
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mooreorless
Just worried
Reged: 07/05/05
Posts: 2248
Loc: Cornpropst Mills,Huntingdon,Pa
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Hi Sparrow, I guess I thought it seemed foolish, but it is a common sense sort of thing. Thanks I hope it helps.:-)
BTW I bought a Meade basic camera adapter and Pentax T-ring for the Pentax 100D Super, all I need now is the OPT 1.25-2 inch adapter with T threads. I like the idea of this adapter because I can leave it in the telescope and it has brass compression ring to hold my diagonal when I use it. Thanks for the link to this.
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Regards,Steve M
Edited by mooreorless (11/26/07 06:17 AM)
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sparrow
Pooh-Bah
Reged: 02/10/06
Posts: 1002
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Quote:
Hi Sparrow, I guess I thought it seemed foolish, but it is a common sense sort of thing. Thanks I hope it helps.:-)
A fool does not use common sense and you were using common sense ergo your suggestion was not "foolish".
Sparrow
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AdrianL
member
Reged: 12/26/06
Posts: 62
Loc: Folsom, Louisiana
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Sparrow,
Where do you get the mounts you are using between your scopes and photo tripod?
Thanks
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Orion ED100
SkyView Pro Mount
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sparrow
Pooh-Bah
Reged: 02/10/06
Posts: 1002
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Quote:
Sparrow,
Where do you get the mounts you are using between your scopes and photo tripod?
Thanks
I use a standard Bogen 3246 tripod with a Bogen 3421 Gimbal fork mount. The fork mount screws directly into the tripod with no further hardware needed. I got both at B&H Photo in New York over the internet.
Sparrow
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vikingcraftsman
Wood Worker
Reged: 02/24/05
Posts: 3770
Loc: Long Island, N.Y.
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The scope is very long and is only made out of light weight sheet metal.
For instance the 80mm Astro Tech's tube, at less than half the length,
is made out of heavier gauge tubing than the 120mm Orion. I beginning to
think that there is just not enough mass in the scope tube to properly
dampen the kind of vibrations setup by a SLR camera mechanism. I suppose
for 300 bucks Orion only sees this scope as a bright wide field low
power visual scope and works fine for that purpose Sparrow I am just a poor country boy, but when I look at your long scope I think of some kind of wood stick support. You could make a wood dove tail and then attach the wrings that hold the scope out to both ends of the scope.
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Vikingcraftsman"A craftsman relies on science when the state of knowledge allows it, tradition and experience when it does not, and makes art whenever he can."
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