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How To Use C8 w/Photo Tripod?

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#1 cavecollector

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Posted 27 October 2020 - 06:05 PM

I have a fork mounted C8 and a truly massive old tripod (designed for use with the huge video equipment news stations once used many decades ago) with the standard 1/4 - 20 bolt for attachment. The C8 fork base dosn't have a center hole, it just has the three screw holes equally spaced on the bottom forming a triangle.

 

What I need help with is - how do I mount and use my C8 on this tripod? Is there some kind of adapter out there that converts the single standard photo tripod 1/4 - 20 into something one can attach to the three holes in the bottom of the C8? This is the only tripod I have for the C8 and I can't use the scope until I figure something out. I am really hoping someone here has already solved this problem and can offer some advice.  Thanks!

 



#2 06AwzIyI

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Posted 27 October 2020 - 06:23 PM

Can't you just make a simple adapter out of a piece of plywood?


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#3 luxo II

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Posted 27 October 2020 - 06:24 PM

Personally I would not rely on a single ¼ x 20 bolt to secure a C8, that's kind of like using a piece of string to moore the Titanic.

 

Posting some pics of the top of the tripod would help..


Edited by luxo II, 27 October 2020 - 06:25 PM.

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#4 maroubra_boy

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Posted 27 October 2020 - 07:02 PM

Good God! NOOOO!

The C8 may not only overwhelm the bolt (too short thread length & bolt diameter), but the forces the bulk of the C8 will be way too much for a photo tripod, particularly as you point the scope higher in altitude. It will also be way too difficult, even dangerous, when releasing the clamps to move the scope, especially when it is pointing high up!!! ESPECIALLY with the scope pointing high up!

Unless you are prepared for the scope to tip back when the clamp is released, the scope will tip back very fast, hitting you in the face, jarring the tripod head when it hits the end of its travel & topple over the whole assembly, if not snap a bolt! And it will happen as you only takes one moment to forget to support the scope and the whole show is over. And it will happen!

A photo tripod is not the right mount by any means.

This is from experience with attaching big binos to photo tripods with those stupid "bino-tripod adapters". If big binos are difficult and dangerous enough NOT to do it this way, with a C8 even less so.

And a short 1/4" bolt of a photo tripod doesn't have enough meat on it either. There is also the head assembly of this photo tripod to consider if it is strong enough too.

You need to find a better mount for that scope.

Alex.

Edited by maroubra_boy, 27 October 2020 - 07:02 PM.

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#5 cavecollector

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Posted 27 October 2020 - 07:22 PM

Trust me, the tripod and head can handle it. They were designed for carrying 40 lbs of heavy video gear. Remember those giant video cameras from the 1970s? That's what it can handle.

 

I'll take pictures to post later.

 

I can understand the bolt being inadequate though. It looks like the head was designed to use a heavier bolt and the current one can be removed/replaced. What if I was to replace the current  bolt with something heavier duty (preferably with two heavier duty bolts on either end of the head/top plate) and make an adapter of sorts out of wood?



#6 cavecollector

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Posted 27 October 2020 - 07:27 PM

P.S. this tripod is vastly superior to the old locking triangle tripod and wedge. I have an older C5 with a center hole which attaches to this tripod via a larger older type of standard photo bolt. It is so much more stable than the older Celestron tripod/wedge, it's a night and day difference.  This is why I rather foolishly sold my wedge and tripod which I didn't realize until buying the C8.

 

The C5 on this tripod is rock sold - zero vibration at over 200x. 


Edited by cavecollector, 27 October 2020 - 07:30 PM.


#7 luxo II

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Posted 27 October 2020 - 07:45 PM

Sure the tripod, maybe, but not a singe ¼" 20 screw into soft alloy.


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#8 alphatripleplus

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Posted 27 October 2020 - 08:35 PM

Yes, I agree that a 13lb OTA is too much for a 1/4 x 20 screw bolt. 


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#9 maroubra_boy

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Posted 27 October 2020 - 09:58 PM

Trust me, the tripod and head can handle it. They were designed for carrying 40 lbs of heavy video gear. Remember those giant video cameras from the 1970s? That's what it can handle.

 

I'll take pictures to post later.

 

I can understand the bolt being inadequate though. It looks like the head was designed to use a heavier bolt and the current one can be removed/replaced. What if I was to replace the current  bolt with something heavier duty (preferably with two heavier duty bolts on either end of the head/top plate) and make an adapter of sorts out of wood?

That is fine for video gear.  But how was that video gear used?  Was it being tipped up to view at a high altitude all night long?  When I say high altitude I'm talking higher than 45degrees because MOST of your viewing will be above 45deg.  This includes the risk of overbalancing the whole system when the scope is pointing at or very close to zenith.

 

How about its panning capability at this altitude?  This is very important.  It has little to do with the head strength and everything to do with it at the same time.  Will the whole system be stable when pointing straight up?  These are things that need serious consideration.

 

The reason I am challenging you here is to make sure you really understand and really thought about what is involved with a scope the size of a C8 and how things are when it is being used.  The last thing I want to see happen is the scope come to a grizzly end!  It certainly is not about putting you or anyone down.  I hope you can see this.  Lapses in concentration can and do happen, and you do not want one of these lapses to mean your gear comes crashing to the ground.

 

You are asking our opinion because you have doubts.  So, WE need to offer our ideas which includes challenging your thinking waytogo.gif  Photos will help for sure.

 

Alex.


Edited by maroubra_boy, 28 October 2020 - 06:46 AM.

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#10 luxo II

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Posted 28 October 2020 - 12:19 AM

If all it had was a ¼" 20 bolt the most that tripod carried was an amateur VHS or Beta VCR. Anything serious had a 3/8" bolt even back when I was a kid.

 

OP pony up a pic of this tripod, if you want useful advice. I don't think this tripod is as substantial as you claim.


Edited by luxo II, 28 October 2020 - 12:21 AM.

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#11 jgraham

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Posted 28 October 2020 - 09:20 AM

If you look in the original C8 manual you'll see that Celestron actually made a tripod adapter for the C8. You basically deforked the C8 and bolted it to a fairly substantial tripod adapter. One option it to just mount the C8 in altaz mode as shown in some of the original adds and brochures.

Food for thought.
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#12 cavecollector

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Posted 29 October 2020 - 01:42 AM

Everything you all are saying makes a lot of sense to me. Sounds like the best plan will be to use this tripod with the C5 and buy another Celestron tripod and wedge for use with the C8. Thank you everyone,  you probably saved me from a big mistake. 


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#13 chris charen

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Posted 29 October 2020 - 05:15 AM

I hated mounting my 5.6 Ib Orion ED80 on to a heavy duty tripod with the 1/4- 20 bolt, never a mind C8. The shearing stress on that small bolt esp. on an angle would be immense. Bad idea.


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#14 Jon Isaacs

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Posted 29 October 2020 - 06:31 AM

I hated mounting my 5.6 Ib Orion ED80 on to a heavy duty tripod with the 1/4- 20 bolt, never a mind C8. The shearing stress on that small bolt esp. on an angle would be immense. Bad idea.

Ever looked up the shear strength of a grade 5, 1/4-20 bolt?

 

Nearly 2000 lbs.  Proof in tension is 2700..

 

https://www.fastenal...load-calculator

 

I am not saying I would recommend using one with a C-8... 

 

There are video tripods and then there are video tripods.  This Houston-Fearless tripod from the 1950's and 1960's handles a C-8 and more. 

 

1891174-Houston-Fearless.jpg

 

Check out this "Video Camera."  It's the 1960s version of the Johnny on the spot new camera, same tripod.  

 

http://www.big13.com.../todd150dpi.JPG

 

I would like to see a photo CaveCollector's tripod.  The tripod in the photo, I used that with an 1970's C-8, the old fork on a wedge. Quite prone to vibration. With the Houston-Fearless, it was rock solid. 

 

It's possible that the 1/4-20 is an adapter and the mount has is designed for a Mitchell base like mine.

 

Jon


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#15 Migwan

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Posted 29 October 2020 - 08:09 AM

Everything you all are saying makes a lot of sense to me. Sounds like the best plan will be to use this tripod with the C5 and buy another Celestron tripod and wedge for use with the C8. Thank you everyone,  you probably saved me from a big mistake. 

Can't quit on us now.  Photo please.  Has to be 500kb or less.  You can email (and reduce) it to yourself or reduce in Paint.

 

jd


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#16 chris charen

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Posted 29 October 2020 - 03:01 PM

''Ever looked up the shear strength of a grade 5, 1/4-20 bolt?
Nearly 2000 lbs.  Proof in tension is 2700..
https://www.fastenal...load-calculator
I am not saying I would recommend using one with a C-8''.

 

Yes I remember Edz writing about the shearing forces with this bolt in the binocular forum some years ago.

Technically it may work but practically it would not and it is not recommended as you say. 

I am sure 99.9% of observers here would not use this mounting method with a C-8.

It make me nervous just thinking about it.

 

Chris


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#17 luxo II

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Posted 29 October 2020 - 05:33 PM

 
Sure the bolt might take that, but soft alloy wont, it will tear out.
 
Great tripod, but I'd make an adapter plate to secure a C8 using 3 bolts 

Edited by luxo II, 29 October 2020 - 05:36 PM.

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#18 maroubra_boy

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Posted 29 October 2020 - 05:39 PM

Many, if not most, tripod 1/4" bolts are not a thread that goes all the way down to the head.  Rather most tripod bolt have a smaller stem that connects between the head and the threaded section that reaches through the coupling plate.  All of a sudden you do not have the same tensile strength of a full thread 1/4"...  This is an important aspect - how the whole device is constructed in its many parts.

 

The other aspect is the role for which the mount that couples to the tripod head is designed for - not so much the tripod itself.  The Houston-Fearless tripod that is pictured above is not the problem.  **** fine tripod that one is!  The issue is the mount taking the scope.  How it is designed and made is dictated by the job it is intended for.  Most video & film mounts are not designed to be used for astro purposes when a big scope is put on them.

 

Mounts designed for video and film will not have a great deal of capability for high altitude/elevation aiming.  The main reason being the way the load acts upon the clamp and mount, and the ability of these to be released and be able to SAFELY move and handle the big load of a big scope, such as a C8.  Of course there are many big cameras that are heavier than a C8 and these mounts and tripods handle these without blinking, but these big cameras are not being cantilevered off the hub of the tripod.  The problem actually compounds the higher the scope is pointed and the further away the scope is set from the centre of the tripod.  The way loads are then being applied to the whole mount-tripod system this way are not for what photo tripods are designed for.

 

And of course it depends on the mechanical strength of the mount if it can handle a scope on its back and pointed up at zenith.

 

Alt-az mounts for scopes are designed specifically to deal with the way scopes are used and to handle these loads.  These are totally different from the way photo and video mounts are designed, and this is where the distinction between mount and tripod needs to be made.  The two are separate entities, even though with a photo tripod the mount/coupling platform and tripod are one unit, the two are actually separate components.

 

Another part in this is the ability of the clamps to deal with the load in a SAFE manner.  If the scope/mount system is very top heavy with the higher the scope is aimed the greater the torque you need to apply to the clamp so it does not slip.  You will not have an assembly that is safe for you to use nor will you be able to relax with it because you will always have foremost in your mind if the clamp is tightened up sufficiently and then how easy it will be for you to loosen the clamp without having the scope tip back uncontrolled, and certainly not smack you in the face.  You cannot be at ease with such a system.

 

Then there is the tripod...

 

AND the final piece of the puzzle is the stability of the whole system.  Tip a photo/video mount back to or close to zenith with a C8 on its back, and is the whole system (scope, mount & tripod) a secure one?  Or is there a propensity for the thing to topple over will little effort?  This is why I hate those blasted binocular-to-tripod stalk adapters - these are diabolical contraptions for astro because most people use these on photo tripods and end up with all the problems mentioned above...

 

If you do consider a photo tripod for astro use, you need to consider the different components of a photo tripod separately, not as one unit.  If one component is not up to the job, then the whole system is not up for the job.  Weakest link dictates.

 

A practical solution option - within limits

There are ways to be able to use a seemingly unsuitable photo tripod for astro use, and within limits.  Rather than sitting the scope (or binos) on top of the tripod head, slinging the instrument under a platform what sets the instrument in line with the altitude pivot of the tripod is a much more stable solution.  It is then possible to position the instrument in such a way that the scope/binos are also balanced across the altitude pivot and the tripod head clamps can be left totally open!  A semi isostatic solution.  It is only semi isostatic because the instrument is still cantilevered off from the centre of the tripod, limiting how much load you can hang off the platform before the tripod topples over.

 

The pics below shows the astro platform I made.  The scope is an 80mm f/5 achro with a 2" focuser & diagonal and a huge Meade eyepiece - and the clamps are not engaged!  The pic is of the proof of concept set up I made - I don't have a pic of the final rig.  The bino set up is the one I always use.  The binos in the pic are 11X70.  It would be impossible to use this modest photo tripod with either one of these instruments if they were placed on top of the tripod head.

 

Alex.

Attached Thumbnails

  • bino rig (3).JPG
  • photo tripod platform (2).JPG

Edited by maroubra_boy, 29 October 2020 - 05:42 PM.

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#19 cavecollector

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Posted 29 October 2020 - 08:31 PM

It's a Moog Quickset Hercules.  I just checked the bolt and it's larger than 1/4-20 and doesn't have a narrow neck. It's the same size as what the older Celestron Pacific C5 uses which isn't the 1/4-20. Does someone happen to know what size that is? BTW, I picked up the Hercules for $100 at second hand store, these are great places to find fun stuff.



#20 maroubra_boy

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Posted 29 October 2020 - 08:53 PM

Well, credit where credit is due!

 

Have a look here at how someone has set up a refractor (not a wee little thing either) on a Moog Quickset Hercules :) 

 

https://www.cloudyni...-camera-tripod/

 

I would still be little concerned about putting a C8 on it.  Mostly because of the size of the C8.  It's size cantilevering off this mount head could make the rig a little unstable.  With the C8's long focal length, it could prove awkward to pan the scope too.  Pay close attention to the spread of the legs too, they need to be long a spread out wide.

 

With mounts that are scope specific on offer, I would be a little hesitant to put such a bulky scope on this mount.


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#21 Benni123456

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Posted 29 October 2020 - 08:53 PM

you could in fact put it on a video had. A sachtler fluid head that can carry a 600/4 from Canon/nikon can also handle a c8 if you screw a compatible plate on the prism rail...But the head will be almost as expensive as the scope..

 

sachtler makes heads that can carry up to 115kg....

https://www.sachtler...=26&category=85

 

 

 

 

But unfortunately, i found for photography the c8 does not have enough contrast.It is simply the f ratio.

 

For a modern sensor and terrestrial photography, you need lenses with f8 maximum. Otherwise, diffraction starts to reduce the contrast. In astrophotography, this is not that much of a problem. For terrestrial, you put on your apo lens and see that a refractor always has more precieved sharpness (edge contrast)....


Edited by Benni123456, 29 October 2020 - 08:57 PM.

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#22 cavecollector

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Posted 29 October 2020 - 09:29 PM

Cool links/threads, thank you! My head is larger than the one shown in the refractor thread, it's wider and longer and isn't a fluid head. Going by the size of the head, I thought it might be ideal for the C8 but after reading your comments,  I am thinking Celestron wedge/tripod will be better and safer.

 

The C5 on this is amazing - rock solid and I can lfit up/take it all out at once. The optics in the C5 are the best I have everseen in a Cat.

 

I also have a small Astro-Tech refractor and a collection of old Cave reflectors. I thought the C8 would be a nice "does everything" scope that's fairly fast and easy to use when I don't want to drag out one of the big guns for observing. 



#23 cavecollector

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Posted 29 October 2020 - 09:32 PM

You guys are so awesome,  thank you so much for your help and ideas!



#24 Jon Isaacs

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Posted 29 October 2020 - 09:51 PM

Many, if not most, tripod 1/4" bolts are not a thread that goes all the way down to the head.  Rather most tripod bolt have a smaller stem that connects between the head and the threaded section that reaches through the coupling plate.  All of a sudden you do not have the same tensile strength of a full thread 1/4"...  This is an important aspect - how the whole device is constructed in its many parts.

 

 

Actually, you do have the same tensile strength.  The tensile strength is based on the minor diameter of the thread which is basically the diameter of the unthreaded region. And look at the numbers.. thousands of pounds.. big safety factors.

 

The reason for the unthreaded region is because the head or QR plate is threaded to capture the bolt. 

 

Photo tripod heads can be used effectively for astronomy.  The scope just needs to be mounted alongside the head instead of on top of it. This is called side saddle sometimes.

 

In this thread, the tripod is the question, not the mount.

 

Jon



#25 Migwan

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Posted 30 October 2020 - 05:06 AM

Nice tripod!  Great buy.   Hanging the C8 to the side of the off a cross member sounds like a good idea.  Maybe hang a small refractor on the other side as a counter weight. 

 

Good luck. 

 

jd




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