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Surveyor tripod "spreader" (AKA camera tripod)

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#1 Widespread

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Posted 30 January 2013 - 05:49 PM

I have read a lot of discussions about bracing surveyor tripods.

Some examples: http://www.cloudynig.../Number/4505349
http://www.cloudynig...3432349/Main...

I recently got a used Vixen Porta mount that came with a wooden surveyor's tripod, and while I'm waiting for my 90mm refractor to arrive, I've been playing around with ideas for stabilizing it further.

I do a lot of viewing from my 2nd floor deck in winter, so I won't be able to stomp the spikes into turf. I may not need to stabilize it at all, I'm just thinking of options.

Mine came with chains, which should prevent the legs from splaying, but won't do much for rigidity. So here's what I came up with.

Here is the tripod. You can see the chains connected to small eyelets

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#2 Widespread

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Posted 30 January 2013 - 05:51 PM

Here is a close-up of the chains and hooks.

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#3 Widespread

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Posted 30 January 2013 - 05:52 PM

Here is the camera tripod with center column removed.

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#4 Widespread

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Posted 30 January 2013 - 05:53 PM

I raised the center spreader to collapse the camera tripod, and inserted it under the surveyor tripod.

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#5 Widespread

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Posted 30 January 2013 - 05:55 PM

Then I just lowered the camera tripod spreader to spread the legs until they press against the insides of the chains to create tension and rigidity.

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#6 Widespread

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Posted 30 January 2013 - 06:01 PM

That's it!

Basically, instead of building a spreader, I'm using the spreader on the camera tripod.

There's more than one way to skin a cat, and this certainly isn't the most elegant solution. More importantly, it has not been validated by actual field use. An informal "whack test", however, indicates a significant improvement in rigidity.

As I said, I don't know if I will even need to use this. If I do, I may look for a more elegant long-term solution.

But I figured there may be some other folks who have camera tripods who might want to give it a go. If nothing else, it should give you an indication of how much improvement a spreader will make.

I will follow up with a field report if the weather ever clears.

Clear skies,
David

#7 smallscopefanLeo

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Posted 30 January 2013 - 06:21 PM

Thank you very much for your cool tip, I like seeing suggestions like these. That could just come in handy some day. Hmm, now you got me thinking... what if you hung a small weight now on each length of that triangle formed by the chain? (like this http://www.amazon.co...n/dp/B006U4MR8I ) could the weight help cinch everything down a tad more perhaps, and how much weight could that chain realistically hold? :scratchhead:

#8 orlyandico

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Posted 30 January 2013 - 07:07 PM

i made a spreader for one of those surveyor tripods from some hinges and aluminum flat bar.

http://orlygoingthir...r-surveyor-t...

strong enough to carry 50lb of mount, CW, and scope...

#9 Widespread

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Posted 31 January 2013 - 01:56 AM

Hi Leo, I do plan to replace the chain with something stronger. I was thinking of trying thin cable. Some added weight is definitely a good idea, because the camera tripod legs press not only outward but also upward due to their angle.

Orly, I saw the great work you did. If I can access something better than a steel file for filing the corners, I may give that a go. Or is the filing easier than I imagine, and quite manageable with manual file?

Best,
David

#10 Jon Isaacs

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Posted 31 January 2013 - 06:22 AM

Hi Leo, I do plan to replace the chain with something stronger.



The tripod may be plenty sturdy with just the chains. The important thing is to make sure the legs don't slip and cause the tripod to tip over. The chains do that.

What is the focal length of the 90mm that you will mount on your Partamount?

Jon

#11 orlyandico

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Posted 31 January 2013 - 10:25 AM

Yes i just used a steel file. aluminum is quite soft. you can put a neat satin finish on it with sandpaper and elbow grease.

of course a drill is also needed. even a hand drill would do. and a saw to cut the aluminum. powered is better, but again aluminum is so soft. even a file can cut it. would take some time and have a lot of swarf though.

#12 Widespread

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Posted 31 January 2013 - 10:49 AM

Hi Jon,

It's a 90mm f/7 (SVR90T), probably about 8 pounds with rings/dovetail. I expressed myself poorly; what I meant is that the current chain looks weak, and I intend to put a stronger chain on it if I can find something suitable.

I agree that chains may be sufficient, and should be plenty for preventing the legs from slipping. I wasn't sure, though, if the chains alone would keep the assembly rigid enough.

In any case, I'm just playing around with possibilities while waiting for my scope to arrive (tomorrow, I hope!).

Hi Orly,

Thanks for the information. I will take another look at your method. I have a drill, so that shouldn't be a problem. I think a manual hacksaw would be less than optimal, but the DIY shop might cut it to size for me.

Best,
David

#13 Jon Isaacs

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Posted 31 January 2013 - 01:03 PM

Hi Jon,

It's a 90mm f/7 (SVR90T), probably about 8 pounds with rings/dovetail. I expressed myself poorly; what I meant is that the current chain looks weak, and I intend to put a stronger chain on it if I can find something suitable.

I agree that chains may be sufficient, and should be plenty for preventing the legs from slipping. I wasn't sure, though, if the chains alone would keep the assembly rigid enough.



David:

Hopefully it will be clear when the scope arrives... :whee:

Based on my experince with the Portamount and a couple of 4 inch apos, my gut feeling is that the Portamount on the surveyors tripod will be fine just as it is, even the chains will be sufficient though stronger ones would not hurt.

I do like having a place to store my eyepieces while observing. When I upgraded my Portamount tripod to the Hands on Optics wooden legs, I transferred the folding plastic spreader from the Portamount legs to the wooden lets, it is easy to fold up.

Jon

#14 Widespread

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Posted 31 January 2013 - 01:41 PM

Jon, I'm glad to hear you think the surveyors tripods will be okay as is. One thing I like about it is that the legs collapse when you pick it up, and this makes it easy to get it out the door.

Interestingly, after I got the surveyors tripod and mount, I contacted the seller to ask a question. In the course of the conversation, he offered to send me another aluminum tripod, gratis. Not one to look a gift horse in the mouth, I said yes.

He mentioned that I might be able to adapt the spreader from the aluminum tripod and use it on the wooden one. The spreader apparently doesn't have the center tray to lock it, but I may be able to fashion one from plywood.

He also apparently filled the aluminum tripod with Great Stuff to dampen vibrations, so even that one might work with my new scope, though my intention is to use the wooden one.

Well, I have a few things to think about, and lots of options to try. Domo arigato!

Cheers,
David

P.S. Tomorrow's high is 30F and what I can see on the Clear Sky Chart looks mediocre at best, but the oulook is mostly sunny, so I should be able to take a quick peek at least.

#15 Widespread

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Posted 04 February 2013 - 07:46 PM

You were right, Jon, the tripod works fine as is. There's no such thing as too much stability, though. ;p

I got the scope Friday night and I have used it every night, albeit briefly due to cool temps.

Friday night was first light. This is not the forum for observation effusion, but I was elated.

Saturday night was a true sucker hole, barely had time to view M42 before it clouded up. But it would've clouded up while I was still aligning with my other mounts, so I'm not complaining. I had time to confirm that the mount is stable at 72x with 8.8ES 82, even on my 2nd floor deck. Things got a bit touchier with a Barlow, but The vibration was more due to the deck than the tripod/Mount.

And now the seller has sent me the original tripod, filled with "great stuff", gratis. I wish I were more handy, but I need to take a look at it and see if I can use its spreader. One thing I love about this wooden tripod is the ability to pick it up on my shoulder and walk out the door, so if it ain't foldin', it ain't happenin'.

I knew that wood has good damping characteristics (I even have loudspeakers with wooden cones), but didn't know it would be this good.

Let's just say, when it comes to my tripod, I've got wood.

Ambiguously,
David

Edit: P.S. Last night's 45 min. session courtesy of the Superbowl power failure!

#16 hottr6

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Posted 05 February 2013 - 10:40 AM

I don't know why I have not seen CNers suggesting this:
http://www.amazon.co...g/dp/B001DQRB9I

Rather than using stones, excess counterweights work really well.






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