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90SLT on grass

Celestron Mount Accessories
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11 replies to this topic

#1 Nicole Sharp

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Posted 21 October 2021 - 06:35 PM

I noticed that when I leveled the Celestron NexStar 90SLT mount, and then added the optical tube to the mount, the mount was no longer level (in the middle of a grassy field).

 

Should I wait until the OTA is on the mount to level it?  I thought it had to be leveled before the OTA is added?

 

Should I place a plastic/vinyl tarp under the mount if it is being set up on grass?  I would be worried about the tripod slipping on a plastic/vinyl surface.

 

Would using anti-vibration pads on grass be helpful or unhelpful?



#2 mikenoname

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Posted 22 October 2021 - 01:11 AM

I misread your thread title. I thought 'on grass' was referring to something else and was hoping to learn something.

 

Since I'm here though, I suppose I can offer some assistance. Or at least marginally-useful advice.

 

I would not hesitate to level the mount once the OTA is on it, if the mount is settling when the OTA is installed. Yes, leveling the mount before the OTA is installed is a bit easier, and even safer, but if it's settling once the OTA is on it, then don't be afraid to to it after.

 

Just be a bit more careful as everything now weighs more, so have a good hold on the tripod leg when you loosen the adjuster so as to not let the whole thing crash to the ground.



#3 Nicole Sharp

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Posted 22 October 2021 - 09:40 AM

Maybe I should get a rubber mat like a yoga mat perhaps? But it would be lumpy on the grass....

A meadow isn't just grass but a variety of other plants of varying heights that the deer come to munch on. I would also be worried about ticks and ants getting into the mat.

It doesn't seem like an anti-vibration pad would work on grass? The grass and dirt is already supposed to absorb vibrations.

#4 Padremo

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Posted 23 October 2021 - 03:42 AM

I use Celestron anti vibration pads when I'm on grass (insert immature lol here). I set the scope up on them, push down, then take the scope of and then level using the tripod leg height adjusters then put the scope back on. Works for me.
The base of the pads is much wider than the tripod foot, so it does stop sinkage, unless you're in a swamp.

If it does still shift, you can get thin bits of flat wood to put under each leg, that will give more surface area on the grass for the weight to distribute.
You could leave the wood on the grass for next time, so chances are it'll be level straight away.

Edited by Padremo, 23 October 2021 - 03:50 AM.


#5 aa6ww

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Posted 27 October 2021 - 07:21 PM

Since I'm in California, I'm usually on grass when I do my back yard astronomy. 

 

When I've used light mounts, I usually push the tripod legs into the ground so I know the feet are planted and secure so the leveling doesn't change. Also, I think its better to be fully set up before making your final leveling adjustments.

 

If the ground is overly dirty or wet, a tarp might help you stay more clean. We use to use a series of tarps when me and friends would set up at a friends place who had a big opened field. He would mow the field down every month or so, but the tarps kept dust and dirt from making things dirtier. Usually, I avoid dirty areas because dust can cling to dew on your front element.

 

Anti-vibration pads wont make any difference in the grass regarding reduced vibration.

 

..Ralph

 

 

I noticed that when I leveled the Celestron NexStar 90SLT mount, and then added the optical tube to the mount, the mount was no longer level (in the middle of a grassy field).

 

Should I wait until the OTA is on the mount to level it?  I thought it had to be leveled before the OTA is added?

 

Should I place a plastic/vinyl tarp under the mount if it is being set up on grass?  I would be worried about the tripod slipping on a plastic/vinyl surface.

 

Would using anti-vibration pads on grass be helpful or unhelpful?


Edited by aa6ww, 27 October 2021 - 07:24 PM.

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#6 mlord

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Posted 27 October 2021 - 07:50 PM

I use the pads on grass and any other surface.  They do indeed keep the tripod from sinking into the soft earth.



#7 rboe

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Posted 27 October 2021 - 11:10 PM

I push down fairly hard on the mount when on grass (don't use the pads then), level, re-push, double check then add the scope.

 

I do it that way because the tripod has a very nice flat area to put my bubble level on.

 

Never worried about it after that. Maybe I should!



#8 BrushPilot

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Posted 05 November 2021 - 12:42 AM

I first started observing with a C8 at a Fire Lookout Tower and since I was using the same location night after night what I came up with – and this solves several problems is to use three empty soup cans buried flush to the grass (so you can still mow) and filled them with cement. I also wanted to be able to avoid constant polar aligning so I had the cans placed exactly where the tripod legs were at my last alignment (easy to do, working in the daytime) and when the cement was almost set I placed the tripod legs on the surface, on plastic wrap and gently pushed down to make divots in the mortar. I used a level on the tripod head and pushed each leg a bit more or less to achieve level. After the cement was fully cured, the next night I took the whole rig out, tweaked the alignment until it was good and then all subsequent nights, all I had to do was set the legs into the divots and - voila! - instant set-up and ready for action. Worked like a charm but I'm sure it left the next inhabitants of the Lookout scratching their heads a bit.


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#9 Nicole Sharp

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Posted 05 November 2021 - 01:26 PM

You should set up the telescope on grass for daytime astronomy, but I don't think this is important for nighttime astronomy.  The field was covered in deer poop the other day, so watch where you step, and probably don't go on the grass at night.  Also remember to check yourself for deer ticks.  A plastic tarp won't help much unless you can wash it before you put it back in the car.

 

The soup can idea sounds interesting, maybe with some sand.  But I think the legs would still slip inside the can unless it was rubber-lined on the bottom.

 

If you level the optical tube, it should remain level as it rotates in azimuth.  That is a good way to test for tripod stability.


Edited by Nicole Sharp, 05 November 2021 - 01:27 PM.


#10 whizbang

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Posted 05 November 2021 - 08:14 PM

A tripod needs to be rough handled into place.  As the other posted suggested, PUSH it into the ground.  Really lean on it.  Then tighten the spreader knob/nut and tighten the leg nuts.  Check level, and lean on it again.  If the legs sink into the ground or the spreader is lose, your alignment will be bad.


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#11 Noah4x4

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Posted 06 November 2021 - 05:45 AM

Different solution....

 

Fed up with regular muddy footprints following my astro-observations, I laid high quality artificial grass at home, then decided that I wanted to protect it from the sharp bottoms of my tripod legs. Hence I built the (illustrated) tripod jig from three pieces of treated timber in an equilateral triangle, three furniture castor cups, plus a Silva compass.

 

The super thing about this contraption is that it works great on any surface as it spreads the load. I still use it to initially align my scope North-South and a nudge with a toe is all that is needed for that final precise adjustment. On good quality artifical grass it is especially good as the springiness of the grass dampens all vibration. Whilst I have not tried this, I suspect that a portable square of similar artifical grass and this jig might resolve the OPs problem, and the grass square can simply be rolled up and hosed down after use. But then deer, bear and possum poo hasn't been a problem in England since the time of Shakespeare, albeit the occasional urban fox might soil my grass.

 

Polaralignjig.JPG

 

 



#12 Nicole Sharp

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Posted 07 November 2021 - 12:55 AM

A tripod needs to be rough handled into place.  As the other posted suggested, PUSH it into the ground.  Really lean on it.  Then tighten the spreader knob/nut and tighten the leg nuts.  Check level, and lean on it again.  If the legs sink into the ground or the spreader is lose, your alignment will be bad.

 

I returned the 90SLT and will be getting something heavier.  I figure the heavier the mount, the less of a concern about "settling in" there will be.  Pushing down on the mount might not work since you have to unlock the tripod legs to adjust the leg heights for leveling.  Also, the SLT tripod is not designed to handle more than 8 pounds of downward force, so I doubt it would be advisable to sit on it or lean on it.

 

I put the power supply on the tripod accessory tray to help weigh down the tripod for stability.


Edited by Nicole Sharp, 07 November 2021 - 01:01 AM.



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