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How long is too long

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#1 EZ73

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Posted 27 November 2022 - 09:37 PM

With my 140mm refractor the second I go over 200x it takes my current setup upwards of 4 seconds before the image settles down..

I suspect my mount might be the culprit, but I'm not sure.

Low power and up to 140x it's works great. I do visual only

When using higher magnification is three or four seconds settle time common?

What's been your experience?

PS any advice on if I need to upgrade my mount or tripod

Clear and stable skies

Bryan

#2 Spikey131

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Posted 27 November 2022 - 09:49 PM

Of course it is your mount, or the tripod under it.

 

What mount are you using under your 140mm refractor?



#3 scngc7317

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Posted 27 November 2022 - 09:52 PM

Most of the time the Mount is more important than the scope gramps.gif especially a F-15 scope gve.gif
 
IMG 3616

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#4 luxo II

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Posted 27 November 2022 - 09:53 PM

Consider the entire solution - the mount, tripod, and possibly whatever surface it is on.

 

For example:

 

Hard surface like concrete or ashalt, great but... you may see vibrations transmitted via the ground from passing traffic on nearby rounds.

The average wooden deck or patio will shake quite visibly when people move around.

Thick soft grass looks nice, but is really bad - like being on a rubber sponge.


Edited by luxo II, 27 November 2022 - 09:54 PM.

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#5 weis14

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Posted 27 November 2022 - 09:55 PM

I'd definitely upgrade the tripod and probably the mount too.  A 140mm refractor is a beast and it is doubtful that a UNI tripod is up to the task.  I have a UNI-24 and whenever I tried using it with my 160mm refractors it was noticeably shaky.  It was fine with my AP130GTX, but that was a light scope for its aperture.  

 

I think a 140mm refractor is firmly in Berlebach Planet territory (it's what I use for my bigger scopes).  A 140mm refractor is also well outside what I'd be comfortable using a M2C to support.  I'm not familiar with the NoH mount in your signature, but unless it is in DM-6/AZ100 territory (or GM811/G11 for a GEM), I would feel under mounted.


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#6 luxo II

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Posted 27 November 2022 - 09:58 PM

@scngc7317,

 

That photo of your scope is interesting in this topic because I note you have the OTA in rings attached to a long dovetail bar. I'll guarantee that bar flexes a lot more than you realise - the OTA being a tube is actually a lot stiffer than the bar.

 

Would be a LOT better with a very short dovetail bar - bring the rings in as close as possible to the dovetail clamp so the load is transmitted from the rings to the dovetail clamp.

 

My 10" is in rings and originally the rings were far apart on a 14" Losmandy dovetail and I never thought it would flex significantly under load, until one day I looked down the tube and could see it twisting. This explained much of the issues I had with poor GOTOs and the significant cone error I was seeing. Bringing the rings close so they were on either side of the dovetail clamp eliminated the flexure.


Edited by luxo II, 27 November 2022 - 10:02 PM.

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#7 JMW

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Posted 27 November 2022 - 10:17 PM

I am picky about damping time. My most stable setup is my DM6 on a Planet tripod. The next most stable mount is my AZ100 on another Planet tripod. This is with a TEC140ED mounted. I see damping times under one second. I can move the focuser without waiting for the image to settle.


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#8 EZ73

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Posted 27 November 2022 - 10:24 PM

Of course it is your mount, or the tripod under it.

 

What mount are you using under your 140mm refractor?

After reading a good review on a South Korea Mount I took the plunge.

 

It's a Noh CT-20. It's rated for 44 lb



#9 EZ73

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Posted 27 November 2022 - 10:28 PM

I'd definitely upgrade the tripod and probably the mount too. A 140mm refractor is a beast and it is doubtful that a UNI tripod is up to the task. I have a UNI-24 and whenever I tried using it with my 160mm refractors it was noticeably shaky. It was fine with my AP130GTX, but that was a light scope for its aperture.

I think a 140mm refractor is firmly in Berlebach Planet territory (it's what I use for my bigger scopes). A 140mm refractor is also well outside what I'd be comfortable using a M2C to support. I'm not familiar with the NoH mount in your signature, but unless it is in DM-6/AZ100 territory (or GM811/G11 for a GEM), I would feel under mounted.

Yeah I was really worried about the Uni 18. Was trying to get some feedback and thought that would be enough tripod. But I guess I should have went with the planet. The Noh CT-20 is rated for 44lbs

My Stellarvue is just for my 4" refractors

Edited by EZ73, 27 November 2022 - 10:37 PM.

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#10 TOMDEY

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Posted 27 November 2022 - 10:38 PM

Well... a good scope on a good mount on a good pier (or good tripod on good ground) --- acceptable ~settling time~ should be pretty close to zero sec. Something that would be barely noticeable even at highest mag. The reason I say this is because shaky mounts also suffer pernicious instability at the slightest buffeting by someone strolling by, a refreshing zephyr or focus adjust... annoying for visual and catastrophic for image capture. Very few telescopes satisfy this ideal --- but your 4 seconds is gargantuan, albeit not all that uncommon. Find the cause and correct it, otherwise it will wear you down every moment of every otherwise pleasant observing session.    Tom  Tom



#11 weis14

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Posted 27 November 2022 - 10:49 PM

Yeah I was really worried about the Uni 18. Was trying to get some feedback and thought that would be enough tripod. But I guess I should have went with the planet. The Noh CT-20 is rated for 44lbs

My Stellarvue is just for my 4" refractor.

My Uni 24 is a great tripod for my grab and go setup with a manual mount and Stowaway.  I no longer use it for anything heavier, preferring the Planet despite its extra weight.



#12 EZ73

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Posted 27 November 2022 - 11:01 PM

If I order the planet tripod with the DM6 Mount and their 8" extension. Will I be able to view at zenith, or will there be a clearance problem with the tripod leg?

#13 weis14

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Posted 27 November 2022 - 11:35 PM

If I order the planet tripod with the DM6 Mount and their 8" extension. Will I be able to view at zenith, or will there be a clearance problem with the tripod leg?

I think you will be fine, though I don't know for sure without seeing your setup.  I never had a real issue with my 160mm refractors I used when I had a DM6 and extension.  However, whenever one of them got close, I mounted a small counterweight on the focuser end of the scope so I could balance the scope further forward in the rings. ADM and others make counterweight kits for this purpose.  


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#14 Applal

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Posted 28 November 2022 - 11:27 AM

If you can test  without losing too much time, try suspending a 10# bag of sand from under the tripod with a sash cord (not a bungie!) and see if that added mass helps settle things down without having to invest any extra money in mount or tripod.


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