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Mount payload

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#1 Jack160219

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Posted 06 June 2020 - 05:20 PM

I’m considering getting the cem70, but just reading the specs, the payload is 70lbs excluding counter weights. So the actual payload is a lot less.

do all mounts do this I.e. exclude cw in their advertised payloads?  Thanks jack

 



#2 B 26354

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Posted 06 June 2020 - 05:33 PM

"Excluding counterweights" means "not including" the weight of the counterweights. So in theory, the mount will handle up to 70 lbs of actual payload. The generally-accepted "Rule of Thumb", if you're doing astro-photography, is to divide that listed payload in half. grin.gif


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#3 Jack160219

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Posted 06 June 2020 - 06:33 PM

Ok, thanks. I read that as the listed payload minus the counter weights. I’m relieved. Jk



#4 gotak

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Posted 06 June 2020 - 07:12 PM

As I have said before 1/2 rule is not hard and fast a lot depends on the OTA dimensions and other factors.

1/2 was always just a way to sandbag against factors a beginner might have trouble with.
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#5 B 26354

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Posted 07 June 2020 - 01:25 AM

As I have said before 1/2 rule is not hard and fast a lot depends on the OTA dimensions and other factors.

1/2 was always just a way to sandbag against factors a beginner might have trouble with.

Exactly. Which is why I referred to it as the "generally-accepted" Rule of Thumb. grin.gif



#6 SonnyE

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Posted 07 June 2020 - 10:59 AM

Ok, thanks. I read that as the listed payload minus the counter weights. I’m relieved. Jk

Common mistake, Jack.

I subscribe to the 50% rule, myself, for AP. But I have always been way under that.

 

But before you decide, do add up the weight of everything you might possibly use.

Good "future proofing" would be to think ahead about electronic focusers, electronic filter wheels, and upgrades you might toss in down the road.

 

I do DSO imaging. My currant "Rig" weighs 15.4 pounds from the bar up. Including the bar.

It sets atop a 50 pound Photography rated mount.

I thought my telescope, et al, would look small on the mount. But it does not.

And being so grossly underweight, my mount hardly knows it is there. 3.24 to 1 ratio. (50# / 15.4# = 3.24r)


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#7 bjkaras

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Posted 09 June 2020 - 05:39 PM

There is more than just payload weight. You have to look at dimensions as well. A mount that might handle a short focus refractor might not be able to handle a long focus tube. Longer tubes have a higher moment arm and are more susceptible to bumps or little gusts of wind. In another thread I saw a pic of a short 6” refractor on a Meade 826 mount. I also have my 6” refractor on that mount, but mine is f12, and any disturbance at all affects it. While it’s fine for visual I would never try imaging with it even though fully loaded the OTA comes in at only around 27 lbs.




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