Equatorial Mount loading questions

[Rockenrock]

Hi,

I have been studying equatorial mounts for doing astrophotography (like galaxies), and confused by the different capacities I see. Some say instrument capacity and total capacity. Others just say capacity. Does a scope/camera that weighs 40 lbs require additional 40 lbs counterweights? (They have to balance, right?) So the total capacity used is 80lbs? Can you really put 40 or 50 lbs scope/camera on a mount that has a total capacity of 100lbs? Are these 'marketing' numbers or really practical numbers?  

I am considering either the F8 GSO 12" RC and F8 GSO 10" RC plus filter wheel + camera on Losmandy G11 which says 100 lbs total weight and 60lbs instrument. The 12" scope is 49lbs + camera + filterwheel. Maybe 56 lbs total. Is that too much for this mount?

Thanks for your advices for my system.

Roger

[Merlin66]

All mounts are rated for the carrying capacity excluding the counterweights.

A rule of thumb for astrophotography is to work around 50-60% of the rating.

[Cornelius Varley]

The capacity or loading capacity is the amount of payload the mount can carry, excluding the counterweights as these are considered as part of the mount. Any item attached to the mount via the dovetail ie telescope, eyepiece, finderscoope, camera etc is considered the payolad.

[Rockenrock]

Thanks Merlin, that sound reasonable. I will continue to study the forums regarding specific mounts and what payloads users are using on them.

Best regards,

   Roger

[damnut]

Hi There,

You might find this interesting. :-- http://www.chuckhawks.com/telescope_mount_list.htm

[astronomer2002]

Hi,

I have been studying equatorial mounts for doing astrophotography (like galaxies), and confused by the different capacities I see. Some say instrument capacity and total capacity. Others just say capacity. Does a scope/camera that weighs 40 lbs require additional 40 lbs counterweights? (They have to balance, right?) So the total capacity used is 80lbs? Can you really put 40 or 50 lbs scope/camera on a mount that has a total capacity of 100lbs? Are these 'marketing' numbers or really practical numbers?  

I am considering either the F8 GSO 12" RC and F8 GSO 10" RC plus filter wheel + camera on Losmandy G11 which says 100 lbs total weight and 60lbs instrument. The 12" scope is 49lbs + camera + filterwheel. Maybe 56 lbs total. Is that too much for this mount?

Thanks for your advices for my system.

Roger

Roger,

Couple of points on the G11.

1).Damien Peach uses one on a portable pillar with his C14 so it is possible to carry that much weight and take spectacular images

2). I mounted my C14, filter wheel and camera plus a WO 66mm as a guide scope on a permanently mounted G11. In my opinion this was as much as the mount could carry and I eventually acquired a MI250 to replace it.

A 12 inch RC plus filter wheel heavy camera etc is probably going to be a bit too heavy for the G11. I am sure it will work, but you will be at the limit of the mount. A 10inch RC is completely different and  I am sure you will be happy with that size.

I purchased a 12inch RC and a MX to put it on. By the time I'd added a 4 inch APO on the back as a guide scope I was unhappy with the carrying capability of the MX, certainly for imaging. The added weight of the refractor took the overall weight to no more than 65-70 lbs, but I felt the MX performed well when it only had teh 12 inch RC with camera that reduced the weight to under 55 lbs. Might have been better with a side-by-side arrangement but with the refractor so far out  and 80lbs of counterbalance weights it had issues guiding when less than 30 degrees from the horizon..

I did a lot of research into the carrying capacity of the MX (claimed to be 100lbs)  and found everyone who was producing excellent images were using 10inch RC's or similar. You just have to be careful when deciding who to believe when choosing a mount carrying capacity.

I believe the G11 is a class above the mass produced mounts and certainly better made than the skywatcher EQ8, which in theory can carry more. The Goto is old, but surficed for my needs and the mount can be controlled from a PC planetarium program if desired. To get a high quality mount capable of carrying more than the G11 is double the cost of a G11. Some have been lucky and got excellent EQ6's and EQ8's, but these are the lucky few. Quality control and after-market support is non-existant for these mass produced mounts.  

Ian B