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Orion Sirius - pushing the weight limit

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#1 CapPic

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Posted 22 September 2012 - 08:54 PM

I am currently looking at the combo deal Orion has that includes the EON 120 and their Sirius mount. If I got it, I would want to use the EON 120, an 80ED for a guidescope, autoguider, and a DSLR.

I believe the EON is 15 lbs, the 80ED is about 7, and the guidescope and DSLR are about 2 pounds each. With rings, it probably just hits that 30 pound limit.

Does anyone have any experience with this mount? Is right at 30 pounds going to be way to much for astrophotography?

#2 Joe Cipriano

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Posted 23 September 2012 - 02:47 AM

You've got two strikes against that working out from the start. First, you're at the weight limit for the mount - and that's for visual. The rule of thumb for imaging (and I, for one, feel that there's plenty of latitude in that rule) is 50% of listed capacity. The second strike is the moment arm of that OTA - at 900mm fl, the tube is close to a meter long. IMHO the combination of weight and long OTA is going to doom you to many unuseable subs and loads of frustration.

If it was one or the other (say a short Cat at the weight limit, or a long tube at around one-half to two-thirds mount capacity), I'd say give it a try - you'd probably be tossing out some subs, but you might get some useable images. In this instance, you need too many things to be absolutely perfect - no wind whatsoever, no vehicle traffic nearby, perfect balance, perfect AG settings, and a mount on its best behavior.

If you really want to try it, I'd suggest losing some weight somewhere. Maybe nix the 80ED as a guidescope, and pick up Orion's Mini AG; it's listed at 1.3 lbs total (including mounting hardware, apparently) - a whole lot less than the ED80, seperate AG, and associated mounting hardware.

Just my dos pesos. I'll be interested in what others have to say, as the Sirius is on my short list.

#3 brianb11213

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Posted 23 September 2012 - 03:07 AM

Joe's right, it's way too much. Your kit list might work on a well-tuned Atlas on a very solid permanent pier but I think even that might not be enough - you might get away with it in a slitted observatory where at least you won't have wind vibration to deal with.

My experience with Sirius/HEQ5 Pro mounts is that the effective maximum load for long exposure AP is about a 90mm short focus scope with a lightweight camera & guider package. 10-12 lb total, tops.

#4 rmollise

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Posted 23 September 2012 - 08:25 AM

Too much. If you don't want to go up to the Atlas, substitute Orion's 50mm guider or the KW Telescopes equivalent for the 120mm achro.

#5 jsines

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Posted 23 September 2012 - 04:59 PM

I asked the same basic question in the DSLR imaging forum - I have an Orion Sirius Mount and an Orion ED80T on backorder, expected ship date is 9/27. I also have an Astroview 120ST, and I was wondering if I could buy a guiding camera and use that as the guiding scope in some combination. I got several responses and they all said the same basic thing - get Orion's 50mm autoguiding package. The large guidescope would have added flexure to the photos. Someone said that even the 80mm guidescope package was causing flexure. I'm saving up for the 50mm guidescope package. When I start guided imaging, I'll have the Sirius mount, the ED80T, and the 50mm guidescope. That's it.

#6 CapPic

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Posted 23 September 2012 - 05:06 PM

I appreciate the input. The Sirius is now off my list.

#7 Joe Cipriano

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Posted 23 September 2012 - 07:45 PM

... When I start guided imaging, I'll have the Sirius mount, the ED80T, and the 50mm guidescope. That's it.


That should work well. Light setup - and it's best to start out imaging at short fls.

I appreciate the input. The Sirius is now off my list.


Happy to help.

#8 gustavo_sanchez

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Posted 25 September 2012 - 12:35 PM

I think that the Sirius can handle the load of the 120ED, provided that you use the Mini Autoguider instead of a 80mm scope. I normally use my Orion F/4 8" Newtonian (800mm FL) on that mount without any stressing on the mount. The camera that I use is an Atik 314L+. That said, I have to admit that swapped the 1.75" tripod for a CG-5 2" tripod.

#9 gustavo_sanchez

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Posted 25 September 2012 - 12:39 PM

I asked the same basic question in the DSLR imaging forum - I have an Orion Sirius Mount and an Orion ED80T on backorder, expected ship date is 9/27. I also have an Astroview 120ST, and I was wondering if I could buy a guiding camera and use that as the guiding scope in some combination. I got several responses and they all said the same basic thing - get Orion's 50mm autoguiding package. The large guidescope would have added flexure to the photos. Someone said that even the 80mm guidescope package was causing flexure. I'm saving up for the 50mm guidescope package. When I start guided imaging, I'll have the Sirius mount, the ED80T, and the 50mm guidescope. That's it.


I think that you could get away with that combination, but if you use the mini-guider package you will be more than comfortable imaging with the ED80T-CF. I have that same setup and it does not stress the mount at all.

#10 RandallK

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Posted 25 September 2012 - 02:01 PM

I found using my DMK21 and part of my Antares 7 X 50 finderscope with an Agena Astro 1.25 Blue Fireball extension the key to my guiding on my HEQ5 Pro along with my 8" Meade. I ditched the ST-80 and guide rings which were much to heavy. With the sensitivity of the chip in the DMK21, it makes guiding very easing with PHD Guiding. My weight comes down to about 19 lbs. I use the same guide setup with my 80m apo.

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#11 EricRemy

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Posted 26 September 2012 - 07:42 AM

That's a nice guide scope RandallK .

#12 RandallK

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Posted 26 September 2012 - 04:00 PM

Hi Eric,
Although the picutre doesn't show it here, there is a Synta type dovetail mounted to the guidescope base. I purchased two Synta type "sockets" with only 1 mounting hole in them from ScopeStuff and mounted these on one of the scope rings on my 80mm APO, and the other on the rail of my 8" SCT. That way I can use this guidescope on both scopes by just inserting it into either "shoe" and tighten the thumbscrew. Easy!

#13 CapPic

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Posted 26 September 2012 - 07:17 PM

I did eventually decide to just go with the Atlas (plus an 8" reflector at a good combo price) to go with the EON 120. Just waiting on them to ship it now :4

#14 Gray

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Posted 28 September 2012 - 11:21 PM

You won't be disappointed with the mount or the scope, but the focuser will. I replaced mine with a Moonlite CR2 and adapter kit, from Moonlite @ ~$214.

I already had the 8"(never been able to use it because of EQ5 mount), and was also looking at that nice but expensive refractor. Eventually I came to my senses and decided it was time for a new mount. CGEM or Atlas was the only mounts in my range. No vendor except Optcorp had the Atlas in actual stock so I called Astronomics and inquired on the CGEM. I really liked the look of that mount and a few of it's software features, but the saddle was Losmandy compatible only and I have all Vixen style dovetails. No go on the CGEM. It's a good mount from what I've read but still in a developmental stage.

Alas, Optcorp & the Atlas. Cost $30 to ship, arrived in two beaten boxes, but all was well. The mount head weighs a tremendous amount compared to the EQ5. My mount is a newer one that comes with a dual type saddle, both Losmandy & Vixen DT's accepted & no set screws to mar the DT.

Powering the mount up was a nice experience itself. The thing moves so quietly and sounds like a high tech piece of equipment worthy of it's price tag. Enough rambling.. Hope you find your experiences as good as mine. :usa:

#15 CapPic

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Posted 02 October 2012 - 06:08 PM

Just two days left until I get it!

What is wrong with the focuser?






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