AstroTrac 360?

Started Mar 21, 2018 | Discussions thread
Pogo65 Regular Member • Posts: 298
Re: AstroTrac 360?

swimswithtrout wrote:

Pogo65 wrote:

I am surprised at how you think that a 5 arc second error is a really big one. Name me one affordable mount that can do better than that over a 15 minute period, certainly not an EQ6, with all due respect, certainly not most worm gear based GEM within a reasonable price range. I own a Astrophysics Mach 1, quite an expensive mount, with a very smooth 5" error, easily guided out to just below 1" which in most places around the world is better than the seeing anyway.

When shooting at longer focal lengths and when not using very short exposures, there is no way around guiding anyway, not just because of the error, but even slight polar misalignment will make guiding a must.

Peter

I am very well aware of how HUGE, 5" of error is !!!

On my LAST NIGHT OUT , my Atlas/EQ6 had a peak error of 0.75", as reported by PHD2, but I ran for 90% of the 3 1/2 hrs of imaging, at 0.5" to 0.65" with autoguiding.

Astrotrac advertises that it can "easily handle an 8" RC ". An 8" RC with a dSLR like my Nikon D5300 has an image scale of 0.5" /pixel. That's 10 times smaller than the 5" error that Astrotrac claims. At f8, you're not going to be doing short exposures, unless your using a dedicated cooled monocam like a 1600M, and even then you will still be forced to autoguide. Does it autoguide in both axis' or just RA ? If only RA, you're going to need a Polemaster as well, to get good enough alignment, and still keep your fingers crossed that everything doesn't flex.

An 8" RC weighs 16 lbs without a camera attached. But it will have to have an autoguider as well. Weight wise, an OAG would be best, but that's still another lb or two. An old school guidescope/cam is going to be 2-3 lbs. Add in counterweights, rings and dovetail to mount it to the unit, if you even can.....and you're way over the weight limit, if it's even accurate !!

While we're at it, does it include a Vixen saddle, Losmandy saddle, is it a dual, to mount an RC or 101mm APO per there ad, or is going to be proprietary and cost a fortune ?

Or are you going to have to try and fit a saddle to a ball head , even further off balancing the unit.

If you want a light weight, PROVEN, portable travel system, for longer fl, that can autoguide on both axis', there's the iOptron CEM25 that can carry 27 lbs and weighs 10.4 lbs per specs. It costs $900 USD including the tripod.

I am well aware of having to be mobile as well. I gave up, over a year ago, of even attempting to image from my "White Zone" yard. I now drive for 1 hr minimum to get to better skies.

For fl under 200mm, I use my iOptron SkyTracker. Over that I use my Atlas/EQ6.

Since I don't have to move anything more than 5-10', weight is not an issue, and the Atlas/EQ6 with precise GOTO is actually faster to get to first image capture beyond 200mm, even though it takes 10-20 min longer to set up.

If you want to image at 300mm or below, than the old Astrotrac or the new Fornax LighTrack are your best bets.

Beyond 300mm, you'll still be better off going with a GEM.

I hear you and can see what you are saying. If I were to drive an hour for dark skies, sure I would pack my AP Mach1, but I am talking having to take an airline ride to get anywhere dark. This does double as a GEM, even has pointing capability, not unwelcome for hard to find objects at longer focal lengths.

I have to admit, that I find it hard to imagine putting an 8” scope on it as well, besides, that doesn’t travel very well either. I do own the Fornax however and like it a lot and while it is able to handle 400mm or even 600 mm, when properly aligned, it is a bit of a hassle trying to center objects at long focal lengths as well as properly balancing the thing, dealing with flexure etc. I have a Maksutov at 1000mm that seems like a good match in a travel setup. Used it before and while not very fast, produces pretty good results. That was to much for my Fornax.

This sits nicely in the middle I think. While I am not yet 100% sure I think it will guide in both axis as you get two tracking modules that are as far as I know identical. But for those kind of details, we have to wait for Astrotrac to come up with some more details, which they told me they would do coming weeks. They also said they have been testing for two years now.

I know you are not impressed by a 5 arc second error, but I suspect it will be very smooth as with the Fornax and as it is over a 15 minutes period, should be easily guided out. I am still pretty excited about this mount.

cheers,

Peter

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