East Wind Photography said:
candc said:
East Wind Photography said:
thanks, seems like a good value.
Holds a lot of weight too. I can get my 600 F4L with my gripped 5D3 on it but need extra counter balance. But it works. With my 300mm F2.8L it's a perfect balance with only one counterweight. You would likely need the wedge and a couple of other things so if that seems like a good value, make sure you get everything you need.
While you can barely fit a 600/4L and 5D III on the Star Adventurer, it is not recommended. The rule of thumb for imaging is to use only half the rated capacity. More than that, and your tracking accuracy will suffer, which will affect your stars. You shouldn't put more than 5-6 lb on the Star Adventurer for best results. You might get away with 7-8lb, but with longer lenses your star profiles will suffer (you'll have bloated stars, and you'll lose the benefits of the increased resolution of a large lens like the 600mm f/4).
I use an Orion Atlas, a $1500 mount with a 40lb capacity, and at barely 20lb I am still not able to get ideal stars. I've reached the point in my imaging where instead of obsessing over things like just getting tracking working reliably at all, I am now obsessing over maximizing my mount's performance to get the tightest stars. I've come the the simple conclusion that a $1500 mount with 40lb capacity is simply not capable of giving me sub-arcsecond performance, even when guided, with a mere 20lb load.
There are two levels of alternatives. There are the $5000 mounts, like the CGE Pro, the Orion HDX110, the Losmandy Titan. These can perform well, and have higher capacities, but they aren't engineered much better than the entry level mounts that run for $1500-$3000. They can get to 1-2" guided performance, but still can't get to the holy grail of true sub-arcsecond performance (where the worst case performance is still less than an arcsecond peak-to-peak (P2P) periodic error (PE).) Only the high end mounts, which start at $8000 for 45lb worth of imaging capacity, can give you tracking performance that averages >1" PE and 0.1" or better guided performance (which is necessary when you start imaging at a scale of 1"/px or larger...in my case, I am trying to image at 0.73"/px and simply can't do it with my mount.)
The 600/4 and 5D III is 2"/px image scale, and to get the best stars, you really want to keep your guided tracking at around 1-1.25" RMS. The 11lb capacity of the Star Adventurer is not going to give you that kind of performance, not even at half load, let alone full load. You might be able to get away with a 5D III and 300mm f/2.8 on that mount, but I think it would be difficult to get good performance out of it. The 5D III and 400mm f/5.6 would probably do much better.
For beginners, the best recommendation is to get the biggest mount you can possibly afford, and get a small, short, fast refracting telescope (or lens) as your first telescope. That maximizes the mount capacity (i.e. an Orion Sirius or Atlas), and minimizes load, thus maximizing your potential to get the most out of the equipment without a lot of hassle. Focal lengths ranging from 300mm to 600mm are generally recommended for beginners. Once your up over 800mm through 1200mm, your image scales drop to the point where mounts like the Sirius or Atlas are barely going to deliver what you need without extra work (i.e. most Atlas users who are imaging at 1200mm or longer have hypertuned and possibly belt modded their mounts...or, they skipped the Atlas and went strait to the Atlas Pro, which is basically hypertuned and belt modded right out of the box, for another $500 tacked onto the price.)
If your looking at something like the Astro Trac or Sky adventurer, you should be thinking much more wide field. Anything from ultra wide (14mm through 80mm), maybe 100-200mm. To give you guys and idea of how big these fields are (assuming a FF camera like the 5D III or 6D). The ultra wide focal lengths like 14-80mm are either "whole sky", "constellation", or "asterism" in terms of the field coverage. After that, up to 200mm or so, then you can start zeroing in on the really large regions of nebula, like the greater Cygnus region, or the entire Orion Belt+Sword complex, or both Heart and Soul nebulas in Cass, etc. At 600mm your down to just Orion's Sword or the end of his belt where Horsehead is, or just Heart or Soul nebula, or just California and Pelican nebulas in Cygnus, Andromeda Galaxy, etc. At 1000mm, your down to portions of nebula, small nebula (Wizard, Elephant Trunk, Crescent, Tulip, etc.), medium sized galaxies like Triangulum, and beyond that your into bulk (small) galaxy ultra high resolution nebula imaging. Much beyond 1200mm, and you have to start explicitly looking for scopes that have truly massive apertures, and much larger sensors with gargantuan pixels, just to get a reasonable image scale. It's not uncommon to find FF sized CCD sensors with 9 micron pixels being used at 1600-3000mm. A lot of the larger scopes support 65-70mm image circles, which cover 37x37mm and 49x37mm "large format" sensors that have 9, 12, and even 24 micron pixels.
So, as beginners, you should be thinking what is the shortest telephoto lens you can use, and what is the biggest mount you can possibly afford. Shortest Scope + Biggest Mount = Least Hassle, Most Fun. With an AstroTrac or Star Adventurer, I'd say 400mm f/5.6 or around there should be the limit. If you are willing to deal with some frustrations, you might be able to work a 300mm f/2.8 on a Star Adventurer, but just prepare yourself for dealing with tracking issues and other problems about half the time.
