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The tradeoff here is, of course, CASH. So for the money the CGEM (or Orion Atlas) is as good as it gets - for the money. The Losmandy G-11 with an upgraded worm gear (and twice the RA gear diameter) will cost upwards of four thousand US dollars, the Celestron pro more than that.

Again, thanks for using the link to my site and I wish upon all – clear and dark seeing.

If there is something here that I am missing please don't hesitate to correct and/or educate me.

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Most amateur astrophotography, that you see on the web, is merely an artistic rendering subjectively highly manipulated, aligned, and warped on several levels in order to achieve the final result.

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The SOLE reason I posted my reviews in my blog is that there is a lack of TRUTHFUL REALISTIC reviews on the web that would possibly have prevented me from wasting my money on a CGEM.

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I get the strong impression that what is considered realistic in this case is very much a mater of perspective. Nearly the entirety of my imaging has been done on a CG-5 mount! For me a CGEM's failings would be a wonderful blessing! From my perspective I *expect* auto-guiding to be required to achieve 10-minute exposures. I would consider the CGEM well worth praise if it does allow guided 10 minute exposures at relatively long focal lengths.

I can understand being disappointed if you come from the perspective that no guiding should be necessary, but to my mind that is not a realistic expectation at this price point.


(BTW - While I do not consider myself the equal of the top-end astrophotographers, I still do have a lot to learn with processing especially, but I think I am also justified in using myself as an example that good AP can be done with "poor" mounts.)

Anyway, just to be clear I am not trying to be confrontational, just trying to point out the disparity of perspectives.

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I do understand that the machining tolerances are important but being machined with equal tolerances the larger diameter gear WILL ALWAYS be more precise.

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A single ten minute exposure will exceed, by far, ten one-minute stacked exposures.

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The SOLE reason I posted my reviews in my blog is that there is a lack of TRUTHFUL REALISTIC reviews on the web that would possibly have prevented me from wasting my money on a CGEM. By the way if you are interested mine is for sale while I put my name on the AP waiting list.

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I would consider the CGEM well worth praise if it does allow guided 10 minute exposures at relatively long focal lengths.

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Interesting that the link you provided shows that most of the photos, that had the info provided, were captured using a AP 1200 mount. I do understand that the machining tolerances are important but being machined with equal tolerances the larger diameter gear WILL ALWAYS be more precise.

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The latest development from AP with precision encoders on the AP 3600: "The measured tracking error was well below 1/2 arc second for a 20 minute time period" (only in the wildest dreams of a a CGEM user) http://www.astro-physics.com/index.htm?products/mounts/3600gto/3600gto.

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In the photo world, a good mount/tripod is imperative but the job of the mount is simple so one does not expect to pay more for the mount than for the camera and lenses...

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...Steppers suffer from a lack of dynamic range (if you want precision, you can't get fast slews). My GoTo conversion is limited to 160X sidereal, which is pretty slow but surprisingly can be lived with.
...

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I don't really see why there is this story floating around that precision microstepping is "hard" - you can do this with an Arduino and an A4988 driver, which is a single $10 chip.

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This is what microcontroller or what development platform is more suitable type of hardware debate. I'd also recognize that "microstepping" as a software module has existed for a long, long time. But I'd say this: a properly designed microstepping GOTO controller for astro application (or high grade, professional quality) is not so easy. I had a list of requirements previously in CN's ATM forum (and in another forum outside the CN). For some hobby-DIY self-developed attempts, I'd say they only meet some of them (and leave the rest of tasks for future work ) So you decide.

Clear Skies!

ccs_hello

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Greg N - actually, I had a great Ferrari mechanic and bought the 328GTS new, so except for tune-ups/oil changes, I never had a minute's trouble for almost 8 years (never should have gotten rid of it). But I couldn't put groceries or anything in it, hence the Toyota. Now a Lotus!!! That thar's trouble!

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The latest development from AP with precision encoders on the AP 3600: "The measured tracking error was well below 1/2 arc second for a 20 minute time period" (only in the wildest dreams of a a CGEM user) http://www.astro-physics.com/index.htm?products/mounts/3600gto/3600gto.

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I think no one here is surprised that the $27,000 3600GTOPE outperforms the $1500 CGEM in most every way by a wide margin. I myself am surprised anyone would even mention the AP mount when discussing a mount like the CGEM.
Jon Isaacs

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I think the reason he mentioned AP mounts is that someone gave him a link to pictures that were supposedly done with a CGEM, but most were actually done with an AP1200. That said those pictures, although colorful, had a little too much noise reduction for my taste. The excessive noise reduction caused some stars to be misshaped (visible in some of the full sized images) and areas to be featureless hazes. In my humble opinion, although they are not bad, they are definitely not up to the best deep sky images of these areas that I've seen, mostly because of the excessive noise reduction.

-Ray

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