Discussion on Tracking Mounts

Started Apr 3, 2013 | Discussions thread
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RustierOne
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Discussion on Tracking Mounts
Apr 3, 2013

I snagged this discussion from the iOptron thread as my reply was getting further off topic:

Trollmann wrote:

Yes - using an equatorial mount may be a bit off-topic, but if the goal is getting pinpont stars with a tracker and a 300-400 mm lens, then dissapointment may lurk nearby...

To me a tracker is fine with short to moderate focal lenghts (up to 100 mm or so), but we all have different views and different goals (like NoRules tormenting his own Polarie tracker... )

Yes, he's getting some superb results with his Polarie, like the PanSTARRS - Andromeda conjunction. I'm hoping to try my 200 mm Pentax SMC f/4.0 with a barn-door mount. So far with 135 mm on a Tokina 35-135 mm zoom, I've has some success. The easy setup for such trackers is a big advantage.

RustierOne: I guide my G11 with an Orion autoguider (cheap and functional, guiding with PHD), and with a 60/250 mm guide scope I get wonderfully round stars even with 770 mm focal lenght. Would go for a longer focal lenght guide scope if guiding something like a C11. Sitting glued to an guiding eyepiece for hours is experience of the past...

You make some good points, Trollman. As Jerry Lodriguss points out in his article on mounts for astrophotography,

http://www.astropix.com/HTML/I_ASTROP/MOUNTS.HTM

if one is willing to tinker and work around the shortcomings of a less than ideal mount, its possible to get some good results. But each will have its limitations - a barn-door tracker will not work well with a 1200 mm lens. Maybe 600 mm if you push the limits. But lack of guiding capability is a big disadvantage.

Thanks for the info on your guider equipment. I've thought of getting the Orion guider since Razor2277 is getting some great results with his CG5 and C-8. As for a guide scope with my G11, using the C-11 as the guide scope with a piggyback camera lens seems like an over-kill. Maybe using the C-8 (2000mm) as guide scope with the C-11 at 1760mm as imager would work. But that looks to be a lot of setup time.

Oh well, I may have to regress to manual guiding. I have tried using the polar alignment correction routines of the G11 along with periodic error correction for unguided exposures (about 2 minutes) with some success at 1760 mm. Not all the images were keepers, though.

I'd be curious as to what some other astrophotographers are using for tracking mounts, particularly with the longer lenses. What equipment and techniques are working for you?

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Best Regards,
Russ

 RustierOne's gear list:RustierOne's gear list
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