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Built in mount model vs. Maxpoint or tpoint

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#1 Hilmi

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Posted 04 February 2013 - 10:51 AM

OK, so now I have my mount mechanically sorted, and I am now looking at making my imaging sessions easier. Part of making the sessions easier is building the model.

Is there any benifit of going for Maxpoint or Tpoint over the Gemini 2 built in model other than the ability to automate the process? I'm leaning more towards tpoint since I have found that The Sky X plate solves faster and more accurately than Poinpoint LE which seems to regularly fail to plate solve for some reason although all the parameters about focal length and pixel size are entered correctly in MaximDL. So, does this software deliver anything the built in mount modelling can not deliver? Those of you who have it, do you feel it's worth the money? Has it truly enhanced your imaging experience?

#2 Raginar

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Posted 04 February 2013 - 11:07 AM

Hilmi,

I found, for imaging, that platesolving alone removes the need to have an accurate pointing model. Mind you, I just got my Gemini-2 setup, but with my CGEM, I would just do a 6 star alignment and then use the 'sync' feature inside MaximDL to get the target on the chip.

I too had issues with Pinpoint, but it was usually user generated. Keep fiddling with the settings (try swapping from user inputting FL/pixel size and back to automatic, it helps).

I found the pointing models just wasted time I could be imaging and didn't hold up well over time.

Good luck!
Chris

#3 Footbag

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Posted 04 February 2013 - 11:37 AM

Hilmi,

Remember when you were thinking dumping your G11 for a Mach 1? The Mach 1 doesn't have a pointing model. A pointing model may help with goto's, but more important is getting a good polar alignment. That's AP's justification and it makes sense for imagers.

Is this a permanent setup? If it is, you may see some benefit of the pointing model in automating, but you're also saying you want to make your imaging sessions easier. Is that portable setup? If so, that's just adding time you could be drift aligning or imaging. Unless of course you are using the pointing model to get yourself polar aligned in which case it may be worthwhile, but I've been getting good PHD drift alignments in 15m. Hard to beat that.

#4 Raginar

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Posted 04 February 2013 - 12:02 PM

Adam,

He's got an observatory. I think you're right that he'd benefit more from getting a good drift alignment too.

#5 Hilmi

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Posted 04 February 2013 - 12:45 PM

I've done my drift align using PEMPro and I think I have it about as accurate as can get it within the limits of the mechanical accuracy of the adjustment knobs. Maybe if the knobs where double the size I might have been able to dial it in a bit more, but according to PEMPro, I'm within 0.5 arc-minutes of being perfectly aligned. I found that any adjustment I try to do after this just takes me way beyond where I am trying to get.

I use the built in model in the Gemini unit and that usually gets my target to within the FOV of the CCD at 1260 mm focal length. I would then plate solve and right click on my intended target and tell the scope to point there after I have synchronized current position. I then check if there is a guide star available in the FOV of my OAG guider rinse and repeat till I have both the object in a pleasing position on main CCD and a guide star available. But with accurate pointing, I can frame the object from the beginning with the guide star in FOV on The Sky X or Starry Night and just slew directly to the right place. That's my logic behind considering modeling software.

The mount spends all the time in it's observatory and goes out for a weekend trip every couple of months.

#6 korborh

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Posted 04 February 2013 - 04:04 PM

If you are polar aligned to 0.5' of the pole, that is already overkill for all practical work.

#7 Raginar

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Posted 04 February 2013 - 08:04 PM

Hilmi,

Have you tried drift aligning? Just to see how accurate you are from an observational stand point? I always had a 'great' software alignment and I always wondered if I could do better via drift aligning.

#8 Hilmi

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Posted 05 February 2013 - 01:28 AM

I've always been confused by the instructions on how to manually drift align. Besides, I heard PEMPro does a great job on it's own and is pretty accurate

Edit: I use PEMPro to align.

#9 JMW

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Posted 05 February 2013 - 02:20 AM

I have great polar alignment but I don't have a pointing model currently with my AP900GTO. I just recalibrate on a bright star near my target on the same side as the meridian. The puts the target dead on. I usually then take a 1 to 5 minute image so I can see if I like how the subject is framed. I may want to rotate the camera also.

I use Alignmaster when I have to polar align. Only need to do this when my mount goes to star parties. Most of the time it is at home on a concrete pier.

#10 Raginar

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Posted 05 February 2013 - 10:16 AM

Himli,

Did you see the recent article labelled DARV? It explains the process very well. He says it's slightly different for a GEM; really the difference is what way you turn your knobs in reference to the motion seen with your camera.

I think you might be happy spending an hour or two trying to dial in with a drift alignment now that you're permanently mounted.






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