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  #1  
Old 03-08-2018, 10:22 AM
Jasp05 (Aaron)
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HEQ5Pro - Mount Performance & Imaging Scale

Hi guys,

Just chasing some opinions or confirmation on a few details.

My setup is as follows:

Mount: HEQ5PRO with Belt mod pier mounted.

Guiding setup: 50mm orion finderscope with ZWO ASI120mm guide camera.

Imaging Camera: Canon 1200D (unmodified)


So I'm looking to upgrade from widefield imaging with the DSLR to getting an 80mm refractor, or something like a Skywatcher 150mm F5, or a GSO 8" F5.


Now with the HEQ5, how accurate is the average persons tracking? (RMS values in arc/sec and peak to peak).

Previously my mount appeared quite bad. was around 1.3-1.5 arc/sec RMS. anything up to 4-5 arc/sec peaks.

After servicing the mount I'm getting very close to under 1arc/sec total RMS. (Dec axis is sitting around 0.5 - 0.8 RMS 90% of the time. Still got some work to do on the RA axis gear mesh as it's the weak link right now).


But based on the image scale of the above scopes with my imaging camera, they will be around 0.8 - 1.4 arc/sec pixel.

Does this mean my tracking will need to be within those limits for total RMS only? or peak to peak changes will also need to be kept under that arc/sec/pixel limit?


My understanding was that low RMS values basically meant you were going to end up with nice round stars.


But how does a peak to peak variation affect your image. (My mount currently moves 2 arc/sec peak to peak in RA but I think that's because I haven't adjusted the RA mesh properly. its a bit loose still.)

And how do you implement Periodic Error Correction while using ASCOM, EQMOD & PHD2? Or is it not necessary?

I would like to hear of other peoples setups and guiding results, and if my mount will be able to guide well enough to use a scope of 800-1000mm focal length. (I know the mount can handle these scopes, but its more I don't want to invest the money on an OTA until I know " I " can get the guiding within the required parameters to be able to use these scopes effectively for imaging.)

And with some other people's guiding results, it should hopefully give me some figures that I can aim to replicate in my mount. (At the moment I have no idea whats good. As my current imaging scale is about 3.5arc/sec pixel, so all my images have come out with decent stars regardless of the huge changes in peak to peak I was getting.)

Last edited by Jasp05; 03-08-2018 at 11:51 AM.
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Old 06-08-2018, 09:45 PM
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ChrisV (Chris)
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I'd probably go with the 80mm refractor. I've only been imaging for about a year now, so others more knowledgeable will probably correct me. I assume the tracking figures you mentioned are with just your camera on the mount as you don't have a scope? There's a weight issue. The 8" F5 newt is reasonably heavy and will be pushing the mount a bit more.

Also the 80mm refractor with a shorter focal length is easier to start with than the 8" with 1000mm focal length. I've got both an 80mm refractor and an 8" F5. I started imaging on the newt but found it a bit challenging. So reverted to the refractor (470mm focal length). It made it much easier to get acceptable pics. After a year I'm only just using the newt again. Also, none of that collimation fiddling. More time to process those beautiful images you'll get.
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Old 07-08-2018, 08:34 AM
Jasp05 (Aaron)
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Quote:
Originally Posted by ChrisV View Post
I'd probably go with the 80mm refractor. I've only been imaging for about a year now, so others more knowledgeable will probably correct me. I assume the tracking figures you mentioned are with just your camera on the mount as you don't have a scope? There's a weight issue. The 8" F5 newt is reasonably heavy and will be pushing the mount a bit more.

Also the 80mm refractor with a shorter focal length is easier to start with than the 8" with 1000mm focal length. I've got both an 80mm refractor and an 8" F5. I started imaging on the newt but found it a bit challenging. So reverted to the refractor (470mm focal length). It made it much easier to get acceptable pics. After a year I'm only just using the newt again. Also, none of that collimation fiddling. More time to process those beautiful images you'll get.
Thanks Chris,

So you think the lack of weight I've got on the mount may be contributing to my guiding issues? Never thought of that tbh but sounds like it may be a contributing factor. Its literally just a dslr and guidescope atm.

It does have a custom welded bracket to hold camera and guidescope which would add a kilo or so. but still the whole setup maybe 2.5kg worth..

I think I would like to start out with a small refractor, but due to budget constraints at this moment in time, a newt is much more within my means. (I have been stalking these forums for an ed80, and I have seen a few. Just haven't been able to convince the wife to let me throw an offer out yet )

What kind of guiding results are you getting with your heq5? If you link a guide log with your refractor and with your newt that would be much appreciated. (Or even just the guide RMS values and peak to peak).
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Old 07-08-2018, 10:52 AM
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ChrisV (Chris)
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I haven't got an HEQ5. Just a CGEM and a modded EQ5. So hopefully someone will chime in who knows about HEQ5s. If you don't get a response soon maybe post in the beginners astrophotography section - there's a few HEQ5 users there, and some use refractors and others newts.

I understand you concern about cost. You can get an imaging newt real cheap. I got my GSO here second hand.
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Old 07-08-2018, 11:29 AM
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Here is my guide log from the other night, as an example of a HEQ5Pro that is at the upper limit. The payload on this is:
8" f6 Newt,
Meade DSI Pro as a guide cam attached to the finder scope,
Canon 1100D DSLR (Thank goodness it's a plastic body, so not as much weight. ).

I don't stress too much about the weight it's carrying. It seems to do OK in the guiding department, although I haven't looked too closely at the numbers. From memory, the total RMS the other night was running around 0.8". I have no idea if that is good or bad.

I was running 2 minute exposures and the stars looked round. I tried a 5 minute exposure to see how far I could push it, but the stars were a little elongated on that one.

cheers,
Andrew
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File Type: txt HEQ5Pro_GuideLog.txt (93.0 KB, 19 views)

Last edited by middy; 07-08-2018 at 12:11 PM.
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Old 09-08-2018, 07:58 PM
Jasp05 (Aaron)
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Thanks for that guidelog middy. Your numbers are similar to mine in regards to the RMS values. (yours are still slightly better than mine). but one place you do way better than me is in peak to peak values. Yours is consistently under 2". Where as mine can peak to 3 or 4 at random. (could be loads of issues that cause it.)

but at least I have a real guide log that I know produces good results that i can try replicate going forward.
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Old 10-08-2018, 03:22 PM
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OzEclipse (Joe Cali)
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Jasp

My mate Tommy Lim from Malaysia just posted this guiding log on a facebook group.

https://www.facebook.com/photo.php?f...&theater&ifg=1

Joe
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  #8  
Old 10-08-2018, 07:04 PM
Jasp05 (Aaron)
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This is my guide log from last night. Much Much better than what I have been getting prior to the mount rebuild.

Still spikes too high for my liking. Would like to get them within 1-1.5" rather than the 2 - 2.5" currently.

Will try and figure out what causes those spikes, but if anyone has any ideas I'm listening.

What would you consider to be best case scenario for guiding on an HEQ5pro.

I've seen one guy after hypertuning his mount get the guiding to around 0.4" RMS on RA and DEC with a total error of 0.56" RMS.

I'm going to say that's probably a bit of luck with the components in the mount and as good as you could expect from this mount?
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  #9  
Old 17-08-2018, 02:13 PM
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cometcatcher (Kevin)
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I have a HEQ5 Pro. You really don't want to know what I do with it. 8" F5 with guiding gear is okay as long as it's sheltered from the wind, but you may need another counterweight.
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Old 17-08-2018, 03:14 PM
Imme (Jon)
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It seems really jumpy to me, back and forth a lot above and below the line.
Am I right in saying your exposures were 2 seconds? Have you tried longer? It could be you're just chasing the seeing.

Remember this......people who don't guide but have a good polar alignment can run 45 second exposures without star trailing. Do you really need to take an exposure/adjust your tracking every 2 seconds?
If I was you I'd be pushing my exposures out to 4 seconds and see what happens. A few nights ago I tested this theory....I normally do 4 second exposures but pushed it out to 8 seconds and the guiding figures improved. When I pulled it down to 2 seconds my figures were significantly worse.

Regardless, 1.31 isn't hell on earth!
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