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rnobleeddy

EQ6 Rowan belt mod - worth it?

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I picked up a second hand older EQ6 that I got running with EQMOD. Guided for about 2 hours tonight (before clouds) with RMS error of around 0.8". Assuming that holds over more sessions, I'm wondering if I ought to bother with the Rowan belt mod or just leave it as is? 

Just wondering if anyone with experience of the upgrade?

It's also worth pointing out that tonight's guiding had an RMS error of ~0.15 pixels with my current guide scope and guide camera. Is that likely to be a limiting factor?

I'm happy to fit the upgrade, so the only negative is the cost.

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I've belt modded my NEQ6 and seen a slight improvement but I doubt you'll see much if you are already at 0.8"RMS. Maybe 0.1" if you're lucky but seeing, balance, PA etc. will affect things more than that. Belt mod def helps with backlash and runs a bit quieter.

I've also added zero backlash mod also from Rowan but yet to get the best from that (still needs tinkering). And I have replaced bearings, hypertuned, and upgraded other components.

Worth saying I am really pushing the weight on my mount (over 20kg of imaging and 20kg of counterweight) and am seeing typically tracking between 0.6" and 1" RMS.

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Recently I had belt modded my HEQ5-PRO and last night i gave it a full run and i was absolutely stunned to say the least about the guiding results I achieved. I was left wondering if its even too good to be true! 
Below are Before and After images of guiding.

guiding on 30042020-2.JPG

afterbeltmod4.jpg

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12 minutes ago, astrosathya said:

Recently I had belt modded my HEQ5-PRO and last night i gave it a full run and i was absolutely stunned to say the least about the guiding results I achieved. I was left wondering if its even too good to be true! 
Below are Before and After images of guiding.

guiding on 30042020-2.JPG

afterbeltmod4.jpg

Something funny going on with these results. Error in pixels about the same top and bottom (0.27-0.24). Looks like something else has changed?

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Just now, mbalkham said:

Something funny going on with these results. Error in pixels about the same top and bottom (0.27-0.24). Looks like something else has changed?

the parameters seem to be almost the same. the guiding exposure was 3s to beat the seeing which is usually 1.5".  I am myself finding it hard to digest. :)

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Just now, astrosathya said:

the parameters seem to be almost the same. the guiding exposure was 3s to beat the seeing which is usually 1.5".  I am myself finding it hard to digest. :)

Suggest you look at pixel resolution. Maybe the guidescope focal length is incorrect in one set of guiding. Iwould think this amount of change is unlikely to be down to the belt mod.

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1 minute ago, mbalkham said:

Suggest you look at pixel resolution. Maybe the guidescope focal length is incorrect in one set of guiding. Iwould think this amount of change is unlikely to be down to the belt mod.

i'll recheck all the internal settings. I actually did not change any including guidescope params. Mine is the standard finder guider. I'll check the next time i get clear skies. :)

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Can anyone with a beltmod on an HEQ5/EQ6 let me know if it improved dither times?

I've gone for RA + DEC dithering. This seems to work well in that the mount is stable, however, dithering takes about 50s to complete. This isn't the end of the world if I'm exposing for 300s as it's a lot faster than darks, but it'd clearly be better not to lose so much time. 

My guess is that the backlash in the DEC axis means it takes a long time to move and settle down, but the only other experience I have was an EQ5 where I set it to dither in RA only.

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32 minutes ago, rnobleeddy said:

Can anyone with a beltmod on an HEQ5/EQ6 let me know if it improved dither times?

I've gone for RA + DEC dithering. This seems to work well in that the mount is stable, however, dithering takes about 50s to complete. This isn't the end of the world if I'm exposing for 300s as it's a lot faster than darks, but it'd clearly be better not to lose so much time. 

My guess is that the backlash in the DEC axis means it takes a long time to move and settle down, but the only other experience I have was an EQ5 where I set it to dither in RA only.

My belt modded NEQ6 dithers quickly (I haven't measured but I'd guess maybe less than 10 seconds). I'm not sure it's down to the belt though. Sounds like some other setting/issue? I have settle of 1s set after the dither. In the attached image I have taken 6 120s images and 6 dithers in about 12.5 mins so def less than your 50s dithers maybe 5-10s per dither.

Have you changed the amount of dither from the defaults? Mine are just default values (I forget what they are and aren't in front of that computer at the moment). I guess backlash could mean it takes longer to move the required amount of dither but it's moving a number of (or fraction of) a pixel so not like a lot of movement needs to occur. 

Are you running the guiding and dithering over a wifi connection or locally? If it's waiting to confirm receive info to confirm the dither movement it might take a little longer? 

20200930_213151.jpg

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2 minutes ago, mbalkham said:

My belt modded NEQ6 dithers quickly (I haven't measured but I'd guess maybe less than 10 seconds). I'm not sure it's down to the belt though. Sounds like some other setting/issue? I have settle of 1s set after the dither. In the attached image I have taken 6 120s images and 6 dithers in about 12.5 mins so def less than your 50s dithers maybe 5-10s per dither.

Have you changed the amount of dither from the defaults? Mine are just default values (I forget what they are and aren't in front of that computer at the moment). I guess backlash could mean it takes longer to move the required amount of dither but it's moving a number of (or fraction of) a pixel so not like a lot of movement needs to occur. 

Are you running the guiding and dithering over a wifi connection or locally? If it's waiting to confirm receive info to confirm the dither movement it might take a little longer? 

20200930_213151.jpg

Good point about the settings. I have a 10 pixel dither set in EKOS and a 2x scale in PHD2, so perhaps that's 20 pixels? I was aiming for a large dither because I use a relatively noisy Canon DSLR and a large dither was recommended to work around structured noise. I also have a 5s settle time for some reason.

That said, I imagine the recommendation to use a large dither was in terms of main camera pixels rather than guide camera pixels, so I'll do some maths. 

I'm also using PHD2 , primarily because I haven't had enough time to try the EKOS guider, but I guess this might also save time going back and forth.

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