Help with autoguiding and mount setup !

[Tycho65]

Hi Astronomy friends,

I have reached a crossroads in this astronomy hobby. I have a Skywatcher EQ3 Pro Synscan mount with a Starwave 70mm ED refractor. I have tested autoguiding on PhD2 with a ZWO120mm-S guide camera on an Altair 60mm guide scope. I found that autoguiding was difficult as I had to balance the scope on my mount which was only EQ3 Pro. I had to find the necessary dovetail bar to mount on my EQ mount. I found attaching the guidescope to the telescope RDF bracket caused too much rotational loading on the system. After some time I found a small dovetail bar to attach the guidescope to the telescope (I had to buy telescope rings, adapt the rings as it would not fit tightly using some felt to pad it); further delay came from unable to focus the guide camera in the guidescope !! Then my mount failed and I had to get a replacement motor controller....all this took time and money. Then my work and other committments lead to many months of no astronomy.
Then I have decided to come back to this hobby during the lockdown in the UK. I then started practice autoguiding with a ZWO120mm-S and ST-4 connection (USB cable from camera to laptop, and ST-4 cable to the mount autoguider port). I found guiding to be around 1 to 1.3 arc RMS if I can remember. I thought this was not too bad, but the PhD2 guiding showed wild fluctuations of the RA graph, I don't really know how to interpret it all. I suppose I have to study PhD2 ?? in some depth. I started reading all the articles and instructions on PhD2 and autoguiding. Then I decided to go the EqMOD route, and now I have managed to control my mount I think using EqMod and the EqDir cable (and dispense with the Handcontroller)!
I now find my telescope and guidescope (with tube rings on scope and guidescope) is about 4 kg (without cameras or eyepiece in place). It feels heavy on my mount. Is this too much to put on the Eq3 ? I am wondering, do I upgrade to a HEQ5 Pro (with Rowan belt) or EQ6-R Pro, or better ? I suppose that depends on my budget I guess...

I think my 3rd imaging session with the EQ3 (Feb 15th 2018) actually yielded fair results, my problem was getting good flats and enough lights and I had a light pollution CLS filter on the Canon 100D camera (unmodified). I tested different objects with only about 30mins integration times. Anyhow, with my better image integration and processing (still learning !!!), my original data was not bad. I had the Horsehead nebula with reasonable Ha in the image !! I just have to muster some enthusiasm to setup on a dark night to manage HOURS, HOURS of data, learn autoguiding, drift alignment and maybe I will get a better image.

Some advice on mount upgrade or any advice would be really welcome ! (photo of the ED70 and guidescope attached).

Thanks.
Magnus
Then

[UlteriorModem]

I dont understand. Using the ST4 port bypasses any and all 'control' from the laptop.

[Tycho65]

I dont understand. Using the ST4 port bypasses any and all 'control' from the laptop.

Hi,
I have tried the ST4 port before, but now I am going to use Eqmod via a Eqdir cable.
I wondered if OTA and guidescope with tube rings is too heavy for my EQ3 mount.

Thanks
Magnus

[UlteriorModem]

From what I read about the EQ3 it's rated capacity is 5.5 kg or around 12 lbs.

A 'rule of thumb' for accessing a mount's capacity for AP is not to exceed 50-60 percent of the mounts listed capacity. So 8 lbs would be considered the 'maximum' for that mount.

So add up the weight of your equipment and you will have the answer. Unfortunately yes I believe it is too much weight on the EQ3.

[Tycho65]

Thanks Tom,
Looks like I will have to upgrade my mount to something better suited to AP.

[SkyHiker]

There is nothing wrong with ST-4 autoguiding. It is a convenient way to separate tracking from guiding. So you can use EQMod for goto and ST-4 for auto-guiding. If you like to combine it through EQMod, nothing wrong with that either. Your main problem is the mount. Upgrading will solve a lot of problems. If you search on SGL you will find several people who used an EQ3 mount for AP quite successfully so it can be done. I have no doubt it will be frustrating. Also the EQ3 generally has no ball bearings so it will have stiction.

[Tycho65]

Thanks Henk!
I did not know there was no ball bearings in EQ3. There is certainly lots of "stiction" or is that backlash ?

I think my setup with the tube rings on my OTA makes everything too heavy. That is quite a lot of heavy metal there in those tube rings !!
I got 1 to 1.5 arc second RMS on autoguiding using ST4 with the ASI120mm-S camera on the 60mm guidescope. I might go through the graphs and data to see if I can understand it. I still have to read the manual on PhD2 !!

I think I will upgrade the mount, its too much frustrations, and could take me years to control with the number of clear nights we get in the UK.
Now its deciding what mount to get. That depends on if I can get back into work, as I would like to combine my night time astronomy and my daytime solar Halpha interests.

Magnus

[Juno16]

“Stiction” is static friction. The drive motors have to overcome the stiction to move the mount in declination or right ascension. Stiction also makes it difficult to balance. Ball bearings greatly reduce the resistance to movement.

1.0 -1.5 arc SEC total rms error isn’t horrible (I have a Celestron AVX). How do your stars look?

Upgrading the mount would probably be a good idea anyway especially if it is in your budget.

[UlteriorModem]

I got 1 to 1.5 arc second RMS

That's not too bad considering the load on the mount.