Last updated on February 28th, 2022 at 02:57 am

After tinkering with the SkyWatcher AZ-GTi to learn some of the workflows and tooling needed needed perform astrophotography this clearly demonstrated this mount would not work for any long imaging collection sequences. Skywatcher clearly claims this mount is not designed for astrophotography (AP) but I was trying to reuse my stargazing equipment as much as possible to avoid the upfront costs of jumping into AP. I needed to learn as much as possible before really making heavy investments. This mount has served that purpose and I have figured out how to automate a lot of the setup and data collection with Astroberry, EKOS, and kStars. I love this mount but it has reached its limit and I need to move on to a different mount to be able to look deeper into the cosmos. It will be nice to have two mounts so one can be used to stargaze while the other is doing its thing throughout the night.

Budget

The forums say the mount is the most important part of the astrophotography setup so make sure you don’t spare any expense on the mount. I would consider myself a hobbyist and not an avid AP expert so I cannot afford to invest 3, 5, or even 10 grand into a mount. The budget for my mount is around $750-$1500 and if I can find in used from Astromart or Cloudy Nights Classifieds even better.

Equipment Candidates

• SkyWatcher HEQ5 Pro
• Orion Sirius EQ-G (Basically the same internals as HEQ5)
• Skywatcher EQ6-R
• Orion Atlas EQ-G
• Celestron AVX
• Losmandy G8

Mounts such as Paramount, Pierro Astro, Astro Physics, Takahashi too name a few are just too far outside of my price point. I don’t know a lot about the Vixen mounts but those might have been in the mix. Frankly I don’t have the greatest skies Bortle 6/7 so the extra precision these instruments provide would be wasted as the “Seeing” component in Full Width Half Modulation (FWHM) of stars more than likely my limiter. I use guided astrophotography in my setup which also helps to negate some of the gap between these higher end systems.

Selection Process

All the mounts listed above are capable of sub arc second accuracy with a guide scope. Their periodic error is what is going to be the selling point for me.

The minimum payload of the mounts above are around 30lbs so this will limit the AP payload weight to around at most 22lbs. This will max out with a 140mm refactor or a 9″ Cassegrain to fit in these parameters. To be honest, this is probably the max I can envision for myself since I don’t have a dedicated platform for my gear so it has to be setup every night and taken down. The best gear is gear you will use and I am not going to lug out 100 lbs of equipment every night!

I ultimately went with the HEQ5 Pro. I found this mount is able to be modified with a belt drive to reduce period error farther than the manufacturer specs. First Light Optics will perform this mod and also warranty for 2 years which would otherwise be voided by SkyWatcher. The Rowan mod will keep the gear ratio the same so the factory controller can still be used. This was shipped to my door for $1141 which is cheaper than the US resellers (No VAT) new unmodified price so I pulled the trigger.

The SkyWatcher EQ6-R is belt driven from the factory and I almost pulled the trigger but it appears to be real beast to move around so I went with its little brother.

I poked through some forums and read people having horror stories with the AVX so I stayed away.

I was able to find a used Losmandy G8 but the Gemini system looked a little antiquated. It might be rock solid in mechanical specs but I wanted USB cables not serial DB9 and software drivers headaches on my hand.

I decided to stick with SkyWatcher mainly because my experience with the AZ-GTi has been good with EQMOD, ASCOM, and INDI driver support with EKOS and the belt mod hits the PE sweet spot for my budget.

Tech Specs

DarkFrameOptics has some performance data on mounts and tuning they perform. They make money by increasing mount performance so I expect these numbers to be slightly understated since they are more than likely using worst case RMS numbers from multiple test points for the factory and user mods but it is a nice reference table.

Lambermont has a collection of data on mount performance. It is slightly dated but is a great collection of performance numbers on many mounts

Astroforumspace has another table of reported PE data for various mounts

Rowan Belt Mod Performance Comparison

Summary

The HEQ5 with Rowan mod will allow me to get sub arc-second accuracy (with guiding) with an AP payload maxed out at 22lbs. This hits all my numbers and is within budget. Check!

Update 2/28/2022: Measured Performance

My typical night I can achieve between 0.7 to 0.8 arc second RMS accuracy throughout the imaging session. I currently run equipment between 10-15 pounds. I am playing around with different guiding parameters which include multiple star guiding and initial testing looks like this will get me right around 0.4 to 0.5 RMS.