Askar FRA400 version 1.0: A New Portable Astrophotography Platform
Dates: June 2, 2021 - June 24, 2021
Left Side of the FPA400 Platform showing the Powerbox Advanced.
Right side of the FPA400 Platform, showing the focus motor.
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A Portable Rig
I have been having a lot of success using my first two astrophotography platforms - but they are very large and heavy. Not a big deal, I guess - especially given Covid-19 lockdowns - there was no place else to go!
But as vaccinations became available, the option to travel and do some car trips are now a possibility. More to the point, we became grandparents for the first time, and our son and Daughter-in-Law live in North Carolina. We will now travel down there more often - forcing me to leave my scopes behind. I suggested to my wife that we only travel/visit during full moons, and the response to this was - shall we say - not positive. I explained that I only have 12 times a year with no moon, and many of those are clouded over during the late Fall and Winter months - I really can’t miss them. She responded, “Do what you got to do, but we are going!”
So - what do I got to do? Well….. I just need a telescope platform that is lighter and more portable - Right? That would open up some interesting possibilities. So I went about creating a set of requirements.
The mount itself had to be as light as possible
It had to be able to handle a reasonable payload - perhaps 12 lbs
It had to breakdown easily for travel
A smaller form factor scope with a shorter focal length but not too wide
A crisp field to the very edge.
Enabled for Narrowband imaging - so I can operate even under light pollution
The Scope
I started with the scope. A lot of small scopes are APO triplets, but you really need a field flattener/reducer to get a good image. So a 350mm focal length drops to 250mm - too short for what I wanted. Then there was the supply problem - Astro gear everywhere is very hard to find. After doing some research I found the Askar FRA400 astrograph. This is a brand of Sharpstar, and I have been impressed with their offerings. This was a 72mm diameter with a focal length of 400mm - f/5.6 - perfect! It was a Quintuplet-designed Astrograph, the field should be flat without adding a reducer/flattener - even more perfect! AgenaAstro.com had one- Wahooo! Order placed!
I was very pleased with the scope when it arrived. Excellent machining, great focuser, crisp visual images to the edge of the field. This should work out nicely!
The Mount
Now - how about the mount? I had excellent luck with my IOptron mounts, so I looked at their lighter-weight offerings. The best sounded like the new CEM 26. 19.5 lbs photographic load capability, 10 lbs head, lightweight 1.5” tripod. Portable? The head breaks down into a 14”x14” hard case. The tripod also breaks down pretty small. Price - very reasonable. The Problem - it was just barely released, and no one had them in stock - NO ONE. A few were trickling out - I placed an order and was prepared to wait. Then I got to thinking. AgenaAstro.com seemed to be getting more things in stock than others - but they did not even have this mount on their website. Hmmmm. So I sent them an email - “Hey - are you going to carry this? If so, when do you think you might see one?”. The Reply: “Jeez - we just got one at the warehouse, but the website guys have not had a chance to add it yet.”. Wahooo! I claimed it, and the next day, it was added to the website so I could order it. I was pretty psyched about this!
When the mount arrived, I tested it out and was a little disappointed - it has 5 seconds of backlash on the DEC axis, and the tracking was not good. First, I dug into all of the documentation for PHD2 (there is a lot of helpful stuff) and discovered what I had to do to get a decent calibration with that much backlash. Then I learned how to change the guiding algorithms when dealing with that much backlash. With this combination, I got reasonable guiding, and the first image showed nice round star images! I then contacted IOptron to ask about the backlash. They indicated that such backlash was caused by having too little tension on the geared drive belt. They provided a simplified set of instructions - with images - on adjusting to adjust this tension. I recently did this and found that my backlash had dropped to less than 3 seconds - a level that PHD2 can deal with, and test tracking has shown significant improvement. I am now in business!
Guiding
So how was I going to handle guiding? I could use an Off-Axis Guider. This would have kept the rig small and portable, but it would also introduce an element of cost and perhaps even some use complexity as guide star selection can be a bit more limited with AN OAG setup. However, happen to have a William Optics 50mm Guide scope and unused rings, along with an extra ZWO ASI290MM-Mini guide camera. Even though it added to the size of the overall package, I decided, in the end, to go with a larger package and minimize my investment by using the gear I already had. I have been pretty happy with this combination.
Power and USB Distribution
On my other rigs, I used a USB hub to distribute USB connections to various devices and a Pegasus Astro Powerbox to handle power distribution. However, on this small rig, I did not really have the real estate to mount two such devices. So I ended up getting a Pegasus Powerbox Advanced. This provides for power distribution, USB distribution, an environmental sensor, and power and control circuitry for two dew straps. This was just the ticket - it fit well on the OTA and kept connections short and cable management fairly straightforward.
Camera
I have upgraded my camera on the Astro-Physics 130 platform, thus freeing the ZWO ASI1600MM-Pro that I was using there for use on this rig. The camera/scope combination is slightly under-sampled, but I thought I could compensate for that by using Drizzle processing. I also liked having a mono camera on this rig as it gives me flexibility and a greater ability to deal with light pollution should I need that. The ZWO filter wheel holds Astronomiks filters that are not as angle-dependent as some filters so that the f5.5 config would not be an issue.
Focus Motor
I choose the new 5v version of the popular ZWO EAF focus motor. This is a small package, and since it is powered by a USB connection rather than a 12v supply, it eliminates one cable that has to be run. I have gotten very good results with this config, and the mounting worked out just about perfectly.
The Final Configuration:
Scope: Askar FRA400 72mm f/5. 6 Quintuplet Air-Spaced Astrograph
Focus Motor: ZWO EAF 5V
Guide Scope: William Optics 50mm guide scope
Mount: IOptron CEM 26
Tripod: IOptron 1.5” Tripod
Camera: ZWO ASI1600MM-Pro
Filter Wheel: ZWO EFW 1.25x8
Filters: ZWO 1.25” LRGB Gen II, Astonomiks 6nm Ha, OIII,SII
Guide Camera: ZWO ASI290MM-Mini
Dew Strips: Dew-Not Heater strips for Main and Guide Scopes
Power Dist: Pegasus Astro Powerbox Advanced
USB Dist: Pegasus Astro Powerbox Advanced
Polar Alignment Cam Iplolar
