Takahashi Epsilon Setup

I thought I was done with wide field telescopes forever but when an opportunity came to host another remote telescope came about I couldn’t say no. I already had a lot of items on hand from when I sold the ED127 last November. These items include:
QHY268m
Astronomik Deep Sky LRGB filters
Chroma 3nm SHO filters
ZWO 30mm mini guider, ASI120mm camera
iOptron GEM45
Pegasus Powerbox Advanced

As much as I would love a second ONTC10, I didn’t want to have to buy a larger mount for it. Ok, wide field it is. I looked at a few 70-90mm refractors and while a couple looked ok I just wasn’t sold. Plus no diffraction spikes. Hard pass on that. I guess we are looking into small newts then. I’ve been very pleased with my ONTC10 and they do make a 150mm version but thats a little larger than I’d want to put on a gem45 in open air and I’d like something a little faster. Without getting too deep into the weeds that narrows things down to 4 systems: Celestron RASA, Sharpstar HNT, and Takahashi Epsilon.

Since this setup is going to be mono camera based the RASA is out for obvious reasons. Also, I used to have an EdgeHD 8 with Hyperstar and that isn’t an experience I’d like to repeat. The Sharpstar is basically an Epsilon clone and while I know they make pretty decent refractors, I am very weary of cheap Newts (and you should be to). So that leaves the Epsilon. Though not a scope I ever desired I have always been impressed with the quality of images it can crank out. The E130 checks all the boxes. It’s small, fast, mechanically sound (mostly), and produces a very flat field wide field of view. A buddy of mine picked up an E130 a few months back and loves it. Another buddy of mine picked up an E130 and loved it so much be ordered a second one to place them in tandem. I took this as a sign from the astro gods and ordered one. Fortunately a shop in state had a single E130 in stock so it was at my front door within 3 days.

Epsilon scopes ship as just the OTA, mirrors, focuser, and visual adapter. This means I needed to order tube rings and dovetails on my own which I did at the same time I ordered the scope. There are quite a few options available but I went with Rouz Astro rings, dovetails, and sidewinder because I am familiar with him from the IG astro community and he makes quality products. In addition to Rouz’s mounting hardware I also ordered an:
ASG tilt cage
Askar adjustable spacer
ZWO EAF
Deep Sky Dad FP1 flip flat
Pegasus Uranus
Takahashi collimating tube + eyepiece

Saddle Upgrade

I also ended up purchasing an aftermarket ADM saddle for the GEM45 because the gen 1 saddle is less than fun to work with. I installed the ADM saddle on both my EQ6 mounts in the past and I have missed those saddles dearly since selling the mounts. Here’s a quick before and after. As you can see the stock saddle uses 2 independent clamps that are flimsy and hard to tighten by hand. They do have hex heads so that you can use a hex key to really crank them down but who wants to have to keep track of another hex key? The ADM saddle on the other hand has a much more refined clamping system that doesn’t require any tools to operate. In iOptron’s defense the gen 2 GEM45 has a much improved saddle. I had their gen 2 GEM45 but sold it last year because I didn’t need it anymore. It still isn’t as good as the ADM though.

Secondary Mirror Heater

One thing I wanted to make sure I did was to provide the secondary mirror with some dew protection. A friend of mine told me about a CN post he found where someone used a ZWO camera heater as a secondary heater. I happened to have one of those sitting in a drawer so I followed suit. It was as easy as taking out the secondary, putting the heater on, and overing it with some felt wrap that I cut the roughly match the shape of the secondary housing. After remounting the secondary I routed the cable along one of the secondary supports and out of the tube where it plugs into a DC 5.5 x 2.1 male to RCA male cable enabling it to be plugged into one of the dew ports on the Powerbox Advanced.

Autofocus

The EAF mounted with its stock bracket. I did need to get a 5x8x25mm flex coupler for the EAF to fit the stock focuser shaft.

Fully Assembled

Here is the rig fully assembled. Pretty standard stuff. The Powerbox is mounted on the back of the top rail using one of Rouz’s clamp mounts. Over my 4 years of astro I have acquired so many cables that I didn’t want to pay for custom length cables. I ended up just bundling any slack and using a buckle strap to hug the bundles to the OTA. It doesn’t look good but its functional. I’m not one of those Astrophotographers that needs their rigs to be picture perfect. The only thing that needs to be pretty is the data. With the PBA being mounting on the scope itself the only cables leaving the tube are the mount usb, mount power, and usb to the mini PC.

The Rouz sidewinder gives 4 diagonally placed mounting points which I used to mount the guider and the Uranus. The other 2 mounting points on the opposite side are left empty to give the flip flat room to come to rest against the tube when in the open position.

I had to carve out a slot in the flip flat bracket to fit the secondary heater cable but this was easy to do with a round file thats roughly the size of the cable.

I also added a dew strap around the back of the tube for good measure. I double it will ever really be needed but with a remote scope its better to be prepared. That heater is left turned off in the Powerbox software in the meantime.

The only thing I’m not totally satisfied with in terms of hardware is the bottom dovetail. As you can see its not long enough to make full contact with the saddle. Given the ADM saddle has a big of an offset I may be able to revers it to fix this issue but if that fails I’ll just order a longer dovetail.

Collimation

This section could be a post all by itself. As a matter of fact I wrote an entire post on collimating the scope which you can read on my blog HERE, on Astrobin HERE, or on Cloudy Nights HERE.

Long story short the Tak tool isn’t great so I ordered an OCAL v3 and with it get extremely good collimation with minimal effort. Having a camera that doesn’t move and can be zoomed in means you are able to achieve a level of accuracy that just isn’t possible with the naked eye unless you’re using an autocollimator. And while autocollimators are great I just am not a fan of having to look down the drawtube during collimation. Here’s a photo of what good collimation looks like on an Epsilon using the OCAL.

Tilt Adjustments

With collimation squared away it was time for the final step. Fixing the sensor tilt. I knew from use on the ED127 that the camera had some tile and that it would be much more pronounced on a scope as fast as the Epsilon. With the ASG cage and Hocus Focus NINA plugin I set out to fix that while hopefully retaining my sanity. Fortunately ASG has numerous Youtube videos showing the whole process. I spent one night getting familiar with the tilt cage and setting up Hocus Focus. The next night was spent tuning the tilt. Once I knew what I was doing the procedure only took about an hour. I was able to get the tilt down from 11% to 3% which is effectively no tilt. To improve on this would take a motorized tilt cage but I don’t feel its necessary As you can see from the ASTAP tilt inspector below I have a consistent HFD across the entire field which means round well corrected stars all the way to the edge of the frame.

I would like to note that it is important to make sure your collimation is actually good before attempting to adjust tilt because imperfect collimation effects your corner and will cause inaccurate tilt readings. For example, my tilt adjustments were done before I had the OCAL so collimation was done with the Tak tool. At the end of the tilt adjustment I was getting a tilt reading of 8%. Not bad. Once I collimated with the OCAL and the mirrors were better inline that dropped to 3%. Your field needs to be well corrected BEFORE adjusting any tilt.

Conclusion & First Light

All things said and done this scope wasn’t nearly as painful to configure as the many online discussions of Epsilons would have you believe. In fact this was one of the easiest time I’ve ever had getting a scope ready for imaging. Part of that is surely the fact that I am a more experienced imager now but a big part has to do with dispelling the myth that these scopes are difficult to collimate and to fix tilt. Like with any other telescope nothing is difficult when you use the correct tools and methods. I’m going to call the scope done for now but there is a chance I may upgrade the focuser to an Optec Leo some time in the distant future.

During the 2 nights I spent working on the tilt I noticed Cygnus finally late into the night so I figured why not point at something bright and see what happens. I ended up doing 2 short sessions on the Crescent Nebula gathering 5 hours of Ha and another 5 of Oiii. I was quite impressed with the quality of the resulting imagine given the short integration time and the fact that the data was gathered from my bright b7 backyard. As far as first light images go. I also took the scope into the field for some dark sky imagine where I gathered the data for my second image with the E130 but I’m not going the share that just yet. Here’s my first light of the Crescent Nebula as well as some random shots from 2 of my dark sites.