The Esprit scope set up in the back yard ready for an evening of Bortle 8+ Astrophotography.
The Esprit scope set up in the back yard ready for an evening of Bortle 8+ Astrophotography.
I did considerable research before deciding on this telescope. The optical quality and mechanical build are both extremely well made. I haven't been able to see any purple fringes around bright objects, which was my biggest issue with the Megrez 80. Even objects that are a bit small for this 550mm focal length, like Thor's Helmet and the Owl planetary nebula show up with good detail. With this telescope, the upgraded G11 mount and an appropriate filter I have been amazed with the quality of images from my Bortle 8 skies.
Long before I retired I was planning on getting into astrophotography when the time came. The technology was moving quickly so I held off deciding on the specific camera. When the time came ZWO had just released the ASIAir Plus which allows me to remote control the setup as long as I use their imaging and guiding cameras. I went that route and you can see the red imaging and guiding camera in the photo above. The ASIAir Plus is just able to be seen behind the finder telescope. The ZWO cameras with the Esprit 100 and the Losmandy mount all being controlled by the ASIAir Plus has been fun and productive.
Unlike the Megrez 80, the Esprit 100 has grub holes for attaching an electronic focuser. Additionally, a EAF bracket is made for the Esprit. Having experience with many brackets now I designed my own and 3D printed it.
I repurposed the EAF from the Megrez 80 for the Esprit 100 since it has superior optics and will be the imaging telescope.
I checked the backlash on my EAF attached to the Esprit and found it to be 33 steps. From the ASIAir app write down the current values. I did this by setting the course step to 200 and the fine step to 1. Then using course steps I pressed the clockwise (down arrow) button once. This puts tension on the gears in the clockwise direction. Now mark the fine focuser knob with a thin piece of tape straight up (12 o'clock position). To test for backlash stay in course steps and press the down arrow again one time. Then press up arrow (counterclockwise) course steps one time. Did the tape end up back at the 12 o'clock position? If not you need to add a backlash value.
To find the backlash step amount press the course down arrow clockwise again to get tension on the gears. Now peel off and move the tape back to the 12 o'clock position. Next, switch to fine steps and carefully watch the tape as you press the counterclockwise button until you see the tape move. The number of times that you pressed the counterclockwise button is your backlash value. Most of the AEFs that I have seen are in the 30-35 step backlash range. Now try the corse backlash test again (clockwise, reset tape, clockwise and counterclockwise) and see if the tape ends back in the 12 o'clock position. If it's short or long tweak the backlash value a bit. Don't forget to set the fine and corse values back to where they were before this test.
The Esprit doesn't come with a top handle or mounting plate. I knew that I needed the latter. I ended up using some 1/2" black Delrin that a friend gave me. Delrin cuts and machines (drills, taps, routes, etc.) nicely with standard wood tools. It also holds up well in the heat. The edges of the plate were sanded and the corners were rounded over slightly with 400 grit.
The Williams Optics Uniguide guide scope is almost perfectly aligned with the main scope when images from each are compared. This alignment isn't necessary for guiding but it's nice since the Uniguide doesn't have a way to change alignment.
On the bottom of the tube rings I'm using a 15" Adam D-plate that I picked up used at an astronomy swap-meet and that dictated the size and hole spacing for the top mounting plate.
The 3D printed template that I made to make the holes that would align with the threads on the tube rings. Move your mouse over the photo to highlight the template holes that were used on the plate.
Here's the Delrin cut out, drilled and tapped. Later I decided to replace the small finder scope shoe with a larger and longer 3D printed version. It needed two more holes drilled and tapped but it also covered up the two that were no longer in use. The recessed bolts are stainless steel.
Here's the autoguider saddle (red) and the ASIAir saddle (aluminum) mounted on the Delrin plate. The ASIAir is mounted vertically. I used heat set inserts on the 3D part instead of tapping it directly. The soldering iron is used to heat the inserts and then they are embedded (pushed into) in the plastic. The nice thing about printing my part is that I was able to make it the exact length that I wanted.
This is the imaging train used for astrophotography. It requires 55mm of back focus. The field flattener came with the telescope and the other parts came with the ZWO components. The EAF (Electronic Automatic Focuser) is attached to the telescope's focuser with a 3D printed bracket that works well. This is by far the best imaging telescope that I have used and at f/5.5 its much faster than the C11 and better quality than the Megrez. This makes sense since the Megrez's glass has an Abbe number of about 59 and the Esprit 100 has an Abbe number of 94.94. The higher Abbe number the closer that all of the visible/imaging wavelengths of light refract to the same focus point.
