This is well overdue and I owe this to Explore Scientific.
We can sum it up to 3 words: Incredible. Customer. Service. Michelle Rodriguez @ Scientific Explore deserves an award, along with all of the team and techs. There, I said it. (Some of you may recall this awesome chain of events.) Am I going to review this scope over-enthusiastically because of my superb experience as a customer ? Maybe I will. But let’s just say I had 18 months to test it out thoroughly and great products are often backed with great customer service and employees who believe in the products they are selling. Shi**y companies and products always have shi**y client care or maybe they just become that bad after hours and hours of dealing with complaints over the phone. It must rub on you. But that discussion is for another time. Moving on to this Apo. This review covers its use for astrophotography, as I almost never do visual observation.
Part un: THE LOOKS
Let’s just say it’s badass. Yes, a telescope can be qualified as ”badass” as it was rightfully mistaken for a weapon of mass destruction at the borders. All black shiny carbon fiber. It makes me feel less geeky and more testosterone packed. When I say I take pictures of the Universe as a hobby, I now say it flexing and screaming with veins popping on my forehead.
It comes in a big sturdy casing that is easy to transport and well protected.
The coating scratches a little easily but just superficially. Good thing this hobby requires darkness, as I will never notice it unless I develop OCD tendencies.
Part deux: THE FABRIC AKA COMPONENTS AKA HOW AND WHAT
This will always come down to the glass. At a retail price of 5 999$ USD with the Starlight 3” focuser, it’s is not among the priciest. Still, it’s not 10 bucks and great quality is expected. This f/8 air spaced triplet is claimed to be diffraction limited at 0.25PV or better with genuine ED glass from Hoya, Japan. Collimation was spot on and no further adjustments were necessary.
The dew shield is very handy and included. It is also made of carbon fiber coating and is efficient.
The tube is very stiff, lightweight and reaches thermal equilibrium fairly rapidly for a carbon fiber tube. I mainly do 45 minutes subs and the focus shift is minimal. This is not a concern at all if you are into visual observation. Pointing accuracy of an imaging system is important if you have only a few good nights available and if you don’t want to plate solve after every slew. Flexure can impair that pointing and during long subs it can even affect the image quality especially when imaging close to 0° DEC. This becomes less an issue if you have a good pointing model with tools like TPoint that takes those parameters into account. Flexure will come from many sources. The way the OTA is attached to the mount is one of them. In this case, the scope comes with a short dovetail that will do the job 90% of the time and is very light. I switched it up with something longer and more rigid to maximize rigidity.
Another source of flexure and image shift can be the focuser. This is a Starlight FeatherTouch 3” (rack and pinion type) and can always shift a little bit. Just make sure the adjustment knobs are tight and it should be fine. No perceivable play is noticed there nor backlash during focusing.
Finally the way you will adapt the scope to the field flattener (which I recommend) and the filter wheel + camera is the key. I don’t like compression rings so I ordered a custom adapter ring with the help of PreciseParts and Starlight Instrument teams as this adapter didn’t exist because the focuser was a true 86mm. You can now find it there. (”ES FeatherTouch focuser drawtube” and the flattener is the Teleskop Service 2.5” field flattener). The adapter should be 9mm for optimal back focus distance on a STT-8300M Camera w/ Self-Guiding Filter Wheel Package. With all these screw-on adapters, there’s almost no movement. According to TPoint, the whole tube-focuser-camera flexure is 27 arcseconds from one side to the other (180° flip). This is minimal.
To sum this section, the glass performs very well and the resolution is perfect for scales above 0.75”/pix. The tube is stiff and when properly attached to the mount (if you do astrophotography, ditch the dovetail that comes with it) and using the right adapters, it will give optimal performances.
La finale: VERDICT
If you are looking for a great quality refractor at a good price, this might be the one. It is not the best out there but bang for the buck it might be. It is well built, light, easy to use and doesn’t require a lot of maintenance. At 6” and f/8, it is versatile but not the fastest light gathering instrument. Combine it with a good mount and results can be quite astounding due to its stability.
The customer service at Explore Scientific is the best I’ve encountered ( an I’m not just talking about astro here). This is very important to me when it comes to choosing an instrument.
Some of the shots taken with it and projects I’m working on:
Thanks for reading!
The next project for 2016 involves a 32 feet high pier and a new house. Yup. This will get technical.