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  • Telescope Review Shootout between the Explore Scientific 127 ED Apo and AR 152 Achro Refractor Telescopes

    A working schlub's viewing shootout between the Explore Scientific 6" Achro and 5" Apo in orange/red LP skies is my working title for this. The reason for that is because I do work for a living and well… The Google defines schlub as: A talentless, unattractive, boorish person. I am for sure unattractive and am pretty sure I am talentless and boorish at/in many things! :LOL:

    Some quick… Housekeeping:

    All kidding aside I wanted to share my experience with these two scopes from a non-scientific/engineering merits standpoint since I see questions (including my own) asking which is better to get a 5" Apo or 6" Achro that many times end up in "discussions" about very esoteric and complex subjects like unobstructed vs. obstructed systems, Japanese FPL-53 vs. Chinese FPL-51 glass, Modulation Transfer Function, Schlieren tests, and times to reach thermal equilibrium between reflectors and refractors.

    Please note that for the record the best value for dollars spent will always be with a reflector like a Newt or Dob. You just can't beat the light gathering ability of these platforms at their given price point. I, as noted in my signature, also own a reflector. It is an 11" SCT and the views from it are amazing when it's properly cooled down. And yes SCT's are technically reflectors since they use mirrors they just take longer to cool because they are closed systems unlike Dob's which are open. So please folks who prefer reflectors to refractors lets keep this on subject and on topic.

    In the spirit of full disclosure I want to state that the majority of my visual observing kit is from Explore Scientific as is one of the two OTA's I currently own. Almost all of my EP's are from there because after looking through many different manufacturers EP's the ES ones gave me the best views for the money.

    However I am not an ES Fanboi even though based on this review I will sound like one. At work I believe in selecting the best fit for a given need and I apply that to this hobby as well as my other hobbies. In this case ES was the best fit for what I was looking for and based on past experience with them it made sense to stick with them.

    Please note when I quote sizes of objects that is the size it looked to me. It may not have been that actual size were one to measure it in the EP but I am writing this from the working schlub perspective not a scientific/engineering accurate to the 5th decimal point one.

    Now onto the review…

    The problem I was trying to solve was that I wanted something I could use on nights (like when I had to be up at 0530 the next morning for work) when I wanted to take a quick view of whatever might have been up and visible but would still give me views that were comparable (or better) to my Meade LX90 8" SCT from my Orange/Red Light Polluted front driveway skies. This would mean that I wanted to be observing in under 15 minutes start to finish of shlepping gear out, leveling the mount, balancing the OTA, and aligning.

    Based on the views I was getting out of my 4" (102mm) ES ED Apo refractor I knew that a larger 5-6" (127-152mm) refractor was the best choice for me. However my budget of under $2,500 eliminated pretty much everything in the high end refractor range like Takahashi, AstroPhysics, Tec, and the like. This left Canadian Telescopes, AR, Explore Scientific, Meade, Celestron, and Orion.

    My next criteria took all but Canadian Telescopes, AR, and ES out of the mix. That criteria being I didn't want something that looked like it came off of the Battleship Missouri's gun deck in terms of size and I could use for AP if I wanted to aka a "short fast tube".

    Because of my breath taking experiences (and by that I actually mean gasping out loud) viewing with the 102 ED, the great customer service experiences I have had with them, their attention to detail and quality, and because the ES line comes with a 2" diagonal, dual speed focuser, Vixen dovetail bar, illuminated cross hair finder scope, and scope rings included (the Apo models also include a nice ATA style case) I decided that I would stay with that line.

    Again for the record CT, AR, and Orion make great OTA's but with them I would have had to purchase much if not all the kit that came with the ES line as extra's so value for money for me really was in the ES line.

    This had me looking at the ES AR 152 127 ED, and 127 ED Carbon Fiber OTA's as my choices. I picked these because they would still allow me to dual mount OTA's on my LX80 from a weight standpoint so I could use both the C11 and either one of these at the same time for the outreach I do and I could mount them easily on the LX80 individually for that quick nights viewing.

    I was very fortunate in that Farrah from Woodland Hills Telescope and Camera was kind enough to offer me the use of an AR 152 and an 127 ED to see which one I liked viewing from better then purchase the one I decided to stay with.

    Down to brass tacks. What I saw and what I used.

    My targets for the comparison were Mars, Saturn, Spica, Messier 31 (Andromeda Galaxy), and Messier 5 globular cluster. I picked these because they all were moderately low on the West facing horizon for me so I wouldn't have to be laying down to see them, they would provide a fair diversity of objects to look at combining planets, bright DSO's, and bright point light sources (stars), and would provide "messy" air and light pollution conditions to best reflect what I would be seeing on an average night out. And I picked work nights because my primary use for this was going to be the times when I didn't want to bring out or had time to cool off the photon cannon C11.

    Setup time for each OTA was under 15 minutes including setup of the tripod, getting it pointed North, getting the OTA balanced, getting the OTA level, and alignment.

    The EP's used were the Celestron 40mm 1 1/4" that came with my C11, the ES 14mm, 11mm, 8.8mm and 4.7mm 82* 1 1/4" line.

    First night was the ES AR152.

    It wasn't anywhere close to the monster I thought it was going to be in terms of size and it was very manageable to mount and balance which surprised me. After hearing stores about this size of OTA I was expecting something much bigger than it was. In one of the photos below I put a 2 foot level on top of it for scale. As has been true for me and reported by others the ES folks check their gear before it goes out the door and this OTA was no exception. After balancing it I popped in the 40mm and pointed it towards a radio/microwave tower that was a good 20 miles from me on top of a mountain and it was in perfect focus right out of the box! The LX80 handled the large OTA with zero issue and it didn't' feel to me like it weighed 23 lbs like it says it does.

    Side Note: I didn't (and rarely do) use the included finder scope on either OTA. With that 40mm and doing a gunsight aiming I can pretty quickly get the alignment stars in the FOV so I find the extra step of the finder scope alignment useless.

    A word about the dreaded purple haze aka Chromatic Aberration (CA) that everyone tends to bring up when talking about Achro's. In the case of the ES AR152 at a relatively fast f/6.5 it was barely there at all. The only time it was really noticeable was during alignment where I saw it on Arcturus. The purple halo was there but it wasn't annoyingly bright and I would expect that a filter designed for Achro's would take care of it rather handily. Of note I did not see any of it on Saturn or Mars and saw it very faintly on Spica which really surprised me and reaffirmed my belief that ES makes darn fine quality scopes.

    Based on the EP's listed and the 988mm focal length of the OTA divided by EP mm I was going from 24.7 magnification with the 40mm to a mid range of 70.57-89.81 with the 14 and 11mm's to the 112.27-210.21 range in the 8.8 and 4.7mm EP's.

    Saturn in the 40mm was a bright yellow spec of light and I could just make out the ring. At 14 and 11mm it was a clearly defined crisp bright yellow and muddy yellow planet that was about 3 mm in size. No CA at all and not much difference in sizing. Jumping to the 8.8 it jumped up in size to about 5mm with the same clarity and crispness of view and color though I was starting to see it "wiggle" a bit from atmospheric disturbance. At 4.7mm it got the best views. it was a good 7mm (about 1/4") in size but stunning to look at. I could see bands of color and the Cassini divide was very clearly present. It presented on a dark black background and two moons were clearly visible. Again no CA at all.

    Mars was… Well it was Mars. That means that at 40mm it was a spec of dust. Clearly orange but still a spec. At 14 and 11 it was a bigger spec of dust. Maybe 1-2mm in size. At 8.8 it started to look like a planet and at 4.7 it was about 3mm in size and very clearly orange with some hints of black/brown. Still no CA.

    Spica was… A star. A bright one and with a bit of CA to it but not too annoying or distracting at all. Again a filter would knock this down without problem I am sure. It had good clarity and while I had to focus each time I changed EP's the focuser worked very well giving good views.

    On to M5. In the 40mm it was a very faint puff of smoke with no definition and about 2mm in size. In the 14 and 11 it was a defined puff of smoke at about 5mm with some hints of stars with averted vision. There was little difference between the 8.8 and 4.7mm with it being a good 6-7mm (3/8") in size and hints of stars when looking directly at it. It was still faint but not as faint as before and clearly visible and noticeable.

    I finished off by hunting for M31 the Andromeda Galaxy. I started with the 40mm but didn't see anything. The LP was just too strong. I didn't start to see anything even with averted vision until I plopped in the 11mm and only then I was able to catch it as a very faint puff with averted vision. It didn't become apparent until I was up to 4.7 and then it was still a very undefined puff of smoke. But it was a galaxy and it did show up even though I was "only" using a 6" OTA! I didn't spend too much time on it because at this point it was 2145 and I was… well… Tired.

    Second night was with the ES 127 ED.

    I didn't notice much weight difference between the two and including the CF one. None of them were all that heavy though there is a 5.5 lbs difference between the 152 at 23.5 lbs and the CF at 18 lbs. It mounted up quickly and with the removable dew shield it did make for a smaller feeling scope. Once again the Pro's From Dover at ES really showed their stuff. Looking at the same mountain top antenna gave brilliant views though since I was dealing with a different focal length I did have to roll out the focuser a bit. Frankly I do like the removable dew shield and metal lens cap on this OTA better than the plastic one and non-removable one on the 152.

    Since this was an Apo there was zero CA at all on anything. And to be fair the views were overall more crisp, clean, and clear by a noticeable margin compared to the 152. But then at close to triple the price of the 152 I would expect it to be such.

    Based on the EP's listed I was going from 23.8 magnification with the 40mm to a mid range of 68-86.54 with the 14 and 11mm's to the 108.18-202.55 range in the 8.8 and 4.7mm EP's. This is compared to the 152 which was 24.7 magnification with the 40mm to a mid range of 70.57-89.81 with the 14 and 11mm's to the 112.27-210.21 range in the 8.8 and 4.7mm EP's.

    Of noteworthy mention here was that to my eyes there was no real appreciable difference in magnification between the 127 and the 152 even though the numbers say otherwise. However overall the clarity, contrast, and crispness was apparent moving from the 152 Achro to the 127 Apo.

    I am not going to spend much time talking about Saturn, Spica, and Mars because in terms of overall size of object and brightness the views were very close. Close enough that I really couldn't see a difference between them. But as I mention above the clarity, contrast, and crispness were for sure apparent.

    What was of interest was M5 and M31. In the 127 M5 resolved with more detail at a lower magnification with the individual stars becoming more visible and clear. This was the same with M31. it was much more readily apparent at a much lower magnification and stood out much better than in the 152 which was a surprise. Up until seeing this I really did think that all that mattered was aperture. After looking at it in the 127 I still think that aperture does matter because seeing it in my C11 at thermal equilibrium is much better than either the 127 or 152 because of the total light gathering difference between the two BUT in an Apo even at 1" overall smaller size the view was better than the Achro and I could see more detail. I attribute this to the clarity and contrast given by the triplet design in terms of focusing the light and that said light is unobstructed.

    Conclusions:
    Both the Explore Scientific AR 152 and 127 ED are fantastic scopes for the price and for all the extra's they come with. Both performed surprisingly well from my urban light polluted skies. Both were easy to handle and not cumbersome or heavy or hard to get onto the mount and balance.

    The adage about the best scope for you is the one you use applies very well here. Both gave really great views of DSO's, planets, and stars with time between setup to viewing really good for a working schlub who just wants to look at something before going to bed because they have to work in the morning. In both cases and at both price points if you are looking for that OTA that will keep you coming back for views of the stars instead of sitting on the couch watching Dancing with the Stars then these scopes are a option to strongly consider.

    If you are on a budget and you are looking for a very well made refractor at a very fair price for all of the kit included I strongly urge you to consider the AR 152. The value for the money really is there. For visual only this OTA will work on a CG5 with very good balance but just barely and I wouldn't recommend it. Plus any wind is going to be a problem and the vibrations could drive you up the wall. Better to put it on a CGEM and you can take photos with it as well. Just expect to have to deal with the purple and blue fringe in post processing.

    If you have the extra budget, want to have that extra bit of oomph and sharp intake of breath when you look through the EP, or even the slightest hint of CA bothers you then for the price the 127 ED is the way to go. For visual use only this OTA will work on a CG5 with good balance. However you would be better off putting it on a CGEM where it will perform well as an AP scope as well as a visual one with the added bonus of less time in post processing removing of the purple/blue fringe or star bloat that can and will happen with an Achro.

    Personally at the end of this I went with the the Carbon Fiber version of the 127 ED. It was worth it to me to spend the extra on the CF one (it's pictured here and it's the one I ended up buying) because at the end of the day it gives those views that get you off the couch and under the stars and will do quite nicely for Astrophotography on a moderately priced equatorial mount like the CG5 or CGEM which I own.

    Explore Scientific AR152 Achromat on the LX80 side and front views as well as side scale shot with 2' level:

    http://farm8.staticflickr.com/7274/7...0831c65e_t.jpg

    http://farm9.staticflickr.com/8427/7...95040473_t.jpg

    http://farm9.staticflickr.com/8423/7...513196d3_t.jpg

    Explore Scientific 127 ED Apochromat on the LX80 side and front views:

    http://farm9.staticflickr.com/8439/7...b187a638_t.jpg

    http://farm9.staticflickr.com/8292/7...e32c2df1_t.jpg
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