A 1st, 2nd and 3rd light review of The Explore Scientific AR152 (6" Refractor).
The Case for a Big Refractor
I had noticed this scope over a year ago, and had even ordered it last year. But my order could not
be filled. Some more time passed and I thought that ES will at some point likely stop offering a case with the scope -
its just too good a deal to keep going. I think the case is really a lost leader to get sales going.
After waiting 3 months for my order not to be filled locally - I contacted OPT in California and they advised
two weeks was the waiting time. Two weeks later the scope arrived! And from California to Canada!
I have always wanted a 6" Refractor and have on many occasions just missed it. I settled for the 5", afraid
the six would be to big of a monster to handle. Or I went for an 8" SCT afraid of the dreaded CA (Chromatic Abberation)
ruining my enjoyment. With these near misses behind me I opened the shipping carton and gazed upon the F6.5 152mm
Refractor. Wait a minute - why am I gazing at the Refractor when I should be gazing at scope case with the Refractor
inside it. Like a child who's ice cream just got stolen by a dog while he was looking the other way, I lifted the OTA
out of the box half expecting the case to magically materialise, or be somehow under the scope! Nope, there is definately
no case in this box. I called OPT and they began making some calls.
The good news - A 6" Refractor with Case, 8x50 finder and 2" 99% Reflectivity Diagonal for $699.
The bad news - sorry, no more cases - Xmas is over ... ("I knew it")
Despite my disappointment at now having the new scope on the garage floor in a cardboard box (so unceremonious for
the new 6" wonder), I amazingly saw first light with the scope that same night. Normally any club member
who buys a new scope has to apologise to everyone else for the ensuring 3 weeks of cloudy weather.
Getting Down To Business
Our Sunshine Coast Astronomy Club (RASC - Sunshine Coast Centre) met at Sechelt Airport for our first dark sky observing
of the summer. I used my Celestron CG5 - ASGT mount with the tripod fully extended. I was worried that I would return to
crawling around on the ground to get to the eye piece everytime the scope was vertical as I had with my 5" Refractor on my LXD75 mount. But the ASGT tripod is considerably higher when fully extended and The ESAR152 balances almost perfectly in the centre
of the OTA when the finder, diagonal and a 2" EP is attached. This allows the Focuser to remain at the right hight for observing
from an oberving chair or stool.
I had read the dew shield was too short - but I found in two outtings - over 3 hours each in very moist conditions - while my finder had completely dewed up and tables, chairs were soaking, the lens was completely dew free. Perhaps the OTA retained some heat
from being in the warm car immediately before observing. Not sure why there was no dew issue but its 2 for 2 for the dew shield.
Finally to the sky
My first object was Saturn. Well past opposition (and its best) - I knew it shuold still be visible in the western sky.
I slewed near Saturn with 'Quick Align' on Celeston's Nextstar GoTo and found it in the finder scope.
I corrected my alignment (by adding Saturn as an alignment star) and looked through a 13mm Celestron Ultima
LX 2" Eyepiece. Saturn was dull, blurred and yellowish. I attached a 2" Baader Fringe Killer I had purchased for the scope.
I seldom use filters but I do think if anyone knows what they are doing, its Baader. I looked again now with the filter
attached to the front of the 2" diagonal. Saturn was still ugly. I decided to slew to the double double near overhead.
When I got there, E.Lyra 1 & 2 appeared greenish and there was no clean split. At that point I wasn't too thrilled
with the views I was getting. Neil came over and suggested that A) Saturn was in a bad position, low in the sky, and B) the
seeing was so bad he couldn't even get a reasonable image of Vega in his 10". I removed the fringe killer and Neil
suggested M13 the globular cluster in Hercules. I slewed there and looked. Nice, very nice. The sky was still light
but M13 showed stars resolved right across its face at 80x. I had recently looked at M13 through my 8" imaging Newtonian
from the same location and had to use averted vision to really see the stars in M13. My friend Ed had suggested
his view of Saturn was slightly sharper in his F/8 8" Newtonian than in my F/4 and he was right. The mirror obstruction
is 35% by area in my imaging scope. The scope is superb for imaging, but a 35% obstruction loses significant
contrast and detail. This is what sparked me to once again pursue a big refractor for visual use. It was then I had decided to try again for the ESAR152 ....
O.K. so much blah de blah there, but the point is - no contest, the AR152 smoked the 8"
Imaging Newtonian on M13. O.K. 'so one good view - does not a great scope make' (Shakespear?) what else?
The Ring Nebula, The Dumbell, M82, all very nice with sharp stars to the edges. My Celestron Ultima LX 32mm 2" E.P.
had been horrible in my F/4 Newtonian - blurry stars anywhere off-axis. But with the Refractor at F/6.5 it now showed pin point
stars to the edge at 30x. A small group had gathered around the scope, partly because I had borrowed their stuff (Dan's 13mm Ethos to make sure we had the best performance possible from the EP's - Mike's UHTC to view The Swan Nebula) . and partly because they were curious to see what the 6" Refractor could do. We must have stayed on The Swan Nebula for around
20 minutes - it wa a great highly contrasted view.
Sagittarius was low in the sky and the sky is always light
there from my location but we checked out The Lagoon and Triffid Nebula and I remembered the globular
cluster M22. I have visited this GC many times as I love Globulars. I have viewed it with a 4 and 5" Refractors
and with an 8" SCT. It has always appeared as a smallish cloud with little detail. I slewed down to M22 and looked through
the 13mm Ethos. M22 looked like a large starbust firework. The background sky was light and yet I could resolve
stars right across the face. I've never seen it look like this - big and bright. In fact the image of it is burned
in my mind. Its not even a favourite of mine. Now I WAS impressed - because I was seeing views I had not seen
before in any scope. That's sort of the ultimate for a new scope, to deliver new views - despite my first
two objects being disappointing, now I was being surprised by excellent views.
Adrian had mentioned glimpsing M51 The Whirlpool Galaxy in his 12" Dob. Again the sky was not dark in that direction - light
spill from a nearby quarry (the 2nd biggest open pit quarry in Canada I believe). I looked and at first thought - mmm? a
couple of smudges, that's often the view of M51. But as a few seconds passed - I began to see that yes there
were two smudges and beyond the smudges was a definite halo of material. I did not see spiral arms, but I did see more
than the core. That was it for first light - a stumble at first with a great recovery.
2nd Light
We were again at Sechelt Airport - but this time we had 'free forming' clouds. Clouds which don't roll in, but just form overhead from
the moisture in the air. Within an hour we went from 90% clear sky to 90% cloud! But not before we had shown a new
club member a few sights through The ES-AR152. M13 The Hercules Cluster, The Ring Nebula and The Double Double.
This time E.Lyra was split clean and appeared a normal white colour. In fact I noticed that the space between the
components had enough dark space to fit another star between them. I was happy with that. So only Saturn
had to be addressed and with it sinking so low so early I will have to right it off until next viewing season.
Jupiter is just around the corner and it will be a bigger challenge.
3rd Light
3rd light was on my driveway and this Time we had a 1st quarter moon. The Moon was also low in the sky but I
slewed there fearlessly and braced myself against the blast of CA I expected to blow my hair back as I looked
through the eyepiece. But there was nothing! I moved my eye around - oh yes there it is. A thin line of purple
just outside the edge of the Moon's disk. I moved my eye slightly and again it disappeared. I moved the focuser slightly
and I was able to make it disappear that way too. Curious - I've never spent much time analysing CA before,
but this was minimal and of no annoyance whatsover. I'm very pleased with this - an F6.5 152mm Achromatic
Refractor with minimal CA (bear in mind I've never used an Apochromatic).
In each session I used Vega and tried defocusing at 200x to see the fresnel rings. But I could not see them - instead
I saw basically a large snowball of light. Conditions were only clear on the first light night so not sure why I was
unable to see the fresnel rings. Wanted to assess colimation by this method.
OPT are trying get me a case and I'm very happy with the handling of this scope. I'm looking forward to getting
out again and really cranking up the power on an object like Jupiter and running some comparison viewing my friend
David's F/8 6" Refractor and with Ed's 8" Newtonian.
I should also say the OTA, rings, 8x50 finder and 99% Reflectivity 2" Diagonal and 2 speed crayford focuser are
all of excellent quality and arrived in excellent condition. The scope has a quality feel about it and works really well - just don't mentiion the case . shhhh!
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