So, after a long hiatus when I was living abroad, I decided to recently get back into astronomy. Years ago, I had an f/5 150mm Orion Newtonian reflector on an EQ mount. There were many things I liked about that and wanted to start off with something similar again...
So I got to thinking - and mathing... and I wondered if the 150mm reflector was all that brighter than the 120mm refractor that is also now offered. After crunching several numbers, considering average reflectivity of mirrors, the fact that there are two of them, and the fact that fast reflectors have a considerable amount of blockage by their secondary... I came to the conclusion that the light gathering potential would be virtually identical.
So it would be easier to carry, more compact and robust, has a 2" focuser just begging for some astrophotography... the 120ST was sounding like a good idea. So I bought it.
And then it was cloudy for a week. Of course. Anyway, begin review by the beginner.
First I will start with the mount and tripod - it is a EQ mount with polar alignment scope. It's reasonably stable although one's opinion of it will greatly depend on where they are coming from. To someone who has only dealt with "toys", it's going to really introduce someone to a real mount. If I had a complaint, it's more with the tripod. The tripod feels a wee bit shaky and I would say its quality does not match the mount. Overall, for the price though, it isn't bad.
Moving on to the OTA
The tube itself has a feeling of quality to me, quite substantial. The cylindrical areas of the tube are a black enamal coated metal and the transitions are graphite wrinkle paint. Overall, I feel that it is a tasteful job and has a professional look to it. Between the short fat tube, respectable aperture, EQ mount, and dark paint, this refractor looks like it means business. High marks for appearance.
To the mechanicals – the focuser is a 2” rack and pinion. I am pleased they decided to go with this size, as will many people who want to use this scope for photography. There was no backlash or harshness on my focuser at all, but it was quite stiff which can make precise focusing tricky. One can easily overshoot because of the heft it takes. Upgrading the focuser would be a good idea for some, but, once again, considering the price I think it is a reasonable unit.
The dew shield is integrated into the OTA and cannot be removed. On the plus side, there is a mildly rough surface with a dark flat black coating on the inside of the dew shield. This should reward one with both better contrast and some improved dew protection.
The lens itself has some sort of multicoating that appears violet in some light and green at other angles. It is a doublet so there will be some chromatic aberration present… we will get into how much in a bit.
Let’s get to the views! With three hours of clear skies and average seeing conditions, I thought I’d see what this is all about. I will only be reviewing the telescope with equipment that ships with it, just to be fair.
First light – The Double Cluster in Perseus. Easy to find and beautiful even to guests that wouldn’t consider this their hobby, I’ve always thought this is a great one to show people… and the results are great through this scope! With the 25mm eyepiece, I can clearly see the majority of the blue-white stars, with a few orange spattered in as well. Each star is as sharp as I’ve ever seen through a telescope, although this is my first time ever using a “real” refractor. While the overall view as far as brightness and field of view go are more or less identical to my old Newtonian (as math would support), the refractor’s sharpness and, despite fairly light polluted skies in unfavorable conditions, contrast, absolutely trump the Newtonian. First view, and now I finally understand the hype.
No CA whatsoever, but we wouldn’t expect that on this type of object, nor at this magnification.
Next object was the Pleiades. Overall, I can report a similar experience. Brightness was more or less identical to the Newtonian, but each star was so much sharper. By this time, I’m feeling pretty hyped. My favorite things to observe before were DSOs and this scope was really showing some real potential there.
Just as before, I saw no false color whatsoever at either 25 or 10 mm. This shouldn’t be *too* surprising, although these stars may be bright enough to provoke CA in very low quality scopes.
By this time, clouds are starting to roll in and I feel it may be time to get on with a real test to determine the amount of CA. The moon has cleared the tree line so I adjust and look at that. With the 25mm, the view is as sharp as I could expect given the circumstances, but rapidly deteriorating seeing conditions are making this test challenging. Still, at 25mm I am not detecting any noticeable false color. I change over to the 10mm and take a look. The moon now covers most of the view. Out of focus, I can see violet and yellowish arcs offsetting each other, but they fade to reasonable levels when proper focus is achieved. While looking at the moon with the 10mm is showing a tiny fringe around the border, it is not even close to bad enough to obscure the view. To anyone familiar with photography, this would be easily rectified in Lightroom if one could be bothered.
Curious to how much of an effect it would make, I place the lens cap with the center cap removed to stop down the telescope. The results are, from my point of view, probably around a 70% reduction in CA (that wasn’t that bad in the first place). While I cannot see any ill effects at this magnification, it bears mentioning that under greater magnification, stopping down a telescope this much will lower its resolution. Try it out, see what works.
Cloud cover now is moving over the moon and the seeing conditions have deteriorated from not so good to absolute crap. I pack it up and head in.
So, what is my conclusion? Well, I’ve heard people all over the board about the CA with these scopes and decided to take a gamble and buy it. I am completely pleased. It has exceeded my expectations quite a bit. If I were doing high magnification planetary viewing, I may have stuck with the Newtonian or gone with the similar package deal with the cat, but for what I mostly use it for, this cannot be beat.
This is my first impression with a moderately sized refractor (as opposed to the crap kids have) and I'm absolutely loving this so far. Just to pick hairs, what would I change?
The tripod could be more secure, the focuser isn't really a pleasure to use, the polar alignment scope isn't as high quality as the one my Newtonian had, and a removable dew shield might have been nice.|
My first upgrade will certainly be a motor drive though so I can get into astrophotography.