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I owned the Skywatcher ST150 refractor for a few months. What initially caught my eye about it, was the 2" focuser, 150mm appature and short 750mm focal length, ie f5 ratio. I wasn't worried about it being achromatic, as I had intended this scope's purpose to teach me the very basics of astrophotography, but also a low f ratio, was to me a good 'grab and go', even if this meant out to the back yard in polluted city sky.
It's not that hard to balance, but does require a sturdy mount, the EQ5-goto I had purchased with it, really wasn't designed for the weight of this scope as an astrograph, but as a visual goto, it was an excellent combo (but towards the upper limit of the mounts weight capability). The short tube had another advantage in that when you're slewing around the sky, it wasn't a huge long tube coming to knock your head off or other items that may have inadvertently got in the way.
I had major trouble finding a case to transport it around in. I ended up having a large rc-helicopter case donated from my work to solve that. Ironically the case just didn't fit in the boot of my car, so it was an across the back seat job. It meant I didn't have to dissassemble the scope for transport, just remount it.
I remember stars being very crisp, but the blue fringe was always present. It was in good collimation so I never had to fiddle with that in any way. In terms of the scopes actual quality of build, it felt solid. The weight was nearly 8kg with the finderscope and in hindsight I always wished I had purchased a RA finder instead of the straight through one. Likewise, the first attachment I bought after the V block filter was a 2" diagonal.
Stars like acrux were easy to pull apart. I used a 2.5x Powermate with 20mm plossl (that's all I had at the time), and could easily see the 3 stars in Acrux, very crisp and clean. I didn't do much galaxy observation at all with it, but I was always viewing nebula like Orion, Eta Carina and Tarantula with rewarding results.
I couldn't help but feel the colour was a little ...wrong. It's the only way I can describe it. Some colours just felt too green or blue for my liking and compared to my other scopes of ED80 and Mak180 didn't show the same colours as those other scopes did. I never quite really delved into it much, I put it down to a combination of the achromatic lens and the V block filter only removing some of the haze colour.
The negatives...
You will need a V-block filter, or one of the purple/blue halo filters, either it be for visual or astro. It's a necessity.
On a nice bright moon the blue/purple fringe was very obvious. In one simple word - colour.
If you're going to mount a camera of any description to it, you'll also need a 55mm extension tube to achieve focus.
Coma is also quite noticeable. I also found that whilst it has a reasonable dew sheild, you will either need to extend that sheild at least another 6 inches, or use a dew heater on a dewy night.
I found the 2" focuser a little course and a slight image shift when you went to lock the focuser. Whilst I feel many dual focuser's are more gadget than necessity, this scope would benefit from a fine focus.
The positives....
It's 150mm... (need I say more)
Visually its a very good, large aperture grab and go achromatic tube with a fast f ratio - very portable.
Doesn't take that long to cool down ~20mins at most to achieve ambient temperature.
2" focuser holds a lot of weight and didn't slip.
Great for nebula, wasn't too bad a planetry scope, just not as fine contrast and detail vs a MAK for eg on planets like Saturn and Jupiter.
It's the most solid, but heaviest 8kg refractor I've had the pleasure of owning, so you'll grow some muscles lifting it.
In summary, I do miss the scope. It did serve a niche in my collection to which I now do not have anymore. I have a soft spot for refractors, whether they be achromats or apochromats. Visually it was forfilling in it's simplicity and the solid feel of it's construction. It didn't have the finese of the Skywatcher Pro or Black Edition models, but was definately one for good quality, price and performance.
Hope that helps.
Cheers
Mark
Last edited by M_Lewis; 23-04-2010 at 09:28 PM.
Reason: wrote stuff
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