Skywatcher 150p-ds review

[sgazer]

Skywatcher 150p-ds review

I bought one of these scopes as I wanted something that was compact, light weight, fast focal ratio (<f6), short focal length (700-1000mm), good performance (or at least correctable), works with a DSLR and relatively cheap.

As it was delivered yesterday (next day from FLO) and I had chance to try it out last night, I thought I'd write a quick mini-review on it…….(after writing it, I now realise it was not quick and not mini!!).

Disclaimer: I realise this is only one sample of these scopes, so it does not necessarily reflect them as a whole, I'm sure there's lots of variability. These are also my own opinions and please forgive any speellign mistakes, grammatical errors and typ0s!.....

This scope is a F5, 150mm aperture, 750mm focal length Newtonian reflector scope.

It came in a sturdy double cardboard box and was seated in the inner box with 2 polystyrene end caps. It had 2 scope rings and the dove tail already attached to the tube, but there was a layer of thin paper wrapped around the tube under the rings to prevent scratching and the tube and rings were together in plastic bag. A separate box contained the standard 25mm Skywatcher plossl, a spanner and Phillips screw driver, the finder scope and bracket.

The scope tube is painted in a very nice sparkly dark brown, the end castings, scope rings, focuser and finder bracket are white. This scope, being a -ds version, has a chunky 2" dual speed Crayford focuser, which looks nice. The rear mirror cell has the collimation adjusters exposed which consist of a large thumb screw with a spring connected to the main mirror and a smaller locking thumb screw.

I was hoping that this scope would be already collimated out of the box, but I started to have my doubts when I saw the main mirror lock screws were completely loose and the main mirror adjustment screws were just wound in to their tightest position. Then I looked at the secondary, only to find one of the spider vane screws, attaching it to the tube, was missing! Fortunately I found this floating loose in the large box the scope came in, but it meant I was going to have to do the collimation from scratch.

The scope tube is stated to be about 5kg and it feels lightweight, but sturdy. It mounted nicely next to my ST-80 guiding scope on my HEQ5. Overall, it's actually a little shorter than my C80 frac with the DSLR on the end. The scope rings are sturdily fixed to the dovetail with 3 bolts each! Although the rings were not perpendicular to the dove tail as supplied, so needed a bit of adjustment to get them right. There is a small spanner supplied, presumably for the centre bolt holding on the rings, but the outer two bolts are Allen bolts so it's a bit pointless supplying the spanner. It would have been better to have supplied a small Allen key for adjusting the secondary mirror, as not everyone will have one of these.

The focuser is very smooth throughout its travel and the fine x10 adjustment could be done with a finger tip, but the focuser may need the tension increasing a bit as it slipped fairly easily. I also noticed that when I tightened the focuser lock screw, this shifted the focus so that the object (the moon in this case) went out of focus. This is not good of course, but I found that if the lock screw was only tightened a little, then focus wasn't affected. I think it will be a case of increasing the tension on the focuser a bit and then cautious use of the lock screw.

The finder scope was surprisingly good, considering it's only a 30mm one. I wasn't going to use it as I'd found the 30mm finder, which came with the Celestron C80-ED, to be difficult to look through as it had a lot of "blacking out" depending on my eye position. I was going to use a 9x50 finder instead, but I thought I'd give the Skywatcher one a try. It turned out to be much easier to use than the Celestron effort (although it's not a corrected view like the Celestron) and had a slightly wider field than the 9x50 finder. It's also a lot lighter than the 9x50 of course, so I've stuck with it as I'll only be using it for initial star alignment and not star hoping etc.

As I will use this scope mainly for imaging, I wanted to ensure that it would focus with a DSLR attached, specifically my 1000d. Although I've never tried a DSLR on other Newts, I believe that there can be a problem focusing, due to not enough inward travel of the focuser, particularly if a coma corrector is used. Apparently the -ds has the main mirror closer to the secondary to negate these problems. The focuser has a 2" adapter which provides a T-thread attachment to an appropriate DLSR adapter, however (although I need to double check), I don't think you can then attach 2" filters to it. I used a DSLR to 2" adapter on the 1000d, which inserts straight into the focuser and allows 2" filters to be used. The scope came to focus easily with a couple of centimetres still left to spare on the focuser. One point to note is that as the main mirror is further up the tube, when focusing with normal eyepieces, they have to come quite far out of the tube and to cater for this, the 1.25" and 2" adapters bring the eyepieces out about an extra 30mm. This was particularly noticeable with my 30mm 2" moonfish eyepiece, which albeit quite large in itself, ended up sticking out a significant distance.

On to the dreaded collimation! I'm not really an expert on this and it's kind of one of the reasons I like my refractor so much (no collimation!). The only tool I had was an eyepiece cap with a hole in the middle. The secondary mirror is adjusted with 3 Allen key bolts (Allen key not supplied), I adjusted this so that the whole primary mirror was visible and then adjusted the primary mirror thumb screws until the shadow of the secondary was in the centre. A quick star test to fine tune it and all seemed ok. I'm always a bit nervous about collimation as there are so many adjustment variables; main mirror tilt, secondary – position in the tube determined by the spider vane bolts, tilt determined by the Allen bolts, rotation, position up/down the tube determined by the big central bolt! Anyway, I hope I got it right. The only thing is that the spider vanes did not form a cross through the centre of the shadow of the secondary, they were slightly offset. I couldn't work out what adjustment would be necessary to correct this without upsetting the other settings. (I have a Cheshire eyepiece on its way, so hopefully I can double check the collimation).

So, as it was a bit cloudy last night, I only had chance to take a few frames of the moon and to check the amount of coma in the corners of the image using Arcturus. I've attached images of the coma and also a stacked and sharpened image of the moon. I have a Baader MPCC on its way, so I will post the results of using this at a later date to show how well the coma is corrected and whether it is still possible to focus (which I expect it will be as the Baader MPCC is stated to bring the focus out by another 10mm). Hover over the images and it will say what they are.

Hopefully that's everything covered and hopefully it will help anyone else thinking about buying this scope. Let me know if there's anything I've missed.

ps, I will try to get some photos of the scope too.

[samtheeagle]

Thanks for the detailed review

This is one of the scopes on my potential future purchase list... I'll be interested to see your pictures with the coma corrector.

[sgazer]

here's a bit more info on the 150p-ds after I've used it in anger;

There is some vignetting on the images taken with an APS-C size DSLR, but I wouldn't say there's any more than with my ex-8" SCT and 0.63FR. I don't know if this would be improved with a larger secondary as with the 200p-ds.

The focuser tube does stick out into the main tube when focused with a DSLR, however as the main mirror is smaller than the tube diameter, the protrusion of the focuser tube does not seem to impinge on the light path to the primary. The focuser seems to be very good, with very little image shift. My initial findings about the focus shifting when tightening the focus lock don't seem to have reocurred, although I did slightly tighten the tension on the focuser knobs.

My biggest gripe, from an engineer's point of view, is that they've put one of the 3 focuser alignment bolts right under the focuser knob and the other very close, so it would be very difficult to get an allen key on it. This means the focuser mechanism has to be completely dismantled just to adjust the tilt of the focuser. There is plenty of space around the focuser to place these adjustment bolts, so it's very poor planning in my opinion!

The focuser tube is quite shiny aluminium, so with it protruding into the main tube, I expect it could cause some internal reflections. It's not possible to paint it as the bearings of the Crayford run along its shaft, but it could have been blackened by another process.

The secondary mirror has quite shiny glass edges, these could perhaps do with blackening.

The Baader mpcc works very well with the scope. It almost removes all the coma at the edges of the frame. I've only really used it properly on one DSO so a few more nights imaging will confirm. Attached are 100% corner crops with the mpcc fitted (bottom right and top left), these are taken from my M106 image here;

http://stargazerslounge.com/imaging-deep-sky/103164-m106-1h-25min-150p-ds-1000d.html

Focus is not an issue with the mpcc attached directly to a T-thread adapter on the 1000d.

One thing I missed off.....the primary mirror was very loose. After I did the collimation, I simply moved the scope slightly and the collimation went way out. I found that just touching the rear of the primary moved it quite a lot. I tightened down the mirror clamps (not too much) and it now seems ok. This along with the seconday spider bolt which had fallen off and the primary mirror adjustment bolts which were fully tightened up, does make it feel like these scopes are a bit thrown together on a mass production line without many final checks, certainly not for collimation. Astrobaby's review of the 200p also mentioned a loose primary, along with other things.

Overall, I'm very pleased with this scope. It's light weight, compact and much faster (f5) than my C80-ED frac (f7.5). Although I still remain nervous about whether I've done the collimation correct, a refractor with similar specs would cost at least 10x as much.

[samtheeagle]

Thanks again for the info on this scope It nice to see the MPCC doing the business. There are just sooooo many different options I can take with a new scope purchase, I'm all at sea atm!

[riklaunim]

Some nice images from 150/750 Newtonian can be found on astrogaleria.com.pl.

[sgazer]

Some nice images from 150/750 Newtonian can be found on astrogaleria.com.pl.

some nice results there, particularly NGC4565 with 27x7mins and a mod'd 350d. I'll have to spend some more time on that DSO with this scope.

[samtheeagle]

Wow, some great images there!

Are you using a coma corrector? Are the images taken with the 350D cropped at all? They look lovely

[riklaunim]

Those aren't mine images Made by a friend that started with modded canon + IDAS LPS2 and now uses a one-shot SBIG camera and the OTA with Baader steeltrack focuser (due to SBIG weight). All or most of them with Baader coma corrector.

A lot of DS images shown somewhere on astromaniak are made with the good old 150/750 newtonian OTA (Polish forum )

You get a "small" newtonian, put a coma corrector and you have something-like-APO at low price. If SW upgrades 130 mm f/5 newtonian to full nice 2" focuser + T-thread will also be a killer for imaging of wider fields.

[samtheeagle]

Ahhh, ok Yeah the Polish is all Greek to me

[JB80]

The secondary mirror is adjusted with 3 Allen key bolts (Allen key not supplied),

This has caused me quite some annoyance until I figured that out. I have the 150PL and it drove me mad so I just went and bought a heap of different sized small keys until one fit.

IMO it's a bad move for these not to be supplied with one.

Still, it's my only complaint so far.

[riklaunim]

Hm. Those I've got with 150/750 set matched bolts on the secondary.

[JB80]

I am certain mine didn't come with one, I got a screwdriver and spanner but no key.

It is possible I lost it but reading this review with the 'Allen key not supplied' part makes me feel better about it.

It's pretty silly because it renders trying to collimate it useless until you can find the right tool.

[Herakles]

I too can confirm that NO allen key was supplied with mine. Bad form for someone getting it as there first scope TBH. Collimation was off by a country mile with mine as well.

Clear Skies

Pete

[JB80]

Well on the plus side I now have a set of small diameter allen keys, I believe it was the 0.5mm one that is required.

At least it is for the 150pl.

I got lucky and the collimation was pretty good straight out of the box, it was certainly still useable until I got the allen key anyway.

[delsix]

Thanks for all the info. Not sure it helps my current predicament as I think my shortlist has just got longer rather than shorter.

[astroimpulse]

My 150pl came with an Allen key. It was in the bag with the spanner.

I have loads of them anyway but it was definately included

[barry f]

i am looking at the same scope and wanted to see some images of what can be seen thro it but am unable to load  astrogaleria.com.pl. so i can see what i will be getting is this the right site?

[Alkaid]

Nice review, thanks for sharing.

[Roy Challen]

Good review, agree with the missing allen keys thing - my EQ3-2 was missing one as well.

[dweller25]

Great review