Skywatcher Black Diamond 180 Mak

[monoxide]

hi guys,

i've been wanting to get a decent scope to ride on the heq5 purely for planetary work and im thinking that the 180 mak will do the job nicely

has anyone got one of these or had a look over/through one?
looks like a step up in finish from the old 'promak' series

any opinions/advice welcome!

[Wavytone]

... since September and I don't rate it highly. Like you I bought it with lunar and planetary in mind but it did not meet my expectations, frankly. I also have an Orion 102ED f/7 refractor and this shows noticeably more detail on the moon and Jupiter than the 180mm Mak does. I'm using Vixen LVW eyepieces BTW.

1. Mine is not sharp, optically.

On a bright star in 9/10 seeing and with an 8mm eyepiece, just out of focus and inside focus a star test shows symmetrical concentric rings that look textbook perfect, yet as it goes through focus it will not reveal an Airy disk with rings, all I get is a fuzzy blob distinctly larger than the Airy disk should be. I have yet to put a Ronchi grating or knife-edge on it but I can guess what its going to show - a messy wavefront with a "dog-biscuit" surface. It is also unable to split double stars that are easily split by the 102mm refractor.

2. It has no ventilation and takes an hour or more to cool down. Otherwise you will have an image problem due to a current of air inside the tube; this current is easily seen in an out-of-focus star test.

3. Dovetail. Mine has a vixen dovetail which at the rear end is bolted to the mirror cell casting (OK) but at the front end it has one small bolt into the wall of the tube, which is hopelessly inadequate against the twisting forces when the scope is sideways on the mount - it flexes - visibly - and its made a mess (visible distortions) in my tube in just three evenings.

I have recently received a set of tube rings for it from Parallax, these and a decent sized plate IMHO are essential - the dovetail is hopelessly inadequate for the weight of this scope.

4. Dew. Admittedly a thick corrector has lots of thermal mass so it stays warm enough not to dew for an hour or two, but when it does its equally hard to warm it up sufficiently.

5. Focal ratio. I thought a longer focal ratio would be fine so when I saw f/15 it seemed a good idea, however not so. I'm now fairly sure that f/10-f/12 would have been a much better idea.

If I persist with this scope I'm inclined to drill holes in it and add a filter and a fan. However I am at a loss as to what to do with it as I don't have the heart to resell something that doesn't really work as it should to someone else, and the refractor outperforms it.

if you are happy to take a punt on a large Chinese Mak I'd consider either the Saxon 203mm f/12.5 one or this one http://www.bosma.com.cn/en/product_info.asp?id=438 200mm f/12.

Alternatively I'd suggest an ED refractor around 120-130mm aperture, maybe even 150mm if you can afford it - it will get a lot more use and will perform better.

[monoxide]

hmm, thanks for the reply.

thats a bit of a bummer, a few of the reviews i read said the optics were very good but i guess theres bound to be a few not quite up to par.
sounds like i should avoid the skywatcher then and mabee go for an Intes 7"

i have the fs102 and its a beautiful scope to observe through but im not a big fan of ending up at the mercy of wherever the eyepiece happens to end up. not too sure about the other chinese maks, the saxon scopes may well be decent but they look like toys and im not much of a punter :p

[TrevorW]

May I suggest

http://www.telescopes.com/telescopes/optical-tubes/vmc200lota.cfm

available in Aust for around $2k

[monoxide]

i was only having a look at the vixen cats yesterday :)

i really need a new mount before i start looking at bigger imaging scopes though..

[Terry B]

I think you will find that the vixen weighs less than the 180mm MAK due to there being no corrector.

[monoxide]

i added it up before, the payload with a VMC200L and FS-102 with cameras would be very close to 15kg, just under the max load for my poor little HEQ5 :)
it might just be do-able especially since they are both reasonably short tubes.

im trying to hold off getting a new mount until the $AU recovers a bit. $6K for a G11 is a bit steep. i could get an EM200 Temma2 Jr for ~2k more

it might be a VMC200L for christmas and an EM200 Temma2 Jr for my bday in 7 months when its hopefully cheap enough that i can afford it lol

[bmitchell82]

hehehe you sound like your in for some serious sky work. but you know as they say, 1 week of cloud per $1000 spent dyam murphy

[Wavytone]

If you want a 200 mm Mak, I saw one in Astro-Optics (Sydney) - f/12.5 (2500mm f.l.), very reasonable price as it was imported before the $A tanked. Construction looks good - white, it has a fixed primary and a 2" Crayford on the back, and includes tube rings and a dovetail. Makes me regret the one I bought.

[monoxide]

i might just hold off for a Vixen VC200L, i saw some unreal images taken through one of these and they are reasonably priced too.

only problem is, then i have 2 scopes that use their own weird threads/attachments :(