Skywatcher 190 MN, or something else??

[wavydavy]

Think the issue with having to upgrade the focuser,is a big one, even though im fairly hands on I don't like the idea of removing the corrector, and fitting a new focuser, ive been into astronomy some time now, and getting a bit fed up with tinkering to try to improve my equipment, and im mainly an imager these days........

[DaveS]

Looking at the Starlight Feathertouch focuser, it would appear to mount straight onto the plate that's already on the tube, so may not need to remove the corrector.

Pricey though.

[perfrej]

You need to get inside the tube to reach the nuts (how did that sound  ) if your screws are not the original ones. Moonlite comes with smaller screws that need nuts on the inside. The corrector can be removed very easily and will not need adjustment afterwards. Whatever you put on there in terms of focuser needs to have elongated mounting holes so that it can be moved along the tube. The Moonlite unit lacks this possibility and is very difficult to get aligned properly.

I have to vouch for this scope. The optics are stunning! Removing corrector is six M5 screws and the whole top unit comes off - piece of cake even with five thumbs on each hand. R/C scopes usually do not clock in at f/5.3 and have SPIKES! Yikes! Besides, they are subjects for collimation and mirror dew and what have you...

/per

[Earl]

is there a MN of simular spec that does not need to user mods for usage?

[perfrej]

Well, there was the Orion discontinued scope which was the same... Seriously, if youo would consider, for instance, a WO FLT-98 a scope that doesn't need tweaking, then the 190MN is a non-tweak as well if you don't count the collimation (which all relectors suffer from). The focuser on the 190MN is one small notch down from the Moonlite, and the primary mirror cell is fine if you don't have a mount that requires modeling.

So, in essence, the 190MN is a scope that works fine as is, but can be improved upon. I use two 10Micron mounts and had to add some padding in the primary cell in order to reduce mirror shift. I changed the focuser because I have high standards in regards to sag and repeatability. Most people will use it as is and it will outperform any scope in that price range, and many scopes that cost two to three times as much. It is a gem. Orion discontinued it, most likely due to the high cost of the corrector plate from Schott. I am surprised Skywatcher still makes it.

Earl, you have a Tak mount which doesn't do modeling, so you should be up to speed with a stock one. Change the focuser just like you would on a WO scope.

/p

[Earl]

humm ok, nice fl, quick too, i will consider that when my widefield project is nearing its completion so to speak

[alan potts]

I think many of us have the ability to change the focuser, I know I have, it is the stigma of starting out on such a job, we all convince ourselves you should never touch these things and leave well alone. After removing the front cell of my LX 12 inch I was amazed that when I put it back it didn't even need re-collimating, however I was scared to start the job in the first place.

I may well change the focuser on mine as it is the only thing that slightly spoils a fabulous scope for visual when used with the likes of 31mm Naglers, though I understand that this part is much more important when holding a camera of one type or another.

Many thanks for linking Gunnar's thread, I must bookmark it.

Per,

What's Modeling, scope on the catwalk?

Alan

[Earl]

Im not sure my fingers are up to a focuser upgrade i do struggle with the intricate dexterity needed still, but it is improving, besides i know a man who can so id probably go that route

[John]

I've found this a very interesting thread because I'd considering a 190MN but for visual observing rather than imaging

It might fit nicely between my ED120 refractor and my 12 inch dobsonian.

[Stu]

Great minds and all that John , I've often wanted to give one of these a go

[Earl]

im under the impression that some consider these capable of giving a 5" APO a good run for its money?

[alan potts]

Earl,

Visually I would say larger than that, knocking on the 6 door, though I don't have one of those yet. .

There seems to be a good deal of interest in these at the moment, I am sure there was one on Astro the other day 600 quid, to me that is a good deal for a top scope.

Alan

[ollypenrice]

Olly, I don't beieve what I have just read, it is the weather?

 

Alan

Heh heh, nope, it goes back a few years to an M13 done by the talented Steve Loughran with an MN190. It did out resolve, just, myown version in the TEC.

My big passion for refractors is that they are so consitently excellent. Reflector images are varied variable and depend on the skill of the imager to get them tickled up just so.

It is hot here though!

Olly

[perfrej]

"Modeleing" refers to building a mount model of the sky, something you have to do to reach the nirvana of unguided imaging. The 10Microns handle the maths behind this in-mount, while other products do it on the PC. A number of parameters are models, such as repeatable flexure, polar misalignment, cone error and focuser sag. When all these are measured, a set of complex parameters are calculated, similar to a polynomial curve fit, but applicable to the entire sky. At that point you don't need a guide camera.

What disturbs the modeling with a stock 190MN is both the primary flopping around and the focuser sagging, both in unpredictable and incosistent ways. The incosistencies makes the creation of a good model more or less unsuccessful.

After I modified the main mirror cell and finally got the Moonlite to behave almost like a focuser, the 190MN gave me one-hour unguided subs with perfectly round stars, something I never achieved with my FLT-98 with Feathertouch focuser.

/per