Focuser - Helical vs Crayford

[SDV]

Hi all! My name is Sergey, I'am from Latvia, Riga, Baltic States.

Recently I have finished my first ATM project - 16" Dobsonian, made from Explore Scientific 16", although there was used only main mirror from ES setup   . Some pictures are attached.

Now I'm starting a new project - 12" from Orion Truss Tube Dobsonian, the idea is to make more compact and lightweight setup, then now it is. Not super-compact, like Obsession UltaCompact, something in the middle between them.

I want to ask your opinion about focuser for my new project.

In 16" I used Moonlite 2" Crayford. Everything is OK, it works very well, but for the new project I consider something other and cheaper  .

I think about getting new Omegon Steeltrain Helical focuser. Anyone have any information about it? And, also what you think about that kind helical focusers?

Of course, if the helical focuser is the wrong way, then I can just order Moonlite Crayford as I did before.

Thanks,

Sergey

P.S. Sorry for my funny English, i was lazy in English lessons 25 years ago 

[skybadger]

_{Hi Sergey}

_{That looks nice.}

_{Since the largest single weight on the secondary cage is the focuser (other than the cage itself) I would recommend a helical since they are so much lighter than the crayfords, unless the moonlights are made from alloy and lightweighted as well. I used a revelation focuser to start with on my first truss tube and it was much too heavy. I replaced it with a Borg helical focuser and it was light enough I could remove some counterweights. Its much harder to automate and has the problem that if you are imaging, they can still tilt under the weight of the camera as the length of intersecting threads gets shorter.}

_Mike

[SDV]

Hi Mike! Thank you for your reply.

I do use counterweights in my current 16" setup. Actually, I'm very happy with this solution. 

You can see this in the last photo - stainless steel bars attached to the top side of the mirror box. It is not a very big problem to install them before use and remove after. I use 2, 3 to 4 bars, about ~1,45 kilo each. This allows me very flexibly regulate tube balance.

In 12" project I plan to use something similar. So, focuser weight is not so critically important.

Although, the Moonlite focuser comparably light - about half kilo, as written in specification. Sadly, no info about discussing helical focuser.

I found some articles about helical focusers, seems there is is some problems, mainly dirt on threads, as i understand. But this Omegon Helical looks like new version...

The question 239€ for Omegon Helical, or 317€ for Moonlite Crayford.

After some hours reading topics, seems Moonlite is more preferable choice.

[Moonshane]

No question. Moonlite at those prices.

[SDV]

No question. Moonlite at those prices.

OK, thanks. Moonlite then.

[skybadger]

Or the omegon for 79 Eu. Depends what your criteria are.

M

[Lowjiber]

Get a MoonLite again.

My experience with helical focusers is that they don't have the range of back-draw one really needs.  That said, if one mounts one on the back end of a R&P or Crayford they can be a useful tool for fine focusing.  However, for a stand-alone focuser I won't ever use one again.

[skybadger]

Get a MoonLite again.

My experience with helical focusers is that they don't have the range of back-draw one really needs.  That said, if one mounts one on the back end of a R&P or Crayford they can be a useful tool for fine focusing.  However, for a stand-alone focuser I won't ever use one again.

I would agree - theonly focuser that gives you the range of draw you need is a refractor focuser. All the other will leave you messing with spacers. The minimum distance for focus must be 50mm for me - the DSLR lens to focus distance.

But then I have chosen to use spacers to achieve the low weight.

Mike

[mapstar]

That's a lovely looking scope Sergey

I am making a light weight scope too although at F3.5 I need something that will hold a coma corrector.

For your next build I'd agree with everyone above about the moon lite

Damian

[callump]

If you're looking for something low profile and light weight, you could try the Kineoptics helical crayford.

http://www.kineoptics.com/HC-2.html

Callum

[SDV]

That's a lovely looking scope Sergey

I am making a light weight scope too although at F3.5 I need something that will hold a coma corrector.

For your next build I'd agree with everyone above about the moon lite

Damian

Thank You!

Moonlite is excellent focuser, no doubt. But...

What is your opinion about this Omegon Low Profile Crayford 199 EUR vs Moonlite 317 EUR?

Now on Orion OTA i have this Crayford, don't like it. For ATM project better to find something other, in my opinion.

And, Unihedron SKY-L arrived   .

Tonight is clear sky, i will make first sky measurements with it.

[SDV]

Strange. I can't edit my post just after few secs after i sent it.

Anyway, here is Unihedron SKY-L photo.

[mapstar]

Hi Sergey

I can't really comment on the omegon focuser as I've never seen or used one.

I will agree that the one you have on your orion scope is awful. I used to have the same thing and could never get it to quite work right even after modifying it.

The moon lite is more expensive but when you see the build quality it is evident where the extra money goes.

If you ever need to sell it on it will be a better investment as it's much more desirable

Damian

[SDV]

Hi Sergey

I can't really comment on the omegon focuser as I've never seen or used one.

I will agree that the one you have on your orion scope is awful. I used to have the same thing and could never get it to quite work right even after modifying it.

The moon lite is more expensive but when you see the build quality it is evident where the extra money goes.

If you ever need to sell it on it will be a better investment as it's much more desirable

Damian

OK, thank You!

Next week I plan to order one of them, so I have little time to think.

I have made measurements with SKY-L meter at my garden - it shows something around 20,5-20,6. Yellow zone according this map.