Help with focouser

[popeye85]

Evening all.

I recently got a Hotech laser from FLO however after a few uses I noticed that every time I inserted it into the focuser it was showing that collimation was of. So suspecting that the laser was out I inserted it into the laser, slacked it off slightly, and rotated it-sure enough a very obvious circle was getting "drawn" on the primary.

I contacted FLO about the issue however they replied that it was more likely that my focuser wasn't square.

What's the best way to check this? It's a moonlite focuser on a 12"SW truss.

Cheers.

Popeye

[Armand Popa]

You can check the laser on a 5m distant wall. You put in on a mount that hold`s it strait (v-block jig)  and  you can put a piece of paper on the wall where the laser point is. Make a sign on the paper than turn the laser, then make another sign and so on. I the marks you have done on the paper ,makes a circle, then your laser has a problem.

Mine had the same problem. I solved it after 2hours  it is not so complicated as it looks

[popeye85]

41 minutes ago, Armand Popa said:

You can check the laser on a 5m distant wall. You put in on a mount that hold`s it strait (v-block jig)  and  you can put a piece of paper on the wall where the laser point is. Make a sign on the paper than turn the laser, then make another sign and so on. I the marks you have done on the paper ,makes a circle, then your laser has a problem.

Mine had the same problem. I solved it after 2hours  it is not so complicated as it looks

Thanks @Armand Popa.

The Hotech website actually advices against using a v-block to check collimation-and to be honest due to the design of the Hotech I'm not sure what jig would do the job-it's fairly short with a lot of weight on one end so would just topple over! 

I think I need to check the focouser anyway-if the laser is ok then it leaves the question what is causing it to be of 🤔🤔

 

[Armand Popa]

Hotech is a great laser, but just to be sure maybe you should check with another laser. 

[Ricochet]

1 hour ago, popeye85 said:

I contacted FLO about the issue however they replied that it was more likely that my focuser wasn't square.

Square to the OTA? That wouldn't make the laser precess as far as I know. If they mean that the internal walls of the focuser barrel are not parallel then maybe that could be an issue. Have a look at the inside of the eyepiece clamp in case there is anything obvious that could be messing up the registration of the laser. I would insert a cheshire into the focuser and rotate it whilst looking through it. If the cheshire stays pointed at a single spot you know the fault is with the laser, if it draws the same circle you know there is another cause.

I previously had a Hotech laser and had exactly the same problem with it. The cause was the self centring mechanism of the Hotech not self centring or even acting in a consistent way. Both the 1.25" laser and the 1.25"-2" adaptor showed exactly the same fault. Based on my experience, and having read other reports on this forum from people with the same issue, I would suggest you send it back and find a better use for your money. Even if it somehow is your focuser that is at fault, the laser is no use with it, so send the laser back.

[popeye85]

14 minutes ago, Armand Popa said:

Hotech is a great laser, but just to be sure maybe you should check with another laser. 

I wish I had one 🤣🤣 I'm sure it's a great piece of kit but not for me at the minute it isn't!

10 minutes ago, Ricochet said:

The cause was the self centring mechanism of the Hotech not self centring or even acting in a consistent way.

Now this does tally up with what I'm seeing. Even replacing the laser the same way with the target facing towards the primary I'm getting different results. If the laser was squint I would have thought the results would come back the same.