Bored of "First Telescope" Threads yet?

[johninderby]

So much easier just to use the proper tool. Yes more expensive but the perfect tool for the for setting up the secondary. 

https://www.firstlightoptics.com/other-collimation-tools/ts-concenter-2-adjustment-eyepiece-for-newtonian-telescopes.html

https://www.firstlightoptics.com/other-collimation-tools/ts-concenter-125-adjustment-eyepiece-for-newtonian-telescopes.html

Edited January 3, 2022 by johninderby

[Pixies]

46 minutes ago, DhamR said:

if I tilt it to lose the oval shape, I lose the reflection of the primary off the right hand edge. 

It's the rotation that is causing it to look tilted:

You need to get the secondary appearing perfectly circular under the focuser first - before worrying about the reflection of the primary in it. That's one of the hardest parts when first learning how to collimate. Once that's done, it very rarely needs adjusting. When the secondary is aligned under the focuser correctly, then you can start finely adjusting the tilt to get the image of the primary centred.

Get the secondary at the correct distance from the end of the tube and rotated so that the outer edge of the mirror surface appears as close as circular as possible in the focuser. Before you do this, have a check on any tilt that has been set up on the secondary assembly. It should start parallel with the vanes - i.e. all 3 adjuster screws should be at the same length. You might find that with your work so far, it isn't very level. Best start with it as close to straight as possible. In @Spile's guide, this part here:

This gap really needs to be parallel  when you start. It makes this stage a lot easier and with your open-tube design, it should be easy to see. You will be slightly adjusting the tilt later.

 

Does that make sense? Everyone describes this process in slightly different ways, but it's the same thing really. Once you get your head around what you're doing, it all fits into place. There are different tools to help - from the most basic collimation cap, sight-tube/Cheshire,Concenter - all the way up to systems costing far more than the scope! You can do it roughly just looking down the focuser, though.

 

 

[DhamR]

Yeah that's the first step I started with, but, as I explained to FLO via email, there isn't quite enough range in the central screw to get the secondary circular AND directly under the focuser. 

Agree that looks a bit rotated though, I'll have another play with it this week and try and sort that (if I haven't sorted it since that photo was taken). 

On another topic. I got a good view of Jupiter a night or two ago from our holiday apartment in a bortle 4, saw at least one band and managed to split two converging moons. The Plieades shone particularly brightly too, as did the double cluster. Unfortunately I didn't get much in the way of views of nebulae and galaxies because the owners of the property have it so well illuminated I was getting horrendous light interference on the secondary and the wind was a thwarting any attempt to hold things up to protect it.

So once I've sorted collimation, next step is to build a light shroud. 

 

[Spile]

I would first check the spider arms are equal in length and that your focuser is at right angles to the OTA* - see Initial Checks.

I would then get the blue, green and red circles as round and concentric as possible but close is good enough.

* See below from https://www.vicmenard.com/telescopes/addendum-to-perspectives.html

 

 

[DhamR]

The spider vanes and focuser are all fixed on the heritage 150P

[DhamR]

Ignore me pls

Edited January 4, 2022 by DhamR

[DhamR]

So that was me writing a really long post about collimation and how I thought the scope was wrong, I've since paid a bit more attention to the documents out there (including @Spile's excellent guide) and noticed the bit about the reflection of the secondary NOT being centralised in the view.  Now that I've accepted that, and concentrated on a) centring the secondary itself, and b) centring the primary in it, I'm pretty bang on.

I also had a Svbony laser collimator arrive, but it's so loose in the focuser, that I'm more confident in my collimation by eye than I am that it is well collimated itself.  It's going back up the Amazon either way. 

So good in fact, I decided to ruin it by again sticking a big heavy weight on the end of the struts 

Really struggling to get the moon sharp, it almost always looks soft, but I'm taking it as the fact that it's low in the sky and over rooves rather than my focusing, as I managed to also get the below snap of Orion's Nebula (10s at ISO 1600) it's not perfect, but I'm pretty happy as it means I can show Mrs ham what I've spent all night staring at

Visually I got great views of Jupiter today, very clear banding, and the four Galilean moons. M42, M45 are two favourites from my garden due to how easy they are to find, plus darkness of the sky in that direction and the lack of obstructions.  I got probably the best views of M31 I've had so far too (although best if I didn't look AT it and therefore too dim to know the camera was pointing the right way to get a photo of).  Tried to spot M101 but nothing doing.

 

Edited January 6, 2022 by DhamR

[happy-kat]

That's great to read you've sorted it now.