Any reflector “experts” in England?

[a6400]

1 minute ago, Ricochet said:

Yes, for primary collimation. For collimation in the dark I would suggest leaving the secondary and just doing the primary. You could use a normal laser method you half do the secondary but if you've collimated in the light the secondary should be much less prone to movement than the larger primary. 

I have to reassemble the scope every time and want to make sure both mirrors are aligned.

Normal laser method isn't really trustworthy afaik unless you have some ultra expensive laser.

[CraigT82]

I’ve just remembered the ES ultralight dobs are primary collimated from the front and can be done whilst looking through the eyepiece? If that’s the case I’d stick with the simple Cheshire sight tube and shine a light down at night. 
 

Do you need to collimate the secondary each time you set up? That’s a bit trickier to do on the dark. 

[a6400]

2 minutes ago, CraigT82 said:

I’ve just remembered the ES ultralight dobs are primary collimated from the front and can be done whilst looking through the eyepiece? If that’s the case I’d stick with the simple Cheshire sight tube and shine a light down at night. 
 

Do you need to collimate the secondary each time you set up? That’s a bit trickier to do on the dark. 

With cheshire eyepiece don't you need light to go both here:

and both mirrors to be able to collimate?

[CraigT82]

2 minutes ago, a6400 said:

With cheshire eyepiece don't you need light to go both here:

and both mirrors to be able to collimate?

Usually just shining a torch on the angled face of the Cheshire a enough.  That reflects enough light down the tube to do the job 

[a6400]

6 minutes ago, CraigT82 said:

Usually just shining a torch on the angled face of the Cheshire a enough.  That reflects enough light down the tube to do the job 

It would be hard to do all of this without second person.

I mean holding/using that long  collimation rod while looking through cheshire and holding a light at the same time in the darkness... 😅

Or maybe I'm too pessimistic but I wish there was an easier way haha.

Edited September 30, 2023 by a6400

[niallk]

2 hours ago, a6400 said:

I have heard of Barlowed (any barlow) laser collimation and that the laser doesn’t have to be itself collimated.

Is that an option?

Initial secondary alignment requires a collimated laser.  The barlow lens is inserted into the path for primary alignment.

My solid tube 250px rarely needed collimation adjustment.

My truss Obsession 15" dob requires both secondary and primary mirror adjustment every time it is assembled.  Takes 2 mins in the dark with a laser... to me *much* handier than using a Cheshire/sight tube in the dark.

[a6400]

24 minutes ago, niallk said:

Initial secondary alignment requires a collimated laser.  The barlow lens is inserted into the path for primary alignment.

My solid tube 250px rarely needed collimation adjustment.

My truss Obsession 15" dob requires both secondary and primary mirror adjustment every time it is assembled.  Takes 2 mins in the dark with a laser... to me *much* handier than using a Cheshire/sight tube in the dark.

And do you know a good laser that's also easy to collimate?

I have a Badeer Mk3 and SVBONY laser but both are probably not collimated and hard the Badeer one I think doesn't even have the option to collimate it.

I wish Howie Glatter was available here. (and didn't cost fortune)

 

There is also Ocal Electronic Collimator but I'm not sure it works in the dark.

 

Also is TS Concenter 1.25" better than Cheshire?

Edited September 30, 2023 by a6400

[Captain Scarlet]

I’ve heard that Hotech laser collimators are reliably true out of the box. Although not dirt cheap, they are not crazy like the Glatter ones. £145 from FLO. @Stu has had experience of them I think.

[a6400]

Just now, Captain Scarlet said:

I’ve heard that Hotech laser collimators are reliably true out of the box. Although not dirt cheap, they are not crazy like the Glatter ones. £145 from FLO. @Stu has had experience of them I think.

I remember seeing the opposite a couple of times on other forums. Hmmm

It's important for me that it's easy to collimate the laser itself also.

[CraigT82]

2 minutes ago, a6400 said:

I remember seeing the opposite a couple of times on other forums. Hmmm

It's important for me that it's easy to collimate the laser itself also.

Have you checked the Svbony and Baader units you have? Just rotate them in the focuser and see if the dot wanders on the primary. I think a laser is going to be the best option for you to collimate both primary and secondary on the dark 

[a6400]

delete...

Edited September 30, 2023 by a6400

[niallk]

3 hours ago, a6400 said:

And do you know a good laser that's also easy to collimate?

I have a Badeer Mk3 and SVBONY laser but both are probably not collimated and hard the Badeer one I think doesn't even have the option to collimate it.

I wish Howie Glatter was available here. (and didn't cost fortune)

 

There is also Ocal Electronic Collimator but I'm not sure it works in the dark.

 

Also is TS Concenter 1.25" better than Cheshire?

Sorry, I can't comment on ability to collimate other brands.  My Astrosystems laser is well collimated from factory.  You can check your own lasers with a v-wedge and a wall: rotate and see if the laser spot remains fixed and does not describe a circle on a distant wall.

I did purchase a TS Concenter: it's useful to centre the secondary under the focuser, if you don't have a sight tube.  But it has too large a peephole imho - vulnerable to parallax errors.

A Cheshire can be used to collimate the primary - a concenter cannot.

Edited September 30, 2023 by niallk

[Ricochet]

17 hours ago, niallk said:

A Cheshire can be used to collimate the primary - a concenter cannot.

Can you not align the primary doughnut with the more central rings then?

[bosun21]

19 hours ago, a6400 said:

I remember seeing the opposite a couple of times on other forums. Hmmm

It's important for me that it's easy to collimate the laser itself also.

I have used a 2” Hotech laser for my reflector telescopes ranging from 6”-12”. It arrived perfectly collimated and is a very reliable piece of kit. I can collimate my scope then remove and reinsert the laser and it’s still bang on. I set my secondary initially with a concenter and cheshire and everything thereafter I use the laser. It’s invaluable in the dark.

[a6400]

29 minutes ago, bosun21 said:

I have used a 2” Hotech laser for my reflector telescopes ranging from 6”-12”. It arrived perfectly collimated and is a very reliable piece of kit. I can collimate my scope then remove and reinsert the laser and it’s still bang on. I set my secondary initially with a concenter and cheshire and everything thereafter I use the laser. It’s invaluable in the dark.

And in case it loses collimation (the laser), can you collimate it easily?

 

also afaik laser is used mostly to collimate primary?

I have tried using a laser once and could easily make the laser hit the spot on primary and reflect back on secondary in same spot and show on the laser crosshair.

So I am confused about it a little bit.

Edited October 1, 2023 by a6400

[bosun21]

4 minutes ago, a6400 said:

And in case it loses collimation (the laser), can you collimate it easily?

 

also afaik laser is used mostly to collimate primary?

I have tried using a laser once and could easily make the laser hit the spot on primary and reflect back on secondary in same spot and show on the laser crosshair.

So I am confused about it a little bit.

I have never needed to look at collimating the Hotech as it arrived perfectly aligned and still remains so years later. I treat it like a precision instrument and never handle it roughly so losing collimation isn’t a worry. Using it itself is very straightforward and intuitive.

[niallk]

2 hours ago, Ricochet said:

Can you not align the primary doughnut with the more central rings then?

OK, maybe what I said is incorrect!  I only use it for secondary centering.

I collimate in the dark so always use a barlowed laser.

Personally I'm not confident that this tool is more accurate than a Cheshire for primary tilt?  I must try it.  I defer to others who successfully use it as a one-stop, complete collimation tool!

Rather than risk derailing the thread, best to take my post with a fist of salt!!  Apologies for any confusion caused.

Edited October 1, 2023 by niallk

[John]

If you want a laser that is reasonably straight forward to collimate, consider one like this:

 Astro Essentials 1.25" Laser Collimator | First Light Optics

Not the most expensive by any means and it will probably need collimation but the 3 adjusting grub screws (you can see one in the picture) are readily accessible and the unit is symmetrical so that it will sit easily in a V-block to be rotation tested (at a distance of 20-30 feet ideally) and collimated.

I've had the Baader and it's shape does not make it easy to collimate, IMHO. I also had a Hotech once and that was out of collimation as well !

Once you get these lower cost ones collimated, they tend to stay that way.

 

[Spile]

If you want to check a laser is collimated and registered in the focus tube, rotate it and see if the dot “walks” around the donut. Basically it shouldn’t.

[John]

7 minutes ago, Spile said:

If you want to check a laser is collimated and registered in the focus tube, rotate it and see if the dot “walks” around the donut. Basically it shouldn’t.

Personally I use the V-block approach and a flat surface around 20 feet or more away with a "target" marked on paper stuck to the surface. If I can rotate the laser around 360 degrees without the dot wandering more than a mm or two, I'm happy.

The process is described in the first section of this webpage:

SCT Collimation (nightskyimages.co.uk)

 

[a6400]

3 hours ago, John said:

Personally I use the V-block approach and a flat surface around 20 feet or more away with a "target" marked on paper stuck to the surface. If I can rotate the laser around 360 degrees without the dot wandering more than a mm or two, I'm happy.

The process is described in the first section of this webpage:

SCT Collimation (nightskyimages.co.uk)

 

Yes this is a much better approach.

I don’t know how people test it by rotating in a focuser as there is always some movement sideways.

I will try the „V” method again, the problem with the Badeer one is it’s awful irregular shape.

[CraigT82]

5 hours ago, a6400 said:

Yes this is a much better approach.

I don’t know how people test it by rotating in a focuser as there is always some movement sideways.

I will try the „V” method again, the problem with the Badeer one is it’s awful irregular shape.

You don’t need V blocks just to check the laser. With it in the focuser just unclamp the laser, turn it 180 degrees and reclamp it and see if the dot has moved which would tell you the laser collimation is out (or your focuser is rubbish).

If it is out you will need V blocks and paper on the wall to recollimate it.

[John]

9 hours ago, CraigT82 said:

You don’t need V blocks just to check the laser. With it in the focuser just unclamp the laser, turn it 180 degrees and reclamp it and see if the dot has moved which would tell you the laser collimation is out (or your focuser is rubbish).

 

I'd be looking for more precision than that which is why I suggested testing / adjusting the laser over a 20 feet+ range. For an F/4.5 newtonian the collimation "sweet spot" is just 2mm in diameter at the focal plane.

 

Edited October 3, 2023 by John

[AstroMuni]

20 minutes ago, John said:

I'd be looking for more precision than that which is why I suggested testing / adjusting the laser over a 20 feet+ range. For an F/4.5 newtonian the collimation "sweet spot" is just 2mm in diameter at the focal plane.

At this rate, the OP will have to go to a 'professional' collimator 😉 Dont scare the OP too much chaps

@a6400 I was in similar boat around a year ago and I joined the local astro club. Friendly members have helped me collimate my scope so my suggestion is join club 🙏

Edited October 3, 2023 by AstroMuni

[CraigT82]

36 minutes ago, John said:

I'd be looking for more precision than that which is why I suggested testing / adjusting the laser over a 20 feet+ range. For an F/4.5 newtonian the collimation "sweet spot" is just 2mm in diameter at the focal plane.

 

Yes I'd agree that V blocks would be more precise, however I'd counter that by saying that precision is not necessarily required, as any collimation method that involves clamping a device in your focuser will only get you close as there are too many uncontrolled variables. e.g. is the geometric centre of your mirror coincident with the optical centre, does your focuser clamp your eyepieces in the exact same way as your collimation device and is that repeatable and consistent etc etc...

For a true collimation the only method that eliminate those variables is to do it on a star, but granted that has it's own issues