Spile

The best way to rule out collimation as a potential issue is to check the alignment of your mirrors. If your secondary is concentric a=b=c=d and e=f and the primary donut is in the middle of the ring of the cap then your good to go.

On 18/01/2024 at 20:19, Beardy30 said:

Sorry having issues with my phone - what sort of thing has everyone managed to shoot other than the moon? 

These are with a smartphone and NexYz unprocessed and no stacking.

Yes I have one and I’ve managed to grab some reasonable shots with it. One thing I have found is that with a heavier phone it can flex so be wary of that. It’s designed to allow movement across all three planes but it is quite heavy as a consequence. I don’t bother with any more because I have realised that actually seeing rather than recording floats my boat.

It’s a difficult question to answer. Almost certainly your telescope will spend most of its time gathering dust as you wait for the clouds to clear. Take into account that when it is clear seeing might be poor or you might have something else to do and that might lead you to think it’s not worth it. It is for me because I am not in a rush to do everything and am in for the long game.

As @Ricochet states, the star test will not tell you if your secondary is misaligned and in addition to the check list above, it needs to be carried out under high magnification.

Personally the 8” is the right weight and size for me. If you are unsure about the 10”, I would go and see one to see you can accommodate it.

My guide explains the relationship between the outer screws and central bolt which work in a push pull way. As @Ricochet says in order to confirm the secondary is aligned you need to see the outside of the sight tube. Place a sheet of paper behind the focuser and take the picture again. This is what you are aiming for…

A great price and the straight through finder is easily swapped for a RACI. I don’t like the rack and pinion single speed focuser though.

Note that a laser will not confirm or otherwise that your secondary mirror has offset error. It’s much easier to check for secondary errors with a Cheshire eyepiece and sight tube combination tool and in addition you won’t get distracted by registration or collimation errors.
 

On 05/01/2024 at 21:29, greenery said:

OP here. I finally got round to tweaking collimation. First just did the primary. Should have stopped there. Then decided to try to improve the already pretty good concentricity. Slightly loosened the 3 secondary screws, slightly tightened the centre screw. Only 1/4 turn on former. Result: massively worse. An hour of fiddling and it's now maybe similar to how it was. A bit off-putting but hopefully on path to knowing what I'm doing.

It will be because after adjusting the offset with the centre screw which is a coarse adjustment you will always need to change the tilt and probably rotation with the three outer screws. The good news is once a=b you don’t need to touch the centre screw again. Once you get “your eye in” it becomes second nature and far less daunting. Enjoy the views.

I used Baader film to build mine.

I find the secret to finding Mercury is to scan with binoculars first. Once you have found it with them you’ll know where to look with your eyes and then your telescope.

12 hours ago, Chandra said:

On the other hand, the final phase, the alignment of the primary mirror, is the simplest, but also the one that can most easily be lost when transporting or moving the tube.

Interesting that you find that. After transposting in my car, I find the primary mirror rarely moves. So much so, that I have kept the original adjustment and lock screws on the primary as I rarely need to adjust it. 

Very tight spider vanes reduced the number of times I needed to adjust the secondary.

23 hours ago, bosun21 said:

The OP has just bought a new scope. He has never collimated before so he should try it as is before messing with the collimation. They generally arrive reasonably collimated.

Indeed. I was reacting to the comment that those just starting should not attempt to move the secondary and of course not everyone starting will have a new reflector. To leave a badly aligned mirror as that comment suggests makes no sense.

If you are buying new I can see the reasoning about not adjusting the secondary but otherwise I cannot agree with that advice. There may be a number of reasons why a secondary mirror might be poorly positioned and it will be obvious when looking through a Cheshire eyepiece and sight tube combination tool or even a simple cap. If that is the case then it should be corrected. 

I have the same 2” eyepiece as you and I pair in with a Baader Hyperion IV zoom. Take a look at the keenly priced and recommended Svbony equivalent as it gets lots of recommendations on here.

Start with the 25mm supplied EP and develop your skills. When you are ready to upgrade I would recommend a zoom eyepiece. Although I have the Baader Hyperion IV you will see that lots of forum members recommend the excellently priced equivalent from Svbony so that is what I would recommend. 

I’ve just listened to the BBC Sounds version of this on Radio 4 and it’s not only different to the TV version, it is much much better. A lot of good practical tips and advice for the amateur. Highly recommended.

I’ve a 42mm GSO which works fine for large open clusters like the Pleiades although even that wasn’t wide enough for the coat hanger which was better in my finder.

12 hours ago, John_D said:

Are there any recommendations for an observing chair for a reflector telescope? I normally mix viewing and imaging and stand for the viewing and take a seat while the camera is doing its thing. But it would be nice to ba able to have a seat during an extended viewing session.

( +1 for the warm clothing, that makes a huge difference in my experience. I've been taking a flask of tea out as well recently which is very pleasant. Haven't tried the hip flask yet 😁 )

My chairs are here https://astro.catshill.com/denver-chair/ but I’ve been taken by the simplicity of the Lybar.

Looks good...

I’m going to recommend the zoom as well. Although I have and really like the Baader Hyperion IV, user reviews on here and CN suggests the Svbony equivalent is fantastic for the money.

Place a sheet of paper behind the focuser and take the picture with the outside of the sight tube visible because that’s the key point of reference.

The centre screw and three outer bolts work in push pull mode. When you are getting a=b the outer bolts will be loose and you’ll be either moving the secondary towards to primary by turning the central screw anti-clockwise OR moving it away from the primary by tightening the screw. Either way, the next step will be to tighten the outer bolts so the secondary is not “left hanging”.

The edge of the sight tube of the long Cheshire will confirm that a=b but a laser will not.

I’m not going to criticise another guide but one of the reasons I decided to write my own was because I either found the others confusing, unclear or contradictory. I wanted to ensure that what I had written was accurate which was why I spend a lot of time with Vic Menard (and also @Jason D to ensure this was the case. I am of same opinion as @Ricochet , the Cheshire eyepiece and sight tube combination tool to place the secondary and the cap to correctly tilt the primary. 
I also do not recommend covering the primary mirror when aligning the secondary because as my guide shows the reflection of the primary is a very useful point of reference so why would you want to hide that?

It’s important that you do everything in the right order. Start by getting the outside edge of secondary concentric beginning with the offset (a=b). See https://astro.catshill.com/collimation-guide/  Then get c=d and e=f by making small tilt/rotation adjustments.