JD Astro Novice

Ah so It’s collimated correctly in that case then. It naturally wants to be offset towards the primary mirror when I tighten both screws gradually. It’s confusing as the user manual states everything must be centred and concentric. I really feel for people who didn’t have guidance like this back in the day. even makes me wonder how on earth Issac Newton collimated this 😂 just to clarify what are you referring about to as a & b in that example?

Can I also ask should the reflection through the Cheshire be slightly offset towards the focus tube? In order to get the both circles concentric and centred? When you look at my picture the inner most circle is centre however in order to achieve this 2 of the adjustment screws are loosened. If I tighten both then it forces the inner circle to move offset towards the focusser. Almost indicating it should be offset. reading the Astro baby guidance it says for fast Newtonians like mine the skywatcher classic 200p it should be offset not directly centred. Any advice would be great as obviously when moving it around will knock the collination out for secondary without the screws tightened. unless of course I need to perhaps tighten the centre screw down more then tighten the smaller screws. Or the other way around.

Thank you for this, given me a lot of peace of mind. Where I had to play with this quite a bit when first setting up it hasn’t given me a lot of confidence that I have an accurate set up for observing. feels like a bit of relief getting your analysis above on the collimation and nod that it’s correct. I feel like it’s clicked for me now, the sheets of paper helped do that and the collocation cap. I think I assumed just using a long Cheshire site tube would just do it all for me and it really didn’t. Great for the final part e.g. alignment of primary with secondary etc. but the set up of the secondary is the hardest part. what I did find though was I couldn’t fully tighten one of the fine adjustment screws without moving the secondary, so I’ve left only one slightly slack as I’m conscious I’ll mess up what I’ve done.

Thanks Ricochet, this is super helpful! So I think I have cracked it which was down to making a collination cap and not relying on just the long Cheshire. In addition I used the 2 pieces of coloured card method and this helped me see whether the secondary mirror was circular or not. Oddly when I removed the cards it was then a circle from the adjustments with the small screws. I’m not sure why my eyes couldn’t see this as a circle previously but atleast were there I think. Also in the Cheshire it does show all primary clips whereas the cap does so I think that’s what threw me also. I’ve attached a pic of the Cheshire view and then the cap, let me know if that’s what I should be seeing as you mentioned I have been pulling my hair out for about 4 days doing this l 😂.

Thanks Both, appreciate the extra info. I have to admit Spile those steps in the link you sent me aren’t really written in a way for a complete novice like me and loads of other guidance just differs so much. I really need a lehmans description as I sort of get lost when you ref a=b and an offset to x etc. I understand the components and the parts and the purposes. I managed to get a slightly less shaped oval but still can’t get a perfect circle no matter how much I adjust. I’ve followed the initial steps and the veins are all equal. I haven’t loosened the centre screw and only adjusted with the 3 small screws. This still only results in an off centre alignment with the secondary mirror through the Cheshire. Even with this and then alignment of the primary I managed to get a pretty perfect view of the moon tonight with great detail so is it really out of collimation? I then get thrown when looking at a bright object like Mars and when I focus right out it is clearly not aligned with quarter of the primary out of shot. it’s odd that I don’t see many people on here struggling with the secondary shape but I’m assuming it’s what is causing me all the grief. I think I may need to completely reset and tighten everything and then start again? oh and the secondary is under the focusser so that seems to be all good. Any lehmans steps you’d advise me to do would be great from like a reset position. Unfortunately this is all so new to me so you’ll have to bear with me.

Hi guys, apologies in advance if I was supposed to just post this on an existing thread I’ve only just joined today. I can appreciate this is a really common topic that’s probably been discussed a lot and I have read up on here a bit but I’m still at a loss with a few things. I personally chose to go with a Cheshire eye piece to collimate as most forums and YT videos mentioned these can also be out of collimation. When I set up my telescope, at first glance it appeared to be okay in terms of what “good” looks like e.g. 3 primary clips, centred secondary mirror (black) and then the eyepiece reflection with the cross hair inside the circular doughnut. However, from looking at the secondary mirror in the eyepiece this is not a perfect circle, it is somewhat of a tilted oval shape. Now, the instructions in the manual state this should be a circle, and so do the majority of images and instructions on YT. Therefore, I have done just about everything I know to get that mirror circular e.g centre screw adjustment, and the 3 small screw adjustments, rotating the mirror and attempt to tilt it but nothing in the view changes it. Only thing I haven’t done is check the length of the spider veins so that could be something? also when looking through the Cheshire should the cross hair be in line with the veins reflected in the primary mirror? any advice would be great guys, I don’t mind doing stuff like this but without anyone there to show you I have no idea if what I’m looking at is fine as on a few videos I’ve seen the oval shape of the secondary mirror is viable so it could be fine. cheers