SkyWatcher Newtonian Collimation Eyepiece (Cheshire)

[Alex_o0]

Hi Friends,

I have just received my  SkyWatcher Newtonian Collimation Eyepiece (Cheshire) in mail and watched I few videos regarding alignment.

My questions are :

1) is the Cheshire inserted and faced the right way ? that wasn't really clear in the videos I watched.

2) Are any further adjustment required in your opinions?

Telescope :skywatcher 150p heritage 

 

 

[CraigT82]

It can face any way you want, you want the shiny angled face in the cheshire to catch the light, so I usually face it up to the sky or to a nearby light soirce if at night.  

You may want to pull it out of the focuser until you can just see the edges of the secondary mirror, can't quite tell if you can or not from the photos? 

[Alex_o0]

24 minutes ago, CraigT82 said:

You may want to pull it out of the focuser until you can just see the edges of the secondary mirror, can't quite tell if you can or not from the photos? 

Is this what you mean

[CraigT82]

Yeah that looks OK, if we are being really picky the secondary may need shifting towards the 10 o'clock position very slightly but that slight misalignment may just be from the focuser sagging a little. Personally I would leave the secondary alone here. How does the primary collimation look? Is the dot in the donut? 

[Alex_o0]

Thank you 😊 

10 minutes ago, CraigT82 said:

How does the primary collimation look? Is the dot in the donut? 

It’s in the donut yes but it’s does not align with corsair of the Cheshire, is that fine ?

[CraigT82]

Ideally it would align however I think what you've got there is good enough, as I think perfect collimation will never be possible considering that this is a flex tube with a plastic helical focuser (if you turn the focuser the collimation will probably change, same as if you put light pressure on the cheshire with a finger - it's just the slack in the focuser)

Don't worry too much about it though as the difference between perfect collimation and good enough, in terms of damage to image quality, is dwarfed by the damage caused by our atmosphere! 

A common mod on this focuser is to put a wrap or two of PTFE tape around the threads, this helps to take up some of that slack. 

[John]

Good advice from Craig

Re; your 1st photo - I suppose that is a shadow on your secondary mirror rather than a felt pen line, which it looks a little like ?

 

 

[Alex_o0]

On 12/09/2020 at 18:36, John said:

Good advice from Craig

Re; your 1st photo - I suppose that is a shadow on your secondary mirror rather than a felt pen line, which it looks a little like ?

 

 

It does look like that doesn't it, thankfully its only a reflection 😅