Collimation cap versus Cheshire eyepiece

[MarkF]

I Have a cap do I need a Cheshire eyepiece or do they do the same thing?

Any advantage to spend out 25 quid over the free cap I got with my scope complete with doughnut stuck on?

If there is which eyepiece to buy, the cheapest?

[brianb]

Is your scope f/8 or slower? If so the "cap" will be sufficient. Faster scopes get increasingly less tolerant of collimation errors (fourth power), a Cheshire eyepiece - or an accurately collimated laser collimation tool - is more sensitive.

[Astro_Baby]

Whats the scope ?

[MarkF]

Its a 114 f8 reflector, so I guess a cap is sufficient until I upgrade just struggling with it atm as I am getting a ghost image on planets and cannot get a decent collimation. I did twiddle with the secondary, I reckon I need to twiddle a bit more with it.

But its good to know as the plan is a jump to a 10" Dob but that could change any second.

[Rusty Strings]

With a shorter focal length, F5 for example, it's a good idea to have both. The cap is useful when adjusting the secondary as you need to see the primary mounting clips and the cheshire doesn't give a wide enough field of view, the cap, on the other hand, doesn't have the cheshire's crosshair to enable accurate adjustment of the primary.

[Llamanaut]

not trying to flog them at all but the hotech is so easy to use... a bit pricey but its the mutts!

[MarkF]

Yep, that hotech looks very good, but the price doesn't, if you had the 1.25 and then upgraded to a scope with a 2" focuser you would have to buy the adapter for another 30 quid otherwise I would think you will get slop using the thumbscrew and adapter for the scope.

So the cap should do me for adjusting the secondary, I can't quite see how the hotech is used to adjust the secondary, bearing in mind I have no doughnut sticker on my primary. Still if I bought the Hotech it would more than double the value of my scope

I think I might just slacken everything off on the secondary and go for broke as it were, I have read Astrobaby's collimation page but I cannot do some of the adjustments as the secondary is a single fixed arm.

[LukeSkywatcher]

I'm gonna say just use a cap. I used a homemade one on my 130P when it arrived...having never collimated a scope before and it seems pretty accurate.