Fast scopes view correctors

[bomberbaz]

I am aware that one of the issues faster scopes face is poorer viewing if your eyepieces are not up to it.

My query is if a scope is say F4.5, what arwe the extra bits of kit that are commonly used to help improve your viewing experience and hw do they work?

Steve

[John]

For newtonians the relevant device is the coma corrector. These correct the optical aberration called coma which is inherent in fast newtonian scopes.

A coma corrector won't fix aberrations like astigmatism which is an eyepiece defect. To reduce that you either need a slower scope or a better quality eyepiece.

Is that the sort of thing you were thinking of ?

[bomberbaz]

Well almost John.

I have read about them and come accross three that i know of that seem fairly popular choices. There is the Skywatcher, Baader MPPC and the the Televue Paracorr.

Obviously there is the quality thing here otherwise you wouldnt have a price range of just over 100 quid to 450! But what is the difference in real terms.

I just wondered if anyone may have used any of them and if they have any feedback on them. i know for a fact the Paracorr is going to win hands down, in fact i think Shane has one. So its more the other two I am querying.

See the thing is I can't get over the fact I had the 12" dob before and although I didn't have it long, I am pining for the aperture again. The 8SE is great but I definitely notice that missing extra detail when viewing. The Mrs has all but given in to me but only if its a flex-tube as it folds away but its F5 and would almost certainly benefit from a Coma corrector, especially with my mid range set of EP's. So I am making some enquiries as i need to know how much extra I might end up spending on accessories!

The 8SE along with the extras should more or less cover the cost of the scope if sold but its the extras that can soon add up!!

So question 2 is has anyone got either the Baader or Skywatcher coma correctors and how do they find them?

[Bukko]

Steve,

I have only used a corrector for imaging, as I have never been too bothered about the slight softening of the edges using an eyepiece.

I have an MPCC, used it for a while (just imaging) but needed more back focus for the OAG, FW, etc. so use a Rowe now.

As they don't sell my MPCC anymore, now the mk3, which I have not used.

Probably observers will help more, but I would consider the connections - the correctors are designed for 2", so I am not sure how you would adapt to 1.25" EP's, but I am sure it's not difficut, just needs some bits..

Also, there are optimum distances between the CC and EP(or camera), so again, maybe someone with more experience will help.

Optimal focal ratio. CC's are designed for a specific FR. If I rmemeber correctly, the Baader MPCC is optimised for f5, but will largely correct from f4 to f6

The final thing is the MPCC is a 1:1 - it does not change the FL of your scope, I think the SW is a 0.9, so creating a wider FOV.

If you have the scope and want to borrow the MPCC, then PM me, I am happy to lend it, but it is not for sale.

Gordon.