Wanted: Paracorr

[MortonH]

I love my new Dob, but the coma is a bit annoying, although not enough at this stage to convince me to pay full price for a new Paracorr.

Anyone got one they're prepared to part with?

Thanks

Morton

[richardo (Rich)]

Morton,
go for the Baader MPCC corrector, for one thing, what ever your F ratio is, it will stay at that. The Paracorr will slow your FL down by 1.15xs and is expensive new.
Sooo if you have a Dob @ F5 then with the Paracorr it will become F5.75...
The Baader is far cheaper and does a very good job.
Here's a link to Steve Massey's shop..... btw I'm not affiliated with him in any way, just bought stuff off him and he's a top bloke.
Here's a link....
http://www.myastroshop.com.au/

Cheers
Rich

[MortonH]

Thanks, Rich. Only problem I see with the MPCC is that you have to thread it into each eyepiece you use, which would get a bit old after a while if you change eyepieces regularly while observing. I can live with a slight increase in focal length as I'm only interested in visual observing. But you're right about the price. If I can't find one second hand then I'll be putting up with the coma!

Morton

[richardo (Rich)]

Hi Mort,
I just naturally thought you were going to use the dob for imaging.
So I can see your point!
The Televue Paracorr would indeed be the idea corrector for your use.
Make things a lot easier when changing out EP's..
Good luck with the search.
I think these things would go like hot cakes I'd reckon.
Don't see many second hand on astromart either.
But you just never know!

All the best
Rich

[gbeal]

There was one there today (Astromart) and I gave thought to notifying Morton, but by the time I did, it was gone, Quick and the dead, a bit like StrikerMart.

[Starkler (Geoff)]

I think in 2 years on IIS I have only seen one offered for sale.
But if I see one at a good price I'll snap it up myself

[Rodstar (Rod)]

I am on the hunt for one too, so it would seem that if someone has a truckload of Paracorr's to sell, they may hit gold if they find their way to this site.

[Ambermile]

Well, I sold mine a few weeks ago now. To tell the truth it didn't make that much difference on the big dob, and you have to remember that although you are worried about swapping out the MPCC between EP's you still have to tune the Paracorr for each one... Also as mentioned there's that FL increase - which I think is a bit naughty in this instance as a barlow will also reduce coma to a certain extent for much less on the pennies front

Oh - and you can't use some barlows with the Paracorr

Arthur

[Rodstar (Rod)]

Originally Posted by Ambermile

To tell the truth it didn't make that much difference on the big dob
Arthur

I have found that my f/5 mirror causes quite a lot of coma on my 22 Panoptic, and it is bugging me to the point that I really have to do something.

I know a couple of blokes who swear by the TV Paracorr....they say that on an 18" f/4.5 mirror the Paracorr brings out excellent correction, and although you would think that the extra glass cuts down the light transmission, in fact because it brings the stars to a sharp point, a whole lot of extra stars which are just outside the range of visibility when coma-smeared without the Paracorr, become visible with the Paracorr. Suddenly globs have double the number of stars......

I am also led to believe that coma correctors have a more pronounced effect on lower mag EPs. That is to say, you will have far more benefit using one with an EP in the 20-35mm focal length range than below that. Ironically, it is the widefield views, such as open clusters, where you want to have sharp stars to the edge of FOV.

[MortonH]

At the moment I only have three eyepieces - the ones that came with my 8" Dob (my good eps are elsewhere just now). With the 32mm GSO wide view, the view is so wide that I don't notice any coma at the edges. The other eps are 15mm and 9mm. With both these eps I notice the coma. It's also noticeable on Jupiter when it reaches the edges of the field and the detail just gets smeared out.

The dilemma is - a new Paracorr costs almost the same as a used HEQ5 mount. So do I buy a Paracorr or get a mount and keep the objects in the centre of the field of view? Of course, buying a mount ruins the whole convenience factor of a Dob, but I'm tempted to get a mount anyway to try some imaging, so maybe it's a better option.

Either way, you wish you could either not spend the money or else spend it on improving your eyepiece collection.

Morton

[AstroJunk (Jonathan)]

Originally Posted by Ambermile

Also as mentioned there's that FL increase - which I think is a bit naughty in this instance as a barlow will also reduce coma to a certain extent for much less on the pennies front

It's not a big deal - 1.15, and is done to aviod having to shorten the tube by 2". Surely that's thoughtful design?

PS Dear Moderator, some naughty boys have hijacked this thread to talk about a very interesting subject. Could you please make things good again and perhaps split it so we can leave Morton in peace. Sorry M!

[Ambermile]

Originally Posted by MortonH

The dilemma is - a new Paracorr costs almost the same as a used HEQ5 mount. So do I buy a Paracorr or get a mount and keep the objects in the centre of the field of view?
Morton

Tough call - unfortunately I can't do the same with the big beast, it would be some EQ mount

I have therefore taken the plunge and gone the ServoCat/ArgoNavis route instead Whilst there's a lot to be said for push to and learning the skies, there's a *whole* lot more to be said for not falling off a five foot ladder in the dark whilst trying to keep something in the FOV

Arthur

[GrahamL]

Morton both medium power eyepieces i got with my dob are pretty ordinary to look through .. ok but nothing special...
(I'm being a little kind here towards them to IMO )


If this is your problem The little I have read says a parracor may only improve things a little .. a few extra dollers spent around these
focal lengths may well fix things enough to allow you to buy the mount
as well.