Paracorr or Paracorr Type 2?

[Tiotion (Jack)]

Hi all,
I want to buy a Paracorr and ES 14mm while the prices are super low. Just trying to figure out if I need a Paracorr or Type 2 for my 16" 4.5. I see the Type 2 is more for faster scopes (f3/f4)but i figure i just want to make sure.

Cheers
Jack

[xstream (John)]

Paracorr visual PVL-2008 is the one you want Jack as it is optimized for f/4.5, there is no real benefit to you using the Type II as it is optimized for f/3.0. So save yourself some extra dollars.

I hope you are aware though that the 20% off on TeleVue products is now over.

[ausastronomer (John Bambury)]

Hi Jack,

I agree with John that the Visual paracorr Type I (PVL-2008) is the one you need to get for an F4.5 scope. I have 2 paracorr's, the original " tunable top" type I visual paracorr with the green writing (which all wears off when it's about a month old) and the newer PVL-2008 with the silver writing and double lock screws. They both work equally as well on an F4.5 scope, which is the exact focal length they are designed to operate at.

If anything the type 2 paracorr, which is designed to work at F3 to F4, may not work as well as the type I at high powers in an F4.5 scope, due to addiitional introduced spherical aberration.

Cheers,
John B

[rmcconachy]

Originally Posted by ausastronomer

I agree with John that the Visual paracorr Type I (PVL-2008) is the one you need to get for an F4.5 scope...

If anything the type 2 paracorr, which is designed to work at F3 to F4, may not work as well as the type I at high powers in an F4.5 scope, due to addiitional introduced spherical aberration.

First, if you want a Paracorr `Type 1' (PVL-2008) then buy it now because they have just been discontinued. See post #4545806 from one of the guys at Astronomics in this thread on CloudyNights <http://www.cloudynights.com/ubbthrea...fpart/all/vc/1>. For a f/4.5 system the difference between the older and newer kinds of Paracorr should be small and the older kind is noticeably less expensive.

I disagree with the second sentence I have quoted above. From what I've gleaned the Paracorr Type 2 will be better than the original at pretty much any focal ratio but the relative benefit of the Type 2 over the original becomes increasingly marginal at focal ratios of around f/4 - f/4.5 and slower.

BTW, here is an old IceInSpace thread with some good Paracorr information. Bratislav might not be particularly `cuddly' in his manner on forums (although he was once very patient with me in person!) but he certainly knows his stuff when it comes to optical design and fabrication <http://www.iceinspace.com.au/forum/s...ad.php?t=12748>.

Clear skies whichever corrector you choose!

[Tiotion (Jack)]

Thanks guys,
I bought the Paracorr and a explore scientific 14mm from opt corp on Friday, and it was on my doorstep yesterday...only 4 buisiness days and its from the US! LOL! It has taken longer to recieve stuff i bought in Aust!
Cant wait for first light!