Best coma corrector

[Silvio]

Hi ! 

I want some help to choose a coma corrector , what is the best one in performance  for visual?

Tele vue Paracorr type 2 or Explorer Scientific Hrcc ?

Thanks 

[ronin]

A coma corrector is related to the f number of the scope so what make and what specification is the scope?

Don't just say 200P as there are two varieties of 200P an f/6 and an f/5.

[Silvio]

The telescope is a 4.5 ( 16 inch Dob ) 

Thanks in advance  

[Louis D]

The TV Paracorr Type 2 is going to give better correction at that fast of a focal ratio.  It was designed for newer, ultra-fast dobs.  If you had an f/6, just about any would work well enough.  I use a GSO to good effect at that ratio and save a bundle of cash.

[swamp thing]

The best

This is what I fitted to my Dob. It gives you the best focuser and coma corrector all in one package 

[Piero]

The TV parcorr2 will increase your telescope focal ratio by a factor of 1.15x. This will give an increase in magnification (or decrease in exit pupil) for all your eyepieces. 

The ES will increase the focal ratio by a factor of 1.06x. While this affects noticeably less the magnification/exit pupil of your eyepieces, it can require a significant amount of inward focus travel (32mm, see https://www.explorescientific.co.uk/en/Optical-accessories/Explore-Scientific-HR-Coma-Corrector.html). So make sure your focuser can accommodate this. 

Both these coma correctors are quite easy to adjust though, as you just tune to top up or down (using a helical mechanism in the case of the ES), and are supposed to work down to F3.

I can see coma in my F6 only at the edge of my (only) 100deg afov, and this is minor. In seems to me that F4.5 / F5 is the threshold when people start considering a coma corrector. Said this, this decision also depends on the eyepieces you use, as coma increases towards the field stop: you might want one with 100deg afov eps, whereas you might not need it with 50deg afov. 

The coma corrector will also add weight to your focuser. If you use heavy eyepieces, you might also want to consider a stronger focuser (if you don't have one already). The additional weight can also cause some balancing issue. Not difficult to solve though!  

[Silvio]

many thanks  . I will buy the tele vue paracorr type 2.. ?