Pentax xw 20mm vs Tele vu Panoptic 24mm

[coltpeacemaker]

G/day all I'm looking at buying a new EP in the 20-24mm 1.25" range for my C8 cpc edge HD f/10 and have narrowed it down to a Pentax xw 20mm or a Tele vu 24mm panoptic! Now I know there quite different from each other but that's fine, it's mainly for dso so clusters nebular the usual things we like to looks at, so do any off you own these? What's your thoughts on them? Or maybe you might have other ideas to a good lens around $500-600

Thanks...

[Harshil Patel]

Hello..

Calculate the FOV for eyepiece : https://astronomy.tools/calculators/field_of_view/

From this site you will get the specification of your eyepieces which you are going to buy...

And from this site you will get the knowledge that how eyepiece work : https://starizona.com/acb/basics/equ...rstanding.aspx

So enter the different types of EP and do the comparison between them...You will get the specific idea that which on is the best EP for my scope...

Thank you...

[Harshil Patel]

And

Simulation of views through a telescope using different eyepieces. The center image uses an eyepiece of the same focal length as the one on the left, but has a wider apparent field of view giving a larger image that shows more area. The image on the right also has a shorter focal length, giving the same true field of view as the left image but at higher magnification. (Taken from Wikipedia)

250px-Fields_of_view.jpg

so in your case i m go with pentax xw 20mm

[coltpeacemaker]

I know the technical specs off the EP, I want some personal opinions about the lens! specs aren't everything our eye are the best judge and that something no data will be able to do...

[Davesellars]

Hi.

I have the Panoptic 24mm - this is a really nice eyepiece with excellent contrast and I believe the best of the TV Panoptic line. While I don't have the Pentax XW 20mm I believe all the eyepieces from 14mm and above focal length have a reasonable amount of field curvature. at f/10 the 24mm would be a better focal length for mid power for DSOs than the 20mm as the exit pupil is still good for contrast on DSOs (2.4mm) and the field is 0.8 degrees with the 24mm and 0.68 degrees with the Pentax.

A cheaper option is the 24mm ES68 - which is very good (I've been using this for some time). I bought the 24mm Panoptic recently for use with my 12" dob. I haven't been able to compare as such but my feeling was that the 24mm Panoptic had better contrast and a much blacker background.

A more expensive option would be if you use a 2" diagonal and then you've got a plethora of options at 20 to 24 degrees for wide-field eyepieces.

[coltpeacemaker]

Hi.

I have the Panoptic 24mm - this is a really nice eyepiece with excellent contrast and I believe the best of the TV Panoptic line. While I don't have the Pentax XW 20mm I believe all the eyepieces from 14mm and above focal length have a reasonable amount of field curvature. at f/10 the 24mm would be a better focal length for mid power for DSOs than the 20mm as the exit pupil is still good for contrast on DSOs (2.4mm) and the field is 0.8 degrees with the 24mm and 0.68 degrees with the Pentax.

A cheaper option is the 24mm ES68 - which is very good (I've been using this for some time). I bought the 24mm Panoptic recently for use with my 12" dob. I haven't been able to compare as such but my feeling was that the 24mm Panoptic had better contrast and a much blacker background.

A more expensive option would be if you use a 2" diagonal and then you've got a plethora of options at 20 to 24 degrees for wide-field eyepieces.

Thanks for the detailed info! I think the 24mm pan might be the best way to go, as I've read it's got great contrast with deep blacks! The es68 I don't know that one who makes it? Also I definitely need a 2" diagonal mines just the standered one that came with the c8 edge hd and there's no point having great eyepieces let down by a cheap diagonal! Thanks mate for the advice...

[Davesellars]

In that case if you're going to change the diagonal, definitely go 2" if you're not going to use a focal reducer.

As I mentioned there's quite a bit more option once you go 2" for wide-field. for example a 40mm 68 degree AFOV eyepiece will pretty much give you the max view before vignetting may be an issue. For the 20mm (ish) focal length there's options from Explore Scientific (ES82) as well as their 100 degree AFOV offering, although depends if you will get on with these as well. For Televue there's the 22mm Nagler would be a great choice.