Jump to content

Banner.jpg.b89429c566825f6ab32bcafbada449c9.jpg

40mm for SCT


Recommended Posts

I've just ordered a 40mm series 3000 meade as i've read really good reviews on their quality and i need a good wide field 1.25 lens. the supplier says these are the last japanese made ones, but.....

i cant work out the fov i'll get in my edgeHD 8in SCT. After reading through forums on true FOV and actual FOV and how to work it out, i'm still confused!

It states: the PL40mm produces, for example, a power of 50X and actual field of 0.88°, almost two Moon-diameters, with an 8" f/10 Schmidt-Cassegrain"

i cant get to that result using my calculations!

2000 / 40 = 50 , 50 / 44 (apparent field) = 1.13

where am i going wrong?

Link to comment
Share on other sites

True field of view = field stop diameter x 57.3 / telescope focal length.

1.25" format long focal length eyepieces are limited by the barrel size. The largest field stop you could possibly get in the 1.25" format is 31.75mm, which would be a TFOV of 31.75 x 57.3 / 2000 = 0.91 degrees. In reality you have to have a bit less than 31.75mm due to the thickness of the barrel, so 0.88 degrees seems right.

If you want wider true field of view then you need a 2" format eyepiece

Link to comment
Share on other sites

Yeah, balance can be a right pain at times with long focal length widefields, especially if you're swapping between tiny higher-powered eyepieces that weigh next to nothing and the 2lb monsters.

The only thing that immediately springs to mind are the TMB paragons (+clones), they have a reputation for being a bit lighter than other long focal length SWAs but I don't know if it would be enough to make a difference.

Link to comment
Share on other sites

I use a Nagler 31T5 on one end of the SCT, and have had no problems, that beast weighs in at 1kg. With a 2" diagonal I would go for a Panaview 38 or Aero 40mm (the latter is a Paragon clone). I had a 40mm Paragon, and it was just 500 g as I recall, very light for such a big EP, but well built.

Link to comment
Share on other sites

I try the same but the 2in Panaview is a lot heavier than my set of x-cels.

the Panaview gives great views so I was hoping to get near that with a good 40mm ( in my price range)

you can't beat a good 2in wide lens though, I have heard that this 40mm series 3000 Meade has some nice immersive qualities.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.