What would you choose? 20mm or 24mm?

[emadmoussa]

For 8" SCT and 100mm refractor, what would you choose, a 20mm or 24mm wide-angle eyepiece? 

the 20mm is slightly bigger but lighter and more modern, while the 24mm is 200g heavier and, naturally, with a slightly bigger field of view. The 20mm is £20 cheaper brand new.

I'm thinking an EP that remains in the scope most of the time.  

[vlaiv]

Depends on light pollution.

In dark skies I would go for exit pupil around 2mm, while in LP - closer to 3mm. I've read somewhere that most people prefer this as "deep" eyepiece, one to be used to detect the faintest things, but that really depends on target.

Both scopes are F/10, so 20mm will give you 2mm exit pupil

[Ruud]

One way to go if you want to fill a gap between two other eyepieces is to opt for the geometric mean.

For instance, if you already have a 12mm and a 30mm, then 19mm ≈ √(12 * 30) would be a good idea. This because when switching from 30mm to 19mm you get the same increase in magnification as you get when you switch from 19mm to 12mm ( 1.6 more magnification for both switches). It's a kind of 'equal step' choice.

The geometric mean between a and b is:   m  =  √(a * b)

Is the Meade 5000 ultra wide 20mm and 24mm that you have in mind? @cloudsweeper has both.

 

 

[emadmoussa]

36 minutes ago, Ruud said:

 

Is the Meade 5000 ultra wide 20mm and 24mm that you have in mind? @cloudsweeper has both.

 

 

1

Yes. 

[cloudsweeper]

Love 'em!  There is some overlap of course, and it depends on mag, TFOV, and exit pupil, so I tend to use them in different 'scopes, and not both in just one 'scope.  I do however like to have a good range of EPs for variety of choice.  My UWA 5000 82 deg EPs look good, feel good, and perform well - and are not too heavy.  (Can be hard to find though!)

Doug.

[emadmoussa]

2 minutes ago, cloudsweeper said:

Love 'em!  There is some overlap of course, and it depends on mag, TFOV, and exit pupil, so I tend to use them in different 'scopes, and not both in just one 'scope.  I do however like to have a good range of EPs for variety of choice.  My UWA 5000 82 deg EPs look good, feel good, and perform well - and are not too heavy.  (Can be hard to find though!)

Doug.

Any difference between in the two in terms of quality, sharpness, or even targets?

[cloudsweeper]

....no, they seem to me to be consistently good, although sharpness for example is also determined by the 'scope in use.

Also - those Meades are nicely priced.  The ES 82 Maxvisions are said to be their equivalents.

Doug.

[RT65CB-SWL]

3 hours ago, cloudsweeper said:

Love 'em!  There is some overlap of course, and it depends on mag, TFOV, and exit pupil, so I tend to use them in different 'scopes, and not both in just one 'scope.  I do however like to have a good range of EPs for variety of choice.  My UWA 5000 82 deg EPs look good, feel good, and perform well - and are not too heavy.  (Can be hard to find though!)

Doug.

I too have a good range, mainly TeleVue, plus a few Meade, Circle-T Ortho's and a few interlopers.

[emadmoussa]

22 hours ago, Ruud said:

One way to go if you want to fill a gap between two other eyepieces is to opt for the geometric mean.

For instance, if you already have a 12mm and a 30mm, then 19mm ≈ √(12 * 30) would be a good idea. This because when switching from 30mm to 19mm you get the same increase in magnification as you get when you switch from 19mm to 12mm ( 1.6 more magnification for both switches). It's a kind of 'equal step' choice.

The geometric mean between a and b is:   m  =  √(a * b)

Is the Meade 5000 ultra wide 20mm and 24mm that you have in mind? @cloudsweeper has both.

 

 

I totally see what you mean. Often, I have 6-10 numbers between eyepieces. 

I've just learned today that I'm receiving a 15mm 82-deg EP for Xmas. So...well...that pushes the vote towards the 24mm Meade, which I already ordered - luckily.