40mm plossl eyepiece

[alro]

Hello all,

40mm plossl ep from skys the limit, does anyone have any advice on this, i have heard they are similar to celestron omni , but better!

i am delighted with bst's i have and cant speak highly enough of service and advice from alan at skys the limit.

Al

[alan potts]

I do not see the real point in having a 40mm Plossl eyepiece as it has a smaller FOV (43 degrees) than the 32mm Plossl and shows exactly the same amount of sky. The only thing you get is a smaller magnification.

I have the same type of scope to you but larger, I would save your money on the 1.25 inch eyepieces and try for a 2 inch system where the 40mm eyepiece will give you a 68 degree FOV and show you a lot more. Sadly these things do not come in Corn Flakes boxes and even a cheap setup will be close to 200 pounds, you need visual back, diagonal and eyepiece. The secondhand market will make this purchase somewhat cheaper, they do come up fairly often.

[ronin]

Stick with the 25mm BST STarguider, the FoV will come out almost identical.

A 30mm 50 degree plossl will have the same FoV as the 25mm BST (the extra FoV of the BST and the shorter focal length cancel out exactly), and the 40mm plossl is restricted by the field stop so gives the same as a 32mm plossl.

At the end anything you get is so small that I doubt you will notice it as it will be about 6% extra which on say one degree is 1 degree to 1.06 degrees. Hardly worth it.

[nicoscy]

You may also find yourself disliking the extra long eye relief of the 40mm and the really constricted FOV. It really feels like looking through a straw. The 32mm will provide a more pleasing viewing experience and the 24-25mm 68 degree AFOV eyepiece an even more pleasing one, as you see the same FOV with higher magnification and a wider FOV.

Only consideration is exit pupil which with a 40mm may be more suitable for some objects, but as Alan posted, a 2" system is the way to go actually, budget permitting.