William Optics SWAN Eyepieces

[PreludeToADream]

Hi all,

Does anyone know whether the William Optics SWAN Eyepieces are good for the money? I want to do some observing of DSOs like M31. Would the 15mm or 20mm version do the job for that? I have a 130mm Skywatcher scope.

Link here: First Light Optics - William Optics SWAN eyepiece

[NGC 1502]

I've never used the 15mm or 20mm Swans, but I own the 33mm. It has nice eye relief, sharp field stop, but shows fuzzy stars towards the edge of the field of view in my f4.8 Dob. With objects like M31 that matters less.

Review here of the full range -

http://cloudynights.com/documents/swan.pdf

Regards, Ed.

[Capricorn]

Have the set and good but WO say they are OK down to f/6, after that the edges start to lose sharpness. I am guessing that you have an f/5.

The WO SWANS are 72 degree, standard plossls are 52 degree. How about a compromise of the BST Explorers at 60 degrees?

They are also a bit cheaper and good.

A 15mm WO SWAN would give a 1.6 degree view, so M31 should just fit in. The 18mm BST would give the same angular view.

[PreludeToADream]

BST Explorers sound like a good alternative. Yes I have an f/5. I'll have a look at them, might get one of those instead. Thanks for the advice.

[Capricorn]

Made a mistake, the moon is 1/2 degrees not 1/4 so to get all of M31 in you would need a 3 degree view. Know it is 6 times bigger then the moon.

So you need a 3 degree view to get all M31 in.

The 20mm WO SWAN would give 2.2 degrees, the 25mm BST would give 2.3 degrees, a 32mm plossl would give 2.5 degrees. None being sufficent to get it all in. However the edges are faint, so you may not see much if anything there.

Problem with M31 is that it is actually big. That is why a lot of people use binoculars on it, they often have 6 and 8 degrees of view.

[John]

Once of the nice things about low power, wide angle views of M31 is being able to see neighboring galaxies M32 and M110 in the same field of view - a rather lovely sight on a dark night