38mm eyepiece for a 12" Dobsonian

[seanliddelow (Sean)]

Hi, I'm just wondering whether a 38mm skywatcher eyepiece will suit my 12" Dobsonian. My focal ratio is around 5. I'm thinking of using it to observe wide areas such as the LMC or some large open clusters (Pleiades?). Or maybe even to take some point and shoot photos of next years lunar eclipses.

Thanks, Sean

[floyd_2 (Dean)]

Hi Sean,
you'll get about 40x magnification out of the Skywatcher Panaview 38mm eyepiece on your scope. The exit pupil might be a little large though, at 7.6mm. You might need to make sure that your eyes are properly dark adapted before using that eyepiece just in case you get the black spot effect (darkened region in the centre of the image caused by the secondary obstruction). I'm not sure if this eyepiece is prone to kidney beaning too, but the eye relief of 28mm is pretty long so it might be worth doing some extra research there just to be sure.

Dean

[seanliddelow (Sean)]

Thanks Floyd,

I might see if the retailer (camera house) will let me try it out for one night. I have seen good views through 30mm eyepieces before and the eye relief wasnt too bad.

Sean

[pgc hunter]

Here is a user review of the SW 38mm eyepiece which might help http://stargazerslounge.com/equipmen...on-review.html

He mentions some pincushion distortion and field curvature in fast newts, but really the only way to know if you are going to be satisfied with the eyepiece is to try it first. Otherwise, it might be worthwhile considering other tried and true options, such as the 35mm Panoptic. The panoptic will yield a 1.6° TFOV, (the 38mm SW yields 1.8° - so not a huge loss) with an exit pupil of 7.1mm, so it might be a worthwile option to consider. If your wallet is a bit deeper, the 31mm Naglar T5 actually yields a 1.7° TFOV with only 6.3mm exit pupil and excellent field correction which IMO would be the way to go, if funds allow.