Plossls on Moon... Glare Issues

[cshahar]

Hi Everyone:

I have the 55mm, 40mm and 32mm televue plossls which i am using for HAlpha solar viewing. Yesterday evening I turned the plossls on the moon and was amazed to see an incredible amount of glare surrounding the moon using these eyepieces. It almost looked like i was looking at the moon through a dense fog. There was no such effect with my Vixen LVW and Orion Stratus eyepieces. I am just wondering if it is a function of the design of the plossls or something else?

Thanks,

-Charles

[DRT]

Which telescope were you using, Charles, and what focal lengths are the Vixen and Orion eyepieces you are comparing the TVs to?

[cshahar]

Hi. Sorry, I should have mentioned all that. I was using a 4-inch ES refractor. The Vixens were 5,8 & 13mm. The Orion Stratus was 13mm. The Plossls as I mentioned were 55mm, 40mm and 32mm. So they were much wider field. The moon was fairly low and under a city sky, so I wonder whether the plossls simply reflected more of the ambient light in a poor sky, specifically because they were wider?

Thanks,

-Charles

[DRT]

Hi Charles,

Low power eyepieces tend to produce views that are lower in contrast than medium to high power eyepieces, particularly when looking as a bright object like the Moon or where there is significant light pollution. Views through 32mm-55mm EPs are therefore likely to look a bit washed out when compared with the views you will see of the same object at higher magnifications. The low position of the Moon wouldn't help the situation as you would be seeing through lots of turbulent atmosphere.

I don't think it sounds like there is anything wrong with your TV Plossls, it simply sounds like the combination of those powers, your scope and the chosen target were not ideal.

I have owned the 32mm and 40mm TV Plossls and both give fantastic views under the right conditions. One thing to note is that the field of view through both of those EPs is exactly the same so the 40mm is just giving you less magnification across the same area of sky as the 32mm. For that reason is it unusual for people to own both. The 55mm gets mixed reviews but I think that is mainly due to the fact it is designed for a very limited range of telescopes.

[Steve Ward]

I would hazard a guess that a build-up of dew on the objective comes into the equation rather than the eyepieces per se , the long focal length EP's would show this much more as a large diffuse halo round a wider field view of the Moon

[John]

I've seen that effect when eyepieces get cold and fog when the eye gets close to them. I also have an old 18mm ortho that does it because it was badly cleaned (not by me !) at some point which left micro scratches across the lens surfaces.

I've used Tele Vue plossls quite a bit and I've not noticed excessive glare with them. Their glass, coatings and internal baffling are of excellent quality IMHO>

[alan potts]

I know it is each to their but I would not use a 40mm eyepiece to view the moon with in my SC which has a F/L of 3048mm, the other eyepieces you mention is hardly compairing apples with apples.

Alan

[cshahar]

Thanks everyone. It was actually my first time out with any of these eyepieces. I am more into solar observing through an HAlpha filter, and have been doing that for the last couple of months. I was just surprised at the fact that the plossls seem excellent for solar observing, but were not good for lunar views, at least not under such sky conditions. Thanks again!