Celestron Plossl EP performance

[Bart]

Hello All,

Hoping someone can answer the following question.Last night i was observing Saturn through my 6" newt. Using a 9mm EP with a Barlow giving x166 the image was pretty clear. However, the 6mm giving x125 or the 4 mm giving x187 were pretty poor. Can't understand why the Barlowed image was so good compared to the lower mag with the unbarlowed 6 mm or the similar mag with the unbarlowed 4 mm. Are these eyepieces just not as good at the 9mm? Intrigued and puzzled, thought the Barlow would degrade the image. Even if iit does, it beat the 6mm and the 4mm......

Bart

[NGC 1502]

Hi Bart, I'll do my best here.

The 4mm at 187x could have been pushing the magnification too high perhaps.

But if the view was good at 166x, then it's harder to explain the lack of performance

of the 6mm at 125x, should be smaller but sharper, if you focused carefully. Could

it be very dirty/greasy eye lens on the 6mm ? Just one possibility.

If you are using a good barlow, I have found it doesn't degrade the view, unless

it pushes the mag too high for the scope or sky conditions. In fact, in some

circumstances it can make an eyepiece that is not sharp towards the edge of

the field of view better when adding a barlow. I have a cheap 14mm EP that is

only sharp in the centre with my two reflectors, but adding my early model Televue

barlow makes it a much better high power EP, not bad towards the edges

than on its own.

HTH, Ed.

[Bart]

Thanks Ed,

I dont have an expensive Barlow either, it came with the Celestron eyepiece pack. I haven't noticed this happening before so I might try it again and see what happens. I hear what you're saying regarding the 4mm, like you, the 6mm is puzzling me. I have dropped it previously but have used it since and haven't noticed anything wrong with it.

Thanks for the input.

Bart