Is image problem due to mirror?

Doc wrote:
I've been experimenting with a Meade 5" reflector, and find that the
Moon looks incredible, but when looking at Mars, with anything of
greater mag power than the 25mm eyepiece such as a 9mm or 4mm, the
image even at sharpest focus I can manage has traces of an
irregularity most noticeable around the edges, sort of like an
impressionist painting.

Is this likely caused by imperfections in the mirror being magnified
or something else?

It could be:

o Seeing/atmosphe Much more of an effect at high mag. How high was Mars?

o Eyepieces: If they (9 mm, 4 mm) came with a 5" reflector, they are
likely of low quality.

I'm using a new 8" SCT (cleaned and collimated at the factory two weeks
ago) on Mars and with my skies I'm having trouble getting sharp views
most nights using excellent EPs. OTOH .. one early morning in early
July, I was able to take my 5" SCT to 300x and get some really good views.

So it could easily be that conditions do not support the magnification
you are using.

Phil

"Phil Wheeler" wrote in message
...
Doc wrote:
I've been experimenting with a Meade 5" reflector, and find that the
Moon looks incredible, but when looking at Mars, with anything of
greater mag power than the 25mm eyepiece such as a 9mm or 4mm, the
image even at sharpest focus I can manage has traces of an
irregularity most noticeable around the edges, sort of like an
impressionist painting.

Is this likely caused by imperfections in the mirror being magnified
or something else?

Try it out on other planets, Mars is a bit awkward due to it's low position
in the sky. However, I got some nice views with my Tal 100R last night,
even with the light pollution I have to put up with.

Keep to something like the 9mm you are using.

Martin

Try using a barlow instead of a higher power eyepiece. Thais increases
relative focal length and helps with what you're describing. Used this
arrangement on my coulter 10" worked great.

Phil Wheeler wrote:
Doc wrote:

I've been experimenting with a Meade 5" reflector, and find that the
Moon looks incredible, but when looking at Mars, with anything of
greater mag power than the 25mm eyepiece such as a 9mm or 4mm, the
image even at sharpest focus I can manage has traces of an
irregularity most noticeable around the edges, sort of like an
impressionist painting.

Is this likely caused by imperfections in the mirror being magnified
or something else?


It could be:

o Seeing/atmosphe Much more of an effect at high mag. How high was
Mars?

o Eyepieces: If they (9 mm, 4 mm) came with a 5" reflector, they are
likely of low quality.

I'm using a new 8" SCT (cleaned and collimated at the factory two weeks
ago) on Mars and with my skies I'm having trouble getting sharp views
most nights using excellent EPs. OTOH .. one early morning in early
July, I was able to take my 5" SCT to 300x and get some really good views.

So it could easily be that conditions do not support the magnification
you are using.

Phil