Dot in my 2" ep

[scuffer]

Hello , I had a look at the moon tonight and as I was packing up I decided to try my 2" 32mm ep , the moon was blurry in different parts as I moved my eye about , I stood back from the scope and saw with the moonshine coming thru the eyepiece that there was a black dot in the middle of the ep , this was the secondary , I could also see the focus if I screwed it into the tube , I have definitely used this ep before on the moon and never noticed this before , is this normal .... Anything o do with collimation ?

On all my other eps the view was fine ,I even tried 400x on the moon...awesome

[Moonshane]

this is normal and relates to exit pupil vs the size of your own pupil. when observing a nearly full moon your pupil will be very small and probably smaller than the exit pupil of 5.4mm. don't worry.

[astrofox]

Would a ND filter help by reduing the light output and increasing ones pupil size?

[Moonshane]

maybe but I am not a big fan of ND filters. the secondary was only obvious when the eye was drawn back (normal) and I suspect the soft focus on the edges was field curvature/astigmatism in the eyepiece (also probably normal).

[astrofox]

Hi Moonshane,

I always use mine on the moon if nothing else to tone down the brightness at low magnification.

[scuffer]

Thanks for that moonshine , the blurry /soft focus was caused by the black dot of the secondary , I could get it to go anywhere on the moon by moving my eye . When my eye was up to the ep i couldnt see the black dot but where the secondary was affecting the light coming out it appeared blurry . I did have a filter on the 1.25" but not on the 2".

[Carbon Brush]

Do you have one of those tube end caps with the small pick off caps?

I know they have been supplied with the EQ mounted SW200.

Convert your 8" scope to a 2" scope. The moon will still be plenty bright enough.

[scuffer]

I do , and have never tried it , I shall give it a go , would this still be a problem on a 32 mm 1.25" ep or is it specific to a 2" ?