Celestron C90 Mak and cheap EPs.

[Stub Mandrel]

Well now, I do imaging, because I struggle with eyepieces. But I got a C90 which saw first light the other day - but not very successfully because of cloud and bullocks, a tale told elsewhere.

Tonight PHD2 is generating me a nice lumpy graph, so I let it get on with it, and tried out all my EPs on the Moon with the C90.

(I do not have expensive Eyepieces)

First thing, the little finder needs to be screwed to the stop to focus when I have my glasses on. I can't use it specs off, because I can't see the stars to point it in roughly the right direction. Lets say it works but not as well as the stock 9x30 finders on my Skywatcher scopes...

First EP, the supplied 32mm. This (plossl?) EP has a good reputation and gave me the best 'whole moon' view I have seen. very bright, very sharp with great contrast, lots of detail and no CA detectable. A lot of eye relief so very odd 'floating' my eye about 2cm behind the eyepiece.

Second, a 40mm 'Svbony' plossl off the bay for £11 that came today (I wouldn't have got it if I had known I'd be getting the 32). At first looked good but a greeny orange haze - then realised inside of lens was misted up. Once cleared this showed a bit less detail but the moon looked great with some more space around it. Somehow this ep seemed more comfortable to use.

Third, a cheap 4mm plossl from'sky's the limit'. This did put me right up close to the lunar surface, but the magnification of over 300x was too much for the scope and despite careful focusing, everything looked 'soft'. The ep has a tiny hole to look in, but I will try this on my 150PL which is about the same FL, but much more aperture.

Fourth, the 10mm lens (Super 10) that came with my 150PL but is probably the better Celestron stock EP rather than the cheap Skywatcher one. This was really sharp, no CA and I could find all sorts of detail that I had seen in photos, Tycho's central peak, lost of craters, some I recognised but couldn't name. Brilliant.

Fifth the 25mm (Super 25 20mm eye relief) from the 150PL. This had a tiny blue fringe at top and yellow at bottom on the moon, the only time I saw CA. I don't think it was the scope causing it. I was surprised that I could see the whole moon despite the higher mag than with the 32. Really a good view of the whole moon.

As an eyepiece hater, I found being able to sit down and use the erecting RACI prism greatly increased my ability to stay at the eyepiece. this was the longest I have ever done at a scope, perhaps twenty minutes! (don't laugh!) Normally I would struggle to do four or five minutes. I did find focusing the Mak to be very fussy.

I'm sure better EPs would blow me away even more, but these are the best views of the moon I have had, partly because the comfort allowed me to look properly, but also because the view seemed to have so much contrast and dynamic range. The slight shimmer in the seeing over the relief of the craters along the terminator added to the moon's stark beauty.

Now off to change camera battery and retarget!

 

[John]

Nice report Neil !

300x would be a bit much for the 90mm mak but it sounds as if the other eyepieces produced pleasing views.

 

[Stub Mandrel]

Well I've never been spoiled by looking through a Tak with a green eyepiece!

I've just checked, and what I thought were the craters Messier  and Messier A, with the streak of ejecta, were the real thing :-)

[happy-kat]

The 4mm ep would have tiniest of exit pupil, needle in a haystack let alone being soft from over magnification, don't think I'd have seen anything I struggle at 1mm.