more worrying- chill out focus continued

[impactcrater]

I took the nexstar 127 celestron on a country road journey well packed and as my past topic showed from then on just failure to see anything. Now returned I still cannot see the heavens...not a star....some dark views of a quarter moon only....I have set it up during the day and whilst I can see distant objects they are nowhere as in focus as previously. My nice spotter scope sees things way better ! so I looked at the manual and proceeded to remove the diagonal and look down there. What I see is a round white area with a big black dot in the middle and my eye in that. It all looks quite concentric but nothing like the picture suggests is correct. I will try to download a photo at my next post...thanking the pool of wisdom....impactcrater

[impactcrater]

hopefully I have downloaded a pic...

[Stargazer33]

Hi Impactcrater.

With the eyepiece and mirror diagonal removed that is pretty much what you will see. The white area is the corrector plate and the dark circle in the middle with your eye reflected in it is the secondary mirror. This is all quite normal.

You may well have a collimation issue. A good way to test this is to centre your scope on a bright star and then defocus the image either side of 'best focus' - which may not be sharp in your case. How to collimate an SCT can be found by doing a search such as here:

[Stargazer33]

Er...that was just supposed to be a link and not the video itself!

Bob's Knobs make this process a lot easier!

[impactcrater]

thank you southerndriver357...as it turns out my focus problem resulted from the trip to cold damp climes and the severe dew settling on the collector left a not obvious film which required more than one good cleaning....It does sound hopeless but it may prove useful information. I really appreciated that you confirmed my scope was not misaligned as I had travelled some bouncy backroads and did think that was the cause.

but it gets more complex...after correcting all that Herr dummy here managed with a simple moon sighting to lose all the handcontrol data...nearly exploded but kept telling myself I would learn another useful thing.

celestron.com showed how to download the firmware and (not without some challenges...who uses a serial port these days...foam foam...) the firmware updater recognised it and all seemed well

however when it is switched on it displays 'Advanced GT' and not 'nexstar SLT 127" so I expect the dumb downloader has not really recognised my actual scope but taken a guess....less foam but not happy. I have read about how to fix this but any tips appreciated...impactcrater from downunder...

[rowan46]

can't help with the updating computers are not my forte. But one little thing you may need is a dew shield. to make a home made one for pennies get cheap foam camping mat, wrap it round the tube tape it or velcro it so that it stays together and cut it so that it overhangs the corrector plate by about 8-10 inches. The glass at the front is a magnet for dew, refractors come with dewshields but maksutovs and schmidt cassegrains never do. Don't bother with Bobs knobs the 127 slt has no user collimatable parts and doesn't come out of collimation unless you are very rough with it, Bobs knobs are for sct's and newts not skywatcher/celestron maks