First image with recoated 10 inch mirror

[tornado33]

Hi all.
Weather was horrible with wind and cloud but I was determined to star test at lleats, my newly recoated mirror (see thread in general chat). Well, some stars appeared, so I set it up and decided to forgo star testing and wach the modded 350D on after collimating the newly installed mirror. I got off a shot of the jewlbox a single shot of just 20 seconds at ISO 1600, no dark, flat or noise subtraction. Taking other test shots it looks like the sky background will be reached in 60 seconds @ISO 1600, and thats with the uv/ir filter, on a moonless night at my location. It looks like my rig will be able to pull in more photons per minute now with better contrast, shining a light down the tube reveals a perfectly reflecting mirror now, no blemishes :)

Note, I took the pic of the Jewlbox in breaks of cloud, it was being covered up again as I finished the exposure. Then I packed it in for the night.
Scott

[h0ughy]

your a legend Scott, how could you get anything in this cruddy weather!!!

[acropolite]

Very nice Scott, looks promising. :thumbsup:

[Lester]

My favourite open cluster. Nice star images Scott.

[tornado33]

Thanks all, I hope to get some longer exposures done if the weather allows before the moon gets too full.
Scott

[ving]

so i am guessing that you like it? ;)

nice quick image too.

[Robby]

Can't wait to see what you pull with the recoated mirror....!
Bound to be cloudy for weeks now though... :P
Cheers

[tornado33]

Yep ive never seen the mirror look so good, and now I know it will stay that way with Issacs electron gun deposited quartz on top :) Darn weather is a pain now though
Scott

[avandonk]

Yes Scott electron beam evaporation is far superior to just resistance heating a refractory metal boat. The substance that is evaporated is actually silicon monoxide (SiO) it has a lower boiling point than silica (SiO2).
When the bell jar is opened the the SiO slowly oxidises to SiO2. The other good thing about electron beam evaporation is that there are very few or no pinholes in the SiO coating unlike conventional coating which produces hot fast particles of SiO which then fall off and leave small patches of unprotected Al. So still treat the surface as very fragile until the SiO is fully oxidized. The other advantage is the reflectivity does not deteriorate as much, it should stay above about 95%. Fully oxidized Al will fall to about 87% or worse reflectivity depending on purity. I spent many 'happy' years making front surfaced mirrors and more for Kodak in the late 60's and early 70's. Sorry about the rave.

Bert

[tornado33]

Thanks for the information Bert, I wasnt aware of exactly how the process was done, Id always wondered how Quartz was evaporated onto a mirror.
Seeing Issac run his fingernails while pressing hard over a test mirror and not marking it was amazing. The mirror should last the rest of my life, as I treat it very carefully, store the scope tube on its side and covered, not allowing dew on the mirror and washing it very carefully. Even the bare Al coating lasted me many years :) The secondary has its original coating (Quartz overcoated) and is still pristine despite its 1986 vintage.
Scott