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Evan
10-19-2010, 08:27 PM
It arrived today. It's the 10" mirror for my next telescope. No damage and it looks good. I will be subjecting it to some slightly more critical evaluations shortly. As soon as I collect the required parts and get caught up on the winter prep chores around here I will be starting a build thread for the telescope. It will have features designed to make it both portable and fully automated.

The Mirror:

http://ixian.ca/pics8/10_inch_mirror.jpg

miker
10-19-2010, 08:58 PM
Wow, makes your heart skip a beat:)

What is the focal length and who made it?

Congrats!!

Rgds

daveo
10-19-2010, 09:03 PM
Telescope porn....

gwilson
10-19-2010, 09:06 PM
He really stole it from my wife's makeup mirror !:)

Liger Zero
10-19-2010, 09:10 PM
Screw the mirror, I want the packing foam. :D

Paul Alciatore
10-19-2010, 09:17 PM
What? You bought it? You didn't grind and polish it yourself?

Black_Moons
10-19-2010, 09:18 PM
So thats where my bike rearview mirror went...

I can still read the warning text on it..
'Objects in mirror are more likey to run you over then they appear'

Evan
10-19-2010, 09:23 PM
I bought it from Coulter Optical in Florida, the same place I bought the mirror for my six inch scope. This one is specced at 1/20th wave average with a max deviation anywhere of 1/10 wave peak to valley. I will be characterizing it by foucault testing in the next day or so.

This project will involve some serious machining as the first item of business will be an 18 point all floating mirror support that is calculated to produce the minimum distortion of the glass in all positions due to it's own weight.

Focal length is f5. The price is $400 and that includes the secondary. For a mirror of this spec it is a steal. Pat Murnaghan, the owner, is a very nice guy and has had these mirrors in stock for years. They are priced to sell. I asked him about the high specs and he said that when he ordered them made he decided to go with the higher spec to try and grab some business from the other suppliers. It must have worked as he has been in business a long time.

The packaging is first rate too. About the only issue is that Pat is a little slow to ship items so it helps to give him a call after few days and remind him.

beanbag
10-19-2010, 09:39 PM
the first item of business will be an 18 point all floating mirror support that is calculated to produce the minimum distortion of the glass in all positions due to it's own weight.

This problem can be solved by floating the mirror in space.

rohart
10-19-2010, 10:00 PM
Evan, focal length is f5 ?

I know it's easy to calculate, but that's the aperture, isn't it ? So if it's a 10" mirror, the focal length is 50" ? I'm a bit rusty on optics, so correct me if I'm off. I used the Wiki formula. Too late at night to find my books.

Nice mirror, if the tests square up. What's the surface ? Vacuum deposited ally or something similar ?

Evan
10-19-2010, 10:39 PM
50 inches is correct. I am much more interested in wide field imaging than planetary observing. One of the features I have in mind is to focus the scope by changing the length of the Optical Tube Assembly instead of using a focuser. That will be done by using several lead screws that are operated by a stepper motor. The attachment point for the cameras and eyepieces will be permanently fixed and focus points will be set in the memory of my netbook so that whatever I put in the holder I simply select that item and the focusing system homes and then goes to the precise focus point automatically.

This will not only allow for precise focusing but also very easy adjustment for different temperature profiles. Also, it will have a stow position to close up the OTA for transport. It also gives a very wide range of focus adjustment for items such as eyepiece projection adapters.

Astronowanabe
10-20-2010, 01:33 AM
excellent!
Mirror like that calls for a side foray into Bath interferometry to check on the numbers you paid for.

http://starryridge.com/mediawiki-1.9.1/index.php?title=Bath_Interferometer

Evan
10-20-2010, 02:09 AM
That looks ideal. I have all the required optics to make one so that is what I will do. Thanks for the link.

Smokedaddy
10-24-2010, 09:06 PM
... $400 ... I paid nearly $1,300 for my Zambuto 10 inch and $3,000 for the 16 inch. How thick is the mirror and what kind of glass is it? It will be interesting to see how the testing goes. Have a link for Pat Murnaghan?

-SD:

Evan
10-24-2010, 10:02 PM
Pat states "annealed optical glass" as opposed to "soda lime glass" that he uses for the cheaper mirrors. I would assume that it would be BK7 or similar. It doesn't make much difference to me as the price is right. It is an 8 to 1 mirror.

It will be a little while until I get to the optical testing since I will have to clean up my optical bench first. I really want to get the telescope in operation asap so I don't miss the winter skies. Star testing is the ultimate test anyway.

Pat has been in business since 1968 which is a heck of a long time in this business.

http://www.e-scopes.cc/Murnaghan_Instruments_Corp56469.html

Smokedaddy
10-24-2010, 11:26 PM
Thanks Evan, I am familiar with Coulter Optical. I ususally go with Carl Zambuto or Bob Royce and have had excellent results with them both. How thick is the mirror Evan?

-SD:

Evan
10-24-2010, 11:32 PM
8 to 1 which makes it 1.25 thick.

dp
10-25-2010, 12:01 AM
Thanks Even, I am familiar with Coulter Optical. I ususally go with Carl Zambuto or Bob Royce and have had excellent results with them both. How thick is the mirror Evan?

-SD:

Do you have any experience with the Royce conicals? I know only what I've read on the web but expect that anyone who pays a lot for something is not as likely to speak badly of their decision :)

Smokedaddy
10-25-2010, 11:08 PM
dp ...

... if you purchase a scope from Bob, he guarantees you'll be happy with it or he will buy it back, excluding shipping. At least that's what he told me and others I know. I have a couple of his Dall-Kirkhams, a 10 inch and a 12.5 inch. Two of my buds have purchased the 16 inch D-K, the only two made to date. One of them isn't finished and the other is. Here's what he had to say, and I agree ...

FYI: This past Saturday night we had good seeing and the Jupiter show was stunning through the 16 " DK :-O. I KNOW it's closer than usual, and finally higher in the sky this year, but what we saw was loaded with color and appeared much like a soft Hubble photo. Everything was there, and the term "fuzzy" applies only to comparison with Hubble. My 8" TEC APO never came CLOSE to what the 16" DK was revealing ... not even CLOSE! You'll see ;-)

Smokedaddy
10-25-2010, 11:12 PM
I know only what I've read on the web but expect that anyone who pays a lot for something is not as likely to speak badly of their decision :)

I have a story for you about how unhappy I was with a $11,500 GEM that I purchased brand new from Parallax Instruments.

-SD: