Posts Made By: Steve Sands

Hi Steve

That refers to the Northeast Astronomy Forum, held in New York every year. It features all of the latest and greatest telescope and astronomy equipment during a single weekend event. Many companies (i.e. TeleVue) sell factory seconds -an eyepiece with cosmetic defects, for example. So when such equipment is purchased at this event as a factory second, it is referred to as a "NEAF". Hope this helps! (Not a dumb question, by the way!)

Hi Mike,

It came yesterday! I guess they waited a little longer to ship them all out at once.

See you there!
Steve

The one that is run by the Chicago Astronomical Society up near Kankakee, IL September 18-21. Go to S&T's web site and search under their events listing and you will find the AF website. Or you can go to the CAS web site...they have a link off of it for AF.

Hi Floyd,

This is a major point I pondered when I decided I wanted to build a larger aperture Dob. After a lot of reading and some research (this was before the Kriege and Berry book!) I decided to go with a 20" f/4.0 (John Hudek/ Galaxy Optics) and have never regretted the decision...NO ladders! I think that the collimation issue is really overblown. A well designed fast Dob can be collimated tools-free and not need much adjustment when moving it from place to place. I took my dob to AstroFest this year as I always do and when I set it up, I had to tweak one collimation screw an 1/8th of a turn (after 5 hours of riding in the back of a truck and unloading)! Once the scope has been properly collimated the first time (focuser, diagonal, primary) using lots of time and patience, subsequent minor adjustments are quite easy with the advent of the holographic laser collimator. It is wonderful to operate at "ground level", never having to climb steps! This scope has been a dream to operate and use.

Hi Scott,

The material is called Kydex. It comes in several thicknesses. The thinner sheets work best, perhaps someone here can tell you the actual thickness. It can be purchased from plastics suppliers. Also, telescope makers sometimes offer it on AM when they have an excess of it. It comes in 4'x8' sheets and ran about $60.00/sheet the last time I purchased it.

****Addendum....

I just found an old receipt ....the thickness I used was .028" and it was 71.00 (in 1998) total.

Hope this helps!
Steve

Don,

Every coating that Clausing has done for me in recent past has failed in less than 2 years. This includes both Beral and Diamond Bright (sp?). I had to send my 20" f/4.0 mirror back to Galaxy for strip and recoat and now my 10" f/4.5 coating is failing after less than 2 years. Clausing will give every b.s. excuse under the sun. They should stop doing telescope mirrors altogether. I also know of 5 other cases of premature failure within our astronomical society. Years back, the coating from Clausing would last 10+ years. Obviously, I don't use them any more. They won't stand behind their work at all.

Hi Ed,

Here is how I successfully clean my newtonian mirrors:

You need the following supplies:

1. Surgical cotton - purchase this at a drug store NOT COSMETIC PUFFS OR COTTON BALLS - they contain impurities that will cause you problems. This cotton usually comes in a box rolled up in paper.

2. A gallon or two of DISTILLED water. NOT SPRING WATER or anything else - these contain minerals which will leave deposits on the mirror.

3. A drop of Ivory dish soap (unscented).

Once you obtain these supplies, do the following:

1. Remove the mirror from the scope and from its cell.

2. Set mirror flat on a large dishcloth in the sink to keep it from scratching your sink and/or damaging the back of the mirror. (You might want to remove rings or any other jewelery that may get in the way or scratch the mirror).

3. Run WARM (not hot) tap water over the surface of the mirror for several minutes to wash away the larger pieces of dirt and impurities.

4. Put one drop (no more!) of Ivory dish soap in about 2 cups of warm water and stir it up so you have a good even solution.

5. Pour the soapy solution on the surface of the mirror until it begins to overflow the edge and let it sit for a few minutes.

6. Take surgical cotton and pull off decent sized pieces. Soak the cotton in the remaining dish soap solution and then gently drag it over the surface of the mirror. DO NOT SCRUB OR APPLY ANY PRESSURE! Don't re-use the cotton once you have made a pass or two across the mirror - replace it with a fresh piece.

7. Rinse mirror thoroughly with warm tap water. DO NOT LET THE SOLUTION OR TAP WATER DRY ON THE SURFACE!

8. Carefully lean the mirror vertically against the sink or in a dish drainer, making sure that it does not slip and fall flat.

9. Liberally pour distilled water over the surface of the mirror. I usually use 2 gallons on my 20" mirror and 1 gallon on my 10" mirror, but that's just me.

10. Allow mirror to AIR dry completely. If you have small droplets of water at the bottom that remain after the rest of the mirror is dry, take a tissue and just touch the droplets to soak them up.

11. Reinstall the mirror in the cell and then mount back into the telescope.

You are ready to collimate!

This alls sounds more ominous than it really is, but it isn't that bad!

Other folks may have a different approach or want to throw in their 2 cents worth on my approach, which would be great!

These mirrors have **very** thin front surface coatings that can scratch easily. Some of the newer overcoated mirrors offer better protection. Hope this helps (if you haven't fallen asleep reading this by now!!) Steve

Hi Don,

Same for us, also. It is too bad that such a decision had to be made. I have always enjoyed Camp Shaw. It seemed like the perfect setup for this event. We are going to give the Astrofest Carnival one shot and take it from there for next year.

See you in the bouncy room with your cone of popcorn.....

Thank you for posting this, Mike! He will be dearly missed and fondly remembered.

Craig - According to reviews I have read about Portaballs, Peter Smitka ( of Mag1 Instruments) attaches the Zambuto mirrors in his Portaballs with silicon (I am only assuming that it is RTV). You might send him an email and verify what he uses. He has always been friendly and responsive to any queries I have sent him.