Posts Made By: Keith Lawson

Well... Gettin' ready for the "planetary observation" evening bonanza. Built a HD pier and HD "adjustable" wedge to support my Cooled C-8 and the upcomming star parties. I hate "the shakes" associated with the standard wedge and tripod at high magnification and the high cost of an HD wedge is well beyond what I'm willing to pay for one. Will take apart for weatherproofing (paint) soon. Will add hand knobs from Mc Master-Carr also. Still hacking...

Originally Posted by John Biretta

Looks good.  Lots of air motion without filters.  No fans in the light path. <br><br>How well does it work? If you've got a boiling image from a warm primary mirror, how quickly do the fans fix it?  <br><br>If you look at an out-of-focus star, do you see any air currents from the fans?

Hi John,

I don't know if you saw my response I wrote to you a few months back. Seems like it was lost durning the site upgrade/change. Just in case you didn't:

Works extremely well. Truly Plug & Play. The mod is not recommended for those who live in places like Los Angeles where normal evening temp drops are not that severe, or for deep sky observing.

The instant the fan is turned on all the temp patterns disappear. No veins, spikes, v-shaped plumes in the out of focus star pattern. In severe cases, like going from a 20 to 30 degree difference in temperature (warm house to cold outside), the strong internal "weather" patterns are replaced with a delicate swirl pattern that grows fainter as time goes on. I performed such a test and after about 45 minutes all was well within the tube assembly. The swirl pattern had all but disappeared.

Keith (Scopejunkie)

Hi all,

I just sent my 50 year old (1965) 8" F/4.5 Cave mirror to Alcoat today. I believe this will be my third time using Alcoat. Can't beat their prices and my other two mirrors came back with an excellent coatings. I also agree that Bob Fies is an honest gentleman as well. He has always refunded me for my shipping overpayments to the penny

Keith (Scopejunkie)

The mirror will be tested As a visual observer I find a high power image at the eyepiece (moon, planets, stars) to be my final "test." The star test and Ronchi tests were quite good even with the coatings in "see through" condition. The mirror will be tested for increase in image quality (sharpness, contrast, and scatter) and how deep these old eyes can go with it. I will let you know my results.

Keith (Scopejunkie)

Hi All,

Anyone who takes the time to look through old Sky and Telescope magazines can witness the "wave wars" of multiple mirror producers. The producers came up with many creative ways to claim optical quality. One of my favorites is the +/- 1/8th wave claim. As in all industry, there are the good people who are honest with their claims and produce a good product and then there are the cheats, like those who sell flawed or average optics at premium prices hoping the end user will not have enough knowledge to notice.

As once stated decades ago, "there are good optics and there are cheap optics, but there are no good cheap optics." The Chinese seem to be bringing this statement into question with the latest quality I have witnessed. I have had some very good Chinese mirrors. As all experienced telescope users should know, price does not necessarily guarantee quality. I once had a guy get very angry (not at me) when his expensive 130mm APO refractor couldn't compete with my "inexpensive" home made 8" F/9 achromatic refractor on Saturn (at 1/3rd the price).

I have owned "certified" SCT's that were only average, some that were outright dogs, and some that were clearly exceptional yet some would state that they are all lunar/planetary dogs (like me in my ignorant, early, telescope years). What I see in the eyepiece will always tell me what I have in an optic set no mater what the claim. Interferometer not needed.

Some of my best optics:

Orion 8" F4.7 (Chinese)
Orion 10" F/5 (Chinese)
Orion 12" F/5 (Chinese)
Royce 10" F/8 (incredible optic)
Unknown 12.5" F/8 
Old Meade 6" F/8
Current C-14
Current C-8
Intes 7" F/15 Mak 
Intes 8" F/15 Mak
Cave 8" Cassegrain
Meade 10" F/6 (chipped back, picked up in their seconds sale at RTMC for 25.00)
Meade 178 and 127 ED Apo's
Cave 6" F/15 refractor

Keith (Scopejunkie)

All,

Just got the mirror back from Alcoat. Quick turnaround. Looks real good Bob even refunded me my overpayment of $0.10! I have a new secondary that should arrive today. Time to get this old Cave back under the stars!

Keith (Scopejunkie)

Rod,

My optical bench is the night sky. My only baseline for this mirror is the overall optical correction before the new coatings. The original coatings were quite bad. There were fingernail size holes that you could actually look through. Despite the severe weathering of the mirror there were no scratches in the glass. The seeing was bad last night so I will have to wait for a better night to test.

Keith (Scopejunkie)

Will do! It is interesting to note that while you were getting good seeing, I was experiencing bad seeing (2-4/10). I guess that's what I get for retiring in the "land of windmills." Looking at my observing log, my first year up here in the mountains (7 years ago) had many nights of good seeing. Then the drought hit and the seeing has been mostly bad since. Looking forward to a return to normalcy and the advantage of living at 4000ft.

Keith (Scopejunkie)

Hi All,

The old man is at it again. Did a 1500mile turnaround trip a couple of days ago to pick up these, no longer needed, bits and pieces to a 10" F/10 refractor. The college I got them from has much newer stuff so this became obsolete a few years ago. The OTA weighs about 80lbs. Too much for this guy. I will have to rebuild this 55 year old Navy/Air Force tracking refractor.

Stay tuned

Keith (Scopejunkie)

Hi Rod,

We shall see. Right now I'm debating on if I'm going forward with this project. Even if I make a new scope around the lens it may still be too heavy for this old guy. I may end up having to sell it despite my dream to own such a large refractor. The lens assembly weighs around 35lbs.

Keith (Scopejunkie)