Posts Made By: Ron Zick

For the optics experts out there,

I have noticed on my Meade 12" LX200, which stays on a permanent pier mount in my observatory, that the apparent collimation seems to change with temperature conditions, or more precisely with the guide tube lube viscosity. My scope does not have any more more slop than any other sct I've seen and actually less than most.

The question I have for the optics experts is, "At what rate does the primary mirror tilt cause image degradation?"

I have not taken my scope a part to take some measurements but by making some assumptions:

1) .00015in. clearance between the slide tube and mirror carrier
2) the tempature expansion coefficient for the tube and the carrier is the same
3} the effect of the slide tube grease on clearance is zero, which I know is incorrect but I am only trying to simplify the problem definition
4) the mirror o.d. is 12in. and the slide tube od. is 3in.

I have concluded that the .00015 clearance on the tube, which probably is on the tight side, would yield a total tilt envelope of +- .0024" at the outer mirror edges. This is about double what we can manual resolve the focus to on our scopes and with an electric focuser we can probably resolve the focus increments to .0005" or less.

It seems to me +-.0024" is a lot of probable error compared with the focusing movement resolution and that this would have to have a huge effect on image quality. All of the formulas I have come across, always assume an optical system in perfect collimation.

If what I have observed is true, is this why the larger scopes don't tend to perform on average to the smaller counter parts and especially the refractors, central obstruction issues aside?

thanks in advance for any insights and answers

Bill,
There were and are copies, mainly sections of text or books, of the Bible previous to the Gutenburg printed Bible.

Actually there exist today about 25,000 ancient manuscripts of the New Testament alone in various languages. Now these manuscripts all wouldn't be complete sets of text,a complete Gutenberg have you, but they do overlap and give us an extremely high confidence level because of the variety in various language groups.

Here's the run down:

Extant Greek Manuscripts:
Unicials 307
Miniscules 2,860
Lectionaries 2,410
Papyri 109

Manuscripts in othr Languages:
Latin Vulgate 10,000+
Ethiopic 2,000+
Slavic 4,101+
Armenian 2,587
Syriac Pashetta 350+
Bohairic 100
Arabic 75
Old Latin 50
Anglo Saxon 7
Gothiac 6
Sogdian 3
Old Syriac 2
Persian 2
Frankish 1

Total 24,970+

There are much fewer Old Testament manuscripts because of the passage of time but we do know that the New Testament quotes from the Old Testament are extremely accurate, there are really only a handful problem texts.

Prior to Gutenburg the manuscripts were hand copied by a very laborious and precise process.

Josh McDowell's book, "The New Evidence that Demands a Verdict",or one of it's preceding versions is an excelent source for further insight into your question.

Hope this answers your question without boring you with trivia.

Looks like Walker is very likely to remain the Governor of Wisconsin. He's been leading 58% to 42% for most of the count. Looks like the Madison beltway was the major Barret area which is no surprise. What is interesting is that even in some of the counties that Walker lost in, was not by a very large margin.

It also appears that the heavy industry areas along Lake Michigan which has union manufactures such as Cat, Manitowoc, Case-IH, etc seemed to not be very upset on Walker's stance on municipal unions bargaining rights.

I have a PD-10, which I really enjoy. I bought my observatory from another amateur astronomer who was moving so mine was already built.( I moved it complete on a lowboy trailer. We drove about 70 mph for 130 mi. and the dome didn't mind the wind and the ride a bit.) The fiberglass construction seems very adequate and overall quality is excellent as far as fiberglass molding and gelcoat goes. I have not seen the Sirius Domes up close but from what I have heard is that the Sirius Dome's construction is more in the yacht class of fiberglass quality (perhaps overbuilt for what is needed). The Home Dome is approx. .25in. thick. The one thing that I have had trouble with is the automatic shutter mechanism. It uses 1/16 in. aircraft cable and a windlass in a pull pull configuration. Biggest problem has been the cable that pulls the shutter shut sometimes jumps out of the guide tube. This really is a minor problem that some further adjustment of the cable tensioning springs should remedy this. I would not use the dome without the power shutter option, manual operation would be a real chore because of the weight of the two shutter pieces.The shutter is very wind resistant, the dome skirt seems to fit well and is tall enough that wind,dust, and or rain penetration has not been a problem( don't know about snow yet). The construction manual that came with mine is good and has since been improved. I would definetly recomend that you order the Home Dome predrilled. Unless you have a very flat area (bigger than the dome area) to do pre-assembly layout work on you will be greatly complicating your project. I have a 12" LX200 on a wedge mounted to a 14" pier in the center of the observatory. The 10 ft. dome gives plenty of room for 3-4 people and equipment. A 6 ft. dome would be tight if your going to be using a wedge or GEM mounted scope.
I would buy another Home Dome again if I need to. Good luck in your search, domes are a blast.

Brian,
The distance you need to run greatly exceeds the scsi specs for cable length. Scsi-1 is 6m., scsi-2 is 3m., scsi-2 ultra is 12m., scsi ultra is 3m., scsi uw is 3m. You can always stretch the maximum length a little but you are at 2X the length of scsi-2 ultra which is at 12m. The problem is the cable capacitance, which determines signal propogation delay,increases proportionally with the cable length. Add the fact that scsi is a parallel bi-directional bus with a relatively high transmission rate and you have a situation that gets to be very tricky to get to work reliably once the specs. are exceeded. Without knowing the exact camera that you are using and the exact scsi protocol that that camera uses I can't help you further. There is a possible solution and that is to use differential amplifiers at both ends but this also has limitations depending on the data transmission rate and cable length.
Ron

Hello,
It depends on what you exactly mean by re-aligned. If you are using the LX200 alone, polar mount, and no computer attached, then yes, you would need to do a 1 star alignment. This is not like setting up polar alignment the first time. If your going to operate in altazimuth mode, then you would need to do a two star alignment for the most accurate pointing but you could do a single star for casual viewing. If you have a computer attached to the scope, then no, the LX200 command set has a home function which is not available through the keypad. This is valid in either polar or altazimuth modes. Go to Meade's website and download the LX200 Classic manual, it's on page 56 of the Meade manual.
Also MAPUG has several discussions on this.
Ron

Dan,
Since you didn't state the bolt circle diameter or the pier height, I'll have to make some assumptions that the height is probably 48" or more and that the bolt circle diameter is less than 16" and probably closer to 12". With the size of scope you have, the pier setting on nuts and the small bolt circle diameter are giving you an excellent spring. You also didn't say what you have for gussets between the base plate and the column. Any deflection you get in this area is multiplied by your height, millionths of inches easily become arc second vibrations. For starters you should try to bolt the base down tight to the concrete. When structural steel is used for buildings, setting plates are used which the building columns set on. These are leveled and set to the desired elevation and then grouted in place. The columns are set on the piers, usually several days later, and the hold down bolts are then tightened. The whole assembly is then in tension. Your current configuration is isolating the scope pier from the concrete base,allowing the scope to vibrate easily and the base to have little effect in dampening these vibrations. If after you remedy this situation and you still have a vibration problem, then you need to consider adding gussets to the pier base. A larger bolt circle would also help a lot but you will probably have to live with that now. Remember, to dampen vibration, you need to make the whole system appear as a single mass, any joint or connection that is added, in effect reduces this dampeneing effect. Filling your pier as it is with concrete will have only a minimal effect on the vibration problem and adding sand will make the pier sound dead but still will not
change the dampening characteristics by much.

I've got a 12" lx200, my first scope also. All of my eyepices are Meade because of the eyepiece deal which I traded back for the eyepieces I really wanted. I kept the 26mm and the 32mm from the original set and added the 14mmUWA, which is my favorite for general viewing and the 6.7mmUWA for good seeing conditions. These two pretty well ate up the budget. I would like to get something in the 4.7 range for the really exceptional nights. After the 14mmUWA the 26 and 32 are kind of unimpressive but are good eyepieces in their own right. I would really recommend buying fewer but better eyepieces. Hold off if you have to and save up for the good ones, you'll reaaly enjoy them.

Paul,
I am puzzled by where you got your information. It seems there is a substantial amount of physical evidence that supports a very early authorship of the gospels. A late date for the last book of the Bible and the last written, places it around 90 A.D. Yes this is 67 yrs. after the crucifiction date but still in the life span of eye witness accounts. We accept eye witness accounts of Pearl Harbor and WWII with credibility so the time period would seem reasonable for an accurate account. You state that Jesus promised to come back before they died, where or when did Jesus make that specific promise?
The test you use for correctness of religious doctrines correctly addresses the human condition, however your conclusion would also seem to mean that we can not know truth with any degree of certainty. This would also mean that all of the scientific research that has been done is not true to any degree of certainty. Don't you think that we can use a method or system to determine true or false in any system, secular or religious? If a book were to be written by a diety, what do you think it's characteristics would be? It's content and claims?

You raise a very interesting point, especially in relation to currently accepted thought in that it is possible to pick and choose from a menu of value systems (beliefs). I have never found the logic or reason in being able to hold opposing or conflicting ideas and concepts simultaniously as truth. Isn't what you raise how we should be searching for truth,"it is what it is", not making ones own truth. Do you think we have a "choice" in rejecting or embracing a belief? In some ways a logical person would have to make the logical choice of embracing truth when it is presented, to reject would seem to be illogical.