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Posts Made By: Floyd Blue

November 19, 2003 08:39 PM Forum: Equipment Talk

31mm Nagler, Loose lens!

Posted By Floyd Blue

I was noticing an increased amount of coma and astigmatism in my 31 Nagler and today while cleaning it I noticed that it rattled while moving it arround. I unscrewed the barrel and found the inner barrel lens ring had loosened and the lens was moving around. I tighten the ring so that it was held from rattling without overtightening it and causing it to pinch. There was also a bit of black paint that had flaked off the inside on onto the lens, which blew off easily enough.
I am not sure this happens often, but if you notice some degradation in performance on your Nagle, check to see if you are having the same problem.
Floyd

November 20, 2003 07:09 PM Forum: Wildlife Photography

With winter coming a breath of spring

Posted By Floyd Blue

Here is a spring picture of California wild flowers for all those who are Sun and color starved by winters dreary days.
Floyd

November 20, 2003 07:22 PM Forum: Equipment Talk

Garmin GPSMAP 76S

Posted By Floyd Blue

I received my Garmin GPS this week and have had a chance to try it out.
I wanted one to be able to see the location by Lat & Long and the elevation as well as compass headings.
The new Garmin GPSMAP 76S has everything a person could possibly want in a GPS. It has electronic and GPS altimeter and barometer with electronic compass. It does everything from Solar information to Lunar Phases with rise and setting times. Even has tides and navigation with shallow and deep water warnings.
7ozs weight and small enough to fit into a pocket with a good sized display.
If you are into this kind of thing, this is the best one I have seen for the money. I got it on the internet for $300 with free shipping and no taxes. Not really cheap, but they retail for $400-440.
I finally know how high the hill is where I go to observe here in the valley on hazy fall and winter nights, 1749'. Which is 1400' higher than at the house. LOL
Floyd

November 21, 2003 07:29 AM Forum: Wildlife Photography

Sunset in the Valley

Posted By Floyd Blue

A sunset shot of the valley near home. Hope you like it.
Floyd

November 21, 2003 07:30 AM Forum: Wildlife Photography

Another Sunset Pic

Posted By Floyd Blue

Slightly different kind of shot done for a friend.
Floyd

November 23, 2003 07:36 PM Forum: Equipment Talk

Coatings statement!

Posted By Floyd Blue

"Enhanced coatings are not recommended and are not guaranteed by the coating vendor."
This was copied from the Pegasus Optics page!
WOW!
Now that I believe says something about the question of Enhanced vs. Standard coatings. It has been argued here many times and I have been told many things. This is the first time I have seen a disclaimer statement on line!
Floyd

November 27, 2003 01:16 AM Forum: Telescope Making

4 Hole Aperture Mask

Posted By Floyd Blue

Ok, I have given it a lot of thought and I believe I have the answer to why the 4 hole aperture mask works.
The 4 holes are superimposed one upon the other like stacked images taken with a camera when brought to focus. Because of this it actually acts like a one hole mask. If you were looking at 4 holes separately, then there would be large spider veins between the holes and you would have spikes.
Just as a one hole mask removes spikes, so does the 4 hole mask.
Attached is a picture of my four 6.5" hole mask for my 15" DOB. It is a better mask than the original one I made with 1" more aperture per hole for better throughput.
Am I wrong here, or on the right track?
I mean the thing works like a charm, so there must be a logical reason for it to work.
Floyd

November 27, 2003 01:21 AM Forum: Equipment Talk

4 Hole Aperture Mask

Posted By Floyd Blue

Ok, I have given it a lot of thought and I believe I have the answer to why the 4 hole aperture mask works.
The 4 holes are superimposed one upon the other like stacked images taken with a camera when brought to focus. Because of this it actually acts like a one hole mask. If you were looking at 4 holes separately, then there would be large spider veins between the holes and you would have spikes.
Just as a one hole mask removes spikes, so does the 4 hole mask.
Attached is a picture of my four 6.5" hole mask for my 15" DOB. It is a better mask than the original one I made with 1" more aperture per hole for better throughput.
Am I wrong here, or on the right track?
I mean the thing works like a charm, so there must be a logical reason for it to work.
Floyd

November 28, 2003 11:24 PM Forum: Equipment Talk

Feather Touch Focuser has arrived! :^)

Posted By Floyd Blue

I finally got my FeatherTouch I ordered 2 months ago from Anacortes! Starlight was way behind in manufacture because of illness.
It is really a wonderful piece of equipment. :^)
Very pretty and it focuses so smoooooooth! I have to admit it was worth the money.
I got it mounted but of course the cloud gods have moved in for the weekend. :^(
Mounting it was a bit difficult as you had to disassemble it each time you adjusted the leveling screws. It took a while but finally got it just right.
I finally found a formula for the offset, It tells where the laser dot should fall on the diagonal mirror in relation to the actual center of the elipse of the mirror.

How to figure offset for Diagonal Mirror in a Newtonian Telescope

Diagonal offset = mirror size divided by F/R X 4 then X 1.414

Diagonal Diameter = 2.6” = 66mm
F/R = 4.9 X 4 = 19.6
66mm divided by 19.6 = 3.3673469mm
3.3673469 X 1.414 = 4.7614285mm
4.7614285mm = .1874574” = 13/64”
Offset is measured from true center of diagonal mirror ellipse away from the primary mirror.

1 millimeter = 0.0393700787 inch

Many of you problably know this already, but for those that don't I just posted it.
Floyd

November 29, 2003 03:09 AM Forum: Telescope Making

Secondary Offset question.

Posted By Floyd Blue

I got my Feathertouch focuser in today and mounted it. I had to square it to the secondary. To do this I had to work out the offset for the optical center vs. physical center of the mirror.
My question is this.
I used a formula that I found on the internet as follows.

Diagonal offset = Diag mirror size divided by F/R X 4 then X 1.414

Diagonal Diameter = 2.6” = 66mm
F/R = 4.9 X 4 = 19.6
66mm divided by 19.6 = 3.3673469mm
3.3673469 X 1.414 = 4.7614285mm
4.7614285mm = .1874574” = 12/64” (6/32")
Offset is measured from true center of diagonal mirror ellipse away from the primary mirror.

1 millimeter = 0.0393700787 inch

Well after I finished I found 2 more fomulas! Great! They both came out to about 9/64" instead of 12/64" offset.
Well, it was a bitch to square the focuser because you had to remove the focus knob assembly and adjust the leveling screws and tighten the bolts then assemble it and check it with the laser.
So no I am wondering, is the fomula I used correct? If not ,will it make any real difference if I am off 3/64 or 4/64" on the optical center?
I am willing to readjust it if needed, but I am not looking forward to doing it again.
:^(
Floyd