Posts Made By: Donald Durbin

To All,

Here it is and remember you saw it here first!

This is a head to head comparison of vignetting in a 40mm EP with the following binoviewers. The target is a daytime Moon. These images may not show the total vignetting but they show the relative vignetting in the different binoviewer units. The images were taken within a 20 minute span. The order of the images taken is listed below.

1. Burgess BV125C
2. Siebert 22mm BN
3. Burgess 24mm
4. Denkmeier with Dielectric coatings
5. Televue Bino Vue

This is through my William Optics 80mm short tube with the APO upgrade.

1. Burgess BV125C image attached

To All,

I bought a used SM40/BF10/T-Max tuner here on Astromart a little over a year ago.

I was pretty happy with it but I did notice that the detail at the bottom of the field of view was much better than anywhere else.

Recently I got a William Optics short tube for binoviewing and I thought this would be great for Solar viewing also. I put the SM40 on it and once again the bottom of the FOV had the best detail.

I decided to bite the bullet and send it back to Coronado to be looked at. I was pretty sure the BF10 was the problem since I had rotated the SM40 360 degrees without any effect on the problem.

Coronado said they would look at it and get back to me. Today there was a knock at the door and UPS had me sign for a package. It contained a new SM40 and BF10 from Coronado.... "NO CHARGE"

That kind of customer service is hard to beat. I hope everyone else is as happy with them as I am right now.

Don Durbin

To All,

The length of the light path through your binoviewer plays a role in how it will perform with a given EP.

My new super binoviewer scope, (My William Optics short tube with APO upgrade) can focus any known binoviewer without any needed OCA/OCS in the light path.

With a custom 5.5" extension it can also focus a single EP the way a normal scope would. Tonight I decided to measure the light path through the 5 binoviewers I have been testing with a set of digital calipers. The results were a little surprising.

Using an 18mm Radian and the 5.5 inch extension I brought the scope to focus on Jupiter. I then measured the distance between the edge of the tube and the edge of my 2" diagonal. The base number needed for focus turned out to be 204.39mm.

I removed the 5.5 " extension and focused each of the 5 binoviewers using the same 18mm Radian. I made sure any diopter adjustments were full down and that the EP was fully seated. I then made the same distance measurement I had made with the single EP and subtracted that from the base number to determine the light path of the binoviewer. The results are listed below in order of the shortest to longest light path.

1. Burgess 24 107 mm
2. Burgess BV125C 107.76 mm
3. Denkmeier Dielectric 125.47 mm
4. Siebert 22mm BN with SCD's 136.7 mm
5. Televue Bino Vue 139.08 mm

I can probably give a good guess at why these numbers are off from the advertised numbers. I think the light path was measured on units without Self Centering Diopter adjustments. I know the Siebert SCD's are very tall. The Burgess Diopter adjustments are very low profile.

In any event these are real numbers that were measured on a refractor. Try plugging these numbers into the spreadsheet that Tom Hole supplied in an earlier post and you can see just how much of a change in actual illumination the light path can make.

On a side note, if you view with the power switch attached to your Denkmeier it will add another 12.65mm to the lightpath.

These measurements were taken with the standard nose piece on the Burgess, the 1 1/4" nose piece was placed on the Denks and the power switch was removed.

Don Durbin

Hi Floyd,

This surgery may be the ultimate cure for eye strain caused by single eyed viewing.

Don Durbin
Binoviewer Forum Moderator

Hi Floyd,

I could be like this poor guy. He needs a trino-viewer.

Don

Hi All,

I am now the new moderator of this forum.

No personal attacks will be tolerated. (Try to respect the right of others to disagree with you, even if you know the other person is wrong. Count to ten and read it over again before you hit the post button.)

No curse words or pseudo curse words will be tolerated. (I know it sounds a little silly, but, I consider this to be the fastest way for a forum to degrade into a furball.)

No blatant advertisements please. (You are welcome to give your opinions on products that you own or at least have tried out. Please do not try to hype vaporware products here. Before you hit the post button ask yourself if your post really looks like it belongs in the classifieds section of Astromart.)

Thank you all for your help and understanding.
Don Durbin

To All,

The subject is Chinese Optics. Lets make an effort to keep on that subject and see what kind of a forum we have here.


Don Durbin

Hi All,

I own a Takahashi FS-128 and I also have a W.O. 80 mm short tube that I upgraded to APO FPL-51 ED Glass. I have to say that I am quite impressed with the FPL-51 ED Glass. I cannot really do a head to head between my 128mm TAK and the 80mm W.O., but the lens quality is very good on the W.O. 80mm.

I actually put this combination together for Binoviewing. I have a 2" binoviewer that needs a ton of in focus and replacing the standard 480mm lens in the W.O. short tube with the 545mm APO lens gave it to me.

Has anyone else had any experience along these lines?

Don Durbin

Hi All,

I ordered a pair of the new Burgess 24 binoviewers on September 18 and received them on September 21st. It is my understanding that Burgess has these in stock and is shipping them.

I already had a pair of Burgess 24's with the old 3 screw eyepiece centering devices but I wanted to try the new self centering diopters from Burgess. I have to say that they are very nice.

I had a choice between the 8mm Planetary EP's and the 9mm Planetary EP's. I decided on the 9mm. I also purchased a pair of the Ultra Wide Angle: 11mm S1 Special garage sale EP's.

The unit came in a nice case. There are two correctors (One is for use in a Newtonian telescope the other is more for a refractor.) I will check the magnification of the correctors shortly.

Don Durbin

To All,

This forum is for the discussion of products that have a Chinese origin. While these products are generally less expensive, their quality has greatly improved over recent years. In most cases they offer a cost effective alternative to the better known names we have come to use in Astronomy.

We can all find negative things to say about different dealers, manufacturers, or organizations. This forum is not the place for those discussions. If you have an axe to grind, please consider this forum a non-grinding zone.

Thank you all for your cooperation.

Don Durbin
Forum Moderator