Posts Made By: Tom Hole

Mark,

This might ruffle some feathers, but I'm going to post it anyway. This was a post on the Yahoo binoviewer group where we were discussing how to measure the clear aperture of a binoviewer.

http://groups.yahoo.com/group/binoviewer/message/4626

My numbers do not agree with what others have measured or advertised, thus the rub. I'm not sure that bothers me too much. I know what I measured and it is what it is. Why it is, I can't explain that.

"I just went out and used the sun and that took care of the expanding circles issue. The diameter of the illuminated circle appeared to remain constant as I drew the piece of paper away from the ep holders. That takes care of that. Then I taped paper across both ep holders on both my Denk standard and the Televues and marked the width of the illuminated circle with a sharp pencil. I would guesstimate my accuracy at + or - .25mm. Here's what I measured:

Denk standards left and right were 24.5mm
Televue binovues left and right were 26.5mm

I took the measurements 3 times using 2 different methods and it all came out the same.

As far as the different height of the ep holders, I think that gets normalized in that the ep is higher therefore the ep field stop is higher (on the TV's). I think what we are interested in is the diameter of the clear aperture at the ep field stop. I think measuring it anywhere else is relatively uninteresting.

One interesting thing that I noticed and maybe this is an indicator of a flaw in my method. This applies to both binoviewers. I held the binoviewer input end up to the sun and then tilted it until I got a fully illuminated circle. I had removed all ancillary equipment from the nose. As I was tilting the binoviewer around, you could see the illuinated field clipping. I assume this is due to the beamsplitter and such inside the binoviewer. But here's what was interesting. When I got the tilt just right, I could get a complete circle fully illuminated, but it was not in the center of the ep holders, it was offset to the inside a bit. This was true for both binoviewers. With the illuminated circle centered in the ep holder, parts of it were clipped. Not sure what that means."

As far as seeing vignetting, I have not seen any in either binoviewer. It must be there, but I haven't noticed it. I have to use an OCS with a mag of 1.38x, so maybe that eliminates the need for a 27mm clear aperture to illuminate a 27mm field stop ep (24 Pans).

Clear skies,

Tom

Ooooowwwwwww!!!!! That hurts my eyes trying to resolve it into one image.

Tom

Jeff,

I'll jump in as a cronie. I haven't been earning my pay lately and I risk losing my stock options. I'm working my way up to full marketing apprentice.

What worried me about the Power X Switch was how it would switch, especially to high power. I had envisioned a sliding lower element. The 2" OCS in 2.5x mode has only one group of 2 elements in there and it works very well. The Power X switch looks like it just switches between 1.4x and 2.5x mode my removing the upper lens group. That means the 1.4x mode is the same as the old OCS (optically) and the 2.5x mode is the same. Wasn't as worried about the 1.4x mode as I don't use that for critical detail viewing. But the fact that the switch is made by removing the upper group makes me expect it will perform similarly to the current 2.5x mode as they both share the exact same optical setup.

While I am looking forward to the Power X Swtich, a zoom OCS would be keen. Glen asked earlier what benefits that would bring. Well, the exact same as a zoom ep, observing wise. It's just a really BIG zoom ep. But, if you've read many reviews on zoom ep's, most do not replace high power planetary ep's. The Nagler zoom seems to fill this gap well, but I haven't seen any others that do. I have only tried the GTO zoom and it was fun, but did not earn a spot in my ep case. If Harry makes a zoom OCS that does all those things he said it would and retains very high quality images, then good for him.

Clear skies,

Tom

Lesson Learned. Always good to get it from the manufacturer and not from a lackie. I guess my cronie status will be downgraded to village idiot. There goes my shot at apprentice marketer.

Thanks for the accurate info.

Clear skies,

Tom

Floyd,

Nice table. Is that a Sirrius plossl in the middle?

I added an accessory tray to my Starmaster to hold a few ep's and the extra binoviewers. Not as big as your table, but I roll the scope around a lot and needed something that traveled with me.

Clear skies,

Tom

A bullet proof vest.

Another, most excellent contribution.

Michael,

Try the 25mm's and see if they work. That is all I used for my first few weeks of binoviewing. Then I added a pair of 32mm GTO plossls (good), a pair of 9mm Expanses(bad) and a pair of 25mm Orion Epics (no better than the 25mm plossls). Then I went for a pair of 24 Pans and they were very nice, but the 32mm and 25mm plossls were an 80% solution. Then I found orthos and bought a bunch of them. That's where I would go. Get a few pairs of orthos at your favorite focal lengths and enjoy them. They seem less orthoish when they are paired up in binoviewers and they can't be beat in image quality. I'm replacing my orthos with type 6 Naglers, but I'm not in a big hurry.

Here's a page I put together on why I have what I have:

http://www.tomhole.com/Oculars%20Filters%20Etc.htm

Scroll down to life after binoviewers.

Have fun with whatever brand you have. We act like children, but I think we all agree that binoviewing is better than cyclops viewing.

Clear skies,

Tom

I'm watching Ganymede transit right now and I am seeing what looks like another great red spot in the NEB. It is directly above (south) of Ganymede itself right now. It is more rectangular shaped, but the darn thing definitely has a salmon color to it similar to the GRS. Anyone else seeing this?

Clear skies,

Tom

BTW, seeing is good and the 13 Naglers are fantastic.

I compared the 9mm HD to the 9mm classic and didn't see a difference. Others have.

In focal lengths less than 12.5mm, I prefer the volcano tops because they are much more comfortable. I have only used the 7mm, 9mm, 12.5mm and 18mm.

Clear skies,

Tom