Posts Made By: Guy Earle

I'm putting this question out in here and in the Bino forum: does anyone stack a Double-Arm Power X Switch and a Single-Arm together when using a binoviewer? I saw a post somewhere, and was wondering if anyone has had any sucess with it?

Thanks,

Guy
12.5" f/6 Homebuilt Dob
16" f/4.5 Discovery Dob (soon)

I'm putting this question out in here and in the Equipment forum: does anyone stack a Double-Arm Power X Switch and a Single-Arm together when using a binoviewer? I saw a post somewhere, and was wondering if anyone has had any sucess with it?

Thanks,

Guy
12.5" f/6 Homebuilt Dob
16" f/4.5 Discovery Dob (soon)

Hi, all:

I'm in the need for a third (and final) set of eyepieces for my scope. My setup is:
12.5 f/6 homebuilt dob with DenkII w/2"OCS & Dual-Arm Power Switch with Low-Power S lens (whew!)
My eyepieces are the old 24.5 Meade SWA and a recent 15mm Expanse. I've been in this hobby for almost 14 years and have owned many Naglers, Pans, etc. but I find myself stuck on this one.

I've noticed in the bino that Naglers aren't really needed (I have long ago sold all of mine). I like seeing the field stop (preferably in th 60-68 degree range), since it gives the impression of looking out a big window. In a bino, a Nag tends to be too much FOV. The allusion of merging eyepieces makes a medium FOV extremely pleasant.

Last night I did the drift test to get the real magnification, and was surprised that the higher power topped off at 264X, about 40X less that the calculated from the specs. I'm looking for a recommendation for an eyepiece that is anywhere from 8-11mm's in a price range of 50-80 dollars. I know that's not much for price, but I've learned that simple, low-element design tends to yield the brightest and sharpest views, especially in a binoviewer which tends to correct any minor flaws.

I've looked at Antares, Orion, Meade, TV, UO, and I'm just uncertain. Any help would be greatly welcome. I'll also post this in the bino section too.

Thanks,

Guy

In an effort to get true data, I did the drift test on my 24.5's and 15's in the Denk II. Some of it is surprising.

12.5 f/6 Homebuilt Dob. (True FL 1889mm)

Meade 24.5 SWA, 61 AFOV

Power Switch FOV MAGN.
Low 1.1X .64 95X
Med 1.5X .46 133X
High 1.9X .38 161X

Expanse 15mm, 66 AFOV

Power Switch FOV MAGN.
Low 1.1X .44 150X
Med 1.8X .29 228X
High 2X .25 264X

I've been tormented over how to eek out more power (Multiplier, another set of eyepieces, a second power switch), and I totally forgot to try the 2" Big Barlow in conjunction with the 24.5's 8O (the 15's were WAY too much power). In a previous thread, someone had calculated that the barlow yielded 4.3X, 5.78X, and 7.3X with the Power Switch. The following data, again using the drift test, is the overall magnification, including the power switch and barlow. The following totals are less than the 4.3X, etc.

Meade 24.5 SWA, 61 AFOV with Televue 2" Big Barlow (2X)

Power Switch FOV MAGN.
Low 3.51X .2 305X
Med 4.4X .16 381x
High 5X .14 436X

These calculation are, of course, the best I could manage, so I'm sure there's some error in there, but it gets me closer than just using the manufactuer data. What this implies, is that using the barlow in conjunction with the Power Switch and the 2" OCS yields more than the standard 2X (I also have the OCS out about 1/2 inch). The image degradation using the barlow at 305X and 381X was very small, and considering it wasn't a great night and I had just hauled the scope out of the garage, the scope still had not cooled down at all. So the images in the barlow theoretically should be fine under normal observing conditions. 305X should the image of Jupiter that I had been looking for in apparent size.

And if I ever need to get a wider view, I'll just haul out the holy hand-grenade, my 35 Pan!

Clear Skies, Guy

P.S. I will also post in the bino. forum as well.

I put this same post in the eyepiece forum.

In an effort to get true data, I did the drift test on my 24.5's and 15's in the Denk II. Some of it is surprising.

12.5 f/6 Homebuilt Dob. (True FL 1889mm)

Meade 24.5 SWA, 61 AFOV

Power Switch FOV MAGN.
Low 1.1X .64 95X
Med 1.5X .46 133X
High 1.9X .38 161X

Expanse 15mm, 66 AFOV

Power Switch FOV MAGN.
Low 1.1X .44 150X
Med 1.8X .29 228X
High 2X .25 264X

I've been tormented over how to eek out more power (Multiplier, another set of eyepieces, a second power switch), and I totally forgot to try the 2" Big Barlow in conjunction with the 24.5's (the 15's were WAY too much power). In a previous thread, someone had calculated that the barlow yielded 4.3X, 5.78X, and 7.3X with the Power Switch. The following data, again using the drift test, is the overall magnification, including the power switch and barlow. The following totals are less than the 4.3X, etc.

Meade 24.5 SWA, 61 AFOV with Televue 2" Big Barlow (2X)

Power Switch FOV MAGN.
Low 3.51X .2 305X
Med 4.4X .16 381x
High 5X .14 436X

These calculation are, of course, the best I could manage, so I'm sure there's some error in there, but it gets me closer than just using the manufactuer data. The image degradation using the barlow at 305X and 381X was very small, and considering it wasn't a great night and I had just hauled the scope out of the garage, the scope still had not cooled down at all. So the images in the barlow theoretically should be fine under normal observing conditions. 305X should the image of Jupiter that I had been looking for in apparent size.

And if I ever need to get a wider view, I'll just haul out the holy hand-grenade, my 35 Pan!

Clear Skies, Guy

I've read through the old posts, so I would just like some opinions on my idea. I'm getting a 16" split-tube dob soon (have 12.5 split now), and I'm curious about surface fans and which way the fans should point (I agree with Floyd's onto the back setup).

Currently I use three standard, 80mm DC fans at the rear, and will do the same on the 16". Is it worth it to install a small 1.5" fan to blow in across the mirror? Or is it better to have it blow out? Lastly, should it be mounted on the top of the scope, since that's where the heat will go?

I'm confused, some people have fans which blow out the back, most blow in....which is better?

Here is my thought on how I will setup: one 1.5" fan on the left blowing across the mirror to a 1.5" on the right sucking it out, and three 80mm fans blowing onto the mirror from the rear. The cool air hitting the mirror will go up and get caught by the side blowing fans and go out. Just my guess.

Any help would be greatly appreciated.

Clear Skies,

Guy

This post was modified on 7/17/2006 8:48 AM



Thread:

Hi, all:

I sold my homemade 12.5" dob and got my new 16" Discovery last weekend. I made another table for the back, slightly larger this time. I noticed a couple years back when I made the first one, that the 12-3 o'clock position on a dob is dead space. So, make a light table for the rear and have your battery out front for a just-in-case counterweight. You have to make sure the table is as close to the tube in the vertical as you can get it, for balance reasons. I put some speakers and my cd player in the box, cushioned with foam, so there are no vibrations. Takes just an extra minute to put on.

The shots don't have any polyeurethane, which i put on tonight.

Hi, all

I've been observing for some 14 years now, and have always been a dob man. My latest is a 16" f/4.5, coupled with a Denk. I've always been visual, but I'm curious about taking planetary photos. No drive, no eq platform...just push.

I fiddled with my digital camera at the eyepiece, and it got me curious about taking and stacking planetary photos with say, Registax.

Can it be done without a drive? In other words, can I take a series of photos, move the scope, take more, and then stack them? I guess it all depends on whether or not the software can stack photos of say, Saturn, when it isn't in the same part of the field (since with no drive I will have drift....).

As I said...visual man asking a very basic photographic question. All advice is very welcome.

Clear Skies,

guy

Hello, again:

Need an opinion: I'm ready to purchase my webcamera and I have two choices: 1. Toucam and 2. Orion's Star Shoot.

I've been reading all the threads, and the Toucam seems to be the standard/best. Also, I'm sensing that the CMOS chip is inferior to the CCD (not sure how or why really).

So, I'm about to purchase the Toucam and looking for opinions.

Clear Skies,

Guy

Hello all:

I got my Toucam and have started fidiling with it. I'm still recording very small images (no barlow) with the camera, and trying to get used to the motions of the object in the viewscreen--a difficult task to say the least at high magnification.

My question: how do i get registax to process one avi composed of multiple frames? I record four or five 20 second avi's, and put them together into one image. However, I do a single point alignment, which works fine until the next clip starts, which Saturn is back across the FOV. The single point alignment has a stroke and I can't get any further. Any suggestions?

Clear Skies,

Guy