Posts Made By: Tom Hole

Hello,

1278 #15 arrived safely today via FedEx. After the obligatory "whadidya buy now?" from my better half, I quickly opened the package. Bill did a superb job packing the scope to insure its safety. He added two pieces of PVC pipe to keep the box from getting crushed length wise. No damage anywhere that I could spot. First hurdle overcome.

Before I move on, I think a little background on my GEM and refractor experience is in order. I have none. I do have an ST80 on my XT10 as a finder, but it only sees a 32mm plossl. No purple haze at 13x. Nice 4 deg TFOV, though. My only telescopes up till now has been an XT4.5 dob, and my trusty XT10, 10", f/4.7 dob. So, you get to here what a newbie thinks of GEMs and refractors.

MECHANICALS

I tried to mount the rings on the dovetail that came with my Apogee HD and they didn't fit. I paused for a moment, held my breath until my face turned red, then dropped to the floor and proceeded to thrash about while screaming wildly. Not to be deterred, I made a dovetail out of some 1/4" poplar and that was sufficient to hold the scope on the mount and scare me to death. So, I spent about 30 minutes grinding down the Apogee dovetail with the Dremel so the rings would fit. Yeah!

I mounted it up straight away on the Apogee HD. I tried eq mode for a while and darn near had another fit. With a heavy load of binoviewers in there, I did not like the odd twisting that was going on and was scared to death that my favorite stuff would just fall out onto the blacktop. It did not, largely because Bill was nice enough to include a clamp ring on the draw tube instead of set screws. I quickly grew tired of wrestling this beast and set the Apogee mount up in alt/az. Ahhhh, this looks familiar. Now the diagonal stayed in the same orientation all the time and my binoviewers never ended up looking straight down.

My Apogee HD is stock with a set of Celestron dual drives. No mods except a hypertune by me. It is not very good with the 1278. Actually, I hate it. Settle time was about 4 seconds and precise focusing was impossible. Actually, any focusing was a lesson in frustration. I hope my big GEM doesn't wiggle like that. I didn't weigh my setup, but I had removed the finder and was using the binoviewers. Maybe 16 lbs or so.

cont'd

At tonight's star gathering by our club, there were 3 pretty nice scopes. One was a Mark Harry mirrored 10" truss, another was a Zambuto 12.5" portaball and the third was our club's CGE1400 14"SCT in our observatory.

The seeing was very good at a solid 7 of 10 with moments of very steady views. I looked through the 3 scopes several times at 400-450x on Saturn. Without a doubt, the 12.5" Zambuto was the winner, the 10" Harry was a close second and the CGE1400 was third. I'm not sure about the dob's collimation, but the CGE1400 has been collimated by our club's SCT owners.

I had expected the 14" to stomp on everyone else in this most excellent seeing. But the view was not as sharp as the 2 dobs. If that is due to collimation, I would be suprised as our club has some pretty experienced SCT users, but I guess you never know. I can say for certain that my 5" Burgess was left behind in this comparison, but I wouldn't expect a 5" scope of any type to keep up with the bigger dobs.

So now I'm left wondering why I have a 5" refractor. It is the first refractor I have ever looked through. I didn't expect the 5" to keep up with the 10", but I had to try a refractor to see what they are like. Maybe there was something I was missing with the 10" dob that I could get from the 5" refractor. I have an Orion XT10 that shows much more on the planets and deep sky, which is my main interest. The pinpoint stars are nice. It is only slightly more portable than my dob. It shakes like a leaf on the stock Apogee HD. I'll have to mull this one over.

Anyway, just thinking out loud.

Clear skies,

Tom

Sorry, couldn't leave the message counter at 333 + 333.

Tom

In keeping with the SAA spirit that seems to have found its way into the ET forum, here are the top ten topics for the past week:

10. Moving a 330" Mirror to Mt. Graham
9. Dark vs altitude
8. Horizontal not vertical
7. Overseas star parties
6. Help building computer system
5. Hey guys, tell my wife I'm not alone
4. How about a visible forum?
3. Dark or altitude?
2. YOU Grow up, Scarboro!

And the #1 topic on ET?

1. This post (or fill in your nomination)

Sorry, no picture.

Tom

Can someone measure the largest outside diameter of a Pentax 10.5mm XL for me? I seem to remember it being right close to 61mm (2.4").

Thanks,

Tom

Well, my investigations into the 24-25mm and 9-10mm ep pairs is complete. 24 Pans and 9 Nagler type 6's. Big suprise, huh? It is weird to look in my ep case and only see 4 pairs of ep's though (still have the 32mm GTO plossls and the 12.5mm orthos).

Now I am venturing into the 11-13mm and 7mm ranges. The new Starmaster has a 1508mm focal length, so I'm a little out of kilter with my ep numbers. What once was second nature is now a mental chore. Luckily, the 24 Pan fits with any scope but it certainly took a hit with the added focal length. I'm down to 86x and .75 deg TFOV as the best I can do. The 9mm hit a semi-sweet spot (230x w/ 2" OCS and 335x with the 2x corrector). I wanted to fill in around 180x (a popular Jupiter mag) and something around 280x to split the 9mm's mags. That would give me a good range of planetary magnifications to choose from for persnickity seeing and Jupiter's challenging low contrast detail. 11mm fits both those mags with the 2 correctors I have, but there isn't a lot to choose from in that focal length.

The 7mm would be used for the 8+ seeing nights and globular clusters, so not a lot of use. It would give me 295x and 431x. The 295x is somewhat duplicative of the 11mm x2, but I want access to 431x and higher. That's why I bought the Zambuto mirror. I'm thinking I should add a pair of 7mm orthos to start off.

I am also entertaining the idea of putting 2 powermates in the ep holders to get to ludicrous power. But now I'm getting back into the whacky world of multiple amplifiers that I was trying to avoid.

So, I solicit thoughts and recommendations.

Also, I talked to Rick Singmaster at Starmaster telescopes and he recommended I definitely should not crop my truss poles. But I could get a 1 deg TFOV if I went correctorless. Russ recommended against cropping as well. But the tinkerer in me is finding it hard to resist. Sometimes I wake up with the Dremel in my hand pretending to grind things

Clear skies,

Tom

Based on input from a little birdie, I emailed Mike Harvey to ask him about his experience with shortening his truss poles for binoviewing. I don't think I'll be trying this anytime soon. With his permission, here is what he sent back:

"ISSUES? You want ISSUES? I'll give you ISSUES!

Forget it...that way lies madness. I went through this years ago (I've been using binocular viewers since the late 80's).
The first problem you run into is that, once you've cut the poles, you've moved the secondary ~5 inches closer to the primary. The immediate result is that your 1.83" diagonal is smaller than the light cone at that point. The result is a loss of effective aperture. My 18" Obsession, for example, was suddenly performing like a 14" (maybe less).
Let me add that collimation is also a real bitch when you can't see the whole primary.
OK, so in this case, I replaced the 3.1" diagonal with a 4". Seem simple? Nah!
The larger diagonal would not fit under the focuser with the spyder in its original position. I had to get Dave Kriege to make some truss pole extensions that connected to the upper UTA ring and projected OUTWARD 4". This was where the spyder had to be mounted to place the secondary under the focuser.
At this point the scope was impossible to balance and I had to add ~15 lbs. of counterweights to the back of the mirror box.
After all this I was dismayed to find that the larger secondary caused a significant reduction in contrast that was especially noticeable on just the objects I hoped to observe...faint nebulae and galaxies!
I finally gave up and accepted the need for a Barlow, but was ever hopeful that we'd one day have something like the Denkmeier OCS. Thankfully, that day finally arrived.

The only solution I can see to operating optimally with no additional image amplification at all is to build a scope from scratch that would allow more in-travel without introducing a larger diagonal. An off-axis design immediately comes to mind. The object would be to design it in such a way that the secondary is precisely placed to project the focal plane into the bino-viewer.

Hope this helps...

Mike"

The one sitting in my garage.

Clear skies,

Tom

I'm guessing there are a few folks that would still like to know the answer to this question. Even after the minor Xmas sidebar. That seems to be what started this whole mess, but I haven't seen the answer through all the peeing in each others Wheaties.

Tom

Good morning everyone,

I am visiting my parents in southeast Ohio and decided to bring my Starmaster along. They have never looked through a telescope, so I figured I might show them a few celestial treats. Am I ever gld I did. The skies are mag6 with no lights except ones that I could turn off and the seeing was 9+. Oh my goodness, did they ever get a treat. I also had a chance to compare the Denk stds and TV binovues on a tough target (Jupiter) under great conditions (except for the 10 deg F temp).

Equipment: 11" f/5.4 Zambuto Starmaster (16% CO). TV binovues w/ 2x corrector, Denks stds w/ 2" OCS in 1.4x mode and 2.5x mode. 24 Pans, 12.5 UO orthos, 11mm TV plossls, 10mm Antares Ultimas, 9mm Nagler type 6's, 7mm UO orthos. Transparency: very good. Seeing: Perfect 75% of the time.

At 9:00 (2100), Saturn was very good, but we were looking over the house to see it. Not the best I've ever seen, but very good. Lots of Oh my Gods! with this one. No issues with the binoviewers and merging with the entire family ranging in age from 7 to 67.

Went to bed and got up at 0500 for Jupiter. It was not over any man made objects. It was VERY cold out and the Starmaster's exterior had frost everywhere. The ep cases were outside as well and the ep's were COOOOLLLLD. I put the TV's in with the 9 Naglers (339x) and nearly fell over. This is the level of detail I could see (including the color):

http://www.tomhole.com/images/jupitergood2.jpg

Unfortunately, no GRS transit, but there was a moon transit just finishing up. I went up to the 7mm orthos for 436x and could not believe that the image held up. I liked the view better at 339x as it had a bit better contrast, but 436x was very good. So, here I am freezing my butt off looking at Jupiter at the limits of the cpability of an 11" Zambuto dob with a 16% CO using binoviewers on a tracking platform. The only thing missing were the Juggy Girls on trampolines and a bigger telescope

cont'd