Posts Made By: Guy Earle

Well, tonight the scope was rolled out, complete except for the commemorative plate for my grandfather. The protostar paper gave nice, dark contrast, and mechanically the scope performed very well. The table served it's purpose very well, and was sturdy and could rotate freely and smoothly. I didn't tighten the main azimuth bolt enough, and the Sky Commander was slipping in azimuth, but I'll take care of that tomorrow. I have a family member helping to make a shroud, but otherwise I'm done. Frankly, I'm burnt trying to get this done in time for the September starparty. I've spent almost every free hour for the past month working on this, and as satisfying as it is to have it all come together like I had hoped, the best part is finishing.






The stellarvue finder works great, but the seeing was so very bad tonight that even the Moon on low power was too much. Tomorrow is the first time I break it down to put it in my car, and I will do so with a grin on my face as I close the tailgate door with room to spare.

Thanks to all for the encouragement and the advice.

Guy

PS here was the goal image I had put together before I started this rebuild, plus the old scope.

I've been looking at the data of my secondary (3.1") for my 16" f/4.52 dob with NEWT. I tend to go a bit small on my secondary, as I did on my old 12.5" f/6 with a 1.83" in order to achieve a bit higher contrast with the loss of some edge brightness. As I'm looking at this, I'm wondering if I can reduce my secondary to a 2.6"?

Here is the data plugged in with a 3.1"


The same with a 2.6" secondary


With the 3.1, it says that I have vignetting of focuser at 75% ray, whereas the 2.6 does not. However, the reverse is true for the "diagonal too small to admit 100% ray" where the 2.6 says no and the 3.1 says yes.

Opinions? And for those who might say, yes, smaller secondary, then which company would you recommend; Galaxy, Protostar, Pegasus, University?

Thanks,

Guy

I've had nicknames for scopes over the years (I know some hate that), but I always just end up saying "the scope" in conversation. This scope was initially purchased partly from the sale of my old 12.5" and some money that my grandfather had left when he passed in June of '06. I've been desiring a 16" for the past 13 years, and it would be many years until I upgrade I think. I had the option of using it for bills or other things that didn't seem to have the sentimental importance that the scope would. This is my way of saying thanks to him, as I always called him, "the Chief"





Thanks,

Guy

Just spent a wonderful two days in the Withlacoochee State Park north of Tampa this past Friday and Saturday, just getting back this morning. It was the first night for my rebuilt under dark skies, and things went beautifully. We had about 45 minutes of absolutely fantastic transparency and seeing early Saturday about 9'ish, and all sorts of globs, the Omega Nebula, and other things were taking all the power I could give them in my binoviewer.

Here is a picture of me and my setup, all of which fits in my CRV, which I took pictures to prove it (I took them b/c one of my observing buddies said he couldn't believe it would all fit AND I needed to know how to replicate it...lol)












I had a blast, and it's great to be back into the hobby after a nearly two year absence.

Clear Skies,

Guy

I thought I'd share an observation from this past weekend, when I had the chance to use the 31 nag alongside my 35pan in a 16" f/4.5. I remember seeing the 31 a couple years ago, since its memorable balloon shape stuck in my head. I've changed eyepieces many times over the years, but the 35 Pan has had a place of honor in my case--never to be replaced.

I compared views of the 31 to the 35 while looking at M31 and its companions, and the Double Cluster. I did find that the 31 nag did frame the objects better, and there was indeed a slightly better contrast and sharpness to it. However, given the cost, I don't think I'd ever be upgrading my 35 pan simply to view three or four objects in a slightly larger fov. It was nice, mind you, very nice...but not worth another 300 dollars. So my old friend stays in his case, waiting to be called upon again....

On another note, I'm wondering what others find are their most common magnifications? I have 24.5 Meade SWA's (old, old style) in a Denk bino with a dual and a single power switch, so that one pair gives me 6 different mags. I really noticed how introducing the single element for more power darkened things up. There was a time when the transparency and seeing allowed real power on Saturday night, and I tried to keep track mentally which two powers I was using the most. Turns out, it was the middle setting when the single power switch was not engaged, and when it was in. That meant that I was looking at the globs and nebulae at 150X and 349X most of the time. Crunching the numbers on what a pair of 16t5 nags would do, I get 149X and 390X, however, the apparent field is much greater of course. That means my 24.5's will retire to their cases to be called upon for low power views, otherwise I think the 16's will be the main eyepieces. That got me thinking what other people like, and is why I'm asking that now.

Cheers,

Guy

I'm kind of befuddled on this, and would like some opinions. First, a question regarding Jupiter. In all my eyepieces, I'm noticing that Jupiter just isn't sharp. Seeing aside, even on mediocre nights I can still get a sharp low power view, but it mushes in and out, and when it seems just at that sweet spot, there is almost a double image around part of the limb. Now, when I look at the Moon or deep sky stuff, I don't see it, but ever since my rebuild I just can't get it good enough.

I rechecked and adjusted (thinking that was it) the spider, centering it. I'm using the Collimation Handbook, btw. My focuser is square and the secondary centered in each axis. I use a laser collimator to center the secondary, then a Cheshire for the primary. Even so, I'm not quite happy. Does anyone have any ideas?

Also, I have started using a pair of 16 t5 nags I just picked up off astromart. I'm noticing on bright objects, when racked out of focus, there are dark marks like some ink blot test. The images rotate with the eyepieces, so it's not the Denk. When I focus in, they disappear, and all is well. But I'm disturbed by them, b/c I don't remember seeing them in my old pair of 16's. Is this normal?

Thanks,

Guy

Greetings,

I was up at the CAV starparty from last Saturday through Monday night, and have some pics from the trip. I have them on my Flickr account. Click on the link and check 'em out.

http://flickr.com/photos/28447916@N07/

Clear Skies,

Guy

Since everyone here seems so knowledgeable regarding who makes what mirror, does anyone know who makes Discovery mirrors, and do they coat them themselves? I'm very happy with the mirror I have, which arrived in October of 2006. I'm not complaining, just curious. I don't know if you might know who was making them in 2006, but I thought I'd ask. Granted, I think my 12.5" Nova mirror I had made back in '98 was superior (damn, that was a good mirror!) for quality of image (back when they went to QSP for coatings).

Best,

Guy

Hi,

I'm picking up a Nikon D60 this coming week, and I'm stepping my foot into the digital SLR community. I've done webcam imaging and film stuff years ago with a 35mm, but this is all new now. Does anyone have any good links to some intro information that I can start going over?

Thanks,

Guy

EDIT: To clarify, I usually just shoot the planets and the Moon b/c of being a dob man, but I picked up a nice, small 80mm Celestron refractor on an EQ mount the other day (for an unbelievable $3.00! I almost threw the money at him and joyously ran away before he reconsidered), and I wanted to use that to start fooling around. I know my potential results are limited, but I'm just starting down this road.

Last night I was taking some .avi's of Jupiter, and stacked them just now. Does someone have a better image than mine, b/c there is this weird dark smear through the SEB. I don't know if it's me, or the planet.

Cheers,

Guy



EDIT: Do you guys have any tips for squeezing better images out of the scope? I have to let the image drift @ 1280 X 1024 for a max of 24 seconds. I know i can get more, I just don't know how....