Posts Made By: Walter Hamler

OK, north and west drift indicate two things happening simultaneously. The west drift means that the scope drive is running slightly slow,ie, not keeping up with the sideral rate. The north drift means either the azimuth position or the polar angle adjustment is off. You did not say where the star was, so it is hard to determine which is off the most. There are several websites that give very good info on drift alignment. S&T has some info as well as the Astronomical League. Check their websites. Once you have done the drift alignment where there is zero dec drift, then you can tweak the tracking rate by selecting the sideral or king rate on your CI-700 drive controller. Once you get the ra to track correctly OTHER THAN the slight periodic error, then you "train" the pec and it will give a better overall rate. Be advised that on the CI-700 the pec only works as long as the power remains on and you don't change the drive rate or the slew rate. Doing either of those or powering off loses the pec training and you have to start all over. That is why most folks do the pec training just before starting a long exposure. It takes eight minutes for a complete worm cycle and then the pec replays all the corrections you input during the training cycle. After that, the amount and degree of corrections necessary are much less.

Walt

Put it in manual mode, run a series of exposures starting at 1/500 sec and work down. Pick the best one and the work around that +/- one stop or less.

Walt

Nice of you to do the portrait of me, Roland

Walter

Floyd, I am so jealous I want to scream! My very first duty station in the Navy in 1962 was the Naval Ordinance Test Station, now Naval Weapons Station, at China Lake. I worked on the base newspaper as a photographer, and there was an old curdmudgeon there, "Pop" Lofnick, who sorta befriended me. He had started working there as a Range Rider during WW2, riding a horse. He would stay out for weeks at a time, only coming in for supplies. Anyway, he used to take me out to see some of the sights in the northern section of the base (bigger than Rhode Island). We used a Jeep, but a horse might have been better
Several times we spent three or four days out, sleeping in the open. The skies were absolutely unbelievable.
In late 63 I bought my first car, and the very first trip I took was to Whitney Portal on a Saturday drive. We walked about a mile up the trail when I decided mountain climbing wasn't my thing I had borrowed a camera from a friend, a brand new Nikon F. I dropped it and broke the pentaprism and light meter It cost me two months pay to get it fixed. BUT, I still liked that area and used to drive to Lone Pine just for some relaxation after work. I was 22, young, and stupid 8)
Hope you have a great time. And please return with pics. Oh, and there was a sweet young waitress at the coffee shop, could you...... Ah, I'm forgetting how long ago that was

Walt

What were you using for a guide scope?
Very nice shot, BTW 8)

Walt

Interesting. Did that happen in the imaging or the processing?
I shot a pic many years ago of the Horsehead on film and got something similiar. I believe it was diffraction off the spider from the middle star in Orion's belt, but it was not in the actual film fov.

Walt

Jeff, I too think you will be hard pressed to find something better yet smaller than what you already have. If it were me, I would try to find an older Meade 8" LK-90 as your quick look scope. Sell the G-8 to buy it, and then find a G-11 or a CI-700 for the 9.25 for future imaging and when you need absolute stability.

Walt

First, the largest scope I have ever had recently was a 12.5" f/5 dob. I used a red dot with good success.
My latest scopes have all used Telrads and I really love it! However, I admit that in light polluted skies it is difficult if you can't see stars to star hop, and for double stars, for instance, it is really nice to be able to nail down a star field.
A novel idea for a finder that I just thought about. Celestron sells a set of 15 x 70 binos that are actually quite nice, and are available for a lot less than 90.00 at certain dealers. With some judisious modifications, that would make two finders that would be pretty cheap and provide a correct image to boot!
I know, its almost heresy, isn't it

Walt

Ryan, if my calculations are correct and if you were using a 2x barlow, then you were guiding at 592x, which is PRETTY HIGH! That would make your fov of a typical plossl guiding ep at around 300 arc sec. So, you are correct that the observed periodic error was pretty large, maybe in the range of +/- 50 arc sec. That is definitely more than a G-11 should be. I would say to check all your fittings and tolerances and make sure everything is as close to being right as possible. Especially check the mesh between the worm and worm gear. It is adjustable and needs to be perfect for best operation. Basically double check everything, and get someone else that has some knowledge to help you. If you get the same bad results, time to make some phone calls.

Walt

I owned two pair of the Oberwerks, one real good and one almost as good. Both were prone to needing collimation tweaking.
I now have a pair of the Celestrons, and they are essentially the same "appearance" as the Oberwerks, but much better images and collimation. They do have the collimation screws right under the edge of the covering, back at the rear near the prisms. I made a parallelogram mount and they are so much nicer to use when mounted.

Walt