Hanah

Hi all, Recently got a GP-DX with motors and an idea gotostar controller. The mount is in fantastic condition, except for a wobbly drive-shaft on the DEC-axis (and a broken motor casing). It's working, but I expect the wobbly axis will increase wear on the gears, and they are still so nice and shiny Was wondering if anybody here is still active, and may have some spares? Best regards, Han

Thanks for the reply Mike. I'm pretty new so for me it's not that easy to tell what the effects are. But from your reply, and some other people I spoke with, it should be o.k. to live with. I was just a bit disappointed when I noticed, but guess the previous owner didn't see. Got a message that the seller offered me a partial refund. I guess I'll agree to that then and just try to enjoy the views Regards, Han

I found out a diagonal I recently acquired from ebay has some very dim scratches on the mirror. I expect this to be caused by cleaning (I didn't touch it though!). Maybe 4 in total spaced evenly over the mirror's surface. I can't even see them except during daytime, when I hold the mirror close to an artificial light source. Then, at some angles, the scratches appear. Anybody wants to share her/his opinion on how they find scratches on the mirror affect performance? I'm thinking, maybe it's not really an issue, given they're so dim.

Thanks all. Indeed, you can't keep tightening them without loosening others. I think maybe there's just a little burr on the thread, it's not going smooth either ways. But like I said, collimation isn't a problem so I'll just keep it as it is. If I ever take it apart I'll fix the thread by tapping it again, or putting in a helicoil. But thanks for all the replies it at least clarifies the mechanics. Han

Thanks a lot for the picture. Is that from a Celestron SCT as well? Looks pretty straight forward. A pivot in the center and three bolts just threading into the aluminum base of the mirror bracket. Could be the thread is slightly damaged. I may have a look at it when I replace the bolts with Bobs knobs. Then again, I can still collimate the scope, so it’s not really broken, and if it’s not broken, don’t fix it.

Happy that I've added 2 Halloweens to the case today, starting to look like a decent set! If anyone is able to help me fill the gaps, please let me know

Hi all, Many hits on SCT collimation, but I can't find any info about the possibility to break the mirror bracket by over-tightening one of the collimation screws. With my scope (C5+), one of the three screws doesn't turn smoothly, and I wonder if this is caused by over-tightening in the past. Would be interested in a description or proper drawing on how exactly the secondary mirror is mounted, and how the screws tilt the mirror. Regards, Han

Looks like one rotation of the driving shaft on the mount is 10', so I need 1 rotation of the shaft every 10 minutes = 1rev/600sec. For 1/120 gear ratio that makes 1rev/5sec.

Thanks, that should help even if it was only for inspiration. Guess the only unknown for me now is the gear ratio, I'll look at it tonight with the mount in my hands...

Hi all, I'm on a diet astronomy budget and have got my hands on an old GP-DX mount with DEC-motor. It's a Nippon PF42-48i3 G. I've found one spec sheet so far (attached) and this motor seems to be controlled from a DD-2 or DD-3 controller, which I don't have, are hard to come by, and pricey. I do have an Arduino, some stepper controller IC's and all that so it should be easy to get the motor turning. Just wondering if there are more people around doing these things DIY and have more elaborate spec-sheets. Most important question now is how fast to turn the motor for proper DEC-tracking? It's got an internal 1/120 gear ratio but I don't know the ratio on the mount itself. Not difficult to find out experimentally but maybe someone knows. Cheers, Han

My little collection in a custom laser-cut inlay for a 'systainer' case. The systainer cases are easily stacked, so you can carry them as one. I've got my C5 in another systainer, but still have to do a second version of the laser-cut foam inlay for that one. For inquiries on how to make/order your own inlay don't hesitate to contact me. I can send you the drawing templates.

Hi all, I've recently got a few of the 90's Celestron Halloween eyepieces from different sellers (see picture below) and have a questions regarding differences between the eyepieces. The 7.5, 17, and a 26mm all have O-rings. The second 26mm I've got (think they make a nice pair for bino-viewing) doesn't have this ring, and the cap is screwed tight so the groove is closed. Also, the lettering on this one is a more dark shade of red than the others. Can anybody tell me if this is an earlier/later production of the same eyepiece, and if it originally shipped without the O-ring? The 32mm is also missing the ring, but the groove is there. I guess I'll just try to find a proper ring to put there. Anybody some info on the sizes of rings used, AS (American Standard) probably? Regards, Han

A 32mm Celestron Plossl 'Halloween' and a 26mm is on its way. Then another 20 Kelner and a 12.5 Ultima, so a pretty nice range. Have high hopes with the 32 and 26 although with a f/10 scope the exit pupil will still be rather small (3.2 and 2.6). Cheers, Han

A 90's Celestron C5. Its my first and only scope, selected mainly for the low packing volume (it fits in a 'systainer' case). But reading this topic again I have a question about this. What kind of eyepiece would be considered a 'proper match' for this scope (for observing dso's). And why?

Guess this will be my first addition to the SGL. I'm a newbie and really enjoyed reading about the veil. Guess I will start-off my wishlist with this object. Although I'm not a regular observer here in the most light polluted region of the Neterlands (which scores high on a worldwide scale), I will be looking for it on my next trip to the mountains. Cheers, Han