Peter Drew

Certainly makes you jump if you're using an eyepiece at the time! 🙂

These things do happen, I once rebuilt a Velocette Venom engine and was surprised it had no compression when I tried to start it. I suspected a valve lifter malfunction until I noticed a spare pair of pushrods I didn't have beforehand. 🙂

I looked hard at the photo to see which one of us had made it but the resolution wasn't quite good enough to see the difference. On the attachment knobs on mine I used to turn a little recessed styling whereas Rob left his flat. Being that it was sold by Rob I'm pretty sure it was one of his. 🙂

Perhaps we should start a SW150ED users thread. Thursday early evening was the first time I'd had anything like decent seeing conditions since I got mine a few months ago and at last was able to see something of which it was capable. Certainly stands 400x given the opportunity. 🙂

Bit of work to do there I think! 🙂

I think I would be looking at a along term solution. Once such things are out of the house, well you know the rest! 🙂

Should be ok, the astro branded ones are usually more expensive 🙂

I have a recent 150ED, in the limited opportunity to use it so far I've been pleased with it's performance. Its mounted piggyback on a 16" SCT to easy to do comparison observations. Apart from the obvious light grasp superiority of the SCT there is little to choose between the two for lunar and planetary detail. All the usual benefits of refractors over other types can be taken advantage of. The tube is slightly larger in diameter than the 150 F8 achromat but not significantly heavier, it looks heavier than it is. It's considerably front heavy so would need a tall tripod or extension. The dual speed focuser on mine is excellent and in no need of upgrading. I certainly wouldn't spend a considerable amount more for something "better". 🙂

Having the reducer in the wrong place relative to the camera is possibly what is causing the unexpected extension to the focused position. I would suggest trying it in the correct position before ordering anything, you may find that you have an opposite problem. Welcome to SGL.

Most likely a focusing issue although the reflection from the filter suggests that it might be a little tight, the film needs to be completely relaxed and floppy. 🙂

Best night for a long time for me regarding seeing stability but very foggy. During the brighter moments a crisp outlined image of Mars at 500x on the 16" SCT and 400x on the 150ED. Trial purposes only, better viewed at 400x and 300x respectively, pity things were not so steady at opposition. Conditions got more foggy, Mars barely visible to the naked eye. Tricky drive home! 🙂

The best one we've found so far is the Celestron NexYZ. 🙂

For days we had a sunny forecast for today, what do we get? fog and cloud!. No Sun forecast for the next 2 weeks. ☹️

I was treated to a view of the Sun, Moon and Mars today but the seeing was rubbish, still at least a look at the sunspot array. 🙂

15 minutes, that's longer than our visual allowance in these parts! 😀

Not really suitable in my confined space. I am a fan of dual types for night use though. 🙂

+1 I've unscrewed a few, not always easy! 🙂

I think the main difference is that my telescope works in a fairly cramped observatory which is too angular to easily cast an accurate shadow. 🙂

Although I largely avoided these problems in the first instance, it underlines the importance of concentricity and as all machinists know, this depends on items being machined, if possible, in one operation setting. Adding subsequent components machined subsequently leads to errors, I've often seen portions of worms turned separately, bored and then grubscrewed on to shafts with subsequent run out. It's quite difficult to rectify an inaccurate wormwheel as you never know if the gear teeth are concentric to the the bore or the rim unless you try it. It's a bit like judging the quality of a mirror just by looking at it. I think I would would make a "top hat" bush that was a good fit on the shaft but well undersize of the gear bore which would have had to be overbored. The bush would have to have a lip wide enough to accept screws to hold the two firmly together. This composite unit could be trued up on the lathe to a reasonable degree. If the gear was now mounted back on the shaft and the pressure of the attachment screws was relaxed enough to allow the gear to be tap adjusted, it could be manually rotated by the worm to determine the high and low portions of the full cycle. This should initially remove the backlash and finally the mesh by noting the feel of the worm as it is turned. "Feel" is a very good measure of accuracy. Lastly, the screws would be tightened and the feel checked. Once satisfactory, the gear could be doweled to prevent further movement. 🙂

Interesting viewpoint. I made one of these originally and I found that you still had to wave the telescope about or use the shadow to find the Sun whereas my current unit simply made from a piece of flat aluminium stock, ends bent up at 90 degrees, pinhole in the front and translucent target at the rear seems much easier to use. The targeted solar image can be seen from the front, back and side angle without having to go anywhere near an eyepiece. Weighs and costs almost nothing. 🙂

Putting my "poor man's Es Reid" hat on for a moment I could confidently say that it is not astigmatic, does not exhibit any mechanically induced artifacts, the extrafocal rings appear to be expanding evenly without obvious zones, the outer ring fuzziness could be due to seeing considering the rest seems to be in order. A complimentary inside focus image could add to this appraisal. That will be 5 guineas. (How am I doing Es.) 🤣

Apologies to Suiter!. I have looked at the book and to be honest, apart from the type of errors I mentioned, the majority of the finer points of reference take an experienced eye to offer a reliable diagnosis. At the end of the day (night?) if your telescope is giving you the best images you've seen, does it count for much what the book or vendor claims? 🙂

For most amateurs, I think star testing best serves the checking of collimation. There are far too many variables in play to show much other than gross errors like astigmatism and severe zonal or correction issues. A definitive assessment calls for the controlled conditions of bench testing and examination by someone experienced in the nuances of the displayed image, many of which can have an impact on the performance. We're not all Es Reids! 🙂

I spotted this on GONG this morning but as usual the part of the sky occupied by the Sun was cloudy. Not long after I got to the Astronomy Centre the Sun appeared, I quickly fired up my solar telescope which has its own observatory and was just centering the image when a huge bank of fog appeared from nowhere and that was that for the day. No more Sun forecast until Thursday. ☹️

A possible problem could be caused by using the Moon as the alignment point. The Moon is the hardest thing for the goto to go to, the complexity of its motion compared to the fixed stars means that it's not an accurately recognised object as far as position is concerned. I doubt if you are entering any data wrong being as you are so close to the target. 🙂