Peter Drew

They say that they are "unsure how to test it" underlined by the way it is set up! 🙂

I agree with Stu's comments. The depicted star images show collimation and astigmatism issues, either or both would significantly compromise the performance. I have a smaller "fixed" mirror Newtonian and was able to adjust the collimation by loosening the three screws that hold the primary cell, twisting the cell until the collimation was better and then re-tightening the screws whilst being careful not to upset the new position. I don't think the astigmatism can be collimated out and I suspect it is caused by whatever means is used to "fix" the mirror, it is quite common for manufacturers to attach the mirror too firmly that causes this issue.

As a last resort, you could try unscrewing the front half of each that contains the main lens. The lenses are seldom fitted perfectly concentric so rotating them causes the image to wander. If you are lucky, you could find a position where the images merge properly. 🙂

I didn't see the bloke but I only went to see the eclipse. 🙂

Interesting report Stu. I have a Vixen 102FL and a self built 8" with F8 1/20 wave (claimed) OOUK optics and have had a similar experience. For me, the smaller telescope doesn't quite do Mars justice although the SW150ED is another matter! I'm still waiting for a night of more stable seeing, so far there has always been a little something to spoil the potential view. I have a restricted window of opportunity to observe for health reasons and usually have to give up just as things are starting to settle down with the telescopes and the seeing. Looking forward to Mars being higher earlier. 😀

I have it a little better prepared now ready for the next available session. 🙂

I was there too at the same location for my first total eclipse, what an experience!. The S&T guys left an AP Traveller set up on the beach unattended long before the eclipse. 🙂

The new AR continues to entertain. Every fifteen minutes or so it eject lumps of plasma about the size of Africa!, they seem to curve round and gradually get absorbed back into the surface. Reminds me of the old "Lava" lamps. The area is very much brighter than the general surface suggesting that it must be considerably hotter. There seems to be fainter activity way further than the main action and still beyond the limb so hopefully the AR will turn out to be an extensive one. The good seeing is enabling me to get the full advantage of the 150mm aperture. 🙂

Yes, the detached prom dispersed and faded out of sight not long after I posted, it was very intense initially. 🙂

I spoke too soon, the activity has died right down now but the AR is coming so watch that space! 🙂

Interesting solar activity today. Main players are a detached prominence that is constantly changing shape and brightness and an intensely bright bulge not far from it. The bulge is the exciting object, it is a new AR coming into view. From previous experience, I'm optimistic that this could produce a spectacular outburst at any time as it's pulsating like a latent volcanic event, remember Mt St Helens?. Certainly one to keep an eye on. Further round the disc there is a larger, faint, highly detailed prominence. 🙂

I was out from 10pm until midnight so the ADC was more effective early on. I wish I could have stayed out longer as the image was gradually improving but I have a chronic chest condition that gives me a narrow exposure window at night.

It is, but it would easily fit inside our 30" Dob. 🙂

I think I can confirm that observation in general. I was using a SW 150ED piggy backed on a 16" SCT and the views were very similar to your sketch. Still unable to get a night with good transparency and steady seeing, last night was the best so far this apparition but the image was still shimmering annoyingly. I found the ADC to offer an improvement but not a game changer. The detail was similar in both telescopes but different in presentation. The ED gave stronger contrast but the smaller exit pupil at around the same 250x made the image more difficult to see, in better conditions the 16" should do a little better. Nice to have both for the comparison. On that tack, when observing Mars with my C8SE in Tenerife I can routinely use 400x with good results due to the planets higher altitude and the better seeing conditions. 🙂

The biggest thing that determined my astronomical career was not being able to afford to buy a telescope. This forced me to make my own, eventually proving so interesting and successful that it became my business and way of life. Would I change much if starting again? NO!🙂

Same here, had a brief whizz round and spotted the lone thin spike of a prominence. One or two of the tallest spicules could have been mini proms but the seeing wasn't kind to my 150x minimum magnification. 😀

Assuming you are viewing from the UK, then the biggest difference is likely to be a poorer image, 216x is probably the best highest power for the aperture. Using a half decent Barlow shouldn't compromise the image quality noticeably, If you want to try a higher power either get an even shorter focal length eyepiece or a 3x Barlow. It will be a cheaper way to find that the difference would not be worthwhile. 🙂

Second "attempt" at comparing telescopes on Mars. "Attempt" as quickly variable seeing and poor transparency didn't do them any favours. This time, the regular 16" SCT and SW 150ED were joined by a Vixen 4" Flourite, 8" F8 Newtonian with 1/20 wave (claimed) OOUK optics and a 20" F3.5 Dobsonian. As near as possible, a magnification of around 250x was used on each by way of a Baader 8-24 and TV Nagler 3-6 zoom. The immediate impression was that the 16" SCT was giving the best overall view although the 150ED was slightly crisper, the dimmer image not swamping the detail as much and a somewhat steadier focus. The 8" F8 didn't really get a fair trial as it was awkwardly positioned and too heavy to easily move to a better place, all of these telescopes are currently under the same dome and it needs several rotation adjustments to give the telescopes a clear view. The Vixen gave the typical well defined refractor view but at 250x it was too dim to fully appreciate, in better conditions it would have been impressive for its aperture. The 20" was a bit overkill for the conditions but worth a look as it was set up during the day whilst I fitted some encoders for "push-to" operation. Interestingly, what looked like decent collimation with a Cheshire appeared nowhere near according to a defocused Mars so I tweaked it a bit whilst looking at the image, F3.5 is not very forgiving!. Not the night for a large telescope though. Although the seeing didn't improve later, the telescopes settled and started to perform better, ultimately the 150ED seemed to give the best consistent image due to its better focus stability. The colours were more noticeable in the refractors, including the atmospheric dispersion. Overall an enjoyable 10pm-12.15am session, probably the last for a while according to the forecast. 🙂

I would just sit back in a recliner and take in the view naked eye. To use anything optical would ruin its use when back to normality. 🙂

Screws might well be BA standard. 🙂

I don't think I'd start again, I would probably take up something less stressful , like amateur bomb disposal. 🙂

Just had a scan round myself, not a great deal to see, as usual when it's clear! ☹️

Hello Joaquin. Welcome to SGL. The screw might be designed to be captive so that it doesn't get misplaced. Try pulling downwards on the knob to re-engage the threads if this is the case. 🙂

I think I would try exposing the lens to artificial or solar UV to kill off organic activity. A small amount of fungus is better than a can of worms! If you can see fungus it probably has already etched the coating, it will however have negligible effect. 🙂

Best keep your clothes on then! 🙂