Peter Drew

Definitely in need of a clean, that degree of contamination will result in hazy images. If the internal surface also requires cleaning remove the entire corrector cell and secondary assembly taking care not to disturb the orientation of the diagonal mirror. It can only be refitted in one position as the diagonal must face the focuser, the collimation should remain intact. 🙂

"Top drawer" results.

The Astronomy Centre remains closed until we consider it safe for both staff and visitors. ☹️

The seeing was a bit hazy yesterday as well now that the aviators seem to be back in business. A bit light on proms after the recent examples but surface detail was centre stage. 🙂

Size for size a refractor will give a crisper image than a reflector. But, refractors are usually restricted to small sizes, typically 6" and less for the reasons always listed so you have to be sure as to what type of observation you wish to make in the main. A 6" F15 Newtonian would probably give a F15 refractor good competition.

Go to www.astronomycentre.org.uk, click on 30" Dobsonian item on the information list. 🙂

Looks good to me. 🙂

Maybe applied to flourite objectives may protect them against dissolving due to moisture Jeremy?

The only advantage I can see by using an eyepiece rather than a finder is permanent alignment.

Nothing. I made my 17" and 30" Dobsonians. 🙂

I think it worth mentioning that simplicity of eyepiece design does not necessarily equate with low quality, there are plenty of high quality ones made in the past. Short focal length telescopes certainly require sophisticated eyepieces to perform at their best and quality across the design spectrum is always desirable. 🙂

An A/8 specification for a secondary is still a pretty good standard. I don't think the higher quality A/30 would show very much difference other than on a very good night and high magnification. A small aperture does not benefit as much from this type of upgrade as a large aperture. A slightly larger secondary mirror than necessary will not obstruct a noticeable amount of light, a slightly smaller than minimum would lose more. Welcome to SGL. 🙂

lly, "Devil's advocate". 🙂

I have a MN56, amazing telescope for its aperture. 🙂

🌧️ ☹️

My tally was just two. First one at 10.20 passing over Auriga, second one the bright one already described at 10.45, unfortunately by this time it was seen through thin cloud so rather muted. Overcast by 11.00 but cleared again just after midnight. Looked for anothe half hour but saw no more. At least I saw a couple. 🙂

One other advantage of being able to hand sharpen drill bits was that you could vary the point angle to suit different materials and hardness. Also the opportunity to make a drill bit cut oversize if needed. 🙂

Best to get all of your astro bad luck over with in one go. The first views through your new scope will be all the sweeter.

I had a brief but rewarding session today between 5.45 and 6pm and can confirm, as Paul has said, the seeing was excellent. It's sometime since surface detail was so well defined with the bonus of some free double stacking effect from passing cloud. Spoilt for choice with the many filaments on show and a small hedgerow cluster of proms revealed fine structure that looked like the headline of a Japanese newspaper. Definitely one of those days when a large aperture and a high magnification was worthwhile! 😎

In the main I use a 16" SCT and occasionally a SW150ED being as it is piggybacked on the same mount. Anything smaller gives too dim an image for my ageing eyesight at the magnifications I now need to see planetary detail.

Last question, was the reducer fitted during the accident ? 🙂

I agree. I'm visual only but I have considerable optical experience. The only time I've been unable to focus a star with an otherwise ok telescope is when the spacing of a focal reducer is incorrect, hence my comment. Does your telescope have a built in reducer? 🙂

I would expect a collimation issue due to such an accident to show distorted star shapes or comet like rays all pointing in the same orientation. I'm not an AP specialist but to me the stars look reasonably symmetrical ? If that is the best focused image it would suggest that the optical element spacing had somehow altered. 🙂

Looks more like a focus issue rather than a collimation problem. 🤔

Very warm here today as well, seeing was quite good by 6pm with very similar visual images to your photos, which despite your self criticism, most people would be happy with. 🙂