Peter Drew

I would think that if you have your eye lens replaced with one that corrects your current astigmatism and optimised for infinity, there should be no need to wear glasses whilst using an eyepiece, the telescope focuser should take care of any adjustment needed. 🙂

The only impact is likely to be its resale value.

I would look at new objects visually first as if you missed the opportunity you wouldn't see them on your return. By all means take some images of your choice if there is time, you can always take better ones from home by renting time on professional class instruments sited in the S. Hemisphere. 🙂

A pair of 8" F25 folded refractors. 🙂

Following with interest as I've built several 6"-8" long focus folded refractors. 🙂

I can't say that my solar observation yesterday was my best ever but certainly the best this year. Transparency was poor due to heavy haze but the seeing stability was surprisingly good. The main area of interest was, as Roy's description above, the limb area adjacent to the new sunspot pairing. Much brighter than the general solar surface and undergoing rapid changes of shape and several short term surges. Observation mainly between 5 and 6pm, 150mm Ha telescope at 150x. 🙂

A bit optimistic I think, even with a Tak. 🙂

Rule 1) Never shine a light on to an aluminised surface. 🙂 Does the primary mirror have a centre spot?, this might be reflected in the image.

Provided that the camera reaches focus then the LS50 should be good for imaging. My doubt about the DMK42 is that some of the DMK series have been prone to Newton Rings. 🙂

I've seen plenty of good solar images provided by a Lunt50, a monochrome camera is considered the best. No idea about the compatibility of the DMK41. 🙂

I think manufacturers, if pressed, would say that they have produced diagonals that accept 2" fit and 1.25" fit standard eyepieces and that is what the description is based on and not necessarily the clear aperture. Eyepieces are described by their fit standard. 🙂

Even more detail in half a PST, provided that the half is fitted to a larger aperture 🙂. Had a brief chance for a look with my PST mod today and indeed the details were spectacular, the seeing and transparency was good but the whole view spoiled by the shaking from the very strong wind. ☹️

It could possibly be Saharan "dust", this has been coating exposed surfaces for quite a while now. 🤔

Happy Birthday. Time for the next ring? 😀

If Es Reid passed the optics as OK then I think that is reliable. The inference is that there is a problem (more often than not) with something in the imaging train. Good luck with correcting it. 🙂

Yes. 🙂

I made a Ha binocular using two PST's not long after they were introduced. It worked very well and outperformed a 60mm single unit that I was planning to upgrade to. I eventually went down the PST mod route as a relatively inexpensive method of obtaining a larger aperture and since achieved my "holy grail" of a binoviewer equipped 150mm one. I have often considered a true Ha binocular telescope but even a medium sized one would cost far more than my 150 and have less performance. If I did/win the Lottery maybe it would be a different matter. 🙂

Interesting. To be honest, looking back at the OP image and subsequent ones none of them does exactly show the effect I was describing. It would be interesting to know the field of view of the OP image as it appears to be larger than expected for visual. I have several catadioptric telescopes and due to their long focal lengths and small visual fields I've never noticed objectionable coma. Next opportunity I get I'll try an 8" version for a recap. 🙂

As large a diameter as is practical and of a hard composition that doesn't produce "flats" when static for some time. Good sealed bearings will provide long life and reduction in rolling resistance. 🙂

My belief is based on all baffle tubed Schmidt-Cassegrain and Maksutov-Cassegrain telescopes that I have used display this effect visually with defocused stars that are off- axis. Supporting the advice to make sure that a star is centered during collimation procedures. 🙂

I don't think it is anything to do with coma, I believe it is due to vignetting of the outer field by the internal shade tube, normal for this design. The main purpose of the front corrector element is to introduce spherical aberration of equal power but opposite sign of that of the spherical primary thereby cancelling it out. Although it is essential it is of relatively low optical leverage and has no practical focal plane so introduces negligible chromatic aberration. 🙂

Treated to a good solar session today despite having picked up a nasty cold from the astro Show, the only thing I brought back! Spent the time comparing a Lunt 35 and a 4" Vixen PST mod to my main 6" PST mod. Seeing was variable but the transparency was a little better than of late but best of all, hardly any wind. Good result with all three, specially the LS35 considering its small aperture, difficult to get used to the small image scale after the high resolution high magnification of the larger units. One thing I particularly noticed whilst using the 6", I usually observe with it at the best setting for Ha and rarely detune it to view the psuedo white light image. Today though, since the spot is a major one I gave it a go. Rotating the PST tuning collar whilst viewing I was surprised to see jet black streaks and curves surrounding spot area, they did not appear in prime Ha or full white (red) light mode but about halfway between the two. Presumably some sort of Doppler effect. 🙂

If you do not already have a binocular then this would be the best upgrade to your viewing experience as it offers far more versatility than a UHC filter. These filters are much better used with an aperture grater than 70mm. 🙂

I think we are suffering from Sahara sand dust at the moment. Yesterday the setting Sun was perfectly defined but blood red. 🙂

It shouldn't make any obvious difference to the performance but it would affect a sale. The corrector looks as though it also needs a clean. If you follow the tried and tested methods of cleaning in due course all should be well. 🙂