michael.h.f.wilkinson

I do not see what this has to do with this thread. Please also refrain from referring to religion.

Lovely scopes here. I am thinking about getting an ES AR127 (5" F/6.5). They have a great rep, and I want to convert it to a solar instrument. I want to place an 85mm Beloptic tri-band ERF I have halfway down the tube (this filter passes the solar continuum band, a band around H-alpha and a band around CaK, and reflects all the rest back). I could then switch between white light and H-alpha quickly, with the option of getting a CaK module later. Should be a killer solar set-up (and a good-looking scope to boot).

I hadn't noticed that. That is the LS35THa I used to have. I sold it to the Kapteyn Astronomical Institute of our uni, who now use it for outreach. I also have an ST80 somewhere for future use as a guide scope, and then there is the 70mm F/5 frac I use as a 14x70 finder on the SCT

Even though my main scope is an SCT, I do value the frac, especially for solar and wide field workDual H-alpha/white-light set-upTwo Grab and go solutions with the same scopes Solar Spectrum / APM 80 F/6 0.3Å H=alpha set-upand a double-barrel frac

Never seen one of these, although I have heard of them. Interesting tool for scouting out dark areas or assessing how good the sky really is. I have often set up the scope in what looked like dark conditions, but once the eye adapted fully were not that good (not hopeless, but not as good as hoped for).

Some really nice cases and collections there

MVs are very good, and outstanding value for money. I have two 24mm 68 deg (future binoviewing in mind, one is on loan to the observatory of our university until I have either big bins or a binoviewer), and they perform very well indeed.

I have added some screenshots to the first post

Thanks Freddie. Registax wavelets gets pretty decent results The very fine detail is better in LR deconvolution, I feel

In my scope the disk does fill the entire FOV when centred. If this is not the case, you need to use some diffuser (like cling film or a white plastic bag) to create a flat. That does often mean increasing the exposure time.

I have put together a few images which demonstrate in a nutshell how I get from raw input data to the panes I throw into AutoStitch64. It all starts with the AVI, I typically gather 1000 frames per pane. With the Solar Spectrum filter, even a single frame can show a good deal of detail. Carefully tweaking focus until sharpness is optimal is essential. A frame obtained today is shown below. Although it looks decent, this is not a good starting point for mosaic stitching. One reason is the fact that there is a distinct uneven illumination (or shading) visible. By taking flats this can be corrected. Various approaches can be used, I tend to defocus, take an AVI of the same length as the ones for the panes, and create a master stack in AS!2 (under image calibration). I often apply a smoothing filter (100 pixel diameter flat averaging often works) to get rid of residuals of sunspots or bright plage. A caveat is that dust bunnies are not well corrected for if you smooth the flat. Fortunately, the camera shows no sign of them (yet). Loading the master flat into AS!2 ensures all frames are corrected. Not that if you take AVIs of an ROI rather than full frame, you must create flats for that ROI. The result of flat-field correction is shown below. This looks more promising. I then stack 100 (typically) of the frames (letting AS!2 pick out the best ones). The result appears to be not much different from the previous, as can be seen below. Looks can be deceiving, however. If we apply Lucy-Richardson deconvolution (sigma = 1.15, 50 iterations works for these data) and unsharp masking (sigma = 1.15, strength 2.75) in ImPPG to the stack of 100 images, we get a very decent result. I frequently work with higher strength values (3.75) in ImPPG, as can be seen in this screenshot The parameter values used depend heavily on the optical system and camera used. I have recently found that the smaller sigma values work best for my current Solar Spectrum filter, whereas in my previous LS35THa and also SolarMax-II 60mm I tended to use much larger values of sigma for unsharp masking, and slightly larger ones for LR deconvolution. The reason for the small sigma value for unsharp masking in the new set-up might be that the contrast for large structures is good enough, and they do not need to be boosted, so I can focus on small detail. Just experimenting in ImPPG is the way to find what suits you best. The image above is the kind that I use for mosaic stitching. My procedure for that is VERY easy: open AutoStich64, click on the "open files" button, select all your panes, and sit back. Any tweaks of contrast after stitching is done in GIMP. Applying the same settings for sharpening to the flat-field corrected frame yields this: Result ≠ good The noise in a single frame just explodes. By stacking 100 frames we can increase the signal-to-noise ratio by a factor of 10 (square root of the number of frames stacked). I might also want to use a single pane as a detail shot. In that case I like to apply contrast stretching or (partial) invertion of contrast in ImPPG, not GIMP. The reason is that AS!2 outputs 16-bit TIFF files, and ImPPG allows me to work in 16 bit mode with the curves. The results of applying a sigmoidal curve to stretch the contrast in the mid-tones look like this: The exact degree of contrast stretching is entirely a matter of taste. One of my favourite contrast tweaks is partial inversion of the contrast. The aim here is to have the region outside the disk in positive contrast (but heavily stretched to bring out proms and spicule detail), and everything on the disk in negative contrast. To achieve this I create a convex curve with a single maximum near the grey level of the spicule layer. The original black and white values are both mapped to zero. I then insert an extra control point to set the apex of the curve at the grey level of the layer of spicules, or a bit above. This point is set to just below white (255) as output value to avoid saturation. The resulting curve is roughly a parabola, which I then correct with two additional control points on either side of the apex. I move these to make the curve on the right a bit concave, and on the left nearly straight. I then tweak until satisfied. The result looks like the one below, and has a 3D feel to it. A screenshot of ImPPG shows the curves used: Finally, I might want to turn the image into a pseudo-colour version. To do this I open the image in GIMP, and apply a series of curves for red green and blue to achieve this: The latter is done with curves that look more-or-less like this I will add more detail (including screenshots) in due course.

Long orthos and plossls don't give wide views, short orthos and plossls have painfully short eye relief

I would have difficulties fitting a 31T5 Panzerfaust in my trouser pockets. If I stashed it in on of my coat pockets (or a photographer's vest) I would run the risk of doing some serious damage to parts of my anatomy if I made any sudden motions. A 1kg, HARD object dangling too close to groinal areas is asking for trouble,

Lovely report Alan. Glad the clouds relented. The reason you never see a can of beans in photos of big Dobsonians is that the can is hiding in terror behind the giant scope (and even if it isn't hiding, it might just be one or two pixels in size ).

Very nice addition. Quality glass requires quality whisky, just like qualty whisky needs quality glass

I always hate it when manufacturers think they know better than me as a user what should be done under ceertain circumstances without letting you overrule their presets. As it is MY device I should be granted control if I desire it. I never like cameras (or computers for that matter) that do not let me do things the way I want them

My main one is from Dörr. Not that cheap but big enough. My other case was a cheap secondhand one

The T4s do not have 20mm ER across the board like Radian or Delos designs. The 22T4 has 19mm, but the 17T4 and the 12T4 both 17mm (with the 12T4 a touch tighter than the 17T4 in my experience). The Ethos 13mm at 15mm is borderline for me. I find 16mm works (and even the 15.6mm of the MaxVision 20mm 68 deg), but 15mm is just a bit short