Thanks for the update, James. Cloudy, here.

Wow... great images, fantastic.

Great comparisons, Pedro, and interesting camera.

Thanks Pedro, Eric, Alexandra.

I am now using my 80 mm f/11.7 but I am also considering this one , 102mm with 1100mm f.l., had it for few months for testing in 2017 and I was very impressed by both optics and mechanics, one of the best 4 inch achromats I have seen so far. If stopped to 80 mm would lead f/d close to 14, very simil...

Thanks for comments. Yes, Mark, as a TOA is beyond my reach I have been looking for alternatives for calcium imaging. The small 90mm Taka is too short, however, but good for WL and H-alpha and very portable. After many tests I eventually sold the 115 :lol: and returned to my long focus refractors wi...

I had little time for imaging this month, apart from experimenting with my CaK setup I made few images only and always in bad seeing. Few weeks ago I purchased an ASI 178MM camera and immediately realized that it gives rise to a fixed disturbing pattern on every H-alpha image with any of my devices,...

Great captures, Jozef! love the colour version

Great captures, Jozef! love the colour version

Fine discs, David.

AR102S is a quite short refractor but the Cak image is good, have you stopped the aperture ?

Great capture, Franco, those tiny pores came out well!

A really great view

Is the refractor a standard achromat lens ?

Hi Mark, thanks for your comments. You're right in everything you wrote, all images are undersampled and can't show differences in resolution. I wanted to see if making the scope slower makes also the filter more effective. It appears this is the case however from 115 mm to 80 mm I see only a modest...

Seeing improved a little today, however not enough for hires testing. Anyway I made further experiments with the 115mm apo f/6.9 at various apertures and the modified CaK module. Here below my results by using of the ASI 178MM and a slight reducer (0.7x). All images with same seeing, frames, fps, an...

Thanks Bob for your useful advice. Since I removed the original Lunt BF seeing was always poor here, this may be the reason why the disc appears soft, however I agree that further tests at various reduced apertures are needed to evaluate the effect of SCA, if relevant. Whatever the aberrations of th...

Great proms image, I like that red

Great proms image, I like that red

True, however my scope is well corrected in CaK even at full aperture so I would prefer to maintain resolution if I can. However I'll do some tests to see what gives better results, full aperture or higher f/ratio.

I find the CaK filter gives better (repeatable) results when used at f10 (or greater) Totally agree, it's also my experience, however for imaging the full disc I would prefer to avoid making mosaics so I am using the scope at the native f/ratio to contain the disc within the sensor. I could increas...

Yes, just my habit to call "etalon" any device of that kind...

The scope I used for the full disc is f/6.9.

PS, thanks for offering advices on the SHG I would like to build, I am still in the very preliminary stage (i.e. book reading...).

Hi Alexandra, I am using of the Lunt etalon and Quark BF, they match fine. My calcium Quark no longer goes in tune so I am using the pieces for assemblying something else. Next step will be to remove the Lunt etalon from the original barrel for mounting it in a shorter one.

In this discussion I described the problem I had with the blocking filter assembly of my Lunt module, mainly coma and astigmatism due to the tilted filters. Placing a focal extender before the BF helped in obtaining a better definition however this cannot be a solution if one wants to image the full...

Great! congratulations...

Great images, Franco, very crisp.

Bring up this old discussion because I have just published a short note on replacing the o-rings for Lunt LS50, this is the link: https://imagesofoursun.wordpress.com/maintenance/replacing-lunt-ls50tha-pressure-tuner-o-rings/ (for moderators, think this discussion should be moved to a different sect...