SolarChat!

Hi,
This is my first solar images of the season and the first light of my ASI 1600.

Here is the single stack image :
http://www.astrosurf.com/viladrich/astr ... SI1600.jpg

And the double stack image :
http://www.astrosurf.com/viladrich/astr ... SI1600.jpg

By comparison, the single stack image looks a bit "flat".

Best regards

Christian

Lovely full disc's Christian.

The DS is clearly superior to the SS...

Christian:
Super FD´s, but the DS is superior.
Best regards.
Eric.

Hi Christian,

Excellent and huge discs. What is the focal length ?

Superb!! I too vote for the double stack

Alexandra

Thanks to all :-)

Yes indeed, the double stack is clearly better. I was a little bit surprise by this diffence since the Alluxa filter is 0.40 nm FWHM (and not 0.44 nm). This is probably because it is a multi-cavity filter. The exposure time is still reasonnable thanks to the UV sensitivity of the ASI 1600.

The image is taken at the native focus of the TOA 1500 (about 1100 mm). The sensor and pixel sizes are perfect. No need for mosaic. This is just one-shot picture (with a stack of 7 frames).

Next step is triple stacking, just like Pedro in Ha ... No, just joking ;-)

Beautiful results, Christian. The DS is better but the SS is excellent too.

Franco

christian viladrich wrote: ↑Thu Mar 25, 2021 8:58 pmBy comparison, the single stack image looks a bit "flat".

I would be very happy of such a flatness in my CaK discs....

These are superb Christian

The single stack looks fabulous and would be impressive on its own...now the DS version is a step beyond!!!

Brian

Next step is triple stacking, just like Pedro in Ha ... No, just joking ;-)

I'd give it a shot Christian !-)

Excellent images Christian.

Thanks Franco, Brian, Raf and Maurits :-)

Bob Yoesle wrote: ↑Sat Mar 27, 2021 11:00 am

Next step is triple stacking, just like Pedro in Ha ... No, just joking ;-)

I'd give it a shot Christian !-)

Hi Bob, I remember that one. It was quite a teaser for us :-)

BTW, I checked the transmission profiles of the Barr and Alluxa filters : the Barr filter is a two-cavity filter while the Alluxa filter is a three-cavity. This would be equivalent to a five-stacked system is the FWHM of both filters was similar.

Pretty cool Christian. Any chance you can get a hold of a Coronado PST and/or Lunt CaK filters to see what they look like? The only thing I've ever seen regarding them (I assume they are very similar) is shown below, and it's not too informative:

Very nice disks Christian. Have you experimented with tilting the filters in the DS? Your images are hinting at the spicule rings, i've found this is what 'pops out' when the tuning of the filters is spot on.

Hello Mark,
The EO394 is mounted in a tilt-system. Tilting this filter is only for rejecting reflexions away from the main image.
The Alluxa filter is mounted in another tilt-system. The setting of the tilting is relatively straigtforward. The idea is to minimize banding.
Prominences are very faint, so there are not very usefull in my case, but this is certainly a good idea in other cases.
The Barr filter is a bit shifted to the blue, so no need to tilt it.

Just for the fun, here is what the chromospheric fringe looks like :

http://astrosurf.com/viladrich/astro/so ... 00-ddp.jpg

It a bit tricky with this configuration to display the disk and the prominences on the same image .