9 replies to this topic

[bart1805]

About a year ago I optimised the distance between the two lenses of an old 150mm f/8 Skywatcher Achromat for CaK observation.

At the start of this solar season I am trying to optimise my doublestacked CaK filter-train.

 

Two examples to show the progress.

With 150mm on 20032025:

 

 

And an animation of a giant prominence on 21032025. Diaphragm of 80mm.

 

 

CS! 
Bart.

[spicerack0]

great job!

[hopskipson]

Very nice images, Bart! I'm guessing the file compression is doing a number on the still.  The animation shows better detail.

[bart1805]

Very nice images, Bart! I'm guessing the file compression is doing a number on the still.  The animation shows better detail

Thanks! The compression does not do it good. But maybe the seeing was not up to 150mm that day either. And the other thing is that the filters get more narrow hen used in a light cone with a bigger focal ratio. With the diapragm of 80 mm it is something like f/60. Compared to f/32 with the full 150mm. 

[BYoesle]

Really nice Bart 

[bart1805]

Really nice Bart 

Thanks Bob! The Baader TZ-4S seems to do a really good job in CaK. 

[R Botero]

Fantastic Bart!  Thanks for the details about your modification in the astrobin link.   

 

Roberto

[C0rs4ir_]

Very good, what are the actual ca-k filters used?

[rigel123]

Fantastic Bart, particularly that animation!

[bart1805]

Very good, what are the actual ca-k filters used?

Thanks! That are two PST-CaK filters. It is a pity that the Alluxa filters are so expensive.