CaK imaging - Any hints and tips?

[nicoscy]

Probably going to dabble in CaK as well. 

Any hints and tips for acquisition and processing? Seems as if CaK is more difficult (shorter wavelength and all) to do...

Thanks in advance!

Nicos

[Merlin66]

Nicos,

I use a DIY CaK filter. It really needs at least an f10 beam to perform well. (f15 would be even better!)

I stop my ED80 down to 60mm to achieve the minimum f10.

Firecapture for image acquisition, I'm using a ASI 1600MM, stacking in AS3! and final tweaks in ImPPG.

I find an electronic focuser (I have a SW motor belt geared to the 10:1 focus knob) mandatory. Takes practice, but when the detail just crisps up you know you're close.

 

 

[nicoscy]

Even with a Lunt CaK module? Instructions do not mention such re f`10, but I'll try it! I use a 76mm f6.5 achro, which means I have to stop it down to 50mm, but it's worth a shot!

Thanks for the tips!

[nicoscy]

Nice images by the way! I think it will take me quite a lot of work to get there, but I am eager to try!

[Merlin66]

Yes, I believe the Lunt has the same requirements, the CaK bandwidth needs at least f10.

 

[nicoscy]

Aperture mask time then! I think I'll just scoot over to a 3D print shop and have them make something simple!

[Macavity]

I suppose one could (wryly) observe that "inch for inch"(!)
CaK scopes have "2x better resolution" than H-Apha?!? 🥳

Of course such is doubtless a simplification... But if I'm still
around when / if the Sun "livens up a bit", I might try too! 😎

[nicoscy]

Just remembered I have a Borg 50mm f5 achro in storage!!!! 

I could just toss in the mix a 2x barlow before the CaK module and I am there! Still at 500mm which allows me to enjoy a full disk with my ASI178MM 

[Merlin66]

Yeah,

the UV wavelengths can give better resolution, but the seeing gets worse. Also the capabilities of some (most) refractors to imaging at CaK are less than ideal.

[nicoscy]

1 minute ago, Merlin66 said:

Also the capabilities of some (most) refractors to imaging at CaK are less than ideal.

Can you please expand on that?

[Merlin66]

Nicos,

The spherical and chromatic aberrations are not always well corrected at CaK wavelengths.

 

[nicoscy]

Great - means I'll have to think of another solution. I will try with the 50mm achro as it's there anyway and see what comes out!