Alluxa Ca K 393.37- 0.1 nm filter now listed in Alluxa catalog

[christian viladrich]

Hi,
The filter is said "out of stock", but it is now listed in Alluxa catalog, which is good news :-)

https://alluxa.com/optical-filter-catal ... ss-filter/

[marktownley]

That's good news!

[DavidP]

Any links to images or experience with one of these?

[marktownley]

Alfred, Christian, Dennis and myself amongst others are using them.

[christian viladrich]

Any links to images or experience with one of these?

Hi David,

Have a look here :
http://astrosurf.com/viladrich/astro/so ... _2023.html

or here :


Most of my Ca K images are made with the alluxa 0.1 nm filter (single or double-stack), and some with the 0.37 nm Alluxa filter.

[DavidP]

Those are outstanding images Christian.
Alluxa quotes just 1-2 weeks on these

[KMH]

Any links to images or experience with one of these?

Hi David,

Have a look here :
http://astrosurf.com/viladrich/astro/so ... _2023.html

or here :


Most of my Ca K images are made with the alluxa 0.1 nm filter (single or double-stack), and some with the 0.37 nm Alluxa filter.

Those are wonderful images!
I see the imaging train includes a blue Astronomik filter and an EO 394/10 filter. Do these serve as ERF and blocking filter, respectively?
Do you think the RAF filter tilter has enough precision for this application?

Thanks!
Kevin

[christian viladrich]

Hi Kevin,

The blue Astronomik filter has a diameter of 50 mm. It is used as a sub-aperture ERF :

http://astrosurf.com/viladrich/astro/in ... onomik.jpg

Because the Alluxa 0.1 nm is transparent to UV, green, red and IR, it requires the use of a complementary filter to block all these wavelengths. This is why I use the EO394-10 nm (FWHM = 10 nm). Sometimes, I use the Alluxa 0.37 nm instead because of a better off-band blocking.

RAFcamera tilt mounts are quite good. I have three of them. The main thing is a bit difficult to explain in words : if you look carefully at the picture, you could see that the outside of the body is not cylindrical on the side of the knob. In fact, it is part of a portion of another cylinder square to the optical axis (3D machining) :

https://rafcamera.com/tilt-holder-1-25inch-t2

It means that when you screw the knob, the tilt of the filter that not change, which is a very nice feature.

I tune the tilt of the filters(s) with a spectro. Still, with some experience, it seems possible to reach a reasonnable accuracy with tuning by eye.

There are some additional stuff here (some of them are old setup) :
http://astrosurf.com/viladrich/astro/in ... ntCak.html

The spectro measurements I have made are quite consistent with the data provided by Alluxa (usually data provided by manufactures are a bit optimistic ...) :
http://astrosurf.com/viladrich/astro/in ... ilter.html

This being said, hard coating implies some dispersion from one filter to the other. So, it is better to ask Alluxa for the actual data.