G-band filter 430 nm 2 nm FWHM available at Altair

[christian viladrich]

Great news !

A nice G-band filter is now available at Altair :

https://www.altairastro.com/altair-2nm- ... 3245-p.asp

The peak transmission is quite high while the FWHM is only 2 nm.

This type of filter gives a good contrast on granulation and facular plages. It is "easier" to use compared to near-UV filters (K-line, Antlia 393>-3 nm) since the blue part of the spectrum is less affected by turbulence than the near-UV.
On top of that, the optical quality of refractors is much better at 430 nm than at 396 nm.

And finally, with a large telescope (from 150 mm ?), intergranular bright spots can be observed.

[Dennis]

Awesome news. And reasonable priced for the fwhm, thx for sharing.

[marktownley]

Great news! Sounds like you had a hand in writing the blurb Christian

[Montana]

I've just ordered one, I look forward to using it with my TEC140

Alexandra

[marktownley]

Has anyone seen a full transmission profile graph for this filter?

The graph on the website doesn't say much...

altair-2nm-g-band-solar-contrast-filter-1.25-430.3nm-(2)-13245-p.png (10.17 KiB) Viewed 1438 times

Talks about blocking 300-1100nm. Has anyone got their spectrographic text report they want to share?

[Montana]

Mark, that is it, this is the same graph that comes with the filter.

Alexandra

[Dennis]

yes.. nothing else in or on the box.

[marktownley]

Hmmm, that's rubbish. Hopefully someone here will be able to a scan. Was hoping to see what it's transmission is like out of band...

[OlegLviv]

This filter will be better Continium 10nm? And can use with Bader Hershel Prism with Nd filter ?
Thank you!

[arnedanielsen]

This filter will be better Continium 10nm? And can use with Bader Hershel Prism with Nd filter ?
Thank you!

Hi Oleg

The filter can definitely be used with the Baader Herschel Prism together with and appropriate ND filter.

I would say the G-Band filter is a good addition to imaging with the Continuum. The G-band has more contrast as well as increased resolution for a given aperture because of it's shorter wavelength.

Here are a comparison I did using a Baader Cool-Ceramic Safety Herschel Prism Photographic 2", Baader ND OD 0.9, Altair G-Band Solar Contrast Filter (430.3nm) 2nm/Baader 1,25" Continuum (540nm) 7,5nm.

viewtopic.php?p=392477&hilit=AR3340#p392477

[OlegLviv]

This filter will be better Continium 10nm? And can use with Bader Hershel Prism with Nd filter ?
Thank you!

Hi Oleg

The filter can definitely be used with the Baader Herschel Prism together with and appropriate ND filter.

I would say the G-Band filter is a good addition to imaging with the Continuum. The G-band has more contrast as well as increased resolution for a given aperture because of it's shorter wavelength.

Here are a comparison I did using a Baader Cool-Ceramic Safety Herschel Prism Photographic 2", Baader ND OD 0.9, Altair G-Band Solar Contrast Filter (430.3nm) 2nm/Baader 1,25" Continuum (540nm) 7,5nm.

viewtopic.php?p=392477&hilit=AR3340#p392477

Arne thank you very much!!!

[christian viladrich]

Here are the measurement of two Altair G-band 2 nm filters from 300 to 1000 nm made with an Ocean Optics HR 4000 spectrometer (0.37 nm/pixel resolution) :

viewtopic.php?t=42212