Filter Question

[Anthonyexmouth]

Why do i need an ir filter with my ASI290mc and yet astro modded dslr cameras remove the ir filter? or have i misunderstood this?

[LightBucket]

With an Astro modded Camera, they remove one of the two filters in front of the sensor, the one that cuts the Ha signal, the second one is left in the camera as that does and excellent job of IR cut...and also helps protect the sensor, but does not cut the Ha.

Now if you have a full spectrum Astro mod on a canon camera they would remove both filters, and then you would need an IR filter to image with it...

HTH

[Anthonyexmouth]

1 minute ago, LightBucket said:

With an Astro modded Camera, they remove one of the two filters in front of the sensor, the one that cuts the Ha signal, the second one is left in the camera as that does and excellent job of IR cut...and also helps protect the sensor, but does not cut the Ha.

Now if you have a full spectrum Astro mod on a canon camera they would remove both filters, and then you would need an IR filter to image with it...

HTH

ah ok, missed the part with the full spectrum needing an ir filter after, which leads to the question, why do the full spectrum mod?

[LightBucket]

16 minutes ago, Anthonyexmouth said:

ah ok, missed the part with the full spectrum needing an ir filter after, which leads to the question, why do the full spectrum mod?

I think there is some type of Imaging that requires the camera to see the full light spectrum, not sure what...also some people like to use there own filters, like a LP filter that has built in IR then one less piece of glass in front of the sensor...

[symmetal]

2 hours ago, Anthonyexmouth said:

ah ok, missed the part with the full spectrum needing an ir filter after, which leads to the question, why do the full spectrum mod?

You can then do infra-red photography using an external IR pass filter which blocks visible light and UV. It can produce striking results with terrestrial images as a mono image or combined with other colour images.

For astrophotography it's common to take mono images of the moon through a red filter rather than luminance as it will normally be sharper and less affected by seeing distortion due to the longer wavelength. You can take it a step further by imaging the moon through an IR pass filter which being even longer wavelengths cuts through the seeing even more. If you have a larger aperture scope you can image planets as well using the IR image as a luminance in LRGB to get sharp colour images. The IR pass filter needs longer exposures than a red filter  and/or higher camera gain hence the benefit of a larger aperture scope for the dimmer planets compared to the moon.

Alan

[Demonperformer]

It also allows you to explore the methane content in the atmospheres of Jupiter/Saturn using a CH4 filter.