Astronomik ProPlanet IR-pass filter Help?

[zakkhogan]

Hi all

I didn't want to high-jack the other thread re: IR Pass filter.

I recently bought the Astronomik ProPlanet 742 IR-pass filter expecting to achieve better results when imaging. I went out for the first time with it last night and tried using it in different positions in the optical chain.

1) replaced the L fitler for the IR pass filter

2) fitted it into position 4 of the filter wheel without the L filter in place

3) same as above with the L filter in place.

I targeted Venus first, being nice and bright, I had to increase the gain up to 100% and the exposure up to the point that I was capturing at around 14 / 20fps. Introducing the colour filters just made the situation worse. When turning to Jupiter it was impossible to image

Equipment used: 

CPC800

ZWO ASI120MM

LRGB Filters + Wheel

Televue 2x Powermate

Any advice appreciated

Thanks

Craig

[zicklurky]

Hi Craig,

You should use the IR-pass filter by itself without any other filters in the train.

Longer wavelengths of light are less affected by bad seeing, so IR-pass filters work by cutting off most of the short wavelength light and only allowing very long wavelengths through to the camera (this filter only lets through > 742nm). This includes most (all?) of the colour spectrum. This is why sometimes if you image with red filter you get a sharp image, but blue looks like mush - blue is short wavelength and red is long, so blues are much more affected by seeing.

IR-pass filters are nice for either a mono image, or used as luminance for a RGB image.

Hope this helps

Chris

[zakkhogan]

Thanks Chris

So should I use the remove the IR cut \ L   filter from the train competently?

[zicklurky]

When using the IR pass filter yes.