ASI178MC UV/IR cutoff?

mirx9

Hi Sam or anyone else who knows: :)

What is the UV and IR cutoff wavelengths for the ASI-178MC camera? The "relative response" plot on the ZWO website only goes from 400-700nm, but at the 400nm end the blue is still very high and at 700nm the red is very high. It is not clear if or where the cutoff frequency is located.

http://astronomy-imaging-camera.com/wp-content/uploads/QE-ASI178.jpg

I have read that the ASI-224MC requires an IR cutoff because one is not built in. However I suspect the 178MC does have an IR cutoff because I put on a 742+nm IR filter and got essentially no signal.

Incidentally, I happen to have the ZWO LRGB filter set...what is the cutoff frequency for the "L" filter and would it have any effect when used with the 178MC camera?

I am asking these questions because I just used the 178MC with my APO refractor and noticed a fair amount of defocus in the blue & red channels. Before I assume anything about the optics, I want to make sure I'm not picking up UV and/or IR signal.

Thanks!

Matthew

riklaunim

If the cover glass has colorful coatings that are visible on some angles then it has IR/UV cut on it. If it's clear glass then it has no IR/UV cut features. If it's not fused silica window then still most UV may be cut down by the glass itself (but not fully).

landbo

http://astronomy-imaging-camera.com/products/accessories/d21-ir-cut-protect-window/

Hi.

Here is the "window" that should sit in your ASI178MC camera. Note that the cut off wavelengths of the glass is shown under the item.

My experience is that an APO is not suitable for photo, especially not with a color camera.

Regards Leif.