UHC filter

[bomberbaz]

Simple question, I thought a UHC filter would also cut UV and IR, is that not the case?

It is a standard televue uhc bandmate

Edited April 26, 2022 by bomberbaz

[david_taurus83]

Can't seem to find any info on that filter but the Astronomiks cut UV but not IR. Thr UHC-E tails off at the IR end but not much. 

[alacant]

10 hours ago, bomberbaz said:

televue uhc bandmate

Hi

If this is the one you have, it cuts both. It looks like you get only blue/green.

Here's the graph, (from here).

Cheers

[vlaiv]

Depends on filter.

I remember that Baader had UHC filter that had issues with IR leak. They released new / fixed version later on.

First clue should be if filter is classified as visual UHC or photographic UHC.

We can't see IR part of spectrum so there is no harm in visual UHC filter passing some of the IR spectrum.

[bomberbaz]

Just done a quick unprocessed stack of 20 frames with UHC only(top) & 20 frames with astronomik L2 only bottom. (I did stretch the top UHC one a small amount as it was very dark)

I forgot to mark up star but top left it stands out a mile. Very bloated in top picture, nice red star in bottom one.

It is a visual use one I was trying to give a dual life (could always double stack with L2) but anyway, back to r3esults.

From what I see below it appears the star (T cep) which is a pulsating variable is bloating and something is getting past the UHC to cause the bloating. IR I suspect.