Need help identifying a filter (warning: Large photos)

[Mariner]

Hi Guys, I need some help IDing a filter.

I picked this 1.25" filter up in 1998 from a friend in the Astro club. I had never handled any filters before so did not ask what it was and simply assumed its a "nebular filter".









Based on the bluish hue direct view and the reddish hue when viewed sideways, it seems similar to the Celestron UHC/LPR filter I have but the filter rim has virtually no markings and seem to impart the hues onto the images I see thru the eye pieces. For example, when compared with the Celestron filter which only gave a slight blue hue when looking at the moon, this filter turn the moon blue.

Anyone has any idea what this "old" filter actually is?

[weixing]

Hi,
Err... How many filters are there? Or are all these photos belong to a filter?

Anyway, nebula filter will turn image a bit greenish.

Have a nice day.

[Mariner]

All pics are the same filter, viewed from different angles.

So what class of nebular filter should this be? UHC?

[MooEy]

You can do a side by side comparison with a few other lpr/uhc filters to have a feel of the strength

[Mariner]

You can do a side by side comparison with a few other lpr/uhc filters to have a feel of the strength

Good point but I only have a Celestron UHC/LPR filter. I'm just interested to figure out what class of filter it belongs to and the original manufacturer. Will try posting photos of the 2 side by side later.

[Mariner]

Here's a side by side comparison with a Celestron UHC/LPR filter (L) and the unidentified filter (R)



The view through the Celestron filter



and the slanted view of the same Celestron filter



From the effects, the unidentified filter appears to be similar but the effects are more pronounced. Also, the Celetron filter has a silvery coating whereas this filter's coating appears deep yellowish. Anyone has any idea what brand and make it is?

[Mariner]

Looking at the filter housing, seems like it is an old Lumicon filter? Might have been labelled with a sticker which had been removed. I suspect it is a Deep Sky filter and not UHC.

http://www.cloudynights.com/classifieds ... all&page=1

[Mariner]

Just a quick update. I followed a suggestion to split light into the colour spectrum and try the filter to see what passes through. I had 4 filters to play with:

1) Celestron UHC/LPR (Broadband)
2) Omega NPB (Narrowband)
3) Baader O-III (line)
4) Unidentified

Results (described as best as I can):

1) Celestron UHC/LPR - Red, Green through to blue visible
2) Omega NPB - Red, Green through to blue visible. Red brighter than UHC/LPR
3) Baader O-III - Only green visible and quite dark
4) Unidentified - Green through to blue visible

I'm tempted to think that the filter might be bordering on O-III category or narrowband at best.

Hopefully skies clear enough this weekend to try out on some DSOs to gauge performance.