Thousand Oaks vs. Lumicon nebula filters

Are the Thousand Oaks H-beta and OIII filters considered equivalent in
performance to the Lumicon versions?

I have noticed some slight focusing issues with the Lumicon filters as
it seems stars in the field do not focus to a sharp point when using
the Lumicon UHC.

The Thousand Oaks filters are also about 20% less expensive. I also
like the idea of different colors for the filter rings to aid in
id'ing them in the dark.

---
Michael McCulloch

"Michael McCulloch" wrote in message
...
Are the Thousand Oaks H-beta and OIII filters considered equivalent in
performance to the Lumicon versions?

I have noticed some slight focusing issues with the Lumicon filters as
it seems stars in the field do not focus to a sharp point when using
the Lumicon UHC.

Hi Michael,

Lumicon and several other makers use laminated soft film designs which
require that the film (layers) be sealed in a cover plate so the film
doesn`t degrade. If the cover or main plate has any deviations, dimples,
striations, etc, or the epoxy is contaminated the plates don`t sit parallel
and there can be bothersome internal reflections or even double images.

It`s ironic in that Lumicon urges users to "not settle for cheap,
foreign-made imitations" when they use the same technology! (although not
foreign made AFAIK).

Dan McShane
www.dgmoptics.com
http://users.erols.com/dgmoptics/LPRfilters.htm

The Thousand Oaks filters are also about 20% less expensive. I also
like the idea of different colors for the filter rings to aid in
id'ing them in the dark.

---
Michael McCulloch


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I have a 2" Thousand Oaks O-III and am very pleased with it.

Eddie

"Michael McCulloch" wrote in message
...
Are the Thousand Oaks H-beta and OIII filters considered equivalent in
performance to the Lumicon versions?

I have noticed some slight focusing issues with the Lumicon filters as
it seems stars in the field do not focus to a sharp point when using
the Lumicon UHC.

The Thousand Oaks filters are also about 20% less expensive. I also
like the idea of different colors for the filter rings to aid in
id'ing them in the dark.

---
Michael McCulloch

"Eddie Kirkland" wrote in message ink.net...
I have a 2" Thousand Oaks O-III and am very pleased with it.

Eddie

"Michael McCulloch" wrote in message
...
Are the Thousand Oaks H-beta and OIII filters considered equivalent in
performance to the Lumicon versions?

I have noticed some slight focusing issues with the Lumicon filters as
it seems stars in the field do not focus to a sharp point when using
the Lumicon UHC.

The Thousand Oaks filters are also about 20% less expensive. I also
like the idea of different colors for the filter rings to aid in
id'ing them in the dark.

---
Michael McCulloch
See this site for accurate informatiom about filters:
http://home.freeuk.com/m.gavin/grism2.htm
Precise spectroscopic measurements for just about all brands and types...
Clear skies,
Shneor Sherman

On 29 Oct 2003 07:32:16 -0800, (Shneor Sherman)
wrote:

See this site for accurate informatiom about filters:
http://home.freeuk.com/m.gavin/grism2.htm
Precise spectroscopic measurements for just about all brands and types...

Thanks! Hmm, the Thousand Oaks misses one of the OIII emission lines.
I wonder if that results in more contrast, but darker images in
practice. Since I already have the Lumicon UHC, perhaps the Thousand
Oaks OIII would yield a bigger difference than the Lumicon OIII on
certain objects. I have a 12.5" f/5 newt.

The Lumicon H-beta also looks quite good -- centered on the H-beta
emission line with complete rejection of OIII.

The Televue OIII is not very narrow in the passband at all. It looks
more like the Lumicon UHC.

---
Michael McCulloch

I went through the same thought process when buying my OIII
filter...in a side by side comparison I couldn't see any difference
visually between the Lumicon and Thousand Oaks OIII filters...I bought
my Thousand Oaks filter from Adorama in NYC they discount them as
well. It's interesting, in the spectrograph both filters appear very
similar.




Michael McCulloch wrote in message . ..
On 29 Oct 2003 07:32:16 -0800, (Shneor Sherman)
wrote:

See this site for accurate informatiom about filters:
http://home.freeuk.com/m.gavin/grism2.htm
Precise spectroscopic measurements for just about all brands and types...

Thanks! Hmm, the Thousand Oaks misses one of the OIII emission lines.
I wonder if that results in more contrast, but darker images in
practice. Since I already have the Lumicon UHC, perhaps the Thousand
Oaks OIII would yield a bigger difference than the Lumicon OIII on
certain objects. I have a 12.5" f/5 newt.

The Lumicon H-beta also looks quite good -- centered on the H-beta
emission line with complete rejection of OIII.

The Televue OIII is not very narrow in the passband at all. It looks
more like the Lumicon UHC.

---
Michael McCulloch