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OIII filter advise

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#1 droid

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Posted 06 May 2021 - 11:30 AM

one filter is a newer 0III from Celestron, the other is 1.25 thousand oaks, circa mid to late 1080s

 

I've heard that the coating go bad over time.

 

but I very little difference between the older 1.25 and the new 2.00 filter

 

thoughts?

Attached Thumbnails

  • 183480477_10224183814930346_5492878074997756016_n.jpg
  • 1.25.jpg
  • 2 inch.jpg

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#2 droid

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Posted 06 May 2021 - 11:30 AM

the second picture is the old 1.25 filter



#3 MitchAlsup

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Posted 06 May 2021 - 11:38 AM

one filter is a newer 0III from Celestron, the other is 1.25 thousand oaks, circa mid to late 1080s

 

I've heard that the coating go bad over time.

I have an original Lumicon UHC I got in the mid 1980s who's coatings have not gone bad yet, either.


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#4 wrvond

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Posted 06 May 2021 - 12:11 PM

You don't fool me! Neither one of those companies was in business in the 1080's!   ;)

 

As long as they aren't abused, I know of no reason an OIII filter would go bad.



#5 NeilMac

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Posted 06 May 2021 - 12:21 PM

I use the DGM filter and love it and have had no problems with surface.



#6 droid

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Posted 06 May 2021 - 12:23 PM

1980s, lol


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#7 Bob4BVM

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Posted 06 May 2021 - 12:36 PM

My O-III advice :

1-Spend your time using it instead of wondering how long it will last :)

2-Stick it in the biggest aperture scope you have and spend some time on M17, M27, the Veil, etc.

3-A good zoom EP with an O-III makes these targets even more compelling.

4-Stick it in the widest TFoV scope you have, repeat #2.

 

CS

Bob


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#8 J A VOLK

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Posted 06 May 2021 - 12:49 PM

Some go bad, most do not.  It depends on how well they were originally coated and how they were stored. 


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#9 wrvond

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Posted 06 May 2021 - 01:18 PM

FWIW I'm fairly confident the Celestron is a rebranded Baader.


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#10 droid

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Posted 06 May 2021 - 01:49 PM

yeah, if you look at the card and obvious stuff it says celestron, but stamped into the plastic on the back it says baader.


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#11 RichA

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Posted 07 May 2021 - 01:38 AM

one filter is a newer 0III from Celestron, the other is 1.25 thousand oaks, circa mid to late 1080s

 

I've heard that the coating go bad over time.

 

but I very little difference between the older 1.25 and the new 2.00 filter

 

thoughts?

Oddly, the only dielectric filters I've seen go bad were some of the most expensive you can buy.  Meanwhile, I've got a Lumicon OXYIII and UHC from the mid-1990's that are fine.



#12 Miranda2525

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Posted 07 May 2021 - 10:42 AM

one filter is a newer 0III from Celestron, the other is 1.25 thousand oaks, circa mid to late 1080s

 

I've heard that the coating go bad over time.

 

but I very little difference between the older 1.25 and the new 2.00 filter

 

thoughts?

The only way to see any coating flaws is by using a flash at a certain angle. There are some scans on here of the older filters with the coating flaws. Transmission was only about 65-70% compared to 85-90% I think. That would be enough of a difference to not want any older filters. I won't buy any older ones unless I see a picture with the flash at just the right angle to see if there is a coating flaw or not.

 

There is a certain "year" that the coating flaws happened IIRC.
 


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#13 Miranda2525

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Posted 07 May 2021 - 10:43 AM

I use the DGM filter and love it and have had no problems with surface.

The DGM has very hard dielectric coatings.



#14 Starman1

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Posted 09 May 2021 - 06:45 PM

Both the Celestron and Thousand Oaks are "photographic" filters, which concentrate on the passage of the 500.7nm O-III line, and pass the 495.9nm O-III line at a very low %.

As a result, they are darker than most O-III filters, and narrower, so SOME O-III features show through quite well.

For visual use, I would prefer a tiny bit wider to 12-13nm to catch the 2nd O-III line, which will reveal a bit more nebulosity and darken the field a tad less.

 

As for the failure mode in the older, pre-2001, Lumicon filters, see this thread:

https://www.cloudyni...= spectroscopic

from post #4 on.

 

Use this site to compare the Baader/Celestron filter with other O-III filters.

https://searchlight....d-153d7e7c0eb8#

The current state of the art is:

Astronomik

TeleVue

ICS

Chroma

Lumicon Gen.3

On paper, DGM and Orion produce excellent O-III filters as well, but the bandwidth positions vary from optimum.


Edited by Starman1, 09 May 2021 - 06:45 PM.

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#15 MrJones

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Posted 10 May 2021 - 10:55 AM

Your Thousand Oaks OIII filter is not from the 1980s. It could be about 15 years old though. It does seem to be reflecting red which is odd, their OIII filters generally pass 650nm. Hard to tell though. The coatings on both look good. You would get improved contrast from a newer premium OIII filter but really no reason to get one if you're happy with what you have.


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