Recently I inspected my 20 year old Lumicon Deep Sky filter to see that when held to the light, the coating has become somewhat powdery looking. Perhaps that is why I am getting some star halos on photos also. So I have replaced it with an Astronomik CLS and also looking at more from Baader.
What sort of life can I expect out of the Astronomik and Baader etc? Do some last longer than others?
Hi CometC
I have a Lumicon Deep Sky filter as well, which is around 25 years old or more. Apart from some minor dust and grime, I see no evidence of 'powdery' deterioration at all. I would have thought they last a lifetime, barring some mishap or abuse. PS, admittedly I dont know much about filters, and maybe there could be batch to batch variation. Fox.
My Lumicon O111 filter and a Baader Fringe Killer that are both showing mottling. Both have been kept in their plastic boxes which are kept inside a pelican case. Neither have been cleaned with chemicals, only using a brush and lens pen.
I haven't checked to see if their clarity has been affected.
They are around 6 years old.
I'd got the Fringe Killer out to sell a couple of months ago, as someone was looking for one, took one look at it and just tossed it back into the case.
Hi CometC, I see no evidence on my Deep Sky filter of "powdering", but then again I'm not able to get the 'macro' image photo that you show, nor do I have a magnifier - how did you photograph your filter? Fox
PS: over at CloudyNights, David Knisely seems to suggest that the protective lamination of Lumicon filters may deteriorate with time, depending on batch manufacture...?
Hi Fox, I just used a 10X achromatic close up macro lens on a point and shoot Fuji S5600 for the macro shot with the sky as background.
Glad to hear your Lumicon DSF is okay. Must be bad batches of them out there, and not limited to Lumicon if Baader and Astronomik have some bad ones as well.
Though the films on these eyepieces are mostly oxides, some layers do react to sulphur in the air and other contaminants. 20 years is a little longer than they last here in LA, and they might last longer in some pristine environments.
If contemplating replacements, know that there are a variety of orientations for filters today that might influence your choices:
Narrowband filters with Wide bandwidths: These are good for smaller scopes or for observers who prefer the aesthetics of having more stars in the field of view or for use at higher powers. Not the best contrast possible, but a huge improvement over no filter. Examples: TeleVue Nebustar, Baader UHC-S, Astronomik UHC
Narrowband filters with medium bandwidths. Though the overall field of view will be darker, contrast on nebulae is improved and performance is near-optimum, though star images are suppressed more. Examples: Lumicon UHC, Thousand Oaks LP-2, Orion UltraBlock. Usable up to about 10-12X/inch.
Narrowband filters with narrow bandwidths. The maximum contrast, but the greatest suppression of stars and the darkest field. Great in the largest scopes or at very low powers. Example: DGM NPB.
For O-III filters, there is also a hierarchy of bandwidths. The widest ones are close to the width of the medium UHC filters, but don't include the 486nm H-Beta line the way the UHC filters do.
Wide: TeleVue O-III, Astronomik O-III
Medium: Lumicon O-III, Orion, O-III, Thousand Oaks LP-3, DGM O-III
Narrow: Baader O-III, Celestron O-III (these are so narrow they exclude most of the light from one of the two O-III lines and should be thought of more as wider photographic filters than visual filters, though they are usable visually)
This plethora of choices (and i only mention a few of the now 25 brands) wasn't available 25 years ago, so you have to choose wisely based on whether you want more contrast, or a brighter field with more stars. There are valid reasons for both approaches.
I sorted it out by choosing to have both for different purposes. For instance, some of these filters have a lot of transmission at the 656nm line of H-alpha. Some have little or no red transmission shorter than 700nm, so you see none. It may be nice to have some red transmission if you have a large scope or are looking at an object with profound energy of emission at that wavelength.
Lumicon is still the benchmark for highest transmission and near-perfect bandwidths, but have little or no red transmission since 2005. Lumicon is now back in business with new owners, Marc & Debbie Neveux and they are shipping filters again as are their retailers.
