Sigma 105mm
zwo asi6200mm
IDAS M48 H-alpha 6.8nm UHS. OIII 6.0nm and SII 6.3nm UHS
Chroma M48 SHO 5nm
Deneb 400% Halo
zwo asi6200mm
IDAS M48 H-alpha 6.8nm UHS. OIII 6.0nm and SII 6.3nm UHS
Chroma M48 SHO 5nm
Deneb 400% Halo
IDAS UHS Filter VS Chroma 5nm SHO f1.4 & 2
Having used the IDAS filters with 3mm thickness in my case on the Rasa 8, I think they are good value. However based on this comparison, notwithstanding stars in the Chroma images look softer but Deneb itself looks tighter with the chroma. Sadly sold the RASA 8 + filters and on the hunt for a fast scope. Thought I found something but too many nightmare stories. Maybe epsilon 160ed if they ever become available.
I think it is important to remember the obvious, they are filters, not enhancers. When a nebula apperas brighter, it doesn't mean the filter is doing a better job. Actually, It may mean it is doing a poorerj ob and letting in wider or additional wave lengths. An ideal perfect filter would only let in the specific wave length and all else in the image would look like a dark frame.
When looking at the Chroma images, the background is darker, which convinces me it is filtering out more unwanted wave lengths.
As to wether that qualifies the higher cost, is and indivigual decision based on budget and goals.
Lynn K.1
When looking at the Chroma images, the background is darker, which convinces me it is filtering out more unwanted wave lengths.
As to wether that qualifies the higher cost, is and indivigual decision based on budget and goals.
Lynn K.1
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Thanks for posting this. I own the Sigma 105 too and have been working for a while to figure out a way to optimize it. The UHS NBZ doesn't quite cut it because it has no use in my white zone. Currently have a set of Astronomik MaxFR 12nm filters that I'm waiting to test out with it.
According to IDAS, the UHS H-a gets 60% transmittance on an f/1.4 lens. If I'm understanding this correctly, that means the benefit of the fast focal ratio is maintained despite the thin bandpass. The drawback is the 3mm optical thickness. Even the NBZ's 2.5mm thickness makes it impossible to obtain a flat field, in my experience. Astronomik by comparison is only 1mm.
According to IDAS, the UHS H-a gets 60% transmittance on an f/1.4 lens. If I'm understanding this correctly, that means the benefit of the fast focal ratio is maintained despite the thin bandpass. The drawback is the 3mm optical thickness. Even the NBZ's 2.5mm thickness makes it impossible to obtain a flat field, in my experience. Astronomik by comparison is only 1mm.
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Lynn K:
I think it is important to remember the obvious, they are filters, not enhancers. When a nebula apperas brighter, it doesn't mean the filter is doing a better job. Actually, It may mean it is doing a poorerj ob and letting in wider or additional wave lengths. An ideal perfect filter would only let in the specific wave length and all else in the image would look like a dark frame.
When looking at the Chroma images, the background is darker, which convinces me it is filtering out more unwanted wave lengths.
As to wether that qualifies the higher cost, is and indivigual decision based on budget and goals.
Lynn K.1
The key is @f1.4 and f2.0
I'm rediscovering these filters now that I've finally gotten my hands on an adapter for my Sigma 105mm f1.4 lens that can hold a 2" filter.
@noahzhou What Bortle level did you take the test images from? I would like to use the H-alpha to get luminance data from home so I can eventually take the lens to a dark site for color data. If I could do this with the OIII that would be great too, though I doubt the 6nm bandpass is thin enough for my skies.
I also wonder when/if Hutech will make a dual-band filter for f/1.4 with these bandpasses. Their current NBZ UHS isn't too good under severely light polluted skies in my experience.
@noahzhou What Bortle level did you take the test images from? I would like to use the H-alpha to get luminance data from home so I can eventually take the lens to a dark site for color data. If I could do this with the OIII that would be great too, though I doubt the 6nm bandpass is thin enough for my skies.
I also wonder when/if Hutech will make a dual-band filter for f/1.4 with these bandpasses. Their current NBZ UHS isn't too good under severely light polluted skies in my experience.
Well Written
Lynn K:
I think it is important to remember the obvious, they are filters, not enhancers. When a nebula apperas brighter, it doesn't mean the filter is doing a better job. Actually, It may mean it is doing a poorerj ob and letting in wider or additional wave lengths. An ideal perfect filter would only let in the specific wave length and all else in the image would look like a dark frame.
When looking at the Chroma images, the background is darker, which convinces me it is filtering out more unwanted wave lengths.
As to wether that qualifies the higher cost, is and indivigual decision based on budget and goals.
Lynn K.1
Using a NB filter for f/1.4 will give a brighter backgrond than for f/2, because it has to be wider for the fast f-ratio (or, the transmission has to be shifted further to the blue). The Sigma 105mm shoots at open with f/2.8, if im right, and with a NB filter which specs are more matching the telescope, like f/2, you will obtain a better contrast. At least in the ideal world. You can test it by shooting at different apertures.
In reality, there are always fluctuations from batch to batch. I had quite some discussions with Chroma two years ago, and sent a filter back for replacement because of a not suitable central band wavelength. Their filter picking was not optimal. In the meantime others learned the lesson, i think Chroma did, too.