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New CMOS optimised Baader Ultra-Narrowband filters


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Interesting.

I've had my eye on a set of 36 mm unmounted filters from the UNB range but now I'm not so sure.

Baader states a HBWs of 3.5 nm (H-alpha) / 4 nm (O-III / S-II): https://www.baader-planetarium.co.uk/shop/baader-cmos-optimised-h-alpha-o-iii-s-ii-3-5nm-4nm-ultra-narrowband-filterset/ I can't find any more details than this.

On the other hand, Chroma specifies a FWHM  (with measurements) of 3 nm: https://www.chroma.com/products/parts/h-alpha-3nm-bandpass#tabs-0-main-2 and https://www.chroma.com/knowledge-resources/about-fluorescence/fluorescence-applications/glossary

This implies that the passband of the Chromas is only half that of the Baaders.

Having a job that requires a good appreciation of systems engineering, I'm always on the lookout for specification discrepancies like this. ;)

Are we being mis-sold/misled, or is it that the marketeer for Baader just doesn't understand the difference between FWHM and HBW?

Does anyone know the truth?

Edited by Pompey Monkey
Correcting my own ignorance :)
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12 minutes ago, Pompey Monkey said:

Are we being mis-sold/misled, or is it that the marketeer for Baader just doesn't understand the difference between FWHM and HBW?

Does anyone know the truth?

We also have to remember that there is a significant price difference too - an entire set of Baader UNB 2" filters is cheaper than a single 2" Chroma Ha filter (£960 versus £1199).

I can see it says FWHM, but also HBW further down.  What does this mean?  A typo or 2 different specs?  I dont know what those terms mean other that when I see the value eg 3.5nm, I assume that it's a standardised measure against all filters, such as my old 7nm Baader filters.

Edited by tooth_dr
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9 minutes ago, tooth_dr said:

We also have to remember that there is a significant price difference too - an entire set of Baader UNB 2" filters is cheaper than a single 2" Chroma Ha filter (£960 versus £1199).

I can see it says FWHM, but also HBW further down.  What does this mean?  A typo or 2 different specs?

Now I'm really confused!

Here: https://www.omegafilters.com/resources/glossary#:~:text=The width of the band,and shorter than the passband. it says that HBW and FWHM are the same thing....

Maybe I should get me coat.... ;)

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On 07/07/2021 at 15:48, JamesF said:

Is there a description anywhere of what "CMOS-optimised" actually means?  I've been unable to find anything.

James

I have the same question. I'm thinking that it means they are just designed to minimise halos that seem to have been associated with some CMOS cameras? Having said this, I've had halos with my 2013 generation Baader's using my CCD camera (OIII replaced satisfactorily by Baader btw). Corrections/clarifications welcome🙂

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23 minutes ago, kirkster501 said:

Limitless what you can spend in astrophotography. I thought cycling and regular photography was bad 🙈

There is always something 'better' isnt there!

 

Mine arrived this morning :D

 

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Not long home from a long day at work. Clear skies 👍🏼👍🏼
Mounting the filters and noticed a small coating defect on the Sii filter.  Doubt it will have much impact on the image but didn’t expect it 

 

 

7FAFE58E-C79A-4BCD-B51F-449FF63EF5C5.jpeg

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Comparison from last night - wasnt totally clear so not ideal (patchy cloud) and i've a bit of fettling to do with the spacing and tilt but interested to hear what you all think?  Going to try Oiii this evening as that would be a good test of haloes.

 

5gnbb2.gif

Ha-7nm-3.5nm-comparison.jpg

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4 hours ago, tooth_dr said:

Comparison from last night - wasnt totally clear so not ideal (patchy cloud) and i've a bit of fettling to do with the spacing and tilt but interested to hear what you all think?  Going to try Oiii this evening as that would be a good test of haloes.

 

5gnbb2.gif

Ha-7nm-3.5nm-comparison.jpg

Which filter is this?

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28 minutes ago, dodgerroger said:

Thanks I am about to purchase a new Oiii filter, my current cheap filter gives huge halos. I can’t decide between the 3.5 or the 6. 

I’m going to try oiii this evening. Will post up tomorrow. I don’t have any other Oiii filters as comparison but they all have haloes. 

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Just now, dodgerroger said:

Look forward to the results. How long are your exposures and setup?

 

I’m trying out 300s exposures at gain 56 (offset 30) with the QHY268M on a Tak Epsilon 180ed F2.8. 

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21 hours ago, tooth_dr said:

Not long home from a long day at work. Clear skies 👍🏼👍🏼
Mounting the filters and noticed a small coating defect on the Sii filter.  Doubt it will have much impact on the image but didn’t expect it 

 

 

7FAFE58E-C79A-4BCD-B51F-449FF63EF5C5.jpeg

I really wouldn't be happy with that on a new filter. I have an OAG and somehow there's a small chip off the edge of the prism. Didn't think much of it as its only for guiding but I set it to close to the horizontal plane of the imaging sensor one night and the subs all had a terrible reflection artifact. What I'm trying to say is you really want everything in the light path to be as perfect as possible.

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9 hours ago, tooth_dr said:

Comparison from last night - wasnt totally clear so not ideal (patchy cloud) and i've a bit of fettling to do with the spacing and tilt but interested to hear what you all think?  Going to try Oiii this evening as that would be a good test of haloes.

 

5gnbb2.gif

Ha-7nm-3.5nm-comparison.jpg

Huge improvement in contrast there Adam! Or is it passing clouds?! Either way, it's nice to see the halo around Sadr is gone.

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9 minutes ago, david_taurus83 said:

I really wouldn't be happy with that on a new filter. I have an OAG and somehow there's a small chip off the edge of the prism. Didn't think much of it as its only for guiding but I set it to close to the horizontal plane of the imaging sensor one night and the subs all had a terrible reflection artifact. What I'm trying to say is you really want everything in the light path to be as perfect as possible.

Have to admit that's my feeling too.

James

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13 minutes ago, david_taurus83 said:

Huge improvement in contrast there Adam! Or is it passing clouds?! Either way, it's nice to see the halo around Sadr is gone.

Hard to be certain but I think more to do with the filter than clouds.

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16 minutes ago, david_taurus83 said:

I really wouldn't be happy with that on a new filter. I have an OAG and somehow there's a small chip off the edge of the prism. Didn't think much of it as its only for guiding but I set it to close to the horizontal plane of the imaging sensor one night and the subs all had a terrible reflection artifact. What I'm trying to say is you really want everything in the light path to be as perfect as possible.

I’ve brought it up with the retailer and have the option of replacing it or keeping it with some credit towards future purchases.  I’ll try it out when I get a chance as it’s going to 4 weeks before it’s back in stock anyway.  

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On 09/07/2021 at 21:44, Xiga said:

He said even 5nm filters work just fine on fast optics.

I had an Astrodon 5nm Ha filter which worked very well at F3.3, in fact I also used it with my Samyang at f2 and it worked very nicely with that too.

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10 hours ago, tooth_dr said:

Comparison from last night - wasnt totally clear so not ideal (patchy cloud) and i've a bit of fettling to do with the spacing and tilt but interested to hear what you all think?  Going to try Oiii this evening as that would be a good test of haloes.

Looks great, halo free👍

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46 minutes ago, Allinthehead said:

Looks great, halo free👍

Unfortunately not scratch-free.

That’s both Sii and Oiii filters I can now see are marked straight out of the box 👎

I literally have just blown just off them and not so much as touched the glass with anything 

 

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