New CMOS optimised Baader Ultra-Narrowband filters

[Adam J]

Just now, tooth_dr said:

It does look green and the Ha and Sii are red. Any suggestions on a test target, looking clear later? 

Vale should be obvious as to which one you have. 

[Whirlwind]

1 hour ago, tooth_dr said:

It does look green and the Ha and Sii are red. Any suggestions on a test target, looking clear later? 

How about the Dumbbell Nebula as that has a distinct OIII component.  

Have you checked that the filter wheel is cycling every position correctly.  For example if is thinking it has 7 positions and is an actually an 8 position wheel etc.  Should be able to check this in daylight.  If travels in both directions you want to check it selects the same filter going backwards and forwards etc.

[tooth_dr]

19 minutes ago, Whirlwind said:

Have you checked that the filter wheel is cycling every position correctly.  For example if is thinking it has 7 positions and is an actually an 8 position wheel etc.  Should be able to check this in daylight.  If travels in both directions you want to check it selects the same filter going backwards and forwards etc.

Yes I've checked it, and rechecked it  

[rsarwar]

HI

Anyone got a transmission curve of these filters? both 3.5 and 6.5 nm filters are listed to be working from F3.5 to F10. I donot understand how they both have the same range range; especially the Oiii. i would expect the 3.5 nm filter to have narrower profile. if someone has a transmission curve for these, i be happy to calucate the theoratical F limits.

has anyone tried them with a F4.4 scope? 

Also wondering if the halo on the 6.5 nm are also as bad as 3.5 nm or not.

Edited October 15, 2021 by rsarwar

[rsarwar]

On 04/08/2021 at 00:40, Xiga said:

Finally got a chance a couple of nights ago to have a very brief first light with my Qhy268m and the Baader 2" 3.5nm CMOS Ha filter (not the super fast F2 ones). 

Zero processing on this, just a stretch, not even cropped. It's just 9 x 360s so only 54 mins. I need proper calibration frames too, this has only had a very quick BPM and a single 500s dark (not even the same length lol) applied, together with some similarly badly calibrated flats! Time to finally get some decent calibration frames now i'm finally back in the game after a long 10 months out. 

I'm happy with the overall contrast and star sizes, but am a bit disappointed in the Sadr halo if i'm being honest. I wouldn't have been surprised to see halos in Oiii or Sii, but i was expecting the Ha to be virtually halo-free. In all my time using the 7nm Ha i never really saw any halos at all, i was really happy with it. I know Sadr is about as bad a case as it gets (annoyingly i never shot this with my 7nm) but what do you guys think, does it look ok or not? 

I also might have a slight spacing issue. Not completely sure, perhaps a tiny bit more spacing needed. Hard to say for sure, as immediately after the meridian flip i got 2 more subs before the clouds came in, but both had really eggy stars! I had moved my finder-guider to a dovetail on top of the SW 80ed (supposedly for better balance), but i think that may have introduced some diff flex, so i've moved it back again. Just need another test session on either side of the meridian to know for sure if it's ok now, then i'll move on to trying to get any tilt or spacing issues sorted for good. 

this is my sadr on 3.5 Ha on 72ED + QHY268M. i am tempted to say that the halo is more controlled for me. i am quite surprised to see such difference honestly. I am temped to go with astronimik 6nm  honestly for Sii and Oiii. atleast for the Oiii. i think i am happy with the Ha honestly.

 

[Xiga]

2 hours ago, rsarwar said:

this is my sadr on 3.5 Ha on 72ED + QHY268M. i am tempted to say that the halo is more controlled for me. i am quite surprised to see such difference honestly. I am temped to go with astronimik 6nm  honestly for Sii and Oiii. atleast for the Oiii. i think i am happy with the Ha honestly.

 

Looks good to me 👍. I was pretty disappointed with mine tbh. Sadr is ridiculously bright though, so I've just accepted that it's hopefully not going to be a problem for me 99% of the time. 

But I also have been put off Baader now. When the time comes to upgrade the Oiii and Sii filters, I think I'm going to try Antlia next. 

[TakMan]

I sent mine back to FLO and am about to go ‘Chroma’…

There is some chatter over on CN, that may well link to Adam’s issue of the non-existent Squid… that the ultra fast OIII isn’t transmitting at the correct wavelength..?

See: https://www.cloudynights.com/topic/791682-oiii-filter-and-star-halos/

And the link to the Polish forum that ran the test that CN links to:

https://astropolis.pl/topic/68677-obiektywny-test-porównawczy-filtrów/page/11/?tab=comments#comment-923039

Damian

 

[tooth_dr]

21 minutes ago, TakMan said:

I sent mine back to FLO and am about to go ‘Chroma’…

There is some chatter over on CN, that may well link to Adam’s issue of the non-existent Squid… that the ultra fast OIII isn’t transmitting at the correct wavelength..?

See: https://www.cloudynights.com/topic/791682-oiii-filter-and-star-halos/

And the link to the Polish forum that ran the test that CN links to:

https://astropolis.pl/topic/68677-obiektywny-test-porównawczy-filtrów/page/11/?tab=comments#comment-923039

Damian

 

Thanks Damian.

I cant read the polish data, but can see the graphs.  It would be nice to know if indeed my filter wasnt performing correctly. 

[tooth_dr]

@TakMan Google Translate

 

OIII

APPLICATIONS
 filter absolutely unsuccessful due to wrong placement of the transmission band
 an exceptionally high value of the effective refractive coefficient – approx. 2.19 – causes the filter 
is extremely low susceptible to "blue shift"
 370 euros for a useless glass seems to be quite an exorbitant price

[TakMan]

Yes, same here - can’t read the Polish…! It is worth scanning through the pages though on their forum. From the odd meme and image posting, I get the feeing folks aren’t impressed. The OIII filter appears to have halos even worse than the old 8nm filter… how is that possible..!?

What with the (smaller) Ha halo, the massive OIII one and none on the SII, plus your issues and other’s postings of halos on this filter… or that…. no rhyme or reason to which filter was going to produce a halo, well, my confidence in the new CMOS filters was knocked. With not knowing where the transmission of the Ha and SII was truly centred upon, or how efficient the filters actually are, then the ‘we have found a way’ message might just as well be a load of marketing rubbish rather than an acknowledgment of better filter performance…

Although significantly cheaper than ‘the alternative’, the set of mounted 2” Baader’s was still over £900. The only good thing was that it showed me what the difference really is (with my own gear rather than just reading about it), investing in a narrower bandpass.

D

[TakMan]

Sorry, crossing wires!

D

[rsarwar]

I asked @FLO if they have some transmission plots, but I don't think they have anything extra beyond what is in the public domain (was hoping they had a secret stash of datasheets

) 

I think I am going to go with astronomik or antlia and keep the Baader ha as mine seems to have no halo issue. 

 

I still don't understand how a 6.5 and 3.5/4 nm filters have the same f-ratio rating. Controlled Halos, I can live with, but not knowing what I am buying is just not my thing. 

Edited October 20, 2021 by rsarwar

[carastro]

This is rather worrying.  I only have the Ha and Oiii so far on the ultranarrowband filters.  I got the Ha about a year or so ago and have been very pleased with it.  The Oiii wasn't available then.  More recently I purchased the Oiii UNB filter after seeing results by another imager.   I am using the 1.25 filters. 

I have only taken one image with the Oiii so far and there wasn't a particularly bright star in the image, so must do some further testing.

   

[tooth_dr]

27 minutes ago, carastro said:

This is rather worrying.  I only have the Ha and Oiii so far on the ultranarrowband filters.  I got the Ha about a year or so ago and have been very pleased with it.  The Oiii wasn't available then.  More recently I purchased the Oiii UNB filter after seeing results by another imager.   I am using the 1.25 filters. 

I have only taken one image with the Oiii so far and there wasn't a particularly bright star in the image, so must do some further testing.

   

The haloes I think were an improvement on the previous filters for my setup, but not passing any Oiii through the filter was more of an issue 

[Adam J]

You would think every filter would be tested. Especially the fast stuff with tight tolerances. 

[tooth_dr]

2 minutes ago, Adam J said:

You would think every filter would be tested. Especially the fast stuff with tight tolerances. 

I have send Baader an email about it.  If the test are to be believed then the filters may lie outside the band, but if it affects all the high speed ultra narrow filters then I'd expect more reports online about it.

 

[rsarwar]

I cannot tell the reflective index from the plot, but a blue shift of about 4 to 5 nm is correct. I think that plot looks reasonably. But this plot is not correct for a glass with reflective index of 2!! So the question is is it really 2.18?

https://www.cloudynights.com/topic/724945-narrowband-imaging-at-fast-f-ratios/

Edited October 21, 2021 by rsarwar

[tooth_dr]

Would it be possible for my Takahashi Epsilon to be causing the filter to be off band?

[rsarwar]

4 hours ago, tooth_dr said:

Would it be possible for my Takahashi Epsilon to be causing the filter to be off band?

Unlikely. More likely that the bandpass not being correctly shaped or a faulty glass. Have you tried asking for a replacement to try? 

2.18 refrective index is very hard glass, similar to artificial stones used to make jewelries. Somehow I am having hard time imagining those being used in this case. I could be wrong. 

I read in a different thread that you also own antlia 3nm. Can I ask if you tried that one with your f2. 8? 

[rsarwar]

Just had a look at the rated f stops for the high speed ones.  f/3.4 to f/1.8. 

The blue shift will range from 1.5 (f3.4) nm to 4(f1.8) nm. That is very difficult to do, and unless the bandpass have a flat-top, which it is not based on the polish data. I don't expect it to work efficiently. Eg. If the filter has a max performance at f2.5, by the time it reaches f2.8, transmission will be reduced 60-70 pc and <50 pc by the time it reaches f3.4.

 

This is what I am worried about. Baader is being unprofessionally liberal with their specsheet. Which is why they labeled their standard speed 3.5 nm filters as to having the same f stop rating as 6.5nm. I think they are taking a 50 or 60 pc transmission as an acceptable range

Edited October 21, 2021 by rsarwar

[tooth_dr]

3 hours ago, rsarwar said:

Unlikely. More likely that the bandpass not being correctly shaped or a faulty glass. Have you tried asking for a replacement to try? 

2.18 refrective index is very hard glass, similar to artificial stones used to make jewelries. Somehow I am having hard time imagining those being used in this case. I could be wrong. 

I read in a different thread that you also own antlia 3nm. Can I ask if you tried that one with your f2. 8? 

I was offered a replacement but I’ve already returned it and TBH don’t want to waste any more time on it, losing 20 hours moon-free imaging time was annoying enough.

I don’t have any other filters, and I don’t have an antila filter.  I had previously used an Optolong 6.5nm Oiii filter on the same scope and it worked ok, but I’ve since sold it.

[tooth_dr]

@rsarwar I’ve exchanged them for the slower ones to use on an F4.8 scope, do you reckon they will be ok?

[rsarwar]

4 hours ago, tooth_dr said:

@rsarwar I’ve exchanged them for the slower ones to use on an F4.8 scope, do you reckon they will be ok?

I only have the standard 3.5 nm Ha from Baadar. only used it with F5.8 and it works as expected. waiting for the current project about california nebula to finish before i try it on the F5. but i think F5/F4.8 should be dead easy for any filters with 3.5-4 nm passband given that the bandshift would be slightly less than 1 nm. Ideally, if you know what your blue-shift is, you cat get a filter with a bandpass twice that,  and you should not have any issue with f-stops. That is why 12 nm astronomiks are rated to f1.8 (although i think astronimik OIII 12 nm is still F2.8(see screenshot) as their oiii passband does not have a flat top). Having said that, it is still possible to design a 3 nm filter to incorporate a 2-3 nm worth of blue shift with some clever pre-shifting techniques which is what Baader claims to be doing, 

Oiii @ f3

Ha @ f2

I ordered the astronomik 6 nm Oiii - i think that is the right choice as I am planning to get a SharpStar 94 (f4.4) sometime before xmas. currently deciding if i should get the antila sii or just go with 6nm astronimik. 

Edited October 21, 2021 by rsarwar

[tooth_dr]

1 hour ago, rsarwar said:

I only have the standard 3.5 nm Ha from Baadar. only used it with F5.8 and it works as expected. waiting for the current project about california nebula to finish before i try it on the F5. but i think F5/F4.8 should be dead easy for any filters with 3.5-4 nm passband given that the bandshift would be slightly less than 1 nm. Ideally, if you know what your blue-shift is, you cat get a filter with a bandpass twice that,  and you should not have any issue with f-stops. That is why 12 nm astronomiks are rated to f1.8 (although i think astronimik OIII 12 nm is still F2.8(see screenshot) as their oiii passband does not have a flat top). Having said that, it is still possible to design a 3 nm filter to incorporate a 2-3 nm worth of blue shift with some clever pre-shifting techniques which is what Baader claims to be doing, 

Oiii @ f3

Ha @ f2

I ordered the astronomik 6 nm Oiii - i think that is the right choice as I am planning to get a SharpStar 94 (f4.4) sometime before xmas. currently deciding if i should get the antila sii or just go with 6nm astronimik. 

Baader did offer to send me a filter specifically for my F2.8 scope as a replacement.

I briefly had a Sharpstar 94 with the 0.8x focal reducer.

 

[tooth_dr]

I got my new ultra narrowband filters for slower scopes, hoping to have more success with these ones!  This is the third set of filters I've received, and consistent with the previous two sets, the packaging is partly missing in 2 out of the 3 filter boxes.  Does it matter - not really, but the filters arent held securely during storage/shipping, and slightly disappointing QC.  In the photo below, there is no padding above the Oiii or Sii filters.