A poor workman blames ...........

[steppenwolf]

I have been imaging a series of dim Sharpless objects recently and have really struggled to obtain the OIII data that I require to complete bicolour versions. There has been plentiful Ha (as usual) but even my 30 minute exposures have struggled to collect sufficient clean OIII data, so much so that I have decided to keep my current project (SH2-115) as a mono Ha image! I started to suspect (for a second time) that my Astrodon 3Nm OIII filter was failing so decided to get a reality check on how it was performing. SH2-105 (The Crescent Nebula) is rich in OIII so this made for a good test subject to find out if the filter had gone faulty or not.

The data I captured has settled the argument for me - sorry Mr. Filter, I never should have doubted you!

[tomato]

Yes, there are faint nebulae wavelengths and then there are really faint nebulae wavelengths, not the easiest of targets to image from the UK.

[toxic]

it looks like you have loads of OIII in that image  its very nice indeed

 

[steppenwolf]

7 minutes ago, toxic said:

it looks like you have loads of OIII in that image  its very nice indeed

Thank you, Chris - yes indeed, there is plenty there so at least I know the filter is working fine! Confirmation that this is proper OIII data is provided by the extended section at top left which is categorically OIII based from previous images of this lovely object.

[toxic]

the OIII looks like its enveloping the whole object even in the mono version cant wait to see it in colour if thats what the mono looks like

 

[steppenwolf]

14 hours ago, toxic said:

the OIII looks like its enveloping the whole object even in the mono version cant wait to see it in colour if thats what the mono looks like

The colour version is underway, Chris although I had a camera fault last night which lost me a couple of hours of subs!

[Adreneline]

On 23/09/2020 at 13:11, steppenwolf said:

I started to suspect (for a second time) that my Astrodon 3Nm OIII filter was failing

I am somewhat intrigued by this statement.

What mechanism would cause a filter to fail?

Do they have a 'working life'?

Is this something we should all be looking out for?

Adrian

[steppenwolf]

1 hour ago, Adreneline said:

I am somewhat intrigued by this statement.

What mechanism would cause a filter to fail?

Do they have a 'working life'?

Is this something we should all be looking out for?

Adrian

Not normally a problem, Adrian but I noted when I bought them that they had a '5-year limited warranty against delamination' which I guess means that these kinds of coatings can delaminate but this would apply to any filter with this type of coating. I haven't heard of anyone having this problem but I do like to be a pathfinder ........🤣

[toxic]

3 hours ago, steppenwolf said:

The colour version is underway, Chris although I had a camera fault last night which lost me a couple of hours of subs!

ouch i hope its all ok now Steve never heard of that filter problem before ,but plenty of others like filter wheel no connecting - camera window freezing up - scope not seeing anything but that's just my stupidity without me the gear is fine lol.

[steppenwolf]

1 minute ago, toxic said:

ouch i hope its all ok now Steve never heard of that filter problem before ,but plenty of others like filter wheel no connecting - camera window freezing up - scope not seeing anything but that's just my stupidity without me the gear is fine lol.

I don't know what stopped it from working but it was well on its way to taking an infinitely long exposure - the only thing that stopped that happening was the cloud that came in after a couple of hours!!! Examining the CCD Commander logged revealed that the close-down sequence had halted two steps from the end as the camera was still trying to warm up to its first warm-up point of -10 degrees so it looks like the connection to the camera was lost. Reconnecting the camera remotely worked perfectly so I guess there was just a minor 'glitch in the Matrix' 😎 To be sure, I spent an enjoyable 10 minutes in the dome today disconnecting and then reconnecting every USB and power cable in there as potential preventative maintenance.

[peter shah]

Yeah....nothing wrong with that.....so much detail and the contrast is stunning

[toxic]

36 minutes ago, steppenwolf said:

I don't know what stopped it from working but it was well on its way to taking an infinitely long exposure - the only thing that stopped that happening was the cloud that came in after a couple of hours!!! Examining the CCD Commander logged revealed that the close-down sequence had halted two steps from the end as the camera was still trying to warm up to its first warm-up point of -10 degrees so it looks like the connection to the camera was lost. Reconnecting the camera remotely worked perfectly so I guess there was just a minor 'glitch in the Matrix' 😎 To be sure, I spent an enjoyable 10 minutes in the dome today disconnecting and then reconnecting every USB and power cable in there as potential preventative maintenance.

its not an atik 383l+ mono is it i have found that any kind of power fluctuations to my 383l+ tends to make it do very strange things so now it has its very own psu and it seems to behave now.

[steppenwolf]

18 hours ago, toxic said:

its not an atik 383l+ mono is it i have found that any kind of power fluctuations to my 383l+ tends to make it do very strange things so now it has its very own psu and it seems to behave now.

The same sensor but in a QSI 683 WSG-8, Chris and it already has its own PSU. As I have two telescopes, each with their own imaging systems in the dome, I have a remote switching unit to select the system I want to use but I have taken that out of the equation as well as. to be honest, I never use it preferring instead to manually 'prepare' the telescope when I do switch over which is rarely!

[steppenwolf]

19 hours ago, peter shah said:

Yeah....nothing wrong with that.....so much detail and the contrast is stunning

Thanks, Peter

[Uranium235]

Great capture Steve

The QSI683 Im using also throws the occasional wobbler, usually in the form of the dreaded windows 7 "ding dong" to tell me the camera has disconnected itself. The only way to bring it back online is to disconnect/reconnect both the power and USB cables, then wait for the two beeps before reconnecting via maxim.

[Davey-T]

46 minutes ago, Uranium235 said:

Great capture Steve

The QSI683 Im using also throws the occasional wobbler, usually in the form of the dreaded windows 7 "ding dong" to tell me the camera has disconnected itself. The only way to bring it back online is to disconnect/reconnect both the power and USB cables, then wait for the two beeps before reconnecting via maxim.

Had similar problem with one of mine and think I traced it to the power connector, doesn't seem to be a very good fit, I presume its a standard 2.1 pin but only had to breath on mine and it disconnected, squirted some contact cleaner on it and now use it with power cable wrapped around USB cable to keep some sideways tension on it, hasn't disconnected since then but may just be a coincidence, lost a couple of hours subs one night when it first did it.

Dave

[Uranium235]

1 minute ago, Davey-T said:

Had similar problem with one of mine and think I traced it to the power connector, doesn't seem to be a very good fit, I presume its a standard 2.1 pin but only had to breath on mine and it disconnected, squirted some contact cleaner on it and now use it with power cable wrapped around USB cable to keep some sideways tension on it, hasn't disconnected since then but may just be a coincidence, lost a couple of hours subs one night when it first did it.

Dave

Yep, if I velcro all the cables up and dont look at it or breathe on it - its usually ok   Maybe some nice right-angle connectors would help there (looks better too!).

[Adam J]

Would love to know what mechanism you imagined might cause filter deterioration? 

[wimvb]

59 minutes ago, Adam J said:

Would love to know what mechanism you imagined might cause filter deterioration? 

 

On 24/09/2020 at 15:37, steppenwolf said:

Not normally a problem, Adrian but I noted when I bought them that they had a '5-year limited warranty against delamination' which I guess means that these kinds of coatings can delaminate but this would apply to any filter with this type of coating. I haven't heard of anyone having this problem but I do like to be a pathfinder ........🤣

In the days before so called ion assisted deposition, filters were made by evaporating metal oxides onto the glass substrates. This produced films that had a lower density than bulk material. In other words, composition wasn't always accurate and films consisted of grains. In time, water vapour could creep inbetween these gains and cause the films to deteriorate and possibly peel off. Also, to make evaporated films stick to the substrate in the first place, it was absolutely vital to clean the glass substrate thoroughly.

Nowadays, the glass substrate is bombarded by ions while the oxides are deposited. This helps pack the individual atoms, creating denser films, without grains. So there is no way water vapour can penetrate the films. Also, the ion beam is turned on before the deposition starts, and knocks any contamination off the substrate, which makes it easier for the films to bond with the substrate.

Unless something goes wrong during production (especially in the glass cleaning stage before deposition), modern filters should never fail.

@steppenwolf: great image, btw. I also am eager to see the colour version.

Edited September 26, 2020 by wimvb

[PaulB]

Excellent work. I like the contrast and detail in the nebulosity.

 

[gorann]

On 24/09/2020 at 16:17, steppenwolf said:

I don't know what stopped it from working but it was well on its way to taking an infinitely long exposure - the only thing that stopped that happening was the cloud that came in after a couple of hours!!! Examining the CCD Commander logged revealed that the close-down sequence had halted two steps from the end as the camera was still trying to warm up to its first warm-up point of -10 degrees so it looks like the connection to the camera was lost. Reconnecting the camera remotely worked perfectly so I guess there was just a minor 'glitch in the Matrix' 😎 To be sure, I spent an enjoyable 10 minutes in the dome today disconnecting and then reconnecting every USB and power cable in there as potential preventative maintenance.

This reminds me that we are told to warm up CCD cameras slowly after a session, but I have never seen that this should be done to CMOS cameras. I always just turn off my ZWO cameras and ZWO has no routine for slow warm up. Why is it that CCD and not CMOS needs a slow warm up? Or am I misstreating my ZWO cameras?

 

Great image by the way!

Edited September 26, 2020 by gorann

[steppenwolf]

15 hours ago, Adam J said:

Would love to know what mechanism you imagined might cause filter deterioration? 

Ageing?

[Hallingskies]

Glad to see I’m not the only one doubting my equipment (or my sanity!).  I have been having exactly the same crisis of confidence in my OIII filter just lately, and went for the Western Veil nebula as a test.  Needless to say, the OIII-screened photons rattled down the tube and on to the camera, no problem.

I think that there has been a lot of high haze of late, despite the clear-looking skies.  It happens every early autumn, and yet still I have the same old doubts...

[Adam J]

1 hour ago, steppenwolf said:

Ageing?

Nope not with sputter deposition. It's hard to even imagine it delaminating without physical damage to the edge. 

[steppenwolf]

34 minutes ago, Adam J said:

Nope not with sputter deposition. It's hard to even imagine it delaminating without physical damage to the edge. 

Here's an official quote from a UK supplier - not me making it up 🤣  (I have emboldened and coloured the bullet point in question):-

GENERAL SPECIFICATIONS OF ASTRODON NARROWBAND FILTERS:

• 1.25" mounted, mounted in 31 mm rings (for QSI), 36 mm unmounted, 49.7 mm diameter and square unmounted (36 mm filters will not exceed 36.1 mm dia.)
• 3 +/- 0.025 mm thick (5 nm);  3+/-0.05 mm thick (3 nm) substrate prior to coating
• Parfocal with all other Astrodon filters (depending upon telescope optics)
• Peak transmittance guaranteed >90% at the emission line (97-98%T typical) f/10 to f/3.5 for both 3 nm and 5 nm
• >90%T at the emission wavelengths for 5 nm OIII and H-a at f/3. >80%T for SII at f/3
• >90%T for 3 nm OIII at f/3
• Steep spectral profile minimizes halos around bright stars
• >4 OD (out of band blocking)  300 - 1150 nm
• Single, striae-free 1/4 wave fused silica substrate
• 30 arcsecond parallelism
• Durable hard-oxide sputtered coatings with a 5-year limited warranty against delamination
• All filters are coated to the edge and edge-blackened to minimize stray light contamination that can come though the uncoated "rim" in other brands