Richard, in regard to the spectrum response, Ha is down there are well and I have plenty of Ha, Sii is not much further along. However, when I look at the spectrum chart on the ZWO website I can see that it is less responsive in that part. https://astronomy-imaging-camera.com...si1600mm-cool/
But since Ha is so good, unless the cover glass is a cut filter that is affecting Sii spectrum, then I am sure it is just something stupid I have done along the way. I have just been playing around stretching a single Sii sub and it has more signal than my stack of Sii appeared to have. Even on the SGP display I could see signal on individual Sii frames. I need to go back through what I did in DSS with that stack.
Uodate: looking back at my Trifud SII data it was pretty skinny as well when shot on equivalent integration times to Ha and Oiii. I will test tonight on M16 again running just Sii to build up more signal. Is there a 'standard ratio'?
Below is an example of signal strength of SII. The first shows them at their relative strengths to one another. The SII is a LOT dimmer than the Ha. The second shows SII under a normal stretch just to give a bit of an idea of how much it does get stretched.
The main thing to note that is of importance to you Glen is that more data does not change the relative signal strength. If you were to put another 10 hours into SII it would not make it brighter against the Ha, only make it smoother and less noisy.
Thanks Colin, that's pretty much what i see, in the first pics. I was going to run some more tonight, based on Ray's comments. I already have 25 minutes of Sii, but could easily double it and see how it improves. The Signal is already pretty low noise and smooth so maybe it won't improve much but i will build it up abit.
Thanks Colin, that's pretty much what i see, in the first pics. I was going to run some more tonight, based on Ray's comments. I already have 25 minutes of Sii, but could easily double it and see how it improves. The Signal is already pretty low noise and smooth so maybe it won't improve much but i will build it up abit.
just ran the model - guessing what gear you have, 5 minutes of narrowband should get you to the vicinity of sky-limited in average dark conditions. You will not have to stretch the data so much, but watch out for star saturation maybe.
There absolutely is a QE difference between mono and colour. A large one.
The Bayer matrix is RGGB so every pixel has a coloured filter over it. The coloured filters between manufacturers have different transmission rates and the trend has been to increase the transmission rates to improve high ISO performance in digital cameras.
But using a KAF or KAI chip as an example (as they have published figures) say the KAF8300, the mono has a QE of around 56-60% (60% is the no cover slip version) and the colour is probably more like 25-35%.
So yes typically double or more QE than the OSC. Having used both a mono 11002 sensor and the colour version of it I can attest to this large difference in QE in actual use.
Lee i am reprocessing now to produce FITS output files ( I had used TIFF as it was going to Photoshop).
Astrobin has a file sharing space that i can use. I will have a look. I would prefer to share the files as they came out of DSS and before i've had a chance to bugger them up, that way you get the real camera output.
Ah, sorry Glen, TIFF would have been fine. I was basically wanting the stacked, calibrated but linear images for SII, Ha and OIII.
In other news, apparently my camera has arrived at the post locker today, in Brisbane. Unfortunately I'm working from home so I can't pick it up until tomorrow... still, that was fast.
Ah, sorry Glen, TIFF would have been fine. I was basically wanting the stacked, calibrated but linear images for SII, Ha and OIII.
In other news, apparently my camera has arrived at the post locker today, in Brisbane. Unfortunately I'm working from home so I can't pick it up until tomorrow... still, that was fast.
Glad to hear your camera has arrived Lee.
Re the files, I have uploaded FIT files to Astrobin in the shared folder area; however, it seems I can't just post a link here, you have to be an Astrobin user so I can 'invite' you to the location. Do you have an Astrobin user id?
BTW, Astrobin does not seem to acept TIFF anyway, as I found out after I tried to upload the TIFF reg files as well.
You will be prompted for your user id before allowed to it but it should work if it allows you through. Not sure it this applies to folks that are just using the free facilities of Astrobin.
Make sure you read the note attached to the folder when you open it, as the subs are registered to produce these stacked output files, but the output files are not registered against each other at this stage. You would need to register the three against each other before further processing.
I looked at Dropbox but I don't want to add another monthly cost to my budget.
Re the files, I have uploaded FIT files to Astrobin in the shared folder area; however, it seems I can't just post a link here, you have to be an Astrobin user so I can 'invite' you to the location. Do you have an Astrobin user id?
BTW, Astrobin does not seem to acept TIFF anyway, as I found out after I tried to upload the TIFF reg files as well.
I looked at Dropbox but I don't want to add another monthly cost to my budget.
Thanks for going to all this effort, Glen. I'm surprised Astrobin doesn't support TIFFs for that. My username is leemr on Astrobin.
In trying to get a handle on Sii sensitivity of the ASI1600, I had a look at the spectrum response chart and it would seem that, given Ha is right next to Sii on the spectrum (like within about 20nm) it should be able to pick up Sii just as well as it does Ha (which it does very well). So I turned to trying to find out if the AR cover glass has some sort of IR Cut configuration, that might be blocking Sii.
I asked Sam on the ASi1600 Product Q&A page on their website for some idea of the spectrum bandpass of the AR window. He has replied there and posted a spectrum for the window.
Link to the Q&A page is here, https://astronomy-imaging-camera.com...si1600mm-cool/
and his response to the AR window question is down at the bottom (8 June).
So it seems there is no reason that the camera cannot pick up Sii at levels like that of Ha - provide the Sii is there to be picked up, or that you expose for long enough to gather enough Sii to bring it up out of the noise. I would have thought that my 23 minutes of subs was allowing adequate time.
Anyone want to nominate a 'hot' Sii target that I can use for testing?
Thanks for going to all this effort, Glen. I'm surprised Astrobin doesn't support TIFFs for that. My username is leemr on Astrobin.
I will investigate further Lee, it maybe due to the fact that the TIFF files had a .req tag on the end and thus it did not recognise it. Perhaps if I renamed it, I will see.
I think, with Lee's help, we have found the problem with Sii data acquisition in the M16 image. I picked the 19 Sii subs with the highest score and stacked them in DSS WITHOUT any Master Dark or Master Bias, just Subs alone. When I look at the resulting stack file, there is the signal! Plenty of Sii data there, even in 19 x 60" subs. I stretched it abit in Photoshop and I think I could just plug it into the image now. I believe the DSS dark calibration is scrubbing out the Sii data because it is so close to the floor, or the expected noise. So DSS is definitely doing something I don't want it to do. I might rerun the processing for all my data on M16 without dark calibration and see what I get.
Any DSS experts out there have any idea why inclusion of master darks and master bias in the processing would scrub out my data?
I am posting here a small example of the 19 x 60" Sii sub data, and the larger version on Astrobin.
I think, with Lee's help, we have found the problem with Sii data acquisition in the M16 image. I picked the 19 Sii subs with the highest score and stacked them in DSS WITHOUT any Master Dark or Master Bias, just Subs alone. When I look at the resulting stack file, there is the signal! Plenty of Sii data there, even in 19 x 60" subs. I stretched it abit in Photoshop and I think I could just plug it into the image now. I believe the DSS dark calibration is scrubbing out the Sii data because it is so close to the floor, or the expected noise. So DSS is definitely doing something I don't want it to do. I might rerun the processing for all my data on M16 without dark calibration and see what I get.
Any DSS experts out there have any idea why inclusion of master darks and master bias in the processing would scrub out my data?
I am posting here a small example of the 19 x 60" Sii sub data, and the larger version on Astrobin.
not sure Glen but I am intrigued as to why it has colour (blue), perhaps there could be an issue in your settings relating to that (rather than greyscale)?
not sure Glen but I am intrigued as to why it has colour (blue), perhaps there could be an issue in your settings relating to that (rather than greyscale)?
It is blue because I colorised it blue, which is what I would do with Sii data in layering for false natural colouring - its just there as an example. It was originally grey scale when I opened it.
I have added the Sii layer to the M16 image on Astrobin and removed the old bi-colour image. Apologies for the slight misalignment on the stars, which result in not quite round shapes, I forgot to reregister the main files. Might fix that up in time but I suspect it would require going back to DSS and reprocessing.
I realised I'm probably going to need to use the flattener for my Esprit now that I'll be imaging with such a big chip. Looks like I'll need a couple of adapters from precise parts to hook it all up... about $432 to land them here Didn't factor that in.
I realised I'm probably going to need to use the flattener for my Esprit now that I'll be imaging with such a big chip. Looks like I'll need a couple of adapters from precise parts to hook it all up... about $432 to land them here Didn't factor that in.
Puzzled...your Esprit flattener will output M48 male...you should just need M48 female to M42 or whatever your filter wheel uses, and any appropriate spacers. Can't imagine it's any different for any other CCD
Puzzled...your Esprit flattener will output M48 male...you should just need M48 female to M42 or whatever your filter wheel uses, and any appropriate spacers. Can't imagine it's any different for any other CCD
I believe the flattener is M66 on the scope side and M62 on the camera side. I need it to sit between a Celestron OAG, and an Orion Nautilus EFW, and I understand spacing of flatteners to be critical (never needed one before, so I don't know how critical).
Puzzled...your Esprit flattener will output M48 male...you should just need M48 female to M42 or whatever your filter wheel uses, and any appropriate spacers. Can't imagine it's any different for any other CCD
Its all about getting the correct spacing between the flattener and CCD chip. A real PITA sometimes as everything has tolerances that add up!
I believe the flattener is M66 on the scope side and M62 on the camera side. I need it to sit between a Celestron OAG, and an Orion Nautilus EFW, and I understand spacing of flatteners to be critical (never needed one before, so I don't know how critical).
Some are not too critical, I believe that straight flatteners are more forgiving than a flattener & reducer. My last setup was maybe 1.5mm off and it was noticeable.
Didn't factor that in.
