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1 hour ago, Shibby said:

It really should be red - the Hα wavelength is bang in the middle of the red part of the spectrum. It's weird that the light passing through looks magenta; I'll have to try that! It shouldn't look magenta unless some violet is leaking through, but that's at the opposite end of the spectrum.

Normally, with a modified DSLR or CCD the blues are overpowered by the strong Hα reds. That's why I think there are some really nice, colourful images like this one from unmodified DSLRs.

Interesting point, which made me look up a few things. It's true that Ha does lie in the middle of the reds but what may also matter is that, by this part of the spectrum, the eye's sensitivity is dropping off dramatically so, in terms of light to which we're usefully sensitive, Ha is well to right here:

http://www.npl.co.uk/publications/good-practice-online-modules/optical-radiation-safety/the-human-eye-and-light/the-eyes-response-to-colour/

Presumably that's why DSLRs are blocked just to the left of 652 nm. (A guess. I don't know.)

Olly

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The Rosette Nebula and Cluster ( NGC 2237 and 2244 ) in the constellation Monoceros edit:  updated 30th Dec with improved colour balance and slightly increased brightness ...   ..

It really should be red - the Hα wavelength is bang in the middle of the red part of the spectrum. It's weird that the light passing through looks magenta; I'll have to try that! It shouldn't look mag

No not really - the combination is performed using masks.  Only the saturated parts of the image are replaced with the unsaturated portions from the less exposed images.

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On 25/01/2018 at 23:43, Datalord said:

Yeah, it's super funky. And I haven't found a good tool to just "debayer this one file and make a tif". If I REALLY want to see that single file, I asked DSS to stack it (WITH THE RIGHT DEBAYER SETTINGS!!!)...  :-|  

Mmm, still a problem with understanding the file I think.  No matter what I do the noise in the 300s file ( at -15 deg C ) is way more than in one of my D5300 subs ( with air temp 20 deg C).  But this does not make sense to me.  I suspect I am still not comparing apples with apples ( or red channel with red channel  in my case ).  I will have read up some more about how to process a FIT image so as to make Pixinsight recognise it as a CFA image.

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On 25/01/2018 at 23:43, Datalord said:

Yeah, it's super funky. And I haven't found a good tool to just "debayer this one file and make a tif". If I REALLY want to see that single file, I asked DSS to stack it (WITH THE RIGHT DEBAYER SETTINGS!!!)...  :-|  

Still having difficulty understaning the FIT image, although I think I may have found a possible answer to one of my points of confusion related to the size of the image...

The specifications state that the sensor dimensions are 6024 x 4024  but your images are 6088 x 3992.  Apparently, this is a known "image shift issue" that has been solved by QHYCCD; please see posts below:

https://www.cloudynights.com/topic/565331-first-viable-light-with-my-new-qhy247c-coldmos-camera/

5E3A4A28-888E-4E2D-B1C8-C3CD1DFD4D72.jpeg.870ce8d0a96c0d0a724b7552e53978d2.jpeg

2DAD8321-DD77-4D4E-BD6B-FBC18F0EEE0A.jpeg.eb9a1b085f7595f34ab31a2b338cf1fa.jpeg

Cheers

Mike

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On 1/30/2018 at 04:39, MikeODay said:

Still having difficulty understaning the FIT image, although I think I may have found a possible answer to one of my points of confusion related to the size of the image...

The specifications state that the sensor dimensions are 6024 x 4024  but your images are 6088 x 3992.  Apparently, this is a known "image shift issue" that has been solved by QHYCCD; please see posts below:

https://www.cloudynights.com/topic/565331-first-viable-light-with-my-new-qhy247c-coldmos-camera/

5E3A4A28-888E-4E2D-B1C8-C3CD1DFD4D72.jpeg.870ce8d0a96c0d0a724b7552e53978d2.jpeg

2DAD8321-DD77-4D4E-BD6B-FBC18F0EEE0A.jpeg.eb9a1b085f7595f34ab31a2b338cf1fa.jpeg

Cheers

Mike

Wow, this explains the weirdness in the border of my images that I couldn't figure out. Thank you!

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