Wednesday, 15 November 2017

Hypercam 183c - Big Steps Forwards

Hypercam 183c - Big Steps Forwards

In my last post, I showed the results of my early attempts at DSO photography with my new Hypercam.  I think it's fair to say that the images showed the potential of the camera, but results were somewhat spoilt by this halo phenomena that was appearing around the centre of the image, and in some cases, at several points around the image perimeter.  That post sewed the seeds of a new plan of tests as a result of questions asked on a couple of forums and some emails to a few people.
I needed to keep as much as possible the same in the whole process, changing only one thing at a time.  One of the strongest suggestions was to look at omitting the Focal Reducer from the light train, so, with conditions looking favourable last Sunday, I set up all my equipment, got everything polar aligned and then fitted the camera without the FR.
May targets for the evening needed to be the same as the previous attempt, so, C19, M45 and M27.  Exposure, gain and all the other settings were kept the same.  After taking a few test light frames, I took a copy of them and put them into pixinsight to stretch the image data.  If the halo phenomena was going to be present, I would see it in this first stretch of the data.  To my surprise, and relief, I saw no sign of the halo.  I wanted to take advantage of the forecasted clear night, so I set about taking the first image run of the dumbbell nebula, after which I took the dark and bias frames too.
Still with no sign of any anomalies, I moved onto the next targets and concentrated on collecting data.  I stayed with the same settings as I wanted to prove that this first image run wasn't a fluke.  After the first 3 image runs, I decided to take one last run on a new target, M76.
There wasn't much more to the night to be honest.  Data collecting and generally keeping an eye on things.  I decided to take my flat frames the following afternoon, so I took the scope off the mount at the end of the evening, but left everything attached together.

Post data collection.

Over the coming days, whilst the clouds were preventing me from collecting any more photons, I started the prolonged task of beginning the process the data.  It soon became apparent that the simple step of omitting the FR was yielding some good results.  My first stacked and processed image was the dumbbell nebula, and I was pleased to see that there was no sign of the halo anomaly.  

Clearly no blue halo there!  I moved on to processing the data for my second image.  That was M45, which, if you see my previous post, had all sorts going on in it with light circles appearing all over the place.  This was going to be a big test of the new configuration of light train.  But I need not be concerned...

I am really pleased with this image.  The amount of colour and nebulousness that comes through from the 183c's sensor is so much more than I was ever getting with my DSLR.  I posted this image on my Twitter feed, and the number of likes and re-tweets it has got has blown me away.  I've never had so many for anything!
The next image that was processed was the final repeat from the previous session, C19.  My previous attempt at this target actually produced quite a respectable image, considering that it was the first go at photographing it.  However, it did still produce the halo effect which I managed to process out.  For this attempt, again, I kept the parameters the same in terms of data collection.  I went on and processed the new data stack and was pleased to see that again there was no sign of any halo anomaly.

My last set of data collected that night, and the final set of data that I processed from this imaging run was for M76,  A new target for not only the Hypercam, but for me also.  After one hour of collecting data, and then applying all the calibration frames, I was left with this result.  I'm quite pleased with this.  Plenty of colour and definition, although there is still room for improvement!

To get this frames correctly, I have cropped and enlarged the image slightly.  It's made the focus appear a little out, but I was happy to sacrifice that if only to be able to see the nebula a little more clearly.


Since collecting and processing this data, I have taken delivery of a new UV/IR filter which I want to introduce into the light train.  I'll add it to the focal reducer first, and see if I can image clearly with the FR and the filter in place.  If not, I will persist with the filter.  So, now I'm on the look out for some new targets to go for at the next opportunity.  I want to start taking slightly longer exposures and collecting more data on each target, so I will choose the next target wisely.  I'll be sure to post more results.  Thanks for reading!  🌙🌟

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