|
Post by BillW on Nov 29, 2014 20:28:29 GMT
Hi, I've been scanning some old observations by the late Henry Soper of the Isle of Man. (I put some initial scans in other thread) I thought it would take a couple of weekends but that has proven wildly over optimistic, still only about 1/3 through and that's not doing them all! Sadly many of the images are essentially empty, that's just the way it went with old fashioned emulsion photography.... However I have found a couple of interesting shots. It is remarkable what modern toys can achieve. Giving one of the images a modern work over has yielded a nice spectrum. There are a few coded reference numbers but I have no idea what these mean so there is no date/time information. Hopefully there will be a few more buried treasures. Cheers, Bill.
|
|
|
Post by BillW on Nov 29, 2014 20:59:19 GMT
As a PS, what is noticable is the greater effective blue sensitivity of emulsion against silicon chip detectors. The emulsion spectrum cuts off rapidly in the red which itself shows the much great sensitivty of silicon over emulsion here. Both chemistry and physics in action. Also the line wavelengths are an educated guess....
|
|
arp
Full Member
Posts: 96
|
Post by arp on Dec 2, 2014 14:02:54 GMT
Hi Bill,
This is great!
I'm so pleased that some of Henry's original negatives have survived and that the latest digital techniques can be used to reprocess them.
Have a look at the two papers by Henry and Harold Ridley JBAA 1994 February, Vol. 104, No.1.
They explain the cameras and film emulsions used by Henry, his coding system for his exposure runs and a detailed analysis of a spectrum.
Cheers,
Alex.
|
|
|
Post by BillW on Dec 2, 2014 19:51:32 GMT
Hi, Yes, I've got a copy of those somewhere.They discuss the extremely bright fireabll that was also the example in Neil Bones' book. Unfortunately that's the one and it's copies that are missing from the files. I'll dig them out and see if I can decode anything. cheers, Bill.
|
|
arp
Full Member
Posts: 96
|
Post by arp on Dec 2, 2014 22:33:46 GMT
Hi Bill,
Just had another look at Henry's paper in the JBAA.
He used a reference system such as film number "ASC803/20" for his all-sky camera system and "SP30/10" for his spectrographic camera.
Unless his reference log book can be located there's unfortunately not much chance of confirming the dates and times of these spectra.
Good luck with this work,
Alex.
|
|
|
Post by BillW on Dec 4, 2014 11:38:38 GMT
Hi, Yep, that's what I thought. It's exactly what is written on the edge of the negative sheets. According to Dave the other material has all been lost. So it's just a token gesture to preserve some of the images in digital format for posterity. Because I did some medium format imaging myself it's just lucky I've got the right kit to scan the material. I was close to binning the scanner as I didn't think I'd ever use it again! Cheers, Bill.
|
|
|
Post by stewartw on Dec 6, 2014 15:16:02 GMT
I've had a look through the BAA Circulars to see if there are any additional clues in there - searched for "Soper", "Ridley", "Meteor", "Spectra" and "Spectrum" but alas nothing relevant turned up.
|
|