Know Your Digital Camera Sensor
Paul Malley • 20 December 2022
The advances in Sensor technology, coupled to the vast internal micro-processor image library means that good jpeg images are frequently obtained with minimum extra Photographer's input. However, as Photographers, we try to get the best possible image, and this starts by optimising the image taking stage in the camera. My camera offers raw at a 14bit file, giving a maximum of 16.383 tones on a 30.2Mp Sensor; however, as the Sensor histogram is split into 5 equal vertical columns (see images above), these 16,383 tones ARE NOT split equally amongst them all (i.e. they do not encompass 3,277 tones in each of the 5 columns).
STICK WITH ME HERE...
Instead, the right-most fifth (the highlights) accounts for 8,192 different captured tones (that's half of the total in just one column). Moving towards the left, the next fifth represents 4,096, followed by 2,048 levels,1042 levels, and, in the left most Section where the deepest shadows reside, only 512 different tones are captured. When processing my raw files, there are only 512 tones to recover in the shadows (compared to the whopping 8,192 in the highlights), which is why boosting / amplifying them as you raise the ISO increases noise.
HOPE YOUR'E STILL AWAKE...
Rather than accept the standard metered exposure in raw, I add exposure (as shown in the metered 2 and 3 image) - as long as the highlights are not pushed off the edge of the histogram (a term known as 'clipping'). This allows me to use my raw convertor program (either Canon DPP, or the Adobe raw) to bring back the surplus of tones in the highlights, without detriment to having to increase the shadows and potentially introduce noise. It has to be said, that when using this method, my initial raw files look over-exposed, but careful monitoring of the histogram and exposing to the right without highlight clipping ensures a full capture of the tones, with confidence that the shadows are not blocked or introducing noise in post manipulation. The distribution curve of the histogram allows full recovery of the highlights, as they are not 'burnt-out'. The more I work with my histogram, the more useful I find it. This feature is one of a number of useful histogram functions, alongside Bayer Array testing, Colour Balance (RGB) monitoring and use of exposure compensation. It is noticeable in manual mode where, as the Photographer I control the inputs, especially, where subjects permit, turning auto-ISO off.
Louth Photographic Society

The planned event for the evening was to have been a showing of the N&EMPF Exhibition prints, but unfortunately the link for the prints was not available. Instead Harry, and I had both prepared a talk on our respective camera systems. Many regular readers of my musings will know that I had lost my photographic “mojo” earlier on in the year, I was reassessing my photographic style, and camera equipment to recover my enthusiasm, so it was that I sold all of my OM Systems cameras, and lenses, and unknown to most in the club bought a Canon EOS R7 APS-C camera, and 4 lenses as a complete kit. Learning a new camera system has made me reconnect with photography, and begin enjoying my hobby again. In the first half of the meeting last night I talked about my journey, my camera system, and showed some of the images taken with my new outfit. After the break Harry showed some of his excellent, and inspiring macro fungi images, taken with his Canon EOS R6, and a Sigma macro lens. It was an interesting evening, and hopefully everyone enjoyed the evening, and learned something about Canon mirrorless cameras.

Good Morning All The Autumn colours at Sedbergh was one of my entries which sum up the time of year. Last week at the club we held our monthly print competition, with the categories of "Mono" and "Open". There was a very good entry with 27 prints in each subject, well done to Derek Smith for a first in the Mono and Robin Begley for a first in the Open, all the results are on our website. This week, Wednesday 28th October, all being well, I am informed that the N&EMPF Exhibition print show was a bit behind schedule, it will hopefully be finished by now but if not, Derek will let us know, and we will do mini lectures instead. Derek, and Harry have prepared mini lectures on their favourite camera systems, if a couple of other members could prepare a mini lecture on the same theme that would be most helpful. The LPA POTY deadline date is nearly upon us; they are panels of three prints as we discussed last Wednesday. If you want to enter either attend the club PDI competition on 1 st November at Nettleton village hall or bring your prints in on Wednesday and hand them to a member who is going and will take them for you. Regards Graham

Our Society held a print competition last night, the set subject category was "Mono", whereby the prints were black and white, or single tone images. The "Open" category prints consisted of any subject of the authors choice, and the judge for the evening was Grahame Dunkin. It was an exciting competition, with 27 prints in each category, the standard was incredibly high, giving Grahame a difficult time of determining the points for each print and choosing the top three prints in each category. Grahame judges very well, he giving a relaxed, and helpful critique of each image. The website Competition page has been updated with the results of the competition. Our next meeting will be held on the 28th October, and should be a showing of the N&EMPF Exhibition prints, however if the Exhibition prints are not available, I would ask members to think about giving a talk on their "Favourite Camera Systems" just showing what they shoot with, and providing a few sample images.

Today was the LPA Battle finals day at Nettleham, it was the last one in its present form, and six clubs including Louth made the final. The judge was Alan Young from Rolls Royce camera club, Derby. Alan was quite straight to the point and as he said there were so many good prints in the competition, he wouldn't be marking low and would have quite a task giving scores to the best ones. Alan was quick to see anything he didn't think was right with the prints and was looking for more than just a record photograph. Louth had a very good start with our first three prints being held back, it then didn't go so well but we did have six hold backs altogether which were Sleeping-David Whitehouse 18 points, Morning sun Whitby-Dave Turner 18 points, Hairy shield bug-Graham Harrison 17 points, Evening light Chapel St Leonards -Tony Gaskins 17 points, Cosmos-Harry Kerman 17 points and Evening Light Whitby Harbour -Tony Gaskins 18 points. 1 st place - Axholme - 256 2 nd place - Cleethorpes - 255 3 rd place - Scunthorpe - 248 4 th place - Grantham - 246 5 th place - Louth - 244 6 th place - Lincoln - 242

Good Morning, All, Last week at the club Steve West gave a presentation on the history of Louth's cinema's, Steve started at the beginning in 1896 with the original Louth Photographic Society being involved with showing films in what was thought to be Westgate Fields. Steve went through all the other locations ending up with just the one cinema now on Cannon Street. There is a report on our blog page. This week, Wednesday 21st October, we will hold a monthly print competition, with the categories of "Mono" and "Open" judged by the LPA president Grahame Dunkin. There are just over 50 prints to be judged so should be a very good night. Today (Sunday 18th) is the LPA Print Battle final at Nettleham, the judging starts at 1pm. Regards Graham

Last night, Steve West gave a fascinating illustrated presentation on the long history of cinema, and stage plays in Louth. In the late 1890s some films were shown at various locations, in 1910 a “tent” cinema was showing films on Westgate Fields. During 1913 a site was purchased of 2 retail units, on Eastgate, the retail units were demolished, and the Palace cinema / theatre was constructed on the site ready for opening in 1914. During the interwar years many plays were staged at the Palace, and Steve has collected many of the original programs from this era. The current Playhouse was constructed in Canon Street in 1921 in the “art deco” style, some poor quality housing was demolished to make way for this new cinema. The Playhouse, and the Palace both continued in operation until 1960 when the Palace was sold, and the building was converted into a Fine Fare supermarket. During the 1970s when Bingo became popular, part of the Playhouse was used as a Bingo hall, with the reception area restyled to suit the new usage. The Playhouse was converted into a multi-screen cinema when purchased by the Parkway Cinema group in the mid 1990s. Louth is extremely fortunate to have retained a viable cinema in the town, many thanks to Steve West for a very polished presentation.

Good Morning All Sand racing starts again this week at Mablethorpe, this Sunday is practice day, times are on their website. Last week at the club we held a local competition, with the categories of: "Straight out of the camera" and "Open", there was a very good entry in each subject with Tony Gaskins having the task of judging the unedited ones and Robin Begley judging the Open. There is a full report on our website but well done to Harry for first place in the Straight out of the camera and Keith Rossington for first place in the Open. This week, Wednesday 14th, Steve West will be our speaker, talking and showing PDI's on the subject of the Louth cinema. The following week will be a print competition, with the categories of "Mono" and "Open", you need to bring your prints in this week and send an email to Dave Turner with your titles. Regards Graham

At our meeting last night we held a PDI (printed digital image) competition, with the categories of "Local Unedited", and "Open". As this was a members competition one of our members judged the competition, Tony Gaskins was our first judge for the "Local Unedited" category, these were .jpg images taken straight from the camera, without any editing, apart from the resizing for projection. Presenting an image such as this in a competition is quite a difficult task, the photographer has to ensure that the correct exposure is chosen, the composition, and subject matter has to be precise, everything done in camera. Normally for competition entries, a degree of post processing would be involved, simple edits like toning down highlights, or even removing extraneous objects from a scene, emphasising a moody sky, all not allowed. Tony Gaskins did an excellent job with his judging, providing clear and concise critique of the images presented, he "held back" 8 images for further consideration, awarding higher points, and finally choosing the top three placements. After the break it was Robin Begley's turn to judge the "Open" category, as these were post process edited images the standard was higher than the unedited images, but surprisingly not markedly so. Robin is potentially hoping to become a N&EMPF approved judge, and he had a different style, able to suggest edits that could have improved an image, again his critique was clear and concise communicating well with members. Robin chose 8 images for further consideration, awarding higher points, and finally selecting the top three placements. It was a fabulous, and interesting competition with excellent images, many thanks to both our judges, it's not an easy job, probably nearly as bad as being a referee in a football match!! Many thanks to both our judges, well done.





