Know Your Digital Camera Sensor
Paul Malley • 20 December 2022
Histogram 1
Photo By: Paul Malley
Histogram 2
Photo By: Paul Malley
Histogram 3
Photo By: Paul Malley
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
Good Morning All Last week at the club we held our monthly PDI competition judged by Martyn Wrigg, the standard of entries was very high and well done to Tony Gaskins for a first in the Architectural Detail and Derek Smith for his first place in the Open. All the results are on our website under competitions. This week, Wednesday 18th March we will be holding a Committee meeting, just committee members for this one. The following week Chris Birchmore is the speaker for the night. Harry is now accepting entries for the PDI local competition, with the categories of "Local Nature" and "Open". We judge this competition in house so if you would like to judge one of the subjects please let me know. Regards Graham
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A PDI (Projected Digital Image) competition was held last night with the categories of "Architectural Detail", and "Open". Martyn Wrigg was our judge for the evening, and he competently judged the submitted images, although he diid surprise with some of his choices of placing, but that's a judges perogative. Martyn complemented members on the quality of the images presented, which had made some of his decisions difficult. First placed was "It's a Fixer Upper" in the Architectural Detail section, and "Dervish Musician" in the Open section. Congratulations to Robin Begley, who as one of our newest members submitted some impressive images, achieving a 3rd place in "Architectural Details", and 2nd in the "Open" category. All the results are now posted to our website Competition page.
Good Morning All Last week at the club member Steve Chapman gave us an insight into his life and especially his time at Ilam Park in Derbyshire photographing for the National Trust. Steve showed us many photographs he had taken of the people involved with the trust and the Peak District. The second half was dedicated to Steve's own work, some superb aircraft photography as well as many other subjects. There is a report on the evening on our blog page. This week, Wednesday 11th March we are holding a PDI competition, with the categories of "Architectural Detail " and "Open" to be judged by Martyn Wrigg of Barton. The following week is a committee meeting for the committee members only on that evening. For newer members we have two committee meetings a year. Regards Graham
Last night Steve Chapman presented a selection of images from his archives. Steve had previously been a volunteer photographer for the National Trust, and he showed many photos from the Ilam Park Estate, Dovedale, it was interesting to see some of the "behind the scenes" photos. The Jacobite reenactment battle scenes were amazing, the uniforms showed great attention to detail, and there were some real characters among the reenactors. After the break Steve showed some of his general photography, he has a great photographic eye, as some of his photos showed with different colours, shapes, and leading lines. Steve has taken many photos of agricultural machinery, and risked life and limb to create some close up aircraft photos. For atmosphere, just look at these horseriders at the top of the hill on a cool early morning. For heartstopping imagery look at these children on the side of a building, the children are photos on the side of the building, however, Steve wasted no time in capturing this stunning image. Many thanks to Steve for a fascinating evening.
Good Morning All Last week at the club I gave you a PDI (Projected Digital Image) presentation showing photographs I had taken on my travels last year, following up with some past and present photographs of Binbrook. I hope you all enjoyed the evening and maybe saw parts of England you hadn't seen before. This week, Wednesday 4th March, our member Steve Chapman will be showing us photographs he has taken. This is Steve's first time showing the club his work so will be a very good night. Harry is now accepting your PDI's for the next competition, with the categories of "Architectural Detail" and "Open". The closing date is Friday 6th March. Regards Graham
The N&EMPF Exhibition will be on display in Cleethorpes from 3rd March.
It was "President's Night" with Graham Harrison showing some of his images from short breaks, and holidays around the UK. Graham rented a holiday cottage in Newbiggin, Northumberland, and showed many of his photos from that area, including a visit to Lindisfarne, where the castle on the rocky outcrop made for an impressive photo. In Suffolk, Graham visited Pakefield, and photographed the colourful beach huts at the top of the shingle beach, he also showed several photos from the Lake District. One of my favourite photos from last night was St. Mary's Lighthouse, Whitley Bay, with the groins in juxtaposition. Thank you Graham for a very interesting evening.
Good Morning All Last week at the club Harry and Chris gave us an insight into how our exhibition preparation is going, we have a lot of historical photos to go on show and there may be room for some more up to date ones but Harry and Chris will see how much room we have left when they start putting it all together at the museum. I also took the time to find out what you wanted in the new program, filling in the competition subjects and outings. This week, Wednesday 25th February, it is the Presidents night, so that's my night and I will be showing you what I got up to in 2025. The rainbow at Brough castle gives you idea of one area I visited. Harry is now accepting entries for the next PDI competition, with the categories of "Architectural Detail" and "Open". The new program is nearly done and to give you a chance to get ready for the first two competitions in May and June the subjects are May, PDI comp - Landscapes with water and Open and June, Print competition, Trees and Open. Regards Graham
Good Morning All Last week at the club we held our Print Of The Year (POTY) competition, it's one of our highlights of the year and judged by Grahame Dunkin, it proved to be an excellent night with some very good prints on show. The results are on our website under competitions but the highlights were Dave Turner being placed first in the Pictorial, landscape and best Mono print in show; Robin Begley, First in the Record section, Keith Rossington first place in Portrait, Harry Kerman first in the photo/journalism (including Street) and myself taking first place in the Nature as well as overall Print of the Year. My photograph of a Hairy Shield bug was taken at Chambers wood on a camera club outing. This week, Wednesday 19th February, we are sorting out Prints for our 70th anniversary exhibition at Louth Museum. Please bring along any local prints you may have and maybe a few further afield for selection. Please also bring along any prints you may have that you think will be ok for the LPA Foster challenge and LPA Battles. They need to be mounted on a 500mm x 400mm mount and a maximum print size of A3. Don't forget to take a photograph of water if you are doing this years project, no real excuses at the moment. Regards Graham
