Reciprocity failure

Recently I have been doing a lot of pinhole photography, and due to that I have had to explain to a number of people (unfamiliar with the more technical parts of photography) what reciprocity failure is.

Reciprocity is the relationship between shutter speeds and apertures, which means that as you reduce exposure with a change in, lets say the shutter speed by one stop, then increase the exposure by one stop with the aperture, you will have exactly the same exposure. Each one-stop adjustment of the shutter speed, is equivalent to a one-stop adjustment of the aperture. This holds true throughout the normal use of the camera in most lighting situations.

This linked relationship begins to slip away with exposures longer than one second, and the longer the indicated exposure, the more of a difference there is between the indicated exposure and what is actually needed. Many years ago I included in my book on night photography, a chart for working out the amount of exposure correction you might need in situations where exposures were between 1 second and 17 minutes. I have been referring to this chart for my extended pinhole exposures, and I include a link to a word document here which shows the full chart:

https://dl.dropboxusercontent.com/u/88621650/Reciprocity%20chart.doc

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Magazine articles

For a while now, I’ve been meaning to write a post on a series of articles that I’ve had published in Amateur Photographer. Ollie Atwell from the magazine contacted me some time ago and asked me if I’d be interested in describing how and why I had taken some of my pictures. The articles are under the heading of ‘Photo insight’ and so far Ollie has chosen many of my personal favourites. He has very kindly allowed me to reproduce the articles here, so I have added links to the articles on the AP website.

Links:

11 February 2012   http://www.amateurphotographer.co.uk/how-to/icons-of-photography/538678/photo-insight-with-andrew-sanderson-woodland-west-yorkshire

10 march 2012   http://www.amateurphotographer.co.uk/how-to/icons-of-photography/538673/photo-insight-with-andrew-sanderson-bucking-horse

14 April 2012   http://www.amateurphotographer.co.uk/how-to/icons-of-photography/538736/photo-insight-with-andrew-sanderson-steam-train

12 May 2012   http://www.amateurphotographer.co.uk/how-to/icons-of-photography/538799/photo-insight-with-andrew-sanderson-cromer-norfolk

9 June 2012  http://www.amateurphotographer.co.uk/how-to/icons-of-photography/538986/photo-insight-with-andrew-sanderson-portrait-image

30 June 2012   http://www.amateurphotographer.co.uk/how-to/icons-of-photography/538911/photo-insight-with-andrew-sanderson-two-cows

14 July 2012   http://www.amateurphotographer.co.uk/how-to/icons-of-photography/534541/photo-insight-with-andrew-sanderson-child-in-a-forest

4 August 2012  http://www.amateurphotographer.co.uk/how-to/icons-of-photography/539035/photo-insight-with-andrew-sanderson-reservoir

25 August 2012   http://www.amateurphotographer.co.uk/how-to/icons-of-photography/539077/photo-insight-with-andrew-sanderson-family-feet

29 September 2012   http://www.amateurphotographer.co.uk/how-to/icons-of-photography/539222/photo-insight-with-andrew-sanderson-edge-of-the-woods

13 October 2012   http://www.amateurphotographer.co.uk/how-to/icons-of-photography/539286/photo-insight-with-andrew-sanderson-gate-in-morning-light

17 November 2012   http://www.amateurphotographer.co.uk/how-to/icons-of-photography/539353/photo-insight-with-andrew-sanderson-amaryllis-flower

http://www.amateurphotographer.co.uk/how-to/icons-of-photography/539375/photo-insight-with-andrew-sanderson-frosty-graveyard

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Kirk Toft

It’s not very often that I do a post on another photographer, but recently I had a visit from an old friend who I don’t see often enough, and who’s work I think deserves more attention. Kirk is a photographer who has devoted himself to one process and knows it inside out, he also has a really good eye for a classic composition.

He visited recently to give me a large format camera which he was planning to throw out. I said I’d be happy to give it a good home and have been using it a lot recently, so I’d like to say thanks again Kirk! His generosity is not the reason for this write up though. I genuinely think he deserves more attention. He showed me a selection of his oil transfer prints and they were really gorgeous. I managed to prise one from his grip and I’ll be getting it framed soon.

Seeing this image here you get no sense of how subtle the tonality is and how the ink sits in the fibres of the paper. Oil transfer is a lovely process, -as are many of the alt processes when they are done well. These prints take a long time to make, and Kirk only produces them for a few months each year, when the humidity and temperature in his house are favourable. Each one is a special object.

Posted in Alternative processes, Large negatives, cameras, landscape | Tagged , , , | 1 Comment

Making large copy negatives for alt processes.

When I need to produce a Gum print or a Cyanotype, I sometimes use large format original negatives. More often than not I use copynegs made from an RC print as this gives me much more control and flexibility.

The first thing I do is make an RC print to the size that I need my final gum print to be, with all the burning in and dodging that the image requires. I then place that face down on a sheet of either; Lith film, Line film, Ortho film, X-ray film or medical Subtraction film (All of these have different properties, ISOs and contrast, so stick to one and understand how to get the best from it. I would suggest using Ilford Ortho film as it is easy to obtain and works really well). This is placed in a contact printing frame or under thick glass and exposed under the enlarger. An exposure is given and the film is developed for around 1 minute in paper developer under red safelight (shorter times give lower contrast, -longer times give more contrast). Stop and fix as usual. A 5 minute wash in running water is adequate for these types of film. Be aware though that x-ray film has a very soft emulsion and is easily damaged.

To begin with, make a few negatives of varying contrast and density, then when you have become more proficient, you will have an idea which kind of negative works best for the process you are using. I prefer to make two negatives when Gum printing, as this gives me better separation in the tones.

The advantages of this method are that you can make a large negative from any size original, you can get the contrast exactly right for your process and you don’t have to worry about damaging your negative when working with the alt process. I also prefer having a large border around my copy negatives, as this gives a better margin for attaching masking tape when re-aligning for multiple printing.

Posted in Alternative processes, Darkroom, General, Large format, Large negatives, Uncategorized | Tagged , , , , , , | Leave a comment

A nice discovery.

I was looking through a box of old lenses and collected junk earlier this year, with an idea to sell off some bits on Ebay. I had sold some unused brass lenses, enlarging lenses and old cameras, and was about to list a little lens I had found languishing in the bottom of the box. I had acquired it so long ago, that I couldn’t recall where from. When I did a little research to pad out my description it made me reconsider my decision. So before I listed it, I tried it on my 10×8 camera. -Wow! it almost covered the whole negative area, and the corner vignetting was rather interesting. I am looking forward to doing more with this lens. It is a Taylor Hobson Cooke Series VIIb 108mm Wide angle Anastigmat. The information online states that it is meant for a 7×5 camera, but I like seeing what it will do at full stretch.

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Winter light.

I love the low sun and long shadows that are a feature of winter days. Shadows have been a fascination of mine for many years and will continue to be I expect. Every sunny (winter) morning the light shines directly into our kitchen and on this occasion I placed a piece of driftwood on the table to explore the distorted and extended shadows.

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Walker Titan Pinhole 5×4

Using the Walker Titan pinhole 5×4

I have been using the Walker pinhole camera for a few months now, though not exclusively because I’ve been busy with a lot of paper negative stuff. Having shot with it in a few different locations, I have really grown to love it.

When I’ve shot pinhole stuff before, I’ve always enjoyed making the cameras, -and for me this has been an important part of the satisfaction at the end result. I thought at first that using an ‘off the shelf’ camera would be less likely to satisfy and wouldn’t have the quirks of a home made one. I have been surprised to find that this simple plastic box is actually one of my favourite pinhole cameras of all time, -and I’ve been making them since 1978!

Angle of view. I prefer wide and super wide pinhole cameras over ones that mimic a standard lens, mainly because I enjoy the distortions that occur when objects are placed close to the camera. The Walker has an equivalent angle of view to a 70mm lens on a 5×4 camera and considering that 90mm is a pretty wide lens on this format, it would seem that this was in the realm of super wide. It is roughly equivalent to an 18mm lens on a 35mm camera, so that gives you some idea. Previous to using this, I had been using a home made 10×8 pinhole camera which had an angle of view equivalent to an 11mm lens on 35mm. This really did distort and had quite dark vignetting in the corners. Mike seems to have got the angle of view exactly right with this camera, as there is sufficient distortion (yes, I know it’s rectilinear, -no pedantry please), but virtually no vignetting.

Using it is simplicity itself. A standard 5×4 dark slide fits in with a pleasing click and you are ready to expose by removing the tethered plastic cap. With home made pinholes, especially if made from tins or cardboard boxes, there is always the problem of positioning and stability. Unless you go to the trouble of gluing a threaded nut to the base of your tin (no point doing it with cardboard), you are limited to shooting from the ground or any place you can rest it, -this severely limits your compositional options. With a properly made camera you are provided with a tripod bush -two in fact on the Walker Titan, so shooting from a tripod becomes the normal method and opens up all sorts of image making possibilities.

All of the shots I have shown here, were done on Ilford Ortho film. It is great for this kind of thing because long exposures give nicer results (Ortho is 25 ISO -or less, if you want more tonality out of it). I like long exposures for pinhole, because things happen during the exposure which you hadn’t planned for, and provide unexpected and interesting results.

The beach scenes here were all 90 seconds, and during that time people have stood in the scene for a while and then wandered off, leaving a ghost. The boats sitting in the corner of the harbour were bobbing about violently, as the sea was quite rough and have become very indistinct.

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Process, enlarging and simple lenses

I have been using large format cameras alongside other smaller formats for many years. Large format cameras have traditionally been associated with the master photographers, or with high end commercial work, so when I began, I worried about getting ‘perfect’ negatives like the experts. It took me many years to understand that they could be used in a much more relaxed way too.

I have 5×4, 5×7, and 10×8 cameras which all produce very detailed negatives. I can get high quality images from any of them if I need to, but sometimes I really enjoy using them purely for the fun of working in a different way. I often put unusual materials in the camera, such as X-Ray film, graphic Arts film, or Photographic Paper. These materials do not produce technically high quality negatives, but they do produce exciting and interesting images.

All of the light sensitive materials mentioned above are rather slow, that is to say, they need much more light to produce an image. This is actually an advantage, as it means that I can do without a shutter to control the light.  I simply expose by uncovering the lens for a period of time. This can be as little as a second, or much longer, -sometimes minutes.

Optics

Choosing lenses without the need for a  shutter opens up all sorts of possibilities. A high quality lens without a shutter is known as a Process Lens. These can be found on Ebay much more cheaply than the type with shutters built in.

I have used process lenses, enlarger lenses, photocopier lenses and also simple optics such as a magnifying glass. All produce something unique and I find this really exciting.

If you are shooting on slow, or unusual materials and not too concerned about having a really sharp, well corrected lens, then you have an enormous range to choose from.

Process lenses.

For the uninitiated, a general description of a process lens is; A lens without a shutter which gives a flat field of focus. These lenses have been made for copying and reproduction and are made for a particular application. Using them in a way that they were not designed for gives interesting results.

They were designed to be flat field and were optimised for 1-1 reproduction (which makes them great for close up work). These lenses were used in the graphic arts industry for making printing plates and many of these lenses will give excellent quality if stopped down. Some are fixed at one aperture, so are only any use in low light or with very slow emulsions.

Enlarger lenses.

Similar to a process lens, in that they are flat field, but with the advantage of having a variable aperture.

Basically, they are process lenses mounted in reverse. Any enlarger lens can be used on a 5×4 camera, but most will give only a small image on the film unless they are over 150mm focal length (5×4 camera). Some interesting results can be obtained using a lens which is too small, the most obvious being a totally circular image in the centre of the film.

Photocopier lenses.

Again, these are process lenses, but they do not have a controllable aperture. They must be used wide open, this limits the situations in which they can be used.

Projector lenses.

These are amongst my favourites, they are usually very bright lenses and give really lovely out of focus areas. In the picture above you can see an 89mm f1.9 Rosslyte projector lens attached to an Olympus OM10.

Magnifying glass.

An uncorrected (very soft focus), very fast lens with no aperture. The amount of light coming into the camera is often too much even for these slow emulsions. A makeshift aperture could be fashioned out of black card which would reduce the light and also give a clearer, sharper image, though this would still be soft in comparison with proper optics.

Using Process, enlarging and simple lenses on a camera will give your images a different look from those taken using conventional optics. I am grouping these all together because I use all of them at various times to produce some of the work I am interested in. Each type has different characteristics, methods of use and drawbacks. Sometimes those characteristics and drawbacks cause problems out in the field, but they also are capable of beautiful results and that’s why I still think they are worth the effort.

Obtaining these types of lenses is easy. Process lenses appear on Ebay regularly and do not generally cost much, -certainly nowhere near the original cost that they would have been when in proper use. Enlarging lenses usually go for less than £25.00. Camera fairs and antique / junk fairs occasionally have something of interest, -I found a 240mm f4.5 photocopier lens a few months ago which will cover 10×8. It only cost me £4.00.

Anything you can get hold of is going to give you something different than the ‘normal’ optics that are supposed to be used on these cameras. Try it, see what sort of shot suits your unusual lens. Some things will be unsatisfactory, but other shots will be magical.

Posted in 35mm, Experimental, Large format, cameras, lenses | Tagged , , , , | 2 Comments

Paper negatives in Kent

Last month I visited an artist friend in Deal, Kent and took along the Kodak Specialist 5×7, shooting paper negatives on some of my remaining stock of Kentona paper. I had a really nice time. We went to see a painter called Jo Aylward and stayed in the house of another artist called Ruby.

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Print exposure using a metronome.

I recently gave a printing masterclass at Warwick College here in the UK. I do these quite regularly on behalf of Ilford / Harman technology, and one of the things that I talked about gave me the idea for this blog post. I was explaining how I prefer my students not to set their darkroom timers to exposures of less than five seconds when making a test strip. I insist on this because I have seen too many situations where a student’s test does not match their print.

When an enlarger is switched on it doesn’t give full illumination immediately, there is a build up of brightness -which although short in duration, can be a problem. Similarly, at the end of the exposure there is a tailing off of illumination from maximum to nil. When longer exposures are given these slight differences are not important, but if a student was to do a test strip in one second exposures and then decide that ten seconds was the correct exposure, a ten second burst of light would be quite different from ten times one second exposures. For this reason, as I already stated, I don’t like to see my students setting darkroom timers for less than five seconds.

Another method to overcome this problem and the method I prefer for my own printing, is to switch the enlarger on for a few seconds to warm up (with a piece of black card under the lens to block the light path), then uncover the lens to begin the exposure, timing the exposure with a metronome. This way, the light intensity is constant even for very short exposures. With cold cathode enlargers I leave them switched on all through the printing session, as they take longer to reach full, and consisitent brightness.

Using a metronome allows for an even, consistent light source, no matter how long, or short, the exposure is. The important thing to remember is to move the card exactly on the second. This is obviously most important when short exposures are being used, such as when burning in. For this situation, -say when a number of different exposures are needed within the one image, I don’t have to stop and re set the timer between each exposure. I just cover the lens, then uncover when I’m ready and count the appropriate time.

I have used a hand held digital metronome for a long time, but recently it gave up the ghost and refused to work. I had been promising myself for years that I would buy an old mechanical one, as I much prefer the old ticking sound to a digital beep. Instead, I asked my brother to record an old metronome and I now have the sound on my phone. I can use it in any darkroom, I have it to hand at all times and I can hear it through an earphone if I’m working in a busy teaching situation.

For those of you interested in trying this method, I have a 35 minute recording available for download;   https://dl.dropbox.com/u/88621650/tiktok.mp3

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