Friday, 11 January 2013

Ilford G.30 Plates

Ilford G.30 Chromatic backed plates
Following the first vintage glass plates I shot last year, I've been keen to use more, although I have only found time to do so recently. I bought a couple of previously unopened boxes of Ilford G.30 Chromatic glass plates in 4x5 size; one of the film holders for my MPP large format camera takes glass plates (it does also have film sheaths, which can be inserted to shoot film). As the label states 'Open in red light only', the word 'Chromatic' appears to mean orthochromatic; where the label continues onto the underside of the box it also states, "Meter settings for minimum exposure ASA 10 DIN 11". The design of the packaging suggests the plates are from the 1960s; the leaflet inside the box has a code number L.64/D, which might refer to the year of printing, 1964.

For the first test I metered for 10 ISO, and took three successive exposures on the same plate, progressively withdrawing the darkslide between each shot (although not very evenly). Viewed from left to right, this effectively achieved exposures indexes of 10, 5, and 2.5. The plate was stand-developed in R09 One Shot (Rodinal), at a dilution of 1:100 for one hour, with a couple of inversions at the half hour mark.

Ilford G.30 Plate test - three successive exposures at 10 EI
There is some blurring due to a small amount of movement between the multiple exposures, but in terms of a test to determine a working exposure, it's clear enough. The first exposure at 10 EI appears to be workable, and initially I did think that this might have meant that the plates hadn't lost any sensitivity over the 50 years since manufacture, but Flickr member richard314159 reminded me of the doubling of film speed by the ASA in 1960. This change in standards simply reduced the margin of error against under-exposure. Although I can't be sure that the plates are from before the revised ASA settings, if so the plates would have originally been 20 rather than 10 by modern standards, and so may have lost one stop in sensitivity. There's also not much background fog on this plate, probably not much more than I've got with some contemporary films; from my limited experience, slower emulsions do appear to age better.

I subsequently shot two plates at night with long exposures. On first inspection, these seemed like they might have been over-exposed, but, particularly with the second plate below, this was important to register the foreground detail, although at the expense of the clarity of the lit-up lettering. The haloes around the lights are somewhat unusual, this may be due to the fact it's shot on glass. It is also noticeable that there's a line of thicker emulsion at two of the adjacent edges where, as it was poured onto the plate, the emulsion collected as the excess was poured off.

Ilford G.30 Plate - 1 minute exposure at f5.6
Ilford G.30 Plate - 2mins exposure at f5.6

Edit: 29/04/13

As a result of my research into Ilford, I discovered the Ilford Technical Information Book, which contains a sheet on the G.30 Chromatic plates, dated to 1965. This provides additional information for the plates from the leaflet in the box. It describes the G.30 Plate as
widely used for the photo-micrography of metal specimens. It is particularly useful for green-corrected microscope lenses since it allows comparatively short exposures to be given when using a Tricolour Green filter.
Ilford G.30 Chromatic Plates are used in the graphic arts, copying and scientific fields. For graphic arts work the main use is in the preparation of continuous tone negatives.
It gives the ASA setting for tungsten lighting as 5, against the daylight setting of 10. The date of the technical information sheet disproves the idea above after my first test that the meter settings were from before the change in speed ratings for black & white emulsions, and so the plates have lost very little sensitivity since they were made nearly 50 years ago. The table of development times gives further dilutions and times for both continuous and intermittent agitation.

Ilford G.30 Chromatic Plate development times
Ilford G.30 Chromatic Plate sensitometric curves
I subsequently shot some more plates with my MPP Micro-Technical camera, the best of which is below, a difficult subject given the brightness of the fluorescent strip lights under the awning compared to the building above.

Ilford G.30 Plate, 12 seconds exposure at f4.5

Saturday, 5 January 2013

Some thoughts on night photography without a tripod

Offices at Night, Voightl├Ąnder Bessa RF, HP5
I like night photography, but while traveling, or simply going out for an evening, I prefer not to carry a tripod with me. Not using a tripod is a compromise of course; this post is about how I negotiate that compromise. Having stated that, there are some very good small and compact tripods available that aren't a pain to carry around.

There are essentially two strategies, both of which I use: either a combination of a fast film with a fast (enough) lens; or steadying the camera on an immovable object for a long exposure. In terms of the subject matter for night photography, it's often a case of looking out for scenes lit up with street lights, or internal sources of illumination within buildings; light sources themselves can be the subject of the photograph.

The fastest films currently available are Ilford Delta 3200, Kodak Tmax P3200, and Fuji Neopan 1600, none of which have a true ISO as fast as the manufacturers' names suggest, being in the range of 800-1000, but these films give a 'normal' contrast range when exposed at box speed and developed accordingly. With night photography, low-light urban subjects tend to be high contrast to begin with, so push processing in an attempt to squeeze more speed out of a film can make contrast an issue (it may make more sense to pull the film to reduce contrast).

Seven Dials, Canon A1 with Ilford Delta 3200, hand-held


For hand-held night shots, one needs a fast film, a fast lens, and a slow shutter speed. The issues with each of these factors are: grain; a shallow depth of field; and camera shake, respectively. The first two factors can perhaps be accepted as a fait accompli, although the appearance of grain partly depends on the developer, and wider-angle lenses have greater depth of field. Of most concern is camera shake blurring the image. The general rule of thumb for avoiding camera shake is to use a shutter speed higher than the focal length of the camera's lens. On a 35mm camera with a 50mm lens this means 1/60th (or 1/50th depending on the shutter). However, this rule of thumb is worth taking with a pinch of salt- a shutter speed one stop slower is not too difficult to hold with a steady hand, i.e. 1/30th-1/25th with a 50mm lens. Some claim to be able to hand hold speeds of 1/15th or 1/8th, which they may be able to do, but I've found that I do get camera shake at these speeds.

Montmartre, Canon A1, Ilford Delta 3200 rated at 6400 EI, hand held
However, I don't always use a 35mm camera: a number of my recent night shots were taken with a Baldalux medium format camera with a f4.5 105mm lens. It's not a fast lens, and the focal length suggests a shutter speed of 1/100th to avoid camera shake, although I used 1/50th for the night shots. The type of camera and shutter may make a difference to camera shake. The Baldalux is a viewfinder camera with a leaf shutter: SLR cameras suffer from 'mirror slap', vibrations caused by the mirror moving up before the shutter opens. Focal plane shutters and leaf shutters also open and close in different ways which may affect vibrations: the curtains of focal plane shutters move in a single direction from top to bottom or left to right, while the blades of a leaf shutter swing in and out in a circular motion around the lens. When using very slow shutter speeds, it might be possible to minimize shake by using the camera's self timer so that the shutter actually fires separately from the action of depressing the shutter button.

Gartenstra├če, Baldalux with Ilford Delta 3200, hand held
Long Exposures

For long exposures without a tripod, the first consideration is having a camera which will sit flat while exposing. While most modern cameras will happily stand on a flat bottom plate, this is not necessarily a given with vintage cameras. I'm particularly keen on old folding cameras, and often these will only rest on the vertical with a fold-out stand, like the Balda Rigona. Depending on the format, this is either portait or landscape: for example the image below is from a Plaubel Roll-Op, a medium format 6x4.5 camera. Some cameras simply will not stand on their own at all: despite being level on the bottom, the Kodak Retina is too front heavy when opened (it rests on the corner of the front cover facing at a slight downwards angle), and does not have a fold-out stand for vertical shots. Street furniture is good for places to stand a camera: benches, litter bins, post boxes, but also the flat tops of walls, railings, window sills, or even the pavement itself.

Lea Bridge Road, Plaubel Roll-Op, with RPX 400
As with hand held shots, consideration should be given as to how to trigger the shutter for a long exposure. The usual procedure for long exposures is to use a cable release. However, without the camera secured to a tripod, it is possible to move it by the force of pushing in the cable release if the camera's just placed on a flat surface. As with hand-holding the camera, using a self timer can avoid this. One of the most useful aspects of using older cameras for night photography is that the shutters often have a 'T' setting (common on better shutters until the 1950s). Unlike 'B' for 'Bulb' which needs constant pressure to keep the shutter open, with the shutter on 'T' (for Time), the shutter opens with one press of the button or lever, and then closes on a second press. Setting the shutter to 'T', I tend to place the camera, then open the shutter with my hand covering lens in case of any movement, and then remove my hand.

Mildmay Park, Baby Ikonta, Efke R100
I use a very loose starting point for long exposures of scenes lit with streetlights if I'm not metering for exposure: using a 400 ISO film I start with 12 seconds at f8. With exposures longer than a 1/10th second, for many films reciprocity law failure should be taken into account when calculating exposure. This actually builds in a large fudge factor, i.e. the longer an exposure, the less likely it is to be overexposed.

Sacre Coeur, Canon A1, Ilford Delta 3200, rated 6400 EI, hand-held
Wallis Road, Wallace Heaton Zodel, HP5, rated 1600 EI
Zagreb, Agfa Record I, HP5
St Giles, Canon A1, HP5 rated at 1600 EI