Friday, 16 October 2015

A minor fix for the Canon AV-1

Canon AV-1 with 50mm f1.8 lens
Writing about the Canon A-1 SLR camera for my last post prompted my partner to find her old AV-1. This hadn't been used for well over ten years, and I had looked at the camera some time ago to find it apparently inoperable. The battery inside the camera was dead, but fortunately not corroded. Like the A-1, the AV-1 will not work without a battery, but on inserting a new battery, although the meter needle responded to light, the shutter would not fire, nor could the film advance lever be moved. At the time, it seemed like there was little else to do but put the camera away again as a 'non-shooter'.

The Canon AV-1 appeared in 1979, one year after the A-1, and three years after the AE-1, which it clearly draws upon, although there are a few similarities to the higher priced and fully-featured A-1. Canon's Camera Museum website describes the rationale behind the development of the AV-1:
Even though the camera would cost more, shutter speed-priority AE cameras were important to Canon since users could comprehend shutter speeds easier than aperture settings. However, in America and other overseas markets, aperture-priority AE 35mm cameras were in the majority.

Overseas distributors also clamored for an aperture-priority AE model. Canon responded with the AV-1.
Named for Aperture Value, the Canon AV-1 shared much of the AE-1's design and construction, including the use of metalised plastics in its build, to make it both lighter and cheaper (it's around 200g lighter than the more robustly made A-1). However, the AV-1 isn't Canon's aperture-priority version of the AE-1: the design and functions of the camera have been further simplified. Although it has the same EV range (1 to 18 EV at 100 ISO), it lacks the top film speed setting of 3200, 1600 being the maximum (this is set on a dial around the rewind crank, more like the A-1's design). The exposure preview button on the side of the lens mount is missing, although the backlight correction button remains, giving an exposure adjustment of +1.5 stop. Exposure preview is by partially depressing the shutter release, which activates the meter and gives a preview of the shutter speed in the viewfinder, with a needle indicating a range from 2 seconds to 1/1000,  with under- and overexposure indicated at either end of the scale. 1/30th is marked with a black bar: with the needle at or below this speed is a warning of camera shake. The stopping down lever is also absent, as is the PC connection for flash. Flash sync is at 1/60th, a separate setting on the mode dial, which has a red-accented 'A' for automatic shutter speed, 'B' and both self-timer and self-timer-with-flash. The red LED on the AV-1's top plate is only used for the self-timer - like the A-1, but unlike the A-1 it's not used for the battery check function as well (pressing the battery check button raises the needle inside the viewfinder). According to prices given on the Canon Camera Museum, in 1979 the AV-1 cost 57,000 yen (with the 'New FD' 50mm f2 lens, designed to be a low-cost prime), as against the AE-1, which three years earlier was 81,000 yen (albeit with the more expensive 50mm f1.4 lens). As a point of comparison, the A-1 was 83,000 yen in 1978 for the body alone - and 114,000 yen with the 50mm f1.4 lens.

Canon AV-1 with 50mm f1.8 lens
What made me want to write this blog post, not as a full article or review on the Canon AV-1, was my experience in getting the shutter to fire again and the film advance to work. I searched online about how to free the shutter, and found much about the Canon AE-1, which came up in searches for the AV-1. From this information I had a general idea of what might be wrong, but pictures of the AE-1 with the bottom plate removed showed a slightly different layout. The following steps were what I did to release the shutter after being stuck and left for many years - this was very simple - but as I couldn't find the specific information relating to the AV-1, this may be of some use to others.

The first step is to ensure that the camera has a working battery: the shutter will not fire without one. The AV-1 requires a PX28 battery, like other A series SLRs. With the collar around the shutter release set to A, press the small black battery check button just in front of the film speed dial. If the camera's circuits respond, the needle inside the viewfinder will move, and, according to the manual, it should raise above the black bar next to the 1/30th speed (a weak current may move the needle but it may not be enough the trip the shutter). At this stage the shutter release would not trip the shutter, and neither could the film advance lever be moved. The following description of the steps I took to free the shutter mechanism are to be undertaken with caution and at one's (or one's camera's) own risk.

Canon AV-1 bottom plate
The bottom plate is removed by taking out the three small cross-head screws. The fourth screw below the lens mount is for a separate section of the casing and can remain in place. In reading around problems with the AE-1, it seemed the most common reason for the shutter to be jammed is the magnetic shutter release. In the AE-1, this is easier to access: on the AV-1 it is visible, but somewhat buried: in the image below it is located to the right of the tripod fitting underneath the red and black wires with a transparent plastic cover. The magnet itself has copper coiled around it. Perhaps it would have been best to give the camera a proper CLA and clean the magnet's contacts, but this requires more disassembly. I hoped that I could get the shutter to work again without going any further. At this stage it wasn't entirely clear to me whether the film advance or the shutter was stuck.

Canon AV-1 bottom plate removed
With the bottom plate removed it is possible to see whether the stutter is cocked or not. If it is cocked, the magnet circuit is closed: there is a metal release linkage just visible in the image above closing the circuit in contact with the magnet. Using a small screwdriver, I managed to get the shutter to release by forcing the lever on the left hand side (it pivots upwards to the right) which connects the film advance (the large toothed wheel on the left) to the shutter cocking mechanism. The shutter fired once, then stuck again. However by tripping the shutter a few times by forcing the lever with it intermittently sticking, after exercising it enough it stopped getting stuck and I felt confident that the shutter and film advance now worked freely - for the time being. I can't claim this to be an in-depth explanation of how to fix any shutter problems with the AV-1, but it may well be the first action to take to free a stuck shutter; beyond this step, the next would be to take out the tripod fitting and the black plastic next to it, and possibly the circuit board on the right hand side, in order to access the magnet and clean the surfaces that contact when this closes. The reason for the shutter being jammed may simply have been that it had been stored with the shutter cocked (i.e. wound on) for a number of years: when not in use for some time, it may be best practice to fire the shutter, then remove the battery.

Although the New FD mount lenses appeared at the same time as the Canon AV-1 (Canon Camera Museum: "When this camera appeared, a new type of FD lenses featuring instant mounting/demounting was also introduced"), this particular camera had an old breech-lock FD lens (although technically both new and old FD lenses are breech-lock, it appears to be common to refer to the new FD lenses as 'bayonet mounting'). With the shutter firing again, I re-attached the lens to find that it jammed the shutter - or more accurately, it prevented the mirror from fully returning somehow. The mirror did return when I partially loosened the breech-ring, and the lens had the same effect when mounted on my A-1. Looking at the old lens on the all-black A-1, I wonder whether the visual design of the New FD lenses were in part inspired by the look or the general design principles of the A-1, even if these lenses were released a year later, along with the AV-1. One oddity of FD lenses with an 'A' setting when used on the AV-1 is that this simply selects the smallest aperture - and meters for it.

Researching the AV-1, I came across Bob Atkin's website which details Canon's date codes. According to the information listed, the AV-1's body dates to 1979, while my Canon A-1 is a year more recent in manufacture, to 1980. Having got the AV-1 working again, I ran a couple of short rolls of film through the camera, one of Retropan 320, and Ilford Mark V just to make sure everything was working as it should. The AV-1 had a 2x macro teleconverter with it, allowing for 1:1 image reproduction, such as in one of the close up images of plants below.

Sample image with f1.8 50mm lens and Foma Retropan 320
Sample image with f.18 50mm lens and 2x teleconverter on Retropan 320
Sample image with f.18 50mm lens and 2x teleconverter on Retropan 320
Sample image with f.18 50mm lens and 2x teleconverter on Ilford Mark V
Sample image with f.18 50mm lens and 2x teleconverter on Ilford Mark V
Sources/further reading:
Canon AV-1 manual (PDF)
Photography in Malaysia's Canon AV-1 pages 
Fix Old Cameras' AE-1 release magnet video 

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