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(First) Canon Canonet - how does auto exposure work?


john_bear

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<p>At first sight, it appears that any viable shutter speed can be selected, and the aperture will adjust accordingly. However, the user manual advocates a very specific approach which steers the pre-selection of a particular shutter speed for various lighting conditions.</p>

<p>1. Set the lens aperture ring to Auto<br />2. Set the film speed ... by shifting the film speed indicator<br />3. Turn the shutter speed ring and set the film speed indicator lever to the Indoor, Cloudy or Sunny mark ...</p>

<p>The third step brings a preferred shutter speed into operation for any given film speed setting and "Indoor", "Cloudy" or "Sunny" lighting conditions, and I don't follow the logic of this. For example, at a 100 ASA film speed setting, the shutter speed that results from alignment between the Sunny/Cloudy icon is 1/250th.</p>

<p>If we apply the Sunny 16 rule (on a sunny day, set the aperture to f/16 and shutter speed to the nearest reciprocal of the ISO for a subject in direct sunlight: f/11 for slightly overcast, etc.) then the shutter speed/aperture combination would be: f/16@1/60th, or f/11@1/125th, or <strong>f/8@1/250th</strong>, or f/5.6@1/500th.</p>

<p>So why does the operating procedure steer the user to this particular option of f/8@1/250th? What this suggests to me is that there may be tight limits to the parameters of auto-exposure combinations, such that not all shutter speeds are available (even when viable) and/or not all apertures are available (even when viable).</p>

<p>If my camera was working consistently, I could no doubt test which shutter speeds lock the release, but it isn't, so I can't ! However, the results of limited experimentation suggest that deviation from the camera's preferred shutter speed can result in a shutter lock, even when the shutter speed is within the lens aperture limits.</p>

<p>Has anyone experimented with this camera, and found the limits of the auto-exposure system?<br>

<a href="http://www.camera.portraits.srv2.com/">My film camera collection</a></p>

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<p>I can't remember whether this applies to the first Canonets or not, but I <em>think </em>that what you have run into here is the "exposure value system" ( http://en.wikipedia.org/wiki/Exposure_value ).<br>

The idea was apparently that people were generally too dumb to understand the relation between shutter speed and aperture, so they were mechanically linked so that when you changed the one, you also changed the other to keep the same exposure, measured either by a built-in light meter or externally.</p>

<p>It is very frustrating, but it is <em>possible</em> in these systems to choose the combination you want, just more difficult than it should be.</p>

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<p>The shutter lock is active (locking the shutter) whenever the lightmeter detects over- or underexposure. <br>

The lightmeter selects an aperture, depending on film speed and shutter speed setting. Of course, depending on lighting condtitions, not all shutter speed/aperture combos will give correct exposure. You can also see this from the indicator in the viewfinder. When the needle is in one of the red areas on top or bottom of the aperture scale the shutter will lock. </p>

 

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As a long time user of the EV system i can vouch that the system makes live much easier. Not because people using it are too dumb, JDM, but because it is a huge time saver.<br>Whatever exposure you decide would be the right one for a given scene, unless you have a lens with only one f-stop and a camera with only one shutterspeed (in which case you would be lucky if they are the ones you need) there are quite a few aperture-speed combinations that produce that same, single exposure. The one, single exposure you are hoping to use. An EV is just shorthand for that exposure and all the possible aperture-speed combinations. <br>And it is a more convenient way of doing things with uncoupled meters. Your meter gives you a single value, so you only have to transfer one value and then are free to choose whichever resulting aperture-speed combination you wish without having to count stops when you adjust one of the two to make sure you adjust the other accordingly.<br>Maybe just a small convenience. But a convenience still. A very nice idea. Works great.
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<p>Thanks to all who have commented, but you have sort-of answered a question that I didn't ask. Maybe I wasn't sufficiently clear?</p>

<p>Anyhow, I ran some test, during which my camera performed without fault, and to my surprise found that the camera did select an appropriate aperture for each shutter speed within the range of those viable (e.g. f/1.9@1/125 th, f/2.8@1/60 th, f/4@1/30 th, down to f/16@1/2 nd).</p>

<p>So, the camera does do what it claims, and I can only conclude that the Indoor/Cloudy/Sunny procedure was a design afterthought intended to get the initial set-up somewhere in the middle of exposure options. It is however total unnecessary. I think the morale is - sometimes it doesn't pay to read the instruction booklet.</p>

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<p>John, you absolutely correct the Indoor/Cloudy/Sunny symbols are an necessary add-on.<br /> <br /> The Yashica Electro 35 series had them - but the symbols were on top of the lens barrel - where the photographer could easily see them. The sunny day icon lined up with f/11. Considering the slow speed color film we once used, that would be doable with the range of shutter speeds that were available.<br /> <br /> The first generation Canonet was introduced in 1961 when more often than not color film had an ISO speed of less than 100. - AE was still a new feature in 1961. - A novice would probably have used Indoor/Cloudy/Sunny icons on the bottom of the lens barrel.</p>
Best Regards - Andrew in Austin, TX
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<p>Q.G. et al.,<br /> I know what EV is all about, but I would never agree that it is a "good" idea. Nor, in the end, did the marketplace. The idea became moribund well before the Digital Era began and was mostly used on equipment that was, shall we say, not aimed at the photo professional or even serious amateur.<br /> If you like it, go to it, of course. It takes all types to make a world, after all.</p>

<p>I'm still not even sure that the Canonet camera was an EV system, anyhow. If it worries you, look it up. I'm away from my main system and files and am not a big fan of trying to do complex internet searches on my phone.</p>

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On a historic note: The reason the EV system went away, JDM, was that automation had arrived. Not that it was a bad idea disliked by the marketplace. It was something no longer needed.<br>Nowadays, nobody really selects, only adjusts, apertures and shutterspeeds (once the 600+ page user manual has released the closely guarded secret - hence the many pages - about how to correct the decisions made by those cameras the marketplace has embraced).<br>Only in crappy old camera forums do people still mention the EV system now and again. Many thousands and thousands professional photographers did use it on a daily basis once. But those days have indeed past away.
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EV systems:

http://en.wikipedia.org/wiki/Exposure_value

 

I do remember the EV system for Hasselblads and thought it was neat, but you could also read the combinations of applicable shutter speeds and apertures right from the dial of your favorite exposure meter. Built in meters which were coupled to the cameras exposure system (either match needle or AE) was a simpler solution. Frankly I don't know how I managed using match needle exposure systems that didn't have the visual highlight/shadow clipping indications I now see in my EVF before taking the photo.

 

FYI, I still cherish my Canonet QL17 (in black), that I inherited from my father.

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<p>John, I had look at your photos of your Canonet to figure out what you were talking about. I have the same camera, but it's a Bell & Howell imported camera. Curiously, there are no indoors/cloudy/sunny symbols by the ASA adjustment on my sample, only the speeds numbered from 10-400. I wonder if this was added later, or left off the imported versions for some reason.<br>

<br /> I've used the auto exposure once with this camera. It worked well in bright sunlight. I haven't tried it indoors, but playing around with it just now, it seems that the shutter lock-out engages when it should and the meter selects what appear to be appropriate apertures.</p>

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<p>@Robert: The Canonet is not the only camera suffering from light seal detoriation, this applies to almost all cameras with foam seals. <br>

There is at least one guy on ebay selling light seal kits designed for the Canonet. You can also cut your own strips with a sharpie knife from sheets of black dense foam rubber. <br>

BTW there are some Ricoh rangefinder cameras where the light seal foam covers about 1/3 of the inner back door, guess what a mess you can find in some of them...</p>

 

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