Canon AT-1 Metering Pattern

gone · Sep 19, 2013

After spending more time and money on the auction trying to get a decent A series Canon camera that didn't squeal like a stuck pig, I finally found something different. It's an AT-1, the first I've ever owned. I like the simplicity of the camera. It doesn't have AE, so all you see in the viewfinder is the match needle metering. Sort of the poor man's Leicaflex, although that's a stretch, and it's a lot smaller and lighter than a Leica. The shutter, for now, is nice and quiet, and I almost fell out of my chair when I tested the speeds....they're all on the money, including 1/1000, which has never happened in my experience. Unless something I've over looked rears it's head, it looks like a good replacement for my beloved F-1. I really like that F-1, but w/ only one FD lens, it doesn't make sense having it when a lighter and cheaper camera will suffice. I can buy film w/ the money saved once the F-1 sells.

What has me mystified is the metering pattern. Whilst pointing the camera at things and checking the metering (again, on the money), I noticed that it seemed much more sensitive than the AE-1 and AE-1P cameras. Just pointing the camera from the ground, to across the street, and up to the sky saw the needle really swing all over the place. I like that of course, but what exactly is the metering pattern? Anyone here shooting one of these? After thumbing through the manual that came w/ it I'm still in the dark. Said manual only describes it as "central metering", whatever that is. That doesn't sound like center weighted to me, and the meter seems to act as if it's possibly semi spot, for lack of better words. Information on this camera is not readily available like the AE variants. It seems to have an older style CDS meter. You turn it on and off w/ a switch on top like the older FT cameras.

BMbikerider · Sep 19, 2013

The squealing like a stuck pig is not a serious problem with a Canon camera. I have seen/heard a good few Canon A1 models demonstrate this and[peace and quiet is easily restored by a simple service and a mirror hinge lubrication. it is a case of "They all do that sir (at some time)"

blockend · Sep 19, 2013

I'm fairly certain the AT-1 is centre weighted. I just tried mine and the metering is steady and progressive moving from ground to sky. It's unlikely you have the wrong battery, so I'd check electrical contacts. Also, try taking off the lens and see whether the meter still acts erratically. In the end, if the meter is indicating the correct exposure, I'd live with its mood swings.

The AT-1 is mistakenly overlooked, because it emerged in a period when automatic exposure was a must-have accessory. It wasn't even available on the Japanese domestic market, but was aimed at emerging countries where the extra price of auto was a deal breaker. In every other way it's a standard A-series camera. It has some rare assets for a full manual camera today, it takes a readily available battery (not an arcane mercury cell), it's fairly light (unlike most full manual cameras that are heavy metal), it has a proper PC socket for flash, a stop down switch and that huge shutter speed dial under the wind-on lever. The AT-1 isn't as 'cool' as some classic manual exposure cameras, but it is extremely practical and they can be picked up very cheaply. They were often pampered and are likely to be in much better condition than your typical Nikkormat/ Spotmatic. Just remember to turn off the meter when you're done, like an OM-1.

Mackinaw · Sep 19, 2013

Yes, it has center-weighted metering. See this article on the Canon Museum website:

http://www.canon.com/camera-museum/...at1.html?lang=us&categ=crn&page=1976-1985&p=1

Jim B.

flatulent1 · Sep 19, 2013

On page 8 of the manual they refer to it as 'TTL Central Emphasis Metering method'.

I've always admired the AT-1's simplicity. At one time I had several of them, but then I started to accumulate F-1 bodies and stopped using the AT-1. Nice camera, though.

gone · Sep 19, 2013

I read that in the manual. It's an interesting manual. Says things like "remarkably advanced camera", flawless product", "incomparable system", "extremely reasonable price", "superb advantages", "fabulous electronic system", "unsurpassably versatile performance", "wonderfully silent electromagnetic release", etc. You get the drift. So I am not going to put much trust in ad copy written by a bunch of marketing types apparently locked in a hotel room w/ lots of speed and a thesaurus.

Maybe the stuck pig squeal isn't annoying to you BM (there's no accounting for people's taste), but I assure you it is to me, and that's all that matters. It's annoying enough to where it has resulted in a cottage industry of youtube videos devoted to DIY fixes, and repair places offering to cure it (always for more money than simply replacing the camera would cost). The A series cameras actually have a very nice, pleasant shutter sound. When they begin to squeal it's not good, and you can forget about getting a second candid shot. This is the first A camera I've seen in about a half dozen that had accurate shutter speeds. Some of them only fire at 1/250 even at the 1/1000 setting, and two I had fired at 1/200 no matter where you set them from 1/250 to 1/1000.

I'm w/ you blockend, they're sweet little cameras, and their simplicity is the exact opposite of the way Canon was going at the time. I'm willing to bet they're more reliable in the long run too. They never made them in black finish unfortunately, but I have paint. I'll go w/ the advice here on the metering pattern, and maybe play around w/ it w/ a light source, and see if that will tell me just where the pattern actually is.

gone · Sep 19, 2013

A quick test, pointing the camera at a lamp w/ a 135mm lens on it, showed that the metering pattern is significantly different from my F-1n. The F-1 has a rectangular patch in the center of the focus screen around the split prism, and that is apparently where it's metering pattern is. When I tested the F-1 w/ the lamp, that was pretty close. On the AT-1, the metering pattern, at least on this AT-1, is almost like a spot meter. It is much tighter, almost as if most of it's meter pattern was the split prism w/ fresnel circle in the center. Both have CDS meters I think, but the AT-1 is MUCH more sensitive to slight light changes. Of course, shooting film through it will tell the tale, but what I see looks very encouraging. I should probably ck the battery to see what's in there, but as it meters exactly w/ my handheld Sekonic, better to let sleeping dogs lie. Supposedly only the AT-1 requires an alkaline battery, whereas the AE-1, A-1, etc can use any old battery that supplies the proper voltage. I suspect the AT-1 can too.

blockend · Sep 19, 2013

I agree on the Canon Cough, Momus. I only had one camera with it, an A-1 that came with a bunch of prime lenses and which I regarded as a free gift. A guy in the UK fixed the camera and gave it a CLA at very reasonable cost, or it would have stayed in the drawer. Nobody needs a noise like that, and if left it slows everything down until the mirror shows in the image and ultimately seizes altogether. A friend bought an A-1 new in the late 70s and his developed the cough quite early on. It was a design fault because the succeeding T-series never suffered from the malaise.

That said, the A-Series has benefits I mentioned before. Another favourite, for exactly opposite reasons to the AT-1, is the AV-1, which was available in black (I regard black AT-1s as largely mythical beasts). The AV-1 is basically a point and shoot with interchangeable lenses, like the T50 that followed it, though a lot prettier and without the LCD, or that incredibly noisy film advance. The manual wind on is the reason I still return to the A-Series.

Charles Wass · Sep 19, 2013

There seem to be different opinions on the metering pattern. Here's another one. I panned slowly across an intense small lamp, both vertically and horizontally. The needle moved smoothly and gradually through the whole pan showing centre weighting, with some coverage right to the edges of the frame. Interesting the response seems to be symmetrical rather than bottom weighted as some cameras are, eg. the EF.

elekm · Sep 19, 2013

Most consumer cameras from that era that weren't spot metering used a center-weighted averaging meter pattern that took up roughly two thirds of the screen with the emphasis on the center of the screen first and, to a lesser degree, the bottom of the screen.

AgX · Sep 19, 2013

Nearly concentric, oval segments with slight emphasis on the lower half.

John Koehrer · Sep 19, 2013

elekm said:
Most consumer cameras from that era that weren't spot metering used a center-weighted averaging meter pattern that took up roughly two thirds of the screen with the emphasis on the center of the screen first and, to a lesser degree, the bottom of the screen.

Minolta SRT's used their CLC system that biased the reading toward the bottom, reducing the tendency to underexpose.

CLC=contrast light compensating.

benjiboy · Sep 20, 2013

If you need to know the precise metering area and don't want the A series cough that's caused by the mirror braking mechanism I suggest you buy an F1 or FTb they are also both all metal, better made, and more reliable cameras than the AL1.

tokam · Sep 20, 2013

Some of the A series Canon SLR's can also have a problem with a cover over the metering cell. Apparently it can go cloudy over time.
I don't know if this can be cleaned or if the cloudiness goes right through the material. I have my doubts that new replacements are
still available. Perhaps the cover could be removed during a CLA.

I found this out recently when my AE-1 was overexposing by 2 stops. I also checked my A-1 against a Canon EF, an F1-N and a T90 and it
was overexposing by 1 stop compared to the other three bodies. My A series bodies are both in exc condition and were last serviced
within the last 10 years. No mirror squeak. For the time being I'll just compensate via the film speed dial. I like using the A series bodies from
time to time as they are a lot lighter than my other FD's.

Xmas · Sep 20, 2013

see page 32 of the manual the download is free...
http://www.butkus.org/chinon/canon/canon_at-1/canon_at-1.htm
but Lynn will accept a sub
but it is centre weighted with a downward bias to miss out the sky - I.e. no spot meter pattern

Photo-gear · Sep 21, 2013

blockend said:
The AT-1 is mistakenly overlooked, because it emerged in a period when automatic exposure was a must-have accessory. It wasn't even available on the Japanese domestic market, but was aimed at emerging countries where the extra price of auto was a deal breaker.

I also heard this camera was intended for the North American market. As a matter of fact, I got hold of one of these in mint condition for some 20$... And it works perfect. I consider this camera as a perfect camera replacement and much less expensive than the A-1 or AE-1 ones. A real underestimated camera.

AgX · Sep 21, 2013

The AT-1 not just lacks the autoexposure feature of the AE-1. The metering range of the AE-1 starts at EV1 that of the AT-1 at EV3.

Xmas · Sep 21, 2013

the meter pattern is ok in a manual camera 99% of time it is a light meter not an exposure meter the exposure meter is supposed to be between ears.

Canon AT-1 Metering Pattern

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