Just played with a OM4T. Lots fun but because there is wear and tear on it, I hearby declare it to butt ugly. Looks like when something plastic wears.
Yoshihisa Maitani was a genius and came up with some fantastic cameras!
According to the May 1976 Modern Photography review of the OM2, OTF metering works different at 1/60 and above or less than 1/60. At 1/60 and above, it is off the first curtain. Below 1/60 and it is partially off the first curtain and film and will also adjust to the scene's lighting changes. I don't have a review of the OM4 so I am not certain if it continuous to work this way or not.
BTW, the only other camera that I know of that used OTF metering was the Pentax LX. This took the concept a bit further as it can meter for as long as it takes for a proper exposure or the battery dies - monitoring the scene for lighting changes and adjusting exposure in realtime.
More correctly I should have stated that besides the Olympus OM's, the Pentax LX uses OTF on all exposures - manual, aperture priority autoexposure and TTL flash.
Tim, The manual for the OM4T specifies an autoexposure of about 4 minutes - which is what I have managed to get on mine. So for the several minutes exposure you have gotten is that also autoexposure or just bulb?
It doesn'tI wonder how it does OTF exposure in manual?
Unlike the OM2 - which in manual mode has CDS in the viewfinder, the Pentax LX uses the same single SPC metering off the film plane.
Or you could do whatI read on the internet a couple of years ago, for all models of the OM2SP, OM4 and OM4T/i when not being used turn the shutter speed dial to B this disconnects the battery circuit and prevents battery drain. I have been doing this for a couple of years with no adverse effects and no battery drain on my OM bodies, I also do it with my OM2ns.
The Pentax LX when meter in manual doesn't measure the light off the film but rather via the piggy back mirror that reflects light to the sensor (similar to that of the Nikon F3)
The patterned shutter curtain, rear-facing sensor and the two-part mirror, like the OM-2S, OM-PC, OM-4/ti and OM-3/ti?
The design and technology was invented first by Olympus.
Just sayin'...
And both LX & F3 actively meter off the film plane when mirror is locked up. They differ in that the F3 does not use the patterened screen while the LX does. They also differ in autoexposure mode as the F3 determines exposure at the time of shutter trip while the LX will continue to meter the scene in realtime - varying shutter time accordingly, for as long as it takes to get a proper exposure or the battery dies.
Chan, When the mirror is down, the sub mirror reflects the light to the SPC (Silicone Photo Cel). When the mirror is locked up, the backward pointing SPC detects the light off the film plane - more precisely off the shutter curtain, as there is no sub mirror to reflect it back. This of course is very simple to test as you only have to take your F3, lock the mirror in the up position, activate the metering by half pressing the shutter, face it towards a light source and move the aperture ring and you will see the meter respond to the changes. This works this way in manual mode or aperture priority and OTF TTL flash. Meter a long or short exposure - manually or aperture priority, and once the shutter is fired it will stay on course regardless of any changes in light.
I've just read that crash test for the first time (I didn't know about it).
Interesting, but I think the reviewer makes a very common mistake about the lightmeter of the OM cameras, and I would like to know for certain once and for all:
This is what is said in the crash test about the off the frame metering:
"the shuttercurtain contains a complex, computer-calculated field of white dots. This field stands for an average exposure value for your subject. The field is measured by the meter of the camera the moment the shuytter flips up, just before the shutter opens. By means of this, the camera meter can adjust to a change in lighting of your subject in the very last instant and thus expose correctly".
I think this is plain wrong and doesn't do justice to the ingenuity of the lightmeter.
I always understood that the field of white dots on the shuttercurtain is used by the meter to show you BEFORE the exposure what value it measures, but that it adjusts DURING the exposure by metering directly from the film itself at that moment. So, it does not adjust "in the very last instant", it adjusts really while exposing.
This explains why, when "shooting" without film, the exposure time is quite a bit longer than indicated by the meter before pressing the shutter (you don't have to measure it: it's obvious; try with 1/8th to 1/2 of a second: you'll notice the difference): in that situation, during the "expsoure", the camera sees a "black hole" (the pressure plate), since there's no film, and hence uses a much longer exposure time than indicated right before pressing the shutter.
This is also useful when using the Olympus flash: the camera can cut off the flash even DURING exposure. Imagine a lot of photographers making a picture of the same subject, all at the same time, with flash (e.g. newsreporters): the OM will be able to expose correctly, because it will "see" the flashes of the OTHER cameras during exposure and will adjust accordingly while exposing.
I always understood this the case both with the OM-2 and the OM-4. Considering the time when the OM-2 was made, this was revolutionary (but I think often misunderstood and thus underestimated, and the genius of Maitani should not be underestimated).
I don't know if there is or has ever been another camera that can do this. I don't think so.
Stefan.
Is it bright enough to read in the dark (unlike the Nikon's)?
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