FTb dark picuture

greenspun.com : LUSENET : Canon FD : One Thread

A followup on my problem with dark pictures on my FTb.

Thanks for the help so far, but.... I have the proper battery, ran the battery test shutter speed on 1000 and ASA setting of 100. The meter needle is 1/2 inch above the index knob on the RHS. It's "just" above it at a ASA setting of 50 with shutter at 1000. So..... how do I shoot pictures and trust the meter needle.

For ASA100 film, set the camera to ASA50?

For ASA400 film, set the camera to 200? or 350? Or probably just get meter needle calibrated properly at a camera shop? thanks for your help and suggestions. Then maybe as the battery weakens, the camera check will work properly. tom

-- Tom Koman (hiramm@us.ibm.com), May 05, 2000


Hmm. I'm not sure I have the expertise to fully answer your question. I have only ever had one battery in my FTb and it wasn't new when I got it.

It may be that the result you see is normal for a fresh battery - above the line is 'good'. However, as the distance above seems quite large, I suspect that you may be using a 1.5v battery in an unmodified FTb. Your camera shop should be able to confirm the voltage of your current battery.

I'm not sure that adjusting the ASA to give a correct battery test will work. Unfortunately, life is rarely that simple.

You have several options:

1. Request a CLA (Clean, Lubricate Adjust) for your camera from a reputable repairer of FTbs. Specify what type of battery you want to use and supply an example. As part of the CLA, the repairer will adjust the meter to be correctly calibrated for the batteries you will use. This will be a significant cash outlay, probably in the range $50-100.

2. Carry on as normal. Your shots may be slightly underexposed, but this will probably be within the range that print film can produce satisfactory prints.

3. Get hold of all the possible batteries and try them one by one to see which gives the correct battery check result.

4. Perform a careful test in constant light conditions to determine the over/underexposure of your camera. Use (cheap) slide film, as the prints from print film will all look the same. Ideally, the subject should be a 'grey card', but any low contrast mid-toned subject, such as a typical grass lawn, will do. Expose slides at the correct exposure and at 1/2 stop intervals above and below (e.g. 0 (correctly exposed according to the meter), +0.5, +1 , +1.5, +2, +2.5, +3, -0.5 - 1, -1.5, -2, -2.5, -3). Keep careful notes. You can place little cards near the edge of the picture to record the information in the frame.

The frame that is correctly exposed tells you the adjustment you need to make - you can do this using the ASA dial, or by clicking forward or back that many stops using either the shutter speed or the aperture dials.

For example, if the +1 frame (overexposed by 1 stop, e.g. f5.6 where f8 is indicated by the meter) is correctly exposed, you could do any of the following:

A. Set the ASA dial to 1/2 the correct ASA speed and meter as normal (A film with half the ASA requires twice the exposure, or +1 stop). B. Meter as normal with the ASA dial set correctly, then open up the aperture 1 stop (e.g f16 to f11) C. Meter as normal with the ASA dial set correctly, then reduce the shutter speed 1 stop (e.g 1/500s to 1/250s)

The difference may change slightly for different brightnesses of illumination of the subject, but this shouldn't worry you at all if you are using print film.

-- Roger Broadbent (roger_broadbent@yahoo.co.uk), May 05, 2000.

You say you have the proper battery, but what battery? The proper PX625 mercury cells have not been available in the US for several years. The Wein cells are a suitable replacement.

If someone adjusts the meter for alkaline 625 cells, that still doesn't fix the problem, as the alkaline cell has a fairly steep discharge curve, in the it starts at about 1.5 volts, but falls to about 1.1 volts when dead. So the meter is not right most of the life the battery. A mercury cell or zinc-air cell starts at 1.35 and stays at 1.35 until just before it dies quickly.

The other thing is, if you are taking print film, the automatic printer is messing up its exposure.

To really find out what your meter is doing, get some slide film, and shoot a test. Take several typical scenes and shoot them at the indicated exposure, and then bracket by 1/2 stop up and down for at least 2 stops. Most of the shots should be very far off, but one of each set should be right. And that will tell you how your meter is reading.

Also, you have to understand how meters work. The meter tells you what settings to use to make the metering area show up as neutral gray on the negative. So if you meter a bright object (like snow in sunlight) the indicated exposure will be too little and the snow will end up looking gray. If you meter something dark, like a black cat, the meter will indicate too much exposure ending up with the cat looking gray in the picture.

When you do prints, the printing machine also does a similar thing. And if you are taking the film to a cheap one hour place, they are running the machine pretty much on auto, and their "meter" tries to make the whole print neutral gray. A print with lots of light area will end up too dark and a print with lots of black will end up too light. A classic place to see this is shots of fireworks. Most bad processing will end up with prints with a gray sky rather than black.

-- Terry Carraway (TCarraway@compuserve.com), May 05, 2000.

Moderation questions? read the FAQ