Metering in camera with tele converter

[fixedimage]

I posted this over in film and conventional but thought I'd ask here too as more people might see it.

I have a 2x tele converter for my Konicas.

I understand that when i use this it reduces the amount of light that reaches the film.

The Konicas are manual/shutter priority with a ttl meter that displays the correct aperture for the set shutter speed in the viewfinder, there is an auto exposure setting on the lens which when enabled lets the camera set the aperture as per the meter. My TC also has an auto exposure mode.

Fitting the TC changes the meter reading as expected.

Putting the lens and TC into auto exposure mode should result in a correct exposure but if I want to manually control exposure and use the in-camera ttl metering, do I have to compensate for the light reduction factor of the tc? If the camera specifies f4 as being the correct aperture for a scene should I be setting f2.8 or something?

 

[DazJW]

If it's TTL the camera's meter is seeing the amount of light that's actually coming through the lens and I don't think it knows the difference between light loss from a TC, an ND filter or a dimly lit day. The aperture that it tells you is set will be two stops larger than the real aperture being used but it shouldn't affect the metering.

For example if you set 1/250 shutter speed and it decides the appropriate aperture setting is f/4, the real aperture will be f/8 but the camera doesn't know that it's a TC rather than an ND4 filter or a day with a quarter as much light.
You could lose or strongly reduce the effectiveness of autofocus as it needs a certain amount of light to be able to work well.

 

[j37r]

Shouldn't have to, the camera's metering system is measuring the light through both the lens and the converter so should give you a near enough correct reading.

Checking this with my T90 and 50mm F1.4 lens set to F5.6, I had a reading of 1/250, after fitting the X2 adapter I had a reading of 1/125, so the effect of the adapter was taken in consideration by the metering system.

You could cover yourself by bracketing 1/2 stop either side.

John

 

[fixedimage]

That's what I thought but the more I thought about it, the more confused I got!

There's no worry about AF as it's a manual focus Konica I'm using it on.

I dunno why I haven't used this TC before, I now have the option of 40mm f1.8 (really nice walkabout prime, the little bit of wideness over a 50mm is great) or 80mm f4ish (really nice portrait length) by just sticking the tiny TC in my pocket.

 

[Oggy]

Shouldn't have to, the camera's metering system is measuring the light through both the lens and the converter so should give you a near enough correct reading.

Checking this with my T90 and 50mm F1.4 lens set to F5.6, I had a reading of 1/250, after fitting the X2 adapter I had a reading of 1/125, so the effect of the adapter was taken in consideration by the metering system.

You could cover yourself by bracketing 1/2 stop either side.

John

Agreed. I had a 2x on my OM1 and never had to adjust anything to get the right exposure.