Compensate for a 3 stop filter on 35mm f/1.4 + M262

[Adalsteinn S.H.]

Advertisement (gone after registration)

Hi there. I just received a 3 stop MRC filter from B+W it put on my 35mm 1.4 FLE on my M262.

 

My first reaction to the images shot at f/1.4 is that the images are very dark. I thought that the metering happens through the lens and therefore that the meter would compensate automatically.

 

Do I need to compensate for these three stops or what are your thoughts on this?

[Exodies]

Did you have too small an aperture or too fast a shutter speed or too low an ISO or too low an EV adjustment leaving no room for auto exposure to do its job?

[Adalsteinn S.H.]

Did you have too small an aperture or too fast a shutter speed or too low an ISO or too low an EV adjustment leaving no room for auto exposure to do its job?

 

 

Aperture set to /f1.4 in bright daylight (the point of the 3-stop filter in my case). The rest set to auto. My take is that I need to compensate fully for these three stops, at least when the camera is set at f/1.4. Seems though that images shot with the 3-stop filter, shot at f/2 and smaller apertures are closer to being correctly metered. Weird behaviour. 

Edited October 6, 2018 by Adalsteinn S.H.

[totocaster]

Does your filter has a deep thread (or grip) so it causes vignette which might confuse metering? 

 

I'm using a similar setup (2 stop ND on 50 Lux) without any issues, even with automatic shutter and no exposure compensation. My camera is M-D.

[sblutter]

As always with new equipment - get to know it.  Experiment with manual settings etc.

[Adalsteinn S.H.]

On 10/7/2018 at 5:53 AM, totocaster said:

Does your filter has a deep thread (or grip) so it causes vignette which might confuse metering? 

 

 

 

 

I'm using a similar setup (2 stop ND on 50 Lux) without any issues, even with automatic shutter and no exposure compensation. My camera is M-D.

 

It might be the fact that this MRC filter is not a thin one but the regular one. It's obvious that the filter messes with the meter and underexposes all images shot at f/1.4 drastically. 

Might buy another one, thinner this time. 😊

[Exodies]

Advertisement (gone after registration)

If the filter casts a shadow on the meter then the picture should be over exposed.

[marchyman]

On 10/6/2018 at 6:15 AM, Adalsteinn S.H. said:

what are your thoughts on this?

Have you tested with/without the filter in exactly the same circumstances?

I'd put the camera on a tripod and take a picture.   Then, without moving the camera I'd install the filter and take a second picture using the same aperture.   I'd do this indoors using artificial light to ensure the lighting didn't change between shots.

I'd expect the exposures to look the same, albeit the one with the filter shot at a 3x slower speed.  If not I'd start looking as to exactly what the filter blocks (does it pass some colors better than others?) and exactly what the sensor on the M measures.   We know that it measures the light bouncing off the shutter curtain.  Perhaps the curtain is does not reflect as well in low light (if that is even possible).  That can be somewhat tested by adjusting your light/aperture such that the camera uses its highest shutter speeds without the filter and then repeating the test with the lens stopped down to force slower shutter speeds.

If nothing else you'll learn how your camera/lens/filter work and will be able to adjust exposure accordingly.

[Exodies]

The filter causes the picture to be under exposed. This would seem to imply that the meter is seeing more light than the sensor.

[Peter Kilmister]

@Marchyman: Great diagnostic techniques to use artificial light, etc.

[roverover]

On 10/6/2018 at 6:15 AM, Adalsteinn S.H. said:

Hi there. I just received a 3 stop MRC filter from B+W it put on my 35mm 1.4 FLE on my M262.

 

My first reaction to the images shot at f/1.4 is that the images are very dark. I thought that the metering happens through the lens and therefore that the meter would compensate automatically.

 

Do I need to compensate for these three stops or what are your thoughts on this?

An additional thought: You may also want to experiment with the "metering mode."  Perhaps "Muti-Field" metering might provide better results with a Filter if you might be using Spot or Center-weighted metering as light coming through a wider area of the FILTER would be taken into account.

Edited October 19, 2018 by roverover

[marchyman]

M262 does not support multiple metering modes.  You get the "classic" center weighted mode which measures the light reflected  the shutter curtain. 

[roverover]

7 minutes ago, marchyman said:

M262 does not support multiple metering modes.  You get the "classic" center weighted mode which measures the light reflected  the shutter curtain. 

OK, got that, my answer was based on my M240.