Using an AF Nikon As An Exposure Meter

[Ko.Fe.]

I was very skeptical but decided to try one. It’s called simply, myLightMeter. I have iPhone 6 and 7. The app works so well that I stopped carrying a real (gossen) light meter. I think I did pay for this app...maybe $2.99?

I'm using free apps and they are awesome. WYSIWYG.

 

[ic-racer]

If you have a older Nikon DSLR like a D200. Put it in manual, spot meter you get a real time proof.

This thread is about B&W film exposure with the Zone system. Those cameras exposure index is based on the highlight, like transparency film. So not suitable.

 

[Alan Edward Klein]

This thread is about B&W film exposure with the Zone system. Those cameras exposure index is based on the highlight, like transparency film. So not suitable.

Does a spot reading on a digital camera provide a different reading than a spot reading on a dedicated light meter?

 

[mshchem]

I have had several spot meters over the years. Really useful tool. I have no idea what kind of voodoo goes on inside a digital camera. I know that there's a lot of used bodies out there.
I use incident metering, easy and reliable. Modern films, in development, don't respond like the good old films like Ektapan, Super-XX etc.
Using a built in camera meter or a hand held reflectance meter without a gray card can be tricky.

I used a good old Pentax analog spot meter, I bought one of the decals that Zone VI sold, worked great. I would recommend a meter that is easy to understand. The thing nice about my old Pentax was it took 49mm filters, so no fiddling with filter factors etc.

 

[ic-racer]

Does a spot reading on a digital camera provide a different reading than a spot reading on a dedicated light meter?

There is nothing that indicates they would be the same. For example, ISO 12232 for digital cameras quoted below. This is nothing like film ISO or ASA where exposure is based on the minimum gradient of the toe that produces an excellent print by a panel of observers.

Also, if you have a digital camera that shows a histogram of its sensor's response, you will likely see that a uniform target, exposed to the camera's "ISO" setting produces a cluster of pixels 3 or 4 stops from the brightest values available from the sensor, not from the lowest values.

In fact on my wife's camera (Nikon D90) the middle gray is SIX stops from the lowest sensor response. Probably explains why any over-exposure is not tolerated (blown highlights).

To provide a means for simply communicating exposure information, this document specifies an exposure index (EI) that corresponds to the focal plane exposure of a typical mid-tone. It is intended to be used for setting the camera exposure and as a record of the camera exposure in image files. ISO 12232 Digital Still Cameras

 

[Chan Tran]

Does a spot reading on a digital camera provide a different reading than a spot reading on a dedicated light meter?

I have the Nikon F5 and a Nikon Df (the 2 cameras I own that have spot metering mode). Both of them are within 1/3 stop of my Minolta Flashmeter VI in spot mode. Both the camera readings are slightly higher.

 

[ic-racer]

Old digital cameras are inexpensive and there are some resources out there for calibrating them to be used as light meters. Here is just one example, I'm sure one can find other methods of calibration or come up with one's own method.


https://www.image-engineering.de/content/library/conference_papers/before_2009/luminance_meters.pdf

Just to re-align this thread. The idea of using the Nikon's own spot meter was to use the Zone system with the Nikon film camera and not have to carry another meter!

 

[Alan Edward Klein]

My Olympus E-PL1 reads the light at the same exposure as my handheld meters. Either middle gray is middle gray or it isn't. Is a digital camera set up for middle gray at 18%? Now, when in center metering mode or one of the other fancy metering modes, the camera may compensate for highlights. But I don't see why it won't read the same as a handheld meter when in spot mode as long as it's calibrated for 18% gray.

So who knows the answer to that?

 

[ic-racer]

I don't know about 18% gray; I don't think any reflection meter is calibrated to that of which I am aware.

A meter can give any exposure the manufacturer wants based on the chosen "K" constant. Frequently this is listed in the specs for the meter. If your meters agree, that is great, you don't have to re-calibrate the digital camera.

I don't know how you would be metering, but for B&W film, one would want to do like the Matrix meter does, and find the low values that would need to be imaged on film using the digital camera's histogram. If using the histogram of the digital camera, heed the warning that the middle calibration point is based off the highlights. So some calibration is needed.

If you are using the digital camera just like a hand-held spot meter, without the histogram, the results might be inferior to the Nikon film camera's own built-in Matrix metering for film exposure.

 

[Craig75]

What degree is the spot on the F6?

 

[ic-racer]

What degree is the spot on the F6?

Most of the Nikon manuals don't say, because the spot size depends on the lens of the camera. By experimentation, the meter area seems to be within the focus sensor marking in the viewfinder.

 

[Craig75]

Most of the Nikon manuals don't say, because the spot size depends on the lens of the camera. By experimentation, the meter area seems to be within the focus sensor marking in the viewfinder.

Just had a look at the manual and it says "Nearly 100% of the meter’s sensitivity isconcentrated on the 4mm-dia. area (approx. 1.5%of entire frame) within the selected focus area ofthe viewfinder"

Moving focus point moves spot with it.

So nice and tight spot reading straight off sensor.
So just a simple case of read, lock, exposure compensation.

F6 really does look a beast. Im annoyed i slept on this camera as it sounds an animal.

 

[Alan Edward Klein]

I don't know about 18% gray; I don't think any reflection meter is calibrated to that of which I am aware.

A meter can give any exposure the manufacturer wants based on the chosen "K" constant. Frequently this is listed in the specs for the meter. If your meters agree, that is great, you don't have to re-calibrate the digital camera.

I don't know how you would be metering, but for B&W film, one would want to do like the Matrix meter does, and find the low values that would need to be imaged on film using the digital camera's histogram. If using the histogram of the digital camera, heed the warning that the middle calibration point is based on the highlights. So some calibration is needed.

If you are using the digital camera just like a hand-held spot meter, without the histogram, the results might be inferior to the Nikon film camera's own built-in Matrix metering for film exposure.

Using my digital camera instead of my meter is new for me. I'm still experimenting. I set it on Aperture Priority and f/22, the smallest available. I check both the histogram and the view on the screen and snap a shot recording the settings for reference. Then I offset what I need on the film camera. If I'm shooting Velvia 50 chrome, I make sure the histogram isn't clipping the whites. I'll try to get the histogram to fit into the full range. If I'm clipping the whites, then I move the camera or switch to Manual mode and change the shutter speed to eliminate the clipping, and take a reading snap to record the settings. If I'm shooting a negative BW film, I'll do the opposite at the black end of the histogram.

I'm still making mistakes in the operation of my new 4x5 and in transferring settings to it. So, I'm not sure if my procedures are good for the long run. If anyone has suggestions on how to improve my procedures, I'd be glad to hear them.

 

[ic-racer]

Either way, if you use a traditional spot meter, or a digital camera with histogram for B&W film exposure, you will have to calibrate the device to your film. I think if you use a traditional spot meter for Large Format B&W it will be easer to communicate what you are doing with other Large Format photographers. If you run into trouble printing negatives and start writing about the left side of your digital camera's histogram, no one will know where errors might be in your work flow.

 

[DMJ]

With a reflectance K constant of 14 (Minolta) you get a value of 18% reflectance which is the value of the 18% test card.

I shoot 6x6 and used to have an E-PL5 that I bought for metering. I had a 25mm lens to have the same view as the 80mm and I would meter using the histogram and zebra with the live view set to square and B&W. It was always off because of the lens absorption (cheap lens). Now I use a Sony NEX with pentax lens and get "accurate" readings. I like a centered histogram because I scan the negatives to make digital negatives and then work the contrast with curves.
I also developed an incident meter for Android that uses the calibration C=250 (Canon) and works for me. It uses the front light sensor and does average metering by holding a button and moving the phone around to get the readings of highlights and shadows.

Here is the link: https://play.google.com/store/apps/details?id=com.mjsoundlab.incidentlightmeter&hl=en_US&gl=US

I never had a spot meter and I don't think I need one. For incident metering it is nice to have something that works with AA batteries, portable and reliable, like the Sekonic L-308. When I shoot 35mm, I use the built-in meter of my Canon in matrix mode.

 

[George Mann]

I use a DSLR as a doorstop all the time. It also works well as a wheel chock. Or a bookend.

Mine works as a dust collector most of the time.

 

[Sirius Glass]