gvarner Loc: Central Oregon Coast

Each metering system has its own quirks which causes each to render the scene in its own way.

Longshadow Loc: Audubon, PA, United States

davidrb Loc: Half way there on the 45th Parallel

Everything? Apparently not true. If possible look at the focus points used and compare them to metering. Metering is the only variable in the exposure equation. Exposures are different when everything remained the same? Metering was changed.

lamiaceae Loc: San Luis Obispo County, CA

(Sorry for the apparent late response, I started this reply right after User ID's first response, I tend to write slow and methodically) I agree with User ID. Explicitly, differences in the positions of light sources and the reflective levels of objects in the frame will affect the Meter Reading in Manual or AE.

I have seen the same effect as CapMike in my own photographs, though I figured out why on my own. I also have gotten this effect in consecutive frames in the same camera as well as between two cameras of the same scene shot with in seconds of one another. Note, I have Five cameras all different models, and I rarely if ever shoot in bursts. Also I usually have AF set to S or M, and exposure set to Aperture Priority.

As was also pointed out by others, not allowing sufficient flash recycling time can cause this effect too. Because I often share cameras with my wife I usually leave the camera on Center Weighted or Matrix Metering & Focus, but for my own use I prefer Spot Metering and Spot Focusing. I try to meter off something in my frame that is / is to be mid-toned (a Zone System zone V). Enjoy your photography!

User ID

Posts by a few of our Long Form Essayists will help it along .....

Picture Taker Loc: Michigan Thumb

If a spot meter one shot could have picked-up the dark clothing and next the face.

Longshadow Loc: Audubon, PA, United States

Exactly. It depends on what the "spot" is over.

aphelps Loc: Central Ohio

If you are using fill flash might have fired two (or more) in succession, it is possible the flash may not have fully recharged from one frame to the next. Just a thought.

selmslie Loc: Fernandina Beach, FL, USA

Not just a thought but finally the right answer.

It’s disappointing but not surprising how many responses missed this.

aphelps Loc: Central Ohio

Thank you Selmslie. It was the first thing I considered after hearing "outside" and "fill flash". Those facts ruled out many of earlier responses.

larryepage Loc: North Texas area

There's actually another possibility...one that neither EXIF data or looking at example images will help diagnose. Since this is old cameras, it is actually quite a good possibility that the diaphragm blades in the lens are "sticking"...either not opening fully or not stopping down completely when pressing the shutter. Ordinarily, I would expect this to lead to overexposure if it's a lens problem (full dosage not reaching the meter of the aperture doesn't open, or too much reaching the sensor if it the diaphragm doesn't close down). But if the problem is with the actuating lever in the camera, it could possibly go either direction, based on what might have failed or is sticking.

It would be a simple matter to remove the lens and operate the aperture lever manually to check whether it freely and easily changes the lens opening. Then put the lens on the camera, set it to Manual with a shutter speed slow enough to let you see what is going on, and snap some images while looking into the lens at various f/ stop settings to see if everything is working OK. You can probably even do this diagnosis over the phone...don't have to wait for the next visit.

I'm sorry that she is having trouble. Hope she gets it figured out.

Longshadow Loc: Audubon, PA, United States

You mean when the ready light come on it might not actually be ready?
Do flashes fire before the ready light comes on? I've not noticed.

Markag

I've noticed when taking multiple Z7 shots with one shutter press, 3 generally, that the NEF's are of different sizes. Splain that?

selmslie Loc: Fernandina Beach, FL, USA

Exactly!

The ready light might come on and the flash can then fire before the capacitor has reached its full charge. This is more likely when the batteries are getting weak.

JD750 Loc: SoCal

Ok let me ask you a question. Suppose you put the camera on a tripod, with an artificial lighting, i.e., same light, same subject. You take 5 frames not changing anything, would you get the same exact images? (Answer yes).

So if you are hand holding the camera not changing settings and getting different results then something is changing.

Camera exposure meters live in an 18% grey world. Many but not all scenes average out to near 18% grey. But if you scene is not 18% grey, then your auto-exposure can be off. Auto exposure can be "fooled" by brighter or darker surroundings.