Sunny 16 complications

[obsessivephotographer]

Last weekend I went to a horse show where I was shooting show jumping. It was all shot outside, where it was extremely sunny and hot. I shot at a shutter speed of 2000 with my aperture fully open at 4.5. My film was 400iso.

Yet a lot of my shots ended up radically underexposed. How is this possible?

As I understand the sunny 16 rule, with an iso of 400, you would set your aperture to 16 and your shutter speed to 400 (my camera only has 500). When you double the shutter speed, you would have to have the aperture (down to 8). Double the shutter speed up to 2000, and you would have to increase the aperture to 4.

So, if my understanding is correct (and it may not be) why were my shots so drastically underexposed? They turned out very grainy and dark. I was also using a UV filter and Circular polarizer.

 

[mtnman2888]

Now i by no means know what i am talking about as i am a beginner, but i understood the sunny 16 rule to say that if it is sunny go with an aperture of 16 (small opening for light since it's sunny) and a low iso like 200. Like i said i'm not for sure, although it does make a little since to open up the aperture some since your shutter speed is so fast.

 

[Big Mike]

F stops are not on a linear scale...each full stop is factor of (the square root of 2).
One stop open from F16 is F11, then F8 then F5.6, then F4.

Also, when using the sunny 16 rule, you need to consider that a polarizer will block some light...I'm not sure how much, but it may be up to a stop and a half.

Doesn't your camera have a built in meter?

 

[Big Mike]

Now i by no means know what i am talking about as i am a beginner, but i understood the sunny 16 rule to say that if it is sunny go with an aperture of 16 (small opening for light since it's sunny) and a low iso like 200. Like i said i'm not for sure, although it does make a little since to open up the aperture some since your shutter speed is so fast.

The S16 rule is to use F16 and a shutter speed that is the reciprocal of your ISO. So for ISO 100 film, you would use 1/100 or there abouts.

 

[obsessivephotographer]

F stops are not on a linear scale...each full stop is factor of (the square root of 2).
One stop open from F16 is F11, then F8 then F5.6, then F4.

Also, when using the sunny 16 rule, you need to consider that a polarizer will block some light...I'm not sure how much, but it may be up to a stop and a half.

Doesn't your camera have a built in meter?

My camera does have a built in meter, but I'm using film and it's an older camera so the meter is a bit finicky. For some of the shots it did say it was underexposed. But the kicker is that maybe 15 of my shots were horribly horribly grainy and underexposed, but I also had some that were perfectly exposed. Unfortunately I don't have exif data that I could look up because it's film, so I can't tell what shots I shot at exactly what settings due to the fast paced environment.

So I'm trying to work backwards and make sense of this all, since photography with an SLR is still really new to me.

So from F16 to F4.5 is three stops?

 

[Big Mike]

The meter is finicky...how so?

Film (excluding slide film) has a wider dynamic range than typical digital cameras...so you have a good leeway for exposure errors.

So from F16 to F4.5 is three stops?

F16 to F11 is one stop
F11 to F8 is one stop
F8 to F5.6 is one stop
F5.6 to F4.5 is less than one stop...so the difference is three (and maybe a half or 2/3) stops.

As for why some shots were good and others weren't...were they very similar shots? Your exposure may need to change, based on what is in the scene at the time.

 

[obsessivephotographer]

Well, maybe it's more me than the meter. It seems like I go to take a shot, get it properly exposed according to the meter, then I move the camera the slightest iota, even if I'm still standing in the same place, shooting the same object, but now am over or underexposed. Yeah, it's probably just user error.

Thanks for explaining the stops, I'll definitely need to study those a bit more.

As for why some shots were good and others weren't...were they very similar shots? Your exposure may need to change, based on what is in the scene at the time.

That's the thing that really got me. These are all the same sorts of images, all taken outside, in the bright sun, shooting the same types of objects. Yet some are pretty well, if not perfectly exposed, while others are utterly underexposed. Knowing ahead of time that negative film has more leeway for exposure and the similarity of the subjects that I was shooting, I was very shocked when I got my film back and there was such a stark difference between them. I'm wondering if perhaps I went past the capabilities of my lens, if I need something more like an F2.8 lens. But I hadn't expected to need a faster lens in full sunlight.

If you want, I can post the images to see exactly how much difference there is between them. I did vary the exposure throughout the day, which is part of my difficulty. I'm not sure exactly what settings made those shots so grainy and underexposed.

 

[davebmck]

My circular polarizer can drop me by two stops depending on how it is oriented. If you set it for horizontal shooting and then take a vertical shot without readjusting it can change by as much as one stop.

 

[obsessivephotographer]

My circular polarizer can drop me by two stops depending on how it is oriented. If you set it for horizontal shooting and then take a vertical shot without readjusting it can change by as much as one stop.

And since it's only ~3 1/2 stops from 16 to 4.5... wow. That really puts it into perspective. Maybe that's what happened. That would make sense. Doesn't bode well for the rest of the pictures I haven't developed yet, but oh well. You live and you learn.