blackest Loc: Ireland

I'm thinking about what is useable and practical.

Maybe we can start with sunny 16 1/100th f16 iso 100, so on a bright sunny day we are not too restricted.
If say we want a focal length of 200mm then f11, 1/200th and iso 100 still works.

Exposure_value:

Typical scene in full or slightly hazy sunlight (distinct shadows)a, b 15
Typical scene in hazy sunlight (soft shadows) 14
Typical scene, cloudy bright (no shadows) 13
Typical scene, heavy overcast 12
Areas in open shade, clear sunlight 12

So thats roughly what we can expect on a typical day. At EV 12 your typical dull day we have lost 3 stops of light.
so for the 200mm lens and keeping base iso f11>f8>f5.6>f4. It's quite easy for a lens not to be fast enough and keep base iso if the light isn't good.

So on an over cast day and 200mm my F5.6 tamron is going to struggle, either i drop the shutter speed to 1/100th or raise the iso to 200 at the 70mm end i'm still ok at 1/100th and iso 100 where my aperture is f4.

How about depth of field?

Portrait distance I found this:

"Say you need a surface of about 72cm x 48cm (28″ x 18″) to make a portrait of a person (not just a headshot, but with some torso on it too)
Well, the distance between the camera and the person you’re making the portrait of, will be +- 20 times the focal length.

a 50mm ‘portrait’ lens => you need +- 20 x 50mm or 1 meter to make a portrait.
And this scales linearly, so say you need 2,5 times that height: 180cm x 120 cm because 1,80cm is the average height of a person: you will find this at 20 x 2,5 = 50 times the focal distance.

So sticking with the 50mm thats 2.5 meters or about 8-9 feet to do a full length portrait."

Going to a depth of field calculator reveals something interesting at f11 keeping the same framing which means moving further back for a longer focal length or nearer for a shorter one for f11 and a head shot on full frame the depth of field is fairly constant 24.3cm at 50mm and 23.5cm at 200mm focal lengths

so we can a create a table or 2:
f11 24.3 - 23.5 (50 - 200)
f8 17.6 - 17.8
f5.6 12.3 - 12.4
f4 8.8 - 8.8
f2.8 6.2
f2 4.4
f1.7 3.7
f1.4 3.1

full length shot at 50x focal length
f11 1.73- 1.57 m
f8 1.2 - 1.14 m
f5.6 81.6cm 79.7 cm
f4 57.6 - 56.9 cm
f2.8 40cm 39.8 cm
f2.0 28.5 - 28.4 cm
f1.7 24.2 - 24.2 cm
f1.4 19.9 - 19.9 cm

For a 1.5 crop it seems around 1 stop different e.g depth of field at f4 is close to dof for f5.6 (you can make your own tables)

So thats kind of interesting, dof is not that different for a given f-stop at a range of focal lengths if you are keeping your subject the same size in the frame.

If you are doing a head shot and you want all of your subjects head in acceptable focus f11 should do it, If its a bright sunny day then 200mm ,1/200th f11 iso 100 should work cloudy might be better at 100mm f11 1/100th iso 100 with no shadows then you are going to need to raise iso or adding light with flash.

For a headshot on full frame you can pretty much use double the f-stop to calculate your approximate depth of field. The numbers for depth of field are based on acceptable focus so while saying f4 gives 8cm dof rather than 8.8 its a fair approximation.

for a full length portrait 14 x f-stop is fairly close. or perhaps 15 f2 ~ 30 cm - f5.6 ~84cm either gets a ball park figure.

With these thoughts in mind, you should have a fair idea of how a shot should work at least for people, or am I way off :)

lamiaceae Loc: San Luis Obispo County, CA

OR you could obtain a couple of those Kodak Data Guides that summarize all that you seem to be talking about and more...

BebuLamar

I think you're OK!
I want to nitpick a bit. Since you said "Sunny 16" is f/16, 1/100 and ISO 100 it's EV 14 and 2/3 and not 15. I use 14 and 2/3 for sunny 16.

khumiston

I don't have an answer but this is a subject about which I am not well informed, so I thank you and look forward to seeing other responses.

SonyA580 Loc: FL in the winter & MN in the summer

[quote=blackest]I'm thinking about what is useable and practical.

Maybe we can start with sunny 16 1/100th f16 iso 100, so on a bright sunny day we are not too restricted.
If say we want a focal length of 200mm then f11, 1/200th and iso 100 still works.

Are you saying changing focal length necessitates changes in f stop, speed and ISO? Maybe I'm missing something.

Rich1939 Loc: Pike County Penna.

[quote=SonyA580]

Sorta. Your shutter speed 'number' should match or exceed the focal length 'number' of the lens you will be using. so, changing the lens and the shutter speed necessitates adjusting the aperture

selmslie Loc: Fernandina Beach, FL, USA

Spot on for the exposure information based on EV.

However, save yourself some math on the subject distance calculations. Any portrait taken from one meter away is to close for any focal length. You'll end up with big noses regardless of the focal length (which only changes the crop, not the perspective). Just look at Facebook.

Instead, take your portraits from about 2-5 meters from the camera. Farther away and you end up with bigger ears. The only reason to change focal length is to change how much of the surrounding environment gets included in addition to the subject.

If you look at it this way you will understand why there is really no such thing as a proper focal length for portraits.

selmslie Loc: Fernandina Beach, FL, USA

The extra 1/3 stop is about all you need to keep bright white bird feathers from blowing out in direct sunlight.

blackest Loc: Ireland

1 meter would be with a 50mm lens on full frame for a headshot and your right it would be too close if you wanted to flatter your subject. conventionally 85 -200 mm tends to be a portrait length.

The dof calculator shows dof is pretty much constant for a given framing so once you have decided how much of the subject you want in focus. It then becomes a matter of choosing perspective.

There is quite a lot you can have prepared before you take the shot, a little less luck and a bit more judgement.

DWU2 Loc: Phoenix Arizona area

Please don't think I'm being snarky, but I have a light meter in my camera and a DOF guide in my phone. I don't think I need more than that.

BebuLamar

I think you don't get what the OP meant. He listed the lighting condition to say what kind of light he may encounter and what kind of DOF he would have with different lenses. He didn't mean not using his meter.

blackest Loc: Ireland

Ok you have the tools.

heres one for dof https://dofsimulator.net/en/

experimenting with this has shown that you have a pretty consistent depth of field for any given f-stop with different focal lengths if you keep your subject the same size in the frame. Thats nice to know. Many people will know focal length doesn't affect exposure but dof ...

george19

Not going to nitpick this since your technical points are essentially valid. It comes down to balancing constraints and the art of what you want to do.

Camera shake is rarely acceptable, so your focal length and availability of a rigid support constrain the shutter speed.

Once you have picked that, is there some depth of field you need? Can your lens support this? Is flash an option? If necessary, you can tweak ISO.

Or...start with DOF, and work shutter speed.

Maybe you want something a bit darker. What will you pick for the focus point? The exposure point?

Finally, how do you compose the scene? Power lines, roadways, other people, distracting things on the side, angle of view, can you get closer (or in the case of shooting my bathroom, how do I get farther away?)?

jpgto Loc: North East Tennessee

ballsafire Loc: Lafayette, Louisiana

"I'm thinking about what is useable and practical." --

I don't think like that i.e. we should have a pattern or style of using the camera like a musical instrument without going through all this useless bunch of girations to take a photo. Of course you are developing a personal style and I say "good for you" but all of the rest of us are busy learning how to coax the best photos we think possible from our different cameras. You are not way off but developing and learning has always been considered doing the right thing. I wish you success!!