What exactly does the exposure setting do?

tmharter · January 24, 2008

This question may sound silly, but here goes.

I have a Pentax K100D.

If:

I set the ISO
Set my aperture manually
Set my shutter manually

Then:

Take photos with exposure setting at +1, 0, and -1

What exactly does the camera do to reduce or increase exposure? I assume when the aperture is set as priority, the shutter speed is adjusted by the camera and if the shutter is set as priority, the aperture is adjusted by the camera.

Do different cameras function differently in this matter?
Is this a hardware or software function.

Thank you to anyone who can and does answer.

Tess

jfriend · January 24, 2008

tmharter wrote:

This question may sound silly, but here goes.

I have a Pentax K100D.

If:
I set the ISO

Set my aperature manually

Set my shutter manually

Then:
Take photos with exposure setting at +1, 0, and -1

What exactly does the camera do to reduce or increase exposure? I assume when the aperature is set as priority, the shutter speed is adjusted by the camera and if the shutter is set as priority, the aperature is adjusted by the camera.

Do different cameras function differently in this matter?
Is this a hardware or software function.

Thank you to anyone who can and does answer.

Tess

If you really want to know how your camera handles this, then you can just take a few sample pictures anywhere and look at the EXIF on the images. There is no absolute standard that defines this, so if you want to know for sure on your gear, try a few tests.

Here's how I think it "should" work. If you put the camera in manual mode, the EV setting should not affect the aperture or shutter speed at all. But, it will likely affect the metering indicator in the viewfinder (I'm assuming you have that on your camera). Many people who shoot in manual mode still use the meter for guidance, they just manually dial in an aperture or shutter speed while watching the meter in the viewfinder. This is how all my film cameras worked when I was growing up. So, setting + or - EV changes how the metering indicator in the viewfinder indicates, but should not change your actual shutter speed or aperture setting.

tmharter · January 24, 2008

Thank you.

I did that. Set everything manually and then did an autobracket of +2, 0 and -2. Turns out the camera adjusted both the shutter and the aperture accordingly. Since I had set the exposure setting so extreme on either end, the camera seems to have split the difference, 1 stop up/down on shutter and 1 stop up/down on aperture.

Also, I redid the experiment with the flash on. In this case the shutter and aperture remains the same regardless of the exposure setting. The flash must adjust the amount of light being output. However, this photos do not show a true + or - 2 change in exposure. There is some change as shown by the histograms and a visual inspection of the photos. I guess I have more experimenting to do!

I can not imagine having to learn this with film. Take some shots, keep meticulous notes, go back to the lab and develop or have developed. Wait for results. Do the same thing all over. Plus having to take into consideration the workflow of development and whether that had more to do with results than your camera settings!

Tess

jfriend wrote:

If you really want to know how your camera handles this, then you can just take a few sample pictures anywhere and look at the EXIF on the images. There is no absolute standard that defines this, so if you want to know for sure on your gear, try a few tests.

Here's how I think it "should" work. If you put the camera in manual mode, the EV setting should not affect the aperture or shutter speed at all. But, it will likely affect the metering indicator in the viewfinder (I'm assuming you have that on your camera). Many people who shoot in manual mode still use the meter for guidance, they just manually dial in an aperture or shutter speed while watching the meter in the viewfinder. This is how all my film cameras worked when I was growing up. So, setting + or - EV changes how the metering indicator in the viewfinder indicates, but should not change your actual shutter speed or aperture setting.

jfriend · January 24, 2008

tmharter wrote:

Thank you.

I did that. Set everything manually and then did an autobracket of +2, 0 and -2. Turns out the camera adjusted both the shutter and the aperture accordingly. Since I had set the exposure setting so extreme on either end, the camera seems to have split the difference, 1 stop up/down on shutter and 1 stop up/down on aperture.

Also, I redid the experiment with the flash on. In this case the shutter and aperture remains the same regardless of the exposure setting. The flash must adjust the amount of light being output. However, this photos do not show a true + or - 2 change in exposure. There is some change as shown by the histograms and a visual inspection of the photos. I guess I have more experimenting to do!

I can not imagine having to learn this with film. Take some shots, keep meticulous notes, go back to the lab and develop or have developed. Wait for results. Do the same thing all over. Plus having to take into consideration the workflow of development and whether that had more to do with results than your camera settings!

Tess

So, you are saying that with your camera in manual mode, changing the EV setting changes your shutter and/or aperture setting? That is weird and what I would consider a software bug. Oh well, not a big deal as long as you know how it works, I guess.

Adaptive · January 31, 2008

Yeah it works in manual mode too. I don't know how it works technically all I know is that when I am in a dark situation and I'm pushing shutter and aperture to the limit I turn to exposure compensation + flash.

In manual I use +/- 2 ev on my 30d & 5d

My 1dmk2n has +/- 3 ev as do all the other 1D models I believe.

actually I think the 1d3 has +/- 5 ev I could be wrong though.

Icebear · February 1, 2008

That's just counterintuitive to me, unless what you're actually ending up with is flash compensation. I mean, if I tell my camera to use x aperture and y speed, I sure don't want it to willy nilly decide to change those settings.

SloYerRoll · February 1, 2008

Time for pictures. Not words..
All settings on manual including the strobe in a pitch black room.

-5

-4

-3

-2

-1

0

+1

+2

+3

+4

+5

I don't see any differences. Do you?

If your camera is doing something different in full manual mode. It's got issues.

Link to this gallery if for some strange reason you want to see high res shots.

Icebear · February 1, 2008

OK Jon,
But what if you had the strobe set on TTL instead of manual??
Get to work.

Adaptive · February 1, 2008

Also add some depth/dimension to your test setup.

And try exposure compensation in manual mode without flash, you will see changes.

SloYerRoll · February 1, 2008

Why don't you workhorses get to it.? I made my contribution. If you nellies are just gonna talk in circles. I'll move on.

SloYerRoll · February 1, 2008

Icebear wrote:

OK Jon,
But what if you had the strobe set on TTL instead of manual??
Get to work.

If it's set to ttl. Then the camera is making decisions for me.

Icebear wrote:

I mean, if I tell my camera to use x aperture and y speed, I sure don't want it to willy nilly decide to change those settings.

Icebear · February 1, 2008

Page 155 of the D200 manual would seem to indicate that Exposure Compensation in (M)anual Mode is "N/A".

Page 69 seems to indicate that when one sets EV compensation, the analog EV display reads accordingly, but that NO ACTUAL CHANGE TO YOUR SETTINGS takes place unless you set it yourself.

Maybe I'm missing something.

Icebear · February 1, 2008

Well, since Jon took his ball and went home

I'll take up the task. Here are shots taken on full manual, no flash, ranging from -5 to +5 EV compensation. D200 1/15 sec, f4.5. Durned if I see any difference. Maybe it's my monitor.

-

Actually there is a bit more light on the last one, cause it reflected off my shirt. Sorry. I ain't running this test over again. I'm scaring myself as it is.

SloYerRoll · February 2, 2008

You definately need more depth/dimension in your shots

rofl

georges · February 3, 2008

From the pentax manual...
The exposure compensation setting is there for you to overide the cameras's automatic meter. +1 means you want 1 f-stop more exposure than the meter has selected. This only makes sense in the P, Av or Tv modes. (It would also make sense in the green auto mode. Most cameras disable EC in auto to protect you from yourself.)

Checking the K100d online instruction manual -

The chart on page 138 says exposure compensation doesn't work in the M mode. That makes sense, because you have direct control of both aperture and shutter speed. There is no "automatic" meter setting that needs compensation.

If the exposure comp setting is actually doing something, set it to zero. The point of M is that you control the exposure.

I'm guessing we're not talking about flash exposure compensation. From the looks of your instruction manual, flash EC is controlled through the record menu.

For the specific operation of functions on today's cameras you really need to consult your manual or someone with the same model camera as yours. Cameras have become very complex and overloaded with functions. They are similar in a general sense, but often very different when it comes to operational details.

Even identical models work very differently when enough custom settings have been changed.

Your manual is your friend. (even though today's manuals are very poor) Have it open when you do those experiments. You'll often find features you didn't know you had.

What exactly does the exposure setting do?

Comments