f/stops & shutter speed - help please!

Canon EF 16-35mm f/2.8L USM

01/23/2005 04:13:42 PM · #1

Hi everyone,
I just started a beginning photography class (for 35mm B&W) and I have no idea what I'm doing. I have an assignment due (landscape photography) in 2 days & by emailing the instructor I have found out that I have done this assignment almost completley wrong- I just can't grasp the concept of these numbers involved.

The assignment is to use a gray card in Manual mode & take a picture with the suggested settings- pretty easy I have no problem with that! The trouble comes with the other 2 parts of the assignment. He wants us to "stop" down & "stop" up for pictures 2 & 3 (from the initial picture, increase 1 full f/stop & decrease 1 full f/stop). Turns out I did the assignment by doing 1/2 stops which is wrong.

Here is an example we did in class:
Picture: f/5.6 @ 1/60
Stopping down= f/8 @ 1/125
Stopping up= f/4 @ 1/60

What I don't get is, why was the shutter adjusted for the stopping down?

Now, here are 2 things I wrote in my notes, that I don't get:
f/4 @ 1/250
f/2.8 @ 1/250

&

f/5.6 @ 1/60
f/4 @ 1/60

Those 2 settings he said are equivalent...I don't get that, how are they equivalent?

I'm sure this is all a simple process but reading over my notes is just confusing me...I've wasted 2 rolls of film doing what I thought was right, and now I have to go back in the cold & reshoot all this. I thought I understood the f/ series, but maybe I am now...so if I get a reading of f/4, I should adjust to f/8 to stop down. And to stop up from that initial reading I must chose f/2...correct?

But then throw in the shutter and I have no idea what to do with it...I don't know what to do with the shutter settings, I assumed you would keep it where it's at the whole time but I am guessing it must be adjusted when adjusting the f/stops but I don't know how to go about that...

I know I am asking a lot, but please help me, the more I try to learn the further I am burying myself in complication.

thatcloudthere

Canon EOS-1D

01/23/2005 04:17:46 PM · #2

Yeah, those numbers don't really add up...I'm confused as well!

Sony DT 18-70mm f/3.5-5.6 Aspherical ED Zoom Lens for Sony Alpha

01/23/2005 04:32:25 PM · #3

Originally posted by SummerBreeze:

Here is an example we did in class:
Picture: f/5.6 @ 1/60
Stopping down= f/8 @ 1/125
Stopping up= f/4 @ 1/60

Now, here are 2 things I wrote in my notes, that I don't get:
f/4 @ 1/250
f/2.8 @ 1/250

&

f/5.6 @ 1/60
f/4 @ 1/60

Those 2 settings he said are equivalent...I don't get that, how are they equivalent?

Perhaps your notes are wrong or perhaps the teacher did not get his point across well. Didn't the class come with a text book? I recomend reading Ansel Adams' book The Camera. You won't have time to find the book and read it before the asignment is due so perhaps this will help you. Or get online a do a search with words that pertain to your project such as f/stop, bracketing, ect...

kiwinick

Sony DSLR-A550

01/23/2005 04:37:02 PM · #4

If you changethe Fstop (apature) the shutter (time) will change to compensate, and to give the same exposure,. In manual mode this will not happen foor as you close down you will lose light,(underexposure) as you open up the apature more light will come thru( OVerexposure) that is if the shutter speed is constant.

what I suspect your instructor whants is to show how you control depth of field by using the apatures.
your second query F4 @1/60 is equivelent exposuere to F2.8 @1/250. I stand to be corrected ,but moving either the shutter speed OR the apature will 1/2 or double the expoure ie F8 @1/60 is 1/2 of F8 @1/30
hope this makes things a little clearer

01/23/2005 04:56:23 PM · #5

Yeah, I do have a book, I understand what the terms mean, it's just hard to know what exactly to adjust (since I normally would let the camera choose the setting for me).

kiwinick-
So basically, I am not to adjust the shutter speed unless I want an equivalent exposure? So I take the initial picture at the recommended setting, to over expose I go up 1 f/top & to under expose I go down 1 stop - and this whole time I should not adjust the shutter since the purpose is to under, over, and normal expose...correct?

Canon EF 24-70mm f/2.8L USM

01/23/2005 05:01:49 PM · #6

if the ISO/ASA setting was changed as part of the process - these settings could be equal exposures...

f:5.6 @ 1/60th ISO 400 == f:4 @ 1/60th ISO 200

Message edited by author 2005-01-23 17:02:48.

brianlh

Canon EOS-450D Rebel XSi

01/23/2005 05:03:45 PM · #7

typically, stopping 'down' means decreasing the amount of light reaching the sensor/film, and stopping 'up' means increasing it. someone correct me if i am wrong.

i agree that it's possible your teacher wrote something down wrong, you wrote it down wrong, or he's possibly talking/describing this project in a confusing manner. Perhaps his terminology is different from what I have understood - maybe instead of 'stopping down', he meant to use a smaller aperture while increasing the shutter speed? If so, that seems like a poor way for him to describe it.

01/23/2005 05:05:16 PM · #8

../

Message edited by author 2005-01-23 17:05:39.

01/23/2005 05:09:24 PM · #9

Originally posted by SummerBreeze:

So basically, I am not to adjust the shutter speed unless I want an equivalent exposure? So I take the initial picture at the recommended setting, to over expose I go up 1 f/top & to under expose I go down 1 stop - and this whole time I should not adjust the shutter since the purpose is to under, over, and normal expose...correct?

Correct. Or you could achieve the same exposure changes by keeping the aperture constant and ajusting the shutterspeed.

Message edited by author 2005-01-23 17:11:09.

01/23/2005 05:14:18 PM · #10

soup-
We're not even into ISO yet, all I know is I have TMAX ISO 100 film for the class (and I also have the option to use TMAX 400 as well). So far we haven't added the film speed to the equation yet, hopefully we won't have to because that would be an even bigger mess of learning for me!

Brianlh-
It's very possible I wrote something down wrong, I am guessing that's what I did. We had a very short class period because of the snow, so the first 1.5 hours was delayed because of late arriving students - so we really had to rush through all the information.

Sony 16-50mm f/3.5-5.6 E-mount

01/23/2005 05:17:25 PM · #11

nsbca7-
Thank You, Thank You, Thank You!

jmsetzler

Sony Alpha a6000

01/23/2005 05:31:36 PM · #12

Originally posted by SummerBreeze:

Here is an example we did in class:
Picture: f/5.6 @ 1/60
Stopping down= f/8 @ 1/125
Stopping up= f/4 @ 1/60

This is wrong. You stopped down two stops here in the f/8 @ 1/125. You underexposed from your original exposure by two stops. You removed one stop of light with the aperture and another stop of light with the shutter.

In the f/4 @ 1/60, You overexposed by one stop by opening up the aperture. If your original exposure was f/5.6 @ 1/60", the other two 'correct' exposures for the same scene would be:

f/8 @ 1/30
f/4 @ 1/125

These two combinations maintain a correct exposure. I'm not sure if that was your assignment or not...
[/quote]

dsb_mac

Best-Buy Easy Point & Click

01/23/2005 05:32:34 PM · #13

Originally posted by SummerBreeze:

f/4 @ 1/250
f/2.8 @ 1/250

These are not the same exposure. f2.8 will be a 1 stop brighter exposure.

Exposure can be adjusted 3 ways. 1) Aperture size 2) Length of Exposure 3) Film Sensitivity.

As an anology imagine yourself eating yummy whip cream from a big hose. So you open wide and eat whip cream til you pass out. Then you wake up feeling hungry again and go for more. This time you make a small hole with your mouth. What happens now? You have to keep your mouth open longer till you pass out because your mouth is smaller. Each time you get the same amount of cream but notice the different ways you can do it. This is the same with exposure.

All of the individual exposure settings have a standard series of settings. These series are consistent with almost every camera. You can refer to them in your book.
Aperture has the funny series of numbers (2.8, 4, 5.6, etc.) A smaller number means a bigger mouth.
Exposure is expressed as a fraction of a second (1/250). Higher numbers means a shorter exposure.
Film speed is how sensitive it is to light (ISO 100)

People often speak of exposure in units of "stop". When people adjust the exposure they will say crazy things like "open 1 stop higher" or "close 2 stops lower". Going up or down between two consecutive numbers from any of the series of the settings is considered "1 stop" (2.8 - 4 is "1 stop"). Changing the time up or down (usually a doubling or halving of the time) is "1 stop". 1/125 - 1/250 is "1 stop". When you change your film every doubling or halving is "1 stop". 100 ISO & 200 ISO is one stop.

So if you add one stop to any setting you will have to compensate in another setting by going down one stop to get the same exposure i.e. brightness of the picture.

PS many modern cameras make 1/3 stop adjustments for even more precision make sure when someone tells you to adjust by one stop you do it according to the traditional camera settins which I'm sure you can look up in your book.

Message edited by author 2005-01-23 17:42:56.

01/23/2005 05:39:38 PM · #14

Originally posted by dsb_mac:

As an anology imagine yourself eating yummy whip cream from a big hose. So you open wide and eat whip cream til you pass out. Then you wake up feeling hungry again and go for more. This time you make a small hole with your mouth. What happens now? You have to keep your mouth open longer till you pass out because your mouth is smaller. Each time you get the same amount of cream but notice the different ways you can do it. This is the same with exposure.

I never heard it explained that way! LOL!!!

01/23/2005 08:02:47 PM · #15

well - you have gained two stops of exposure with the 400 speed film over the 100 speed film - so the ISO has, to a degree, come into play.
you could choose to use the ISO 400 to gain a couple shutter speed stops in lower light, or a bit deeper depth of field over the ISO 100.

i wasn't sure if that might be part of the equation that was excluded...

Originally posted by SummerBreeze:

or you could tip the can of cream upside down, and pass out from entirely different reasons... ;}

Originally posted by dsb_mac:

Originally posted by dsb_mac:

--------------------------------------------------------------------------------
As an anology imagine yourself eating yummy whip cream from a big hose. So you open wide and eat whip cream til you pass out. Then you wake up feeling hungry again and go for more. This time you make a small hole with your mouth. What happens now? You have to keep your mouth open longer till you pass out because your mouth is smaller. Each time you get the same amount of cream but notice the different ways you can do it. This is the same with exposure.

Canon EF 24-105mm f/4.0L IS

01/23/2005 08:38:35 PM · #16

Originally posted by soup:

or you could tip the can of cream upside down, and pass out from entirely different reasons... ;}

A little NO2 will have you thinking up all kinds of pretty pictures. And laughing about them as you go.

jemison

Canon EOS-5D Mark III

01/23/2005 08:40:22 PM · #17

Originally posted by SummerBreeze:

So I take the initial picture at the recommended setting, to over expose I go up 1 f/top & to under expose I go down 1 stop - and this whole time I should not adjust the shutter since the purpose is to under, over, and normal expose...correct?

don't get confused here...perhaps it is better to think in terms of opening up one stop to increase the exposure rather than "go up one stop". Going up one stop might imply that the f stop *value* should be increased (ie. f/8 to f/11) when in fact that will decrease the amount of light. Remember that the size of the aperture decreases as the "f" number increases.

David.C

Nikon AF Nikkor 50mm f/1.8D

01/23/2005 09:41:09 PM · #18

Originally posted by SummerBreeze:

... I know I am asking a lot, but please help me, the more I try to learn the further I am burying myself in complication.

Make it easy on yourself and take the time to create a couple of charts for each ISO film you are using.

Make the charts with the EV (exposure value) along the side; one with the shutter speed across the top and the aperture setting at each intersection, the other with the aperture settings across the top and the shutter speeds at the intersections.

It sounds like you are getting confused by not knowing how two different settings can be the same exposure -- and that is what the EV (exposure value) is for. Two different sets of aperture, shutter and ISO settings will be the same if they equate to the same EV. This link (The Ultimate Exposure Computer) does a good job of explaining how the four values (EV, shutter speed, aperture and ISO) are related and how adjusting one can be compensated for by adjusting a combination of the others.

David

01/23/2005 10:04:32 PM · #19

Originally posted by Britannica:

This link (The Ultimate Exposure Computer) does a good job of explaining how the four values (EV, shutter speed, aperture and ISO) are related and how adjusting one can be compensated for by adjusting a combination of the others.

My dad was always playing with cameras and I picked up a lot just by being around. I guess as a result of an early exposure I visualize these values in my head as second nature, but I've never seen it written down in a chart that way. Pretty cool.

01/23/2005 10:15:02 PM · #20

is that over exposure?

Originally posted by nsbca7:

01/23/2005 10:17:31 PM · #21

Originally posted by soup:

is that over exposure?

Originally posted by nsbca7:
My dad was always playing with cameras and I picked up a lot just by being around. I guess as a result of an early exposure I visualize these values in my head as second nature, but I've never seen it written down in a chart that way. Pretty cool.

Pun not intended!lol!

Sony 24-70mm F4 Vario-Tessar T* FE OSS

01/23/2005 10:19:41 PM · #22

one benefit of digital over film - you have extra exposure control with the ISO setting... pun intended

well -w/o having to roll a roll of film up.

Message edited by author 2005-01-23 22:20:19.

Bear_Music

Samsung Galaxy S24 Ultra

01/23/2005 11:41:48 PM · #23

Here's what he wants you to do:

1. take a grey card, full frame, at the exposure meter's recommended setting.

2. Do a second shot with shutter speed same and lens one stop larger

3. Do a third shot with same shutter speed and lens one stop smaller

When the film is processed and contacts made; the first one will look liek the grey card, the second will be a lighter gray, and the third will be a darker gray.

What he is teaching you is that the meter assumes that what it is looking at is an 'average gray" and sets exposure accordingly.

here's another exercise:

1. full frame a white card and shoot at the meter's setting.

2. full frame a black card and shoot at the meter's setting (it will be "more" exposure.

3. full frame a gray card and shoot at the meter's setting (It willf all between the other 2.

process the film and if the meter is accurate they frames will be indistinguishabl;e, they will all look gray.

In practical terms, this means if you shoot a snowy field and want it to look white, you need 2 stops more exposure than the meter recommends, and if you shoot a dark forest scene with no higlights (and want it to be dark) you need a stop or two less exposure than the meter recommends.

Either that, or you have to adjust in the printing. The correct exposure to minimize adjustment is always a better negativem fuller tonal ranges.

Hope that helps.

Robt.

grahamp

Nikon D70

Nikon AF Zoom-Nikkor 28-80mm f/3.5-5.6

01/23/2005 11:53:21 PM · #24

keeping it simple..

the light stays the same...

you get to change 3 things to determine how the light gets into your camera..
1. size of hole (f stop .. small number = big hole)
2. speed of shutter (slower the shutter = more light gets in)
3. speed of capture device (film speed = ISO)

You combine these to get different effects - that's the "science" of photography.

The art of photography is this combination and plus subjects chosen and how they appear.

That help?

Graham