Beginers Questions.

[LilPeteMordino]

Sorry about this. But I thougth this would be the best place to ask about it to be honest.

Im getting a little bit confused with full manual. I understand that the higher the ISO, the more sensitive the shot will be to light. And the faster the shutter speed, means teh less light it will take in, so usually the ISO needs to be bumped up aswell. Am I correct in thinking that?

Where I get my confusion from is the F bit (Aperture? Or is that something different?) and what people mean by stops etc?

So the smaller the number (E.G. 3) will let in more light than a higher number (E.G. 22). But, How do you all work out which settings to use? Most of the time I can tell which ISO setting to use dependent on the light available (only have the onboard flash atm so cant fill from the sides etc without natural lighting), but how do you go about choosing the Shutter speed and the F-Number? Is it just guess and keep taking test shots untill it looks right (Much like I am doing at the moment) or is there a way to get accurate results quickly. Or a way to be able to pick all 3 just from doing a simple thing in your head or on the camera?

If you can help me, Thanks. But Remember I'm still learning so please try to give it in simple terms!

Thanks for your time.

[Mr. Pickles]

The aperture (f-stop, or f number) is used to "block" the light, but it also controls the Depth of Field (DOF).

The larger the f/ number, the more DOF. So, f/16 gives more DOF than f/2.8.

Now, as the f/ number goes up, the actual hole in the aperture opening gets smaller, so obviously you need to leave the shutter open longer to get the same amount of light required for an accurately exposed image.

A lot of people use the aperture value (Av) because it controls the DOF. But some use the Shutter value (Tv) to "stop" or "blur" the action. If you use Av mode, the camera will set the Tv. And the opposite is true. If you want to go totally manual and set both, then you need to read about how to read the light. The "Sunny/16" rule is a good place to start. Might google it. But I'd think you should practice with either Av or Tv modes first.

To check DOF's with various camera settings, go here:
Depth of Field Table

[LilPeteMordino]

Thank you very much for that

I googled the Sunny/16 rule and found a nice piece on Wikipedia for it. It explains it quite well. But, I do see what you mean about getting it right in one of the other modes first. That way I can also see what the camera is setting it too and get a breif overview that way aswell.

Thanks again!

[brian.austin]

Mr. Pickle's advice is a good start: use the Av and Tv modes to learn how the camera is adjusting one thing while you adjust the other. As you start to experiment, pick a subject and play with the values. Writing this down helps (and was a requirement in the film days) but you can see the trends using the EXIF data, too.

For instance, in Av, take a picture of a flower in a park or your backyard. Don't move from that spot. Now adjust the aperture up or down a stop and take ANOTHER picture with the same composition. Note the change in shutter values. The image will look the same since the camera automatically adjusts the shutter for your change in aperture. Same with ISO.

[Mr. Pickles]

Yeah, what Brian said. Practice and learn by writing it down or looking at the data.

Every time you adjust the Aperture, the Shutter will adjust. Both change in 1-stop increments (unless the camera is set to do it in 1/3 or 1/2 increments).

A jump from f/2.8 to f/4 is 1-stop of light. From f/4 to f/5.6 is another. From f/4 to f/8 is two stops. A shutter difference from 1/125sec to 1/250sec is also 1-stop.

Lots of math this photography...

[aam1234]

Good advice from Mr.P as usual. I might add few things to what has been said so far:

- The F stops are ratios, so f2.8 is actually f1/2.8. That's why the smaller the number the bigger the aperture opening.

- Going to the next full F stop (as mentioned by Mr.P above) will double or halves the amount of light reaching the sensor or film (everything else being the same).

- Have a play at this camera simulation, it might help.


Cheers

[PavelOlavich]

What the guys above said, and here's a bit more:

Learn the relationship between Stops and Exposure:

To double the amount of light hitting the sensor/film, assuming the camera is in manual mode, do one of the following:

Decrease the aperture F-stop value by one stop (open it up by one F-stop).
Decrease the shutter speed by one stop.

To halve the amount of light hitting the sensor/film, do one the following, and again assuming the camera is in manual mode:

Stop down the aperture by one stop (make the opening narrower).
Speed up the shutter speed by one stop.

Learn about the relationship between STOPS and LIGHT:

ISO has stops, and each increment down halves the sensitivity. Each increment up doubles the sensitivity. For example, ISO 800 is double the sensitivity of ISO 400.

Aperture has stops. Stopping down one F-stop halves the amount of light let in. Opening up one F-stop doubles the light.

Shutter Speed has stops. One stop down in speed doubles the light in. One stop increase in speed halves the light let in.

Some cameras allow stop changes in 1/2 or 1/3 increments.

When exposing, one should have a bias toward the lowest ISO value possible, while providing a reasonable shutter speed, and aperture (depth-of-field) for a given compostion.

You should increase the ISO as a last resort, to mitigate noise/grain, and/or to increase the shutter speed, and/or to increase depth-of-field, because the increase of ISO can effect Av, and Tv values, mode depending.

Know what price you pay for changing the aperture, shutter speed, and ISO:

Aperture too wide, depth-of-field too thin. Too stopped down, depth-of-field too wide. Often if aperture too wide, frenging and other aberrations increases. Too stopped down, defraction shows (soft focus). Lenses have a sweet spot often around F5.6 to F11 model depending.

Shutter speed too slow, camera hand shake manifests, or subject matter shows motion blur. Too fast, everything in composition froozen.

ISO too low, dynamic range gets narrower. Too high, noise increases, and/or color saturation suffers and/or image detail decreases. Most DSLR's have a sweet spot of ISO 100 - ISO 200 model dependent.

This is very generalized information. Please pardon my typos...

[PavelOlavich]

Originally Posted by aam1234

....- The F stops are ratios, so f2.8 is actually f1/2.8. That's why the smaller the number the bigger the aperture opening.....

Good additions, howver you didn't explain what the ratio was of:

The f-stop is a ratio of aperture opening diameter over focal length: Av/FL

So for a given F-stop, the actual opening size will be different for lenses having different focal lengths.

For example, F2.8 on my 24mm prime will be a smaller opening then F2.8 on my 200mm prime. This is because the focal length is different (20 vs. 200).

This is why Canon's 600mm F2.8 lens is HUGE! And if one wanted to make that lens an F2, the thickness would more then double! It would weigh a "ton" and be unwieldy to handle. Canon once made a 1200mm F5.6 and it weighed over 40 pounds! It cost $80,000+ too.

[cyclohexane]

This is why Canon's 600mm F2.8 lens is HUGE! And if one wanted to make that lens an F2, the thickness would more then double!

I'm assuming we're talking about the 600mm f/4 here. Your explanation still holds true though. =)

The only f/2.8 lens longer than 400mm that I can think off of the top of my head is Sigma's 200-500mm f/2.8, and the thing is the size of a small barbeque grill...

[PavelOlavich]

Originally Posted by cyclohexane

I'm assuming we're talking about the 600mm f/4 here. Your explanation still holds true though. =)

The only f/2.8 lens longer than 400mm that I can think off of the top of my head is Sigma's 200-500mm f/2.8, and the thing is the size of a small barbeque grill...

I stand corrected! Thanks for the clarification.

[LilPeteMordino]

Wow thank you guys. I really didnt expect this much enthusiasm from this amount of people! Shows how good the community is though!

Have read most of whats been said and kind of starting to get the understandings of it all. Will have to re-read again and go out and try and get some more practise in!

Thanks again!

[aam1234]

Let's see some examples, and if you have more questions just shoot them here, somebody will gladly answer them for you.

But most of all, have fun.