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DPChallenge Forums >> Tips, Tricks, and Q&A >> Canon 20D
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07/17/2006 11:42:07 PM · #1
Hello; i am searching for some advice from who else but DPCers. Plllllease be kind enough to share your knowledge; i will be forever gratefull. =)

Well i got my Canon 20d Dslr about a month ago for my birthday... & i have yet to understand the Iso,Aperture,& Shutter speed. i read & read & read. i just stick with automatic because the numbers are too overwhelming, well. im ready to learn.

I read that Iso is the sensitivy to light, & the higher, the more sensitive. well i think my camera is backwards?? maybe? i think its me.
Iso of 250 on my camera makes the picture darker, & iso 30" is lighter, but thats backwards acourding to my resources. ahh i dont noe. & i have NOOO idea how to set the shutter speed on this camera. the manaul isnt a huge help. maybe i need to do a lil more manual reading, but would LOVEEEEEE the help of your talented knowledge. please help me.

Message edited by author 2006-07-17 23:43:23.
07/17/2006 11:45:51 PM · #2
Originally posted by brokechic8:

I read that Iso is the sensitivy to light, & the higher, the more sensitive. well i think my camera is backwards?? maybe? i think its me.
Iso of 250 on my camera makes the picture darker, & iso 30" is lighter, but thats backwards acourding to my resources.


I think you got confused between ISO and shutter speed, because those figures look more like shutter speeds...

anyway, ISO alone will not make the image brighter or darker. The shutter speed and Aperture value works in relation as well.
07/17/2006 11:49:21 PM · #3
check out this thread it will help you out I think :0)
07/17/2006 11:49:42 PM · #4
Thank you crayon;
I will get back to shooting & practicing with a stick of deodorant. =)
07/17/2006 11:53:25 PM · #5
I think you should read tutorial at: //www.dpchallenge.com/tutorial.php?TUTORIAL_ID=45

Also there is nothing like ISO 250 in Canon 20D. The ISO settings are 100,200,400,800,1600 and H (with some condition). I guess 250 means you are talking about Shutter speed and not ISO, correct me if I am wrong.

Now when you have shutter speed of 250 or 30" pictures are coming dark/light, this could be because of ISO setting that camera is set to at that point of time, I believe it is set to a lower value (100 or 200) or bracketing is set to -2.

07/17/2006 11:56:49 PM · #6
when i set it to 250 & 30" "iso" was written under it.
What is that suppose to mean?
im sorry i sound dumb; this is just a confusing subject for me.
That tortuial [spellcheck?] is a big help, but i guess help from live people at the live moment helps a little bit more.
07/17/2006 11:58:18 PM · #7
Oh never mind on that last comment, i figured out how to get to the iso part. 1600 is highest, & 100 is lowest, sounds right to me so far.
07/18/2006 12:02:59 AM · #8
Look here: //www.shortcourses.com/using/index.htm
07/18/2006 12:04:45 AM · #9
Originally posted by brokechic8:

I will get back to shooting & practicing with a stick of deodorant. =)


LOL, you stank? :p anyway, as a quicky (I still remember how confusing it was when I first tried to understand ISO, aperture and shutter few months back) so here's what you need to remember:

"always try to use the lowest ISO possible (it results in more details, less noise even when shooting in automatic mode)"

an example: people usually use higher ISO because they have no choice; like when they are shooting fast moving subjects and want to freeze the movement (think sports), they will need to use a faster shutter (say, 1/2000sec) but the picture is too dark, so they increase the ISO and the picture will then be "brighter" because the sensor is more sensitive to light. Aperture is usually used to control the Depth-of-Field, but also sometimes used to "make the image brighter" - I try to leave Aperture separate for now.
07/18/2006 12:07:59 AM · #10
Here's a fun place to start: Enjoy dSLR Canon of Japans Simple but effective approach to learning dslrs.

Edit:
If you want to go right to the Aperture, Shutter and Sensor Sensitivity Click here

Message edited by author 2006-07-18 00:11:01.
07/18/2006 12:16:54 AM · #11
AHH!!!
i think im getting it =)
Yes i notice the lower the ISO the clearly more detailed my teddy bear is. [i threw my deodorant out the window for now, it somehow, doesnt keep my smell a "secret". false advertisement i guess. =) ]
& i notice the slower the shutter speed, the brighter the image may be, because it is letting in more light due to the exposure time. ahhh!
DPC is completely amazing; ive learned SOOO much here the past few months. my images are always improving i personally think, & now it will hopefully improve better with my current learnings of exposure.
07/18/2006 12:18:21 AM · #12

Aw : That is a great link you sent me, very good for me since i am a visual learning, thanks.
07/18/2006 12:19:21 AM · #13
Here’s a quick summary of the simple basics (which you can find in the other threads noted above):

Aperture and shutter speed determine the amount of light that gets to the sensor (sensors in digital cameras are like film to a regular camera).

Aperture is like a water facet, the more open it is, the more water that goes through the facet (or in case of a camera, the more light that reaches the sensor). “Stopping down” is the same as closing the facet or making the aperture smaller, so less light goes through. Where it gets confusing is that f/22 is a very small hole/aperture, whereas f/1.4 if very large – this is confusing for many beginners and seems counterintuitive – UNLESS you know where those numbers come from.

Looking at the center of your lens (which is of course round) f/1.4 basically means that you can fit 1.4 circles within the lens (think of a donut in a cereal bowl). f/22 means that you can basically fit 22 circles within the lens (think of Cheerios in a cereal bowl). Thus f/22 is a small hole letting a little light in, f/1.4 is a large hole, letting a lot of light in.

The other basic rule you just have to memorize is f/22=small-hole/little light=deep depth of field (DOF). Deep DOF means a lot is in focus. f/1.4=large-hole/lot of light=shallow DOF (meaning only the point of the picture you focused on will be in focus and everything else will be blurry).

Shutter speed is how fast the shutter opens and closes – letting light hit the sensor. Short shutter speeds (1/500 of a second) let little light in, longer exposures (1/20, 1 sec, etc.) let more light in. Short shutter speed allows you to “stop” the action in the picture. Longer shutter speeds will blur the action.

ISO originally had to do with the sensitivity of the chemicals on the film to light. Some chemicals were more sensitive to light, meaning just a little bit of light would cause the chemicals change and thus form an image on the film. Other films where less sensitive, thus requiring more light to hit the film in order to react. The higher the ISO (say 800, 1600, 3200) the MORE sensitive the film. The lower the ISO, the less sensitive the film. Higher ISO films, that reacted very quickly to the light, allowed you to capture fast moving subjects in lower light, however, the chemicals acting so fast also caused the image to be grainer (producing lower quality pictures – if that’s not the look you were going for).

Ok, end of basics 101. :-) Hope that helped!

Message edited by author 2006-07-18 00:30:24.
07/18/2006 12:33:30 AM · #14
I was in metropolis and was carrying my zoom lens when I hear people excitedly shouting, "look, it's a bird, it's a plane, no... it's superman!" and when I looked up the sky, sure enough, was the man of steel flying right above the building beside me. He was flying fast!

I took out my camera and took aim, zoomed in to 600mm to get a close-up shot of the man himself, but my pictures came out too blurry because my shutter speed was too slow and supes was flying fast. So I increased my shutter speed and took another shot, this time I got a clear photo of him, but it's too dark. So I tried again, I increased the Aperture to the largest I have (smaller F number) and shoot... this time, I got a clear supes, plenty of light and bright, but only his face is in focus, while his body was out of focus (too shallow DOF)...darn, I said... so on a last attempt before supes flies off, I changed my Aperture back to something smaller (larger F number) and adjusted my ISO to something higher, ISO 1600, took a shot. This time, I got the perfect shot. Entire supes in focus, good light, and frozen photo of him flying with no blur. There are some noise in the photo (those nasty grains) but I guess it's still good enough for printing on the front page of the Daily Planet.

:)
07/18/2006 12:52:04 AM · #15
Glad to hear you are getting out of the dreadful Auto mode... the 20D does some weird things in that mode.

Also are you shooting in AIAF (all Focal Points are active when shooting)? That is another mode that will get mixed results when shooting. Use the single Center Point Autofocus at first (I still don't use AIAF).

Learn Exposure Compensation early...(I goofed around for 8 months without using it...bummer) if you learn ExpComp while getting used to Arp, Shutter and ISO...your pics will have a better feel to them and not blowing out skys is quite a bit easier. ExpComp does affect the shutter speed and they all play together. It's easy to do when in the creative modes (except Manual) just spin the big thumb wheel to make it go up or down.

Same Cartoonish Site...Explaining Exposure Compensation

Ed: Typo

Message edited by author 2006-07-18 00:53:19.
07/18/2006 01:04:25 AM · #16

So crayon;
Post that "clear" shot you got of super man =)
lmao, that was some funny stuff, but man, i must admit, it was humourously working.
07/18/2006 01:11:28 AM · #17
Originally posted by brokechic8:

So crayon;
Post that "clear" shot you got of super man =)
lmao, that was some funny stuff, but man, i must admit, it was humourously working.

I'm not supposed to post it since I was shooting for the paper, but what the heck, here it is... :P

07/18/2006 01:15:01 AM · #18
Oh yeah, i see that grain you were talking about.
other than that GREAT SHOT!
p.s im telling ;)
& im going to take your job once you get fired.


Message edited by author 2006-07-18 01:15:48.
07/18/2006 02:21:37 AM · #19
Originally posted by brokechic8:

maybe i need to do a lil more manual reading, but would LOVEEEEEE the help of your talented knowledge. please help me.


I found the 20D manual to be fairly good. It just has a lot in it. If you go through it step by step trying out the functions as you go along then a visual or tactial learner should be fine.

When the camera is on auto, or in the basic zones, you can't change any settings, be it ISO, shutter speed or aperture. You need to switch the camera into what the manual refers to as a "creative zone mode".

Good luck pressing stuff :)
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