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View Full Version : Noob wants to learn (Pic intensive!)



ricekiller2003
04-02-2005, 12:08 AM
Hey guys. I have my Canon SD500 on the way, so I'm practicing with my Minolta DiMAGE Xt 3.2 for the time being. The camera does not offer any manual controls except for exposure and ISO.


So I decided to play around with these settings and draw conclusions for myself. The best way to learn is to experience it on your own, so I figured this would help me alot.


Exposure: Under low light conditions with no flash

Exposure set at 0.0
http://thickstunalex.smugmug.com/photos/18741725-L.jpg


Exposure set at 2.0
http://thickstunalex.smugmug.com/photos/18741730-L.jpg


Conclusion (Correct if wrong): As exposure increases, the lens stays open longer to allow more light. Overexposure can ruin a picture in low light, while just the right amount of exposure can allow better detail and color to be seen.



ISO: 3 inches away with flash

ISO set at 50
http://thickstunalex.smugmug.com/photos/18741732-L.jpg


ISO set at 400
http://thickstunalex.smugmug.com/photos/18741736-L.jpg


Conclusion (Correct if wrong): ISO relates to the lens sensitivity. As the ISO increases, the lens opens and closes faster. This allows for a better distinction in detail. Along with the increased ISO, more noise is a direct result.



Anything you can tell me (if I'm wrong). What's 'Aperture' exactly, and how would I want to adjust that during what conditions?


Thanks - Alex

speaklightly
04-02-2005, 08:25 AM
Alex-

I am going to share with you a very simple procedure (it can be used on both film and digital cameras) that I have used for 50+ years and it is amazingly simple. When you take a photo, such as yours of the cat, and you obviously have more light (or believe you might, have too much light) than you need, meaning the whole frame is too bright Do this:

Just take your digit (your finger!) and cover a portion of the flash unit lens/cover on your camera as you take the digital photo. I usually begin with about 50% digit coverage, and then look at the result and adjust as necessary to get the level of brightness that I desire in the photo.

Yes, it is crude, but it is very effective. Best of all it can be done very quickly without putting your camera down and going into menus. Keep in mind that the color of the digit we have, does have a bit of effect on the color of light coming from the flash, but that can be easily adjusted with post processing.

I think it might work well for you. If nothing else you can bet your buddy who has that big SLR that you can digitally adjust his flash for him, and be sure of winning the bet.

Sarah Joyce

ricekiller2003
04-02-2005, 10:41 AM
Great advice! It's so simple, yet I wouldn't have figured it out in my lifetime :D




ISO controls the shutter speed, right? Therefore a higher ISO would be used for moving shots, while a lower ISO would be used for stills?

kornhauser
04-02-2005, 03:39 PM
Alex-



Just take your digit (your finger!) and cover a portion of the flash unit lens/cover on your camera as you take the digital photo. I usually begin with about 50% digit coverage, and then look at the result and adjust as necessary to get the level of brightness that I desire in the photo.


Sarah Joyce

Agreed! Or another technique I learned in crime-scene class is to hold toilet paper (try single-ply then double-ply) over the flash to defuse it. I've always been laughed at for doing it that way, but my results speak for themselves! :rolleyes:

gary_hendricks
04-02-2005, 05:26 PM
Thanks speakinglightly, for that tip. That's one of those 'secrets' which many beginners need to know about.

D Thompson
04-02-2005, 05:50 PM
I am by no means an expert, but here is a simple explanation that I hope will help you. Exposure is the combination of shutter speed and aperture used with ISO for a good picture. Each has benefits and uses.

ISO - this is film speed. The lower the number (ISO100) the sharper and less noisy. Also, this will need more exposure than ISO1600. This is accomplished by a slower shutter speed or lower aperture.

Shutter speed - this is how long the shutter/ccd remains open. A fast speed will stop action while slower will blur unless a tripod or a still object is shot. 1/60th is about the slowest that can be handheld without blur.

Aperture - this is how much light the lens will let thru. Lower values let more light in. (f2.8 will let more in than f16). The depth of field is less also with the lower f stops. This means if you want to blur the background, use a low f stop. If you want most of the pic to be sharp then use about f16 or so.

I'm more used to film and have only been dSLR for about 6 months so my explanation is worded toward film, but holds true for digital also. Hope this helps.

Dennis

Newbie
04-09-2005, 02:19 PM
If I can add to what Thompson said...

ISO is the sensitivity... For film, its film sensitivity, for digital, its the sensor.

Shutter speed is all correct, excepted that 1/60th may or may not be enough, the time you can hold a camera still depends on you, depends on how much telephoto or wide angle you are using(not quite the best wording)...

Aperture is how big the shutter will be opened F2.8 means it is opened 1/2.8, while F8 means its 1/8; this explains why the smaller numbers let enter the most light.

So, raising the ISO and leaving the Shutter speed and aperture the same will probably result is overexposure(unless the previous shot was underexposed).

In digital photography, you usually use higher ISO in order to increase the shutter speed. That is because the shutter is opened for less long, you need the sensor to be more sensitive to capture a properly exposed picture. And you need a faster shutter to counter some blur due to an action shot, low light shot, telephoto shot, etc.

Ali_baba
04-11-2005, 02:41 AM
The problem I face is that when I use M mode, I have full control on Shutter and Focal length but not on exposure.

Well, I guess that it is in all cameras (I have C-765).

Here are sample photos.


http://www.cc.jyu.fi/~muamshai/sample/P1.jpg

F-number : F/3.2
Shutter Speed : 1/13 seconds.

I don't remember what was the exposure because it was not fixed. This photo was taken in M mode



http://www.cc.jyu.fi/~muamshai/sample/P2.jpg

F-number : F/2,8
Shutter speed : 0,77 seconds
Exposure : -1

This pic was taken in Aperture priority mode


http://www.cc.jyu.fi/~muamshai/sample/P3.jpg

F-number: F/2,8
Shutter speed : 1/5 seconds
Exposure : -1

Taken in Aperture priority mode.

In my opinion, picture 2 is bad because the blubs don't look natural.

I would love to know the suggestions for improving photos (except suggestion of changing camera :D )

Newbie
04-11-2005, 07:01 AM
In Manual mode you can't set the exposure to +x or -x because that simply increases or decreases the shutter speed(or maybe the aperture too), something which you have control of.

In order to see this, place your camera on a still surface and point towards a well lighted area, place it in aperture priority mode and take a picture. Look at the shutter speed. Repeat the same thing with an exposure compensation of +2 and -2...

I may be wrong since I haven't done any tests about that right now, but if I remember correctly this is what I noticed previously. If that is the case, then you have control over exposure in Manual mode, just in a different way. The reason its only available in other modes is because in other modes the camera has to estimate based on what its programmed for. So if you want something different than what its programmed for, you need to compensate the exposure.