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Old Apr 1, 2010, 7:35 AM   #11
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Originally Posted by Simtech View Post
I hope this is big enough, I am looking back at pictures on my work computer and most look okay. But this one will show you what I mean.
Perfect example of the depth-of-field Mark is talking about. That's a big learning curve for some people coming from a point-and-shoot background. If the focus point the camera used is the one on the dog's nose then everything worked EXACTLY as designed.

Now, another truth is - DSLR cameras apply much less in-camera sharpening than digicams do. The reason is - once an affect is applied and an image altered you can't undo it. So, the default settings in DSLRs tend to be less dramatic - the thought being that people using them want more control over their images. So, sharpening can be done in post processing on the computer. Or, if you want to use your DSLR more as a point-and-shoot you can go into the camera's menu system and bump up the in-camera sharpening.

The truth of the matter is - a DSLR is NOT a magic point-and-shoot camera. Many people buy a dslr because they want a better point-and-shoot. It doesn't work that way.

You can do on-line or book research on depth-of-field so you understand the principles. But it's only through practice that you will understand the practical implications. You have to get a feeling for how much depth-of-field you're going to get with a given focal length, a given distance to your subject and a given aperture.

Now - here's an easy tip - if your subject is a specific person/animal/object select a single focus point in the camera (as Mark indicated many people use center focus point). And make sure that center point is on your subject. In the case of the dog where (after some experience) you'll KNOW the entire subject won't be in focus - you make sure that focus point is on the most important part of your subject - in the case of people or animals that is almost always the EYES.

Here's an example - no way all of the image can be in focus as depth-of-field is around an inch. So I choose for the EYES to be in focus (note - even my son's lips are out of focus):



Here's a link to a quick depth-of-field calculator. Simply plug in the numbers and you'll see just how little space is actually in focus for any given shot:
http://www.dofmaster.com/dofjs.html
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Old Apr 1, 2010, 7:40 AM   #12
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One other thing - the dog image is pretty 'close' - be aware that lenses have a 'minimum focus distance' so if something gets too close they can't focus. Dedicated macro lenses often have the ability to focus on objects closer than standard lenses do.

A bee is a good example of a challenging subject where 1:2 or even 1:1 macro lenses are beneficial. They allow you to get close enough to your subject where your subject fills a large portion of the frame. With normal lenses you have to back away and the subject fills such a tiny portion it is difficult to get detail. Depth-of-field also plays a part - even when up close, you're often shooting macro at f8-11 to get enough depth-of-field to get your entire subject in focus.
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Old Apr 1, 2010, 10:27 AM   #13
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Well if we start talking macro then things get crazy regarding DOF. This fly was taken at almost 1:1 so the image isn't cropped apart from a bit of dead space on the right. As you can see even at f14 it goes out of focus pretty fast.



As for the photos you posted, they are as I was expecting and as John describes.

In regard to the graduation, I would suggest a good external flash to give you the power for reaching to the stage if this is the desire. Even so you will still be wanting to push the ISO to the 1600+ range and have the 70-300 at f5.6. You are likely to get 1/160s quite comfortably which with the IS should do what is needed. However, if you can get inside a hall or something before to practise that would be a good plan if you want usable photos.

So to recap (as I think you got it backwards).

small f number = wide aperture, allowing in more light but reducing how much is in focus (shallow DOF).

big f number = narrow aperture, allowing in less light and increasing what is in focus (wide DOF).

To get your desired results and to maintain exposure you need to balance shutter speed, aperture and ISO.

All of these make for a brighter exposure - slower shutter speed, wider aperture, higher ISO.

All of these make for a darker exposure - faster shutter speed, narrower aperture, lower ISO.

With increasing ISO you also increase noise so again something else to balance..... yep, it's fun as often you need to get a fast shutter speed, but also need enough in focus without going too noisy.... hmmmm how to do it...... well that's the learning curve and what keeps us at this game trying to improve.

Oh not all situations are the same, but indoors work certainly is.

The other aspect I didn't answer was that of the poor outdoor quality, if you have a sample of this that would help a lot.

Hope this is getting you in the right direction.
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Old Apr 2, 2010, 1:58 AM   #14
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Yes it is getting me in the right direction for sure as those F stop numbers always get me! I went out today to practice and I feel pretty good with what the f stops do now and I think I got that part in my head now. But I still received some fuzzy pictures. I did move over to the single center AF point and recompose which I like! However I thought if I had the camera in full auto it would function like a point and shoot and I thought that if I am in Av mode that the camera would figure the rest. I mean it does but does it not do a good job all the time? And same with Tv mode. I see soccer moms walking the streets with canons all the time and I bet they dont get all into the setting but they snap away and they use DSLRs as there regular camera. But again I dont talk to them and they too might not be getting the quality they want either.

I know there is alot to these cameras and I knew there was going to be a rather large learning curve for sure but i just feel as though I am not getting the quality I thought I would be even in full auto. I do get alot of great pictures dont get me wrong but on alot of picture when I zoom in to look at the photo on the camera it just gets fuzzy (looks clear till I zoom in). I did come from a P&S and the reason I wanted DSLR was because my P&S started to not give me what I wanted. I had full manual, AV, TV modes but my ISO's were low and my f-stops and shutter speeds did not get me where I wanted. I know ill get it in time and I did figure it was all me, I just need to get out and shoot more!!

I do get alot of fuzzy shots when I shoot macro but that is because I free hand and my macro does not have IS. But I really love macro shooting!! I fell that that is my favorite type, flowers and bugs. I own bee hives and I love to snap pictures of them coverd in pollen.

Really, thanks for all the info you all have gave me. it really is helping alot!!
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Old Apr 2, 2010, 8:40 AM   #15
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If it has not been mentioned already, besides your f/stop, the focal length and subject distance effect DOF. As you decrease subject distance you also decrease DOF. Instead of stopping down you can try backing up just a bit. I don't remember the math but its quite drastic. For example if the subject distance is 2 feet and you increase the distance to 3 feet, you double your DOF.

Focal length is the opposite. As you gain focal length you decrease DOF. So for example if your at 100mm shooting a subject and you decrease to 50mm you increase DOF by 4.

So don't always fall back to stopping down. As long as distances are not drastic changing distance and focal length can be more beneficial that stopping down. If you have room to crop, and depending on intended use of the photo, just back away a bit.
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Old Jul 1, 2010, 2:31 AM   #16
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i know this thread is old, this is my first post in this forum.
but im having the same problem with my t1i. just recently it wont auto focus, i have to press the shutter half way down like 4 5 times before it even gets a focus. when it tries to focus the focusing just goes back and forth, if you know what i mean..
so would this be a camera problem or the lens? this happend useing the standard 18-55mm lens i havnt tried useing the 50mm or the 75-300 lens yet.

lorenzo
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Old Jul 1, 2010, 6:19 AM   #17
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Quote:
Originally Posted by diz_gti View Post
i know this thread is old, this is my first post in this forum.
but im having the same problem with my t1i. just recently it wont auto focus, i have to press the shutter half way down like 4 5 times before it even gets a focus. when it tries to focus the focusing just goes back and forth, if you know what i mean..
so would this be a camera problem or the lens? this happend useing the standard 18-55mm lens i havnt tried useing the 50mm or the 75-300 lens yet.
Switching lenses would be the fastest way to find out, and sometimes you juet need to remove and replace a lens just to get everything where it's supposed to be.
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Old Jul 13, 2010, 9:25 PM   #18
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Right there with you all! I think I am running into the dof problem. I have used SLR's before, so I thought I was familiar with that issue (I knew that a higher f number would give me better dof)...BUT I don't think I realized just how shallow that dof is. The other thing is, on Auto the T1i doesn't let you choose single point focus...
I found that it kept changing what it focused on if I kept pressing the shutter release halfway--so my subject would be in focus one minute and out the next. Frustrating for the softball photos I was taking! Half are great, the other half are sharp on the fence.
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Old Jul 13, 2010, 9:31 PM   #19
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Quote:
Originally Posted by diz_gti View Post
i know this thread is old, this is my first post in this forum.
but im having the same problem with my t1i. just recently it wont auto focus, i have to press the shutter half way down like 4 5 times before it even gets a focus. when it tries to focus the focusing just goes back and forth, if you know what i mean..
so would this be a camera problem or the lens? this happend useing the standard 18-55mm lens i havnt tried useing the 50mm or the 75-300 lens yet.

lorenzo
Did you ever try the other lens? Were you in low light, by any chance? I was extremely frustrated with my T1i in low light until I chose a center point focus and locked it in by pressing the shutter release halfway prior to taking the picture. Then, once my subject came into view (they were moving), I pressed it the rest of the way and it was usually good.
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Old Jul 13, 2010, 9:34 PM   #20
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Your kit lens are not fast enough to focus for action. Also for shooting action are you using AI Servo? That way the camera keeps focusing when you have the shutter have press, it will keep focusing.
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