View Full Version : Newbie Needs Help with Autofocus & Exposure


JLM
08-02-2007, 05:12 PM
Hello everyone and Thank You (in advance) for any help, tips, advice you can give me.

I've been shooting digital photos for about 3 years ... first with a Sony Mavica and more recently with a Panasonic Lumix FZ20. Both cameras took excellent photos; but I wanted to upgrade to a digital SLR with interchangable lenses.

Last month, I bought a new Canon Rebel XTi with the EF-S 18-55mm kit lens. From all the reviews I've read, the kit lens is basically a throw away. Anyway, I bit the bullet and bought a EF 70-300mm IS USM lens, which cost me almost as much as the camera.

At this point, I'm so frustrated that I feel taking all of my Canon equipment and throwing it off a tall bridge. I absolutely can't get a good, clear shot no matter what I try.

Mostly I've tried shoot outdoors (birds, zoo animals, etc); but I've also tried shooting portraits and indoor (museum, art gallery, etc.) scenes.

My two biggest issues are:

(1) I want my ENTIRE picture to be in good sharp focus; but the camera seems to auto focus where ever the heck it wants. Part of my photos are in focus; but usually not my main subject. I'm almost forced to use autofocus mode because my vision is pretty lousy; but I have tried manual focus mode without much better luck.

(2) Next, most of my photos come out a bit too dark regardless of the settings I choose or whether or not I use the flash. Even in "P" mode, where the camera sets both shutter speed and aperature, they are darker than I'd like. Since I can edit my photos and increase the brightness, this isn't as huge problem; but I'd prefer to get the exposure right with the camera.

I have tried experimenting with different settings; but I'm just not getting something. It seems that everyone who has an XTi loves their camera; so I'm inclined to believe the problem is me ... not my camera.

I'm hoping some of you can give this newbie some pointers that might help me get some good shots.

Also, maybe I just haven't gotten the right lens for what I'm trying to shoot. I really can't afford the L lenses; but any recommendations will be GREATLY appreciated.

Thanks
Jane

livin4lax09
08-02-2007, 05:34 PM
first off, welcome to the DSLR world (and Photography Review!), and over time I have no doubt you will start to enjoy it here. I wouldn't say the kit lens is a throwaway, it is just very dependent on your individual lens. The kit lens is one that canon doesn't have a lot of quality control with, and they just throw it on there. Sometimes you get a really sharp copy, sometimes very soft.

yes, your new lens was expensive. That's how this stuff works. Many people do not realize that image quality is largely dependent on glass, not the camera itself. I just bought a lens for about 3 times what I paid for my camera. But that's the fun about DSLRs, you can try so many different lenses!

to help with your most common problems, try the following.

1) if your camera is not focusing where it is supposed to, it's alright because it's a piece of machinery that doesnt understand what you want to do. Try switching the focus point. There should be a button in the upper right corner of the back of the body. Press it and look through the viewfinder. THis is your AF point. Most likely it is now set on evaluative, meaning all of them. Flick the dial at your index finger, and you will see the AF point switch. I personally use center point for most of what I do. If you set a specific focus point, then put that over the subject before autofocusing, it will focus on that point, and that point only, instead of trying to guess what you want a photo of. AF has improved tremendously over the years, but still can't understand what you want.

2) check your exposure compensation. In P mode it is still possible to get dark photos. There should be a set of dots in the bottom section of your viewfinder and on the rear of the camera in the LCD. I have not used an XTi extensively, but what you want to do is press the shutter button down halfway, and it will give you your exposure values. I believe you can hold down the Av +/- button, and spin the index finger dial, it will move a dot along that "line" at the bottom of your camera. right in the middle yields a correct exposure. it increases and decreases in 1/3 stop increments. If you think that when the exposure is in the middle it is still too dark, you can always just increase the overall exposure. For example, on my camera I know it tends to underexpose about 1/4 of a stop. so I set my exposure for +1/3 to compensate for this.

Of course, just like the AF, the camera isn't THAT smart. If you are shooting a very bright subject, like a white shirt, it will underexpose. Or a black shirt, it will overexpose. Because it is just trying to get an average reading, and turn everything in the scene an average brightness, aka grey between white and black.

so play around with it a little more, read that manual (i know, ugh) and if you have any more problems feel free to come back for more help.

WesternGuy
08-02-2007, 05:52 PM
I agree with all of what Brent says and have little to add, except for one thought...you might want to acquire a copy of Understanding Exposure (Revised Edition) by Bryan Peterson. I learned quite a lot from reading it and often go back and read parts of it to refresh my failing memory. As well, if you are new to digital photography, one of the best books you can by is Digital Photography for Dummies. My wife bought me a copy after I bought my XT and it was extremely helpful. HTH

Cheers,

WesternGuy

DEvianT
08-03-2007, 03:22 AM
I agree with all of what Brent says and have little to add, except for one thought...you might want to acquire a copy of Understanding Exposure (Revised Edition) by Bryan Peterson.

Another vote for Bryan Peterson's book. It's the most clear and helpful photography starter manual I have ever read. I also always recommend to any photographer I train. Every time they are very happy with this book.

It is now a right of passage. Get this book. Read it. Get good. Pass it on to a new photographer. Then they repeat the cycle.

Also check your lens isn't back focusing. Set camera on a tripod. Focus manually on an object like a book cover or box with writing on at 45 degrees to camera a suitable distance away. Take pic and check what you focused on is actually what was photographed in focus. If not return lens and get it calibrated.

May also be useful to check camera with another lens. The shop you got it from should let you do this really.

mwfanelli
08-03-2007, 08:25 AM
first off, welcome to the DSLR world (and Photography Review!), and over time I have no doubt you will start to enjoy it here. I wouldn't say the kit lens is a throwaway, it is just very dependent on your individual lens. The kit lens is one that canon doesn't have a lot of quality control with, and they just throw it on there. Sometimes you get a really sharp copy, sometimes very soft.

yes, your new lens was expensive. That's how this stuff works. Many people do not realize that image quality is largely dependent on glass, not the camera itself. I just bought a lens for about 3 times what I paid for my camera. But that's the fun about DSLRs, you can try so many different lenses!

to help with your most common problems, try the following.

1) if your camera is not focusing where it is supposed to, it's alright because it's a piece of machinery that doesnt understand what you want to do. Try switching the focus point. There should be a button in the upper right corner of the back of the body. Press it and look through the viewfinder. THis is your AF point. Most likely it is now set on evaluative, meaning all of them. Flick the dial at your index finger, and you will see the AF point switch. I personally use center point for most of what I do. If you set a specific focus point, then put that over the subject before autofocusing, it will focus on that point, and that point only, instead of trying to guess what you want a photo of. AF has improved tremendously over the years, but still can't understand what you want.

2) check your exposure compensation. In P mode it is still possible to get dark photos. There should be a set of dots in the bottom section of your viewfinder and on the rear of the camera in the LCD. I have not used an XTi extensively, but what you want to do is press the shutter button down halfway, and it will give you your exposure values. I believe you can hold down the Av +/- button, and spin the index finger dial, it will move a dot along that "line" at the bottom of your camera. right in the middle yields a correct exposure. it increases and decreases in 1/3 stop increments. If you think that when the exposure is in the middle it is still too dark, you can always just increase the overall exposure. For example, on my camera I know it tends to underexpose about 1/4 of a stop. so I set my exposure for +1/3 to compensate for this.

Of course, just like the AF, the camera isn't THAT smart. If you are shooting a very bright subject, like a white shirt, it will underexpose. Or a black shirt, it will overexpose. Because it is just trying to get an average reading, and turn everything in the scene an average brightness, aka grey between white and black.

so play around with it a little more, read that manual (i know, ugh) and if you have any more problems feel free to come back for more help.

To add to this...

On a P&S, the DOF is huge. With a DSLR, it is not. You will have to learn about DOF and its relationship to the choices you make. Remember, a lens can only focus at one point. Everything else depends upon your eye's inability to discern a difference. This can cause an out-of-focus look that is perfectly normal on a DSLR and rarely seen with a P&S camera.

Are your photos really too dark? First, is your monitor calibrated? You can't tell anything about exposure until this happens. Also, the camera has a limited dynamic range, basically the difference between very bright and very dark. If some things have the correct exposure but other things are dark (like a person standing in strong backlight), you have to determine the exposure or change the lighting as the camera can't tell what is important or what you want.

I too suggest learning about exposure. The basics are a must if you are to really get good photographs. Digital makes that faster but doesn't eliminate the need to learn.

JLM
08-03-2007, 02:12 PM
Hi again and THANK YOU for all of your wonderful advice.

I've shot a few pictures using Brent's suggestion about selecting the center autofocus point and I'm getting much better results now. (I still need to get the hang of DOF; but at least I'm getting my main subject is in focus now.)

I also changed the exposure setting and the results are much better too. As for calibrating my monitor, I think it's okay. My printed photos are a near-perfect match for the on screen color and contrast.

I guess my next step will be to head to the bookstore this weekend and also do a lot more practicing.

Once again, thanks for all your help.

Jane

AlbertHurwood
08-18-2007, 01:36 AM
Dear JLM, I have the same camera and the same lens and frankly, for the price, they are EXCELLENT!
To start with are you shooting in RAW?
That is essential if you want to get the sharpest results.
Also, using a very fast shutter speed with a telephoto lens is also essential.
I don't know how steady you are, but I find that I can't shoot at 200mm at less than 1/500 sec and hope to get anywhere near a sharp picture.
I don't have the IS lens I have the cheaper 75-300mm and in sunlight shoot at over 1/1000 if possible.
This is a recent shot I took using the above lens at about 200mm at 1/1600 sec at f8.

http://www.the-web-club.co.uk/caz/girl%20in%20boat-(processed).jpg

It was lightened and sharpened a little but looks quite reasonable.

Also if you look in Photo Critique you will see 2 pics I have taken using the 18-55mm lens with a cheap close up lens attached.

Basically, it comes down to getting to know your camera, exactly what it, and you, are capable of.

It takes time, but be assured, as long as there is no mechanical problem with the camera then there is only one final ingredient: Practice!

Take pictures - hundreds, thousands, and analyze what has gone wrong and how to improve them.

For instance that close up of the spider on the dandelion - I took at least 100 pics of which only that one was any good at all!

And the bee one was one of over 300 shots I took of which only a handful were worth saving.

But the beaty of Digital Photography is that once you have your camera and card the rest is free!

So good luck with your photography, persevere, and you will find that you just get better and better!

Oh and by the way, I have been taking photographs for many years, but like almost all photographers ( as opposed to "Happy Snappers") I consider I am still learning, and always will be.

Basco
08-20-2007, 09:59 AM
what they said up there is pretty sure and accurate,what i can say that with ur cam and lens and more practice ull be able to take nice shots,u gotta hold up steady ur hands (u have the IS version in ur 70-300 anyway) so u should be able to have sharp results especially especially outdoors,good luck.