My canon 450d is struggling on auto focus?

Question

Its probably me rather than the camera, but its getting so frustrating and I need some guidance! I am failry new to photography so please excuse and wrong terms and please go easy on me :-) I have started using my camera on a mode so that I select the shutter speed and ISO. I get the hang of the ISO, and understand the basics of shutter speed. I have been reading up and trying to practice the Apature, but feel i'm better leaving that on auto at the mo! So, the camera seems to be struggling on some landscapes when zoomed right out.... it is happening in most lighting conditions. The lense just goes right out and back in. I dont have a problems if there is something in the forground, but I dont always want this. I have tried adjusting the shutter speed and ISO but not having much luck. I know I can use manual focus but don't feel confident yet that I will get it right. Is there anyone that can shine a light on this please? Thanks for reading.

Answer 1

I make a lot of landscape pictures.



The first thing you need to learn about is Depth of Field (DOF) and how to maximize it for your landscape photography.



The second thing you need to learn about is how to be in control of your camera to achieve what you want.



The third thing you need to learn is that a tripod is mandatory for good landscape photography.



I do applaud your efforts to learn more about ISO and shutter speed though but, in my opinion, you're going in the wrong direction for landscapes.



Here is how I'd use your camera to make landscape pictures with a maximum DOF:



1) Since the lens provides distance information to the camera you can use that feature to focus on an object/subject at 4'-0'' and then lock that focus distance. The Owner's Manual will explain how to do both.



2) Have the camera in Aperture Priority. The goal is maximum DOF and with the camera on a tripod shutter speed isn't all that important.



3) Us the 18mm end of your 18-55mm zoom and set the Aperture at f16.



4) With focus locked at 4'-0'' find a scene and compose your picture. Use the camera's Self-Timer to release the shutter.



With your camera set up as described your DOF will be from 1'-11'' to infinity. Anything from 2'-1'' in front of your imaginary subject at 4'-0'' (1'-11'' in front of your camera) to as far as you can see - infinity - will be in focus. So find something of interest in the foreground (a gnarled tree trunk, bright colored flowers, anything you find interesting) and stay at least 2'-0'' away from it, compose and release the shutter.



Here are a couple of examples:



http://www.flickr.com/photos/drifter45h/4032748624/ 21mm lens @ f16, 6'-0'' set on the Distance Scale on the lens, Circular Polarizer. DOF from 2'-2'' to infinity.



http://www.flickr.com/photos/drifter45h/3982233634/ Same as above.



With an admitted bias I think the examples are pretty good, especially since I used a 30 year old film camera and a lens about that old. The old saying "Its not the camera its the photographer" was, is and always will be true.



At http://www.dofmaster.com/dofjs.html you can begin learning about DOF. For my examples using your camera I used the DOF Calculator, chose your camera model from the list and then from experience chose 18mm @ f16 and 4'-0'' as a subject distance.



Since you've been experimenting with shutter speed and ISO you may as well go all-in and learn about the Exposure Triangle - Aperture/Shutter Speed/ISO. This site explains it in easy to understand terms:

http://jfletcherphoto.wordpress.com/2009/02/20/the-exposure-triangle-in-beginner-speak-the-end-of-auto-mode/ NOTE: When I tried this link it didn't exactly work as it should - it says ERROR 404 but don't dispair. Look to the right, scroll down and under Popular Posts Right Now click on the first heading: The Exposure Triangle. If you can figure out why my link didn't work please let me know.



These sites will also help with your photography education:



http://www.digital-photography-school.com Sign up for the free weekly email tips, tutorials and challenges.



http://www.illustratedphotography.com



http://www.kamerasimulator.se/eng/?page_id=2

Answer 2

Read your camera manual for how auto focus works.



DSLR's are not as smart as point and shoots when it comes to autofocus. That's right, you heard me.



On point and shoots a computer on the camera analyzes the scene. It looks for familiar objects like faces or moving subjects, and prioritizes them for focus.





A DSLR, doesn't actually "see" the image when it auto focuses. Instead, it relies on several sensors called auto focus points shown as little squares in your viewfinder. All they do is to detect horizontal and/or vertical lines of contrast. Unless you have a contrasty line going through an active auto focus point, the camera will not be able to focus. For instance, if you put an active point on the sky, or the surface of water, the camera will not be able to find focus.



I suggest you read the section in your manual about auto focus and how it works on your particular camera.









This is one of the reasons I give for why a DSLR will result in worse images than a point and shoot for many photographers. People just don't realize how much of the photographic process that a P&S automates for you. The major selling point of a DSLR is that it takes the automation out of the process and allows you more control over the images. That only works if you no how to control the camera.

Answer 3

Your choice of shutter speed, aperture and ISO have nothing to do with the autofocus operation.



Have you selected a single autofocus point? If so, what exactly are you trying to focus on with it? It needs something with strong contrast and preferably sharp color transitions.

E.g. when you try to focus on a white wall, a cloud, empty blue sky or a distant green field, then it won't have the contrast that it needs. Does the problem persist if you try to focus e.g. on the foliage of a nearby tree, the grass at your feet or text on a page of an open book?



Edit:

A reflection of e.g. the sky on a lake usually is difficult to focus on, for the same reason why focusing on the sky is difficult. In such situations i'd focus manually or focus on something of approximately the correct distance in another direction, and then to hold the focus lock button while i recompose the shot.



Please explicitly try focusin on something contrasty, just to verify that the autofocus system is working correctly.Also, please verify that your camera is set to use a single user chosen autofocus point, instead of choosing the autofocus points for itself.

Answer 4

Put the camera on Aperture priority. Preferably set the aperture somewhere between F8 and F16. Put the central focus point directly on something far away in your shot (like the horizon - or something with detail or contrast, like buildings, people, trees, clouds etc etc). Depress the shutter release half way. Hold it, and move your camera to compose the shot. Fully depress the shutter release to take the shot.



Auto focus is not magic - you need to point it at something to focus on!!



As far as lakes are concerned - try focussing on the far shore line.



And there is always manual focus as a last resort.



@hondo there is absolutely no reason you can't use auto focus for landscapes, only in low lighting or low contrast conditions would you need to use manual focus.

Answer 5

What you are describing is exactly why most landscape photographers use manual focus for best results. The only time I use auto focus is when I am taking photos of a moving subject, or am hand holding the camera. Landscapes call for using a tripod an manually focusing the camera.

Answer 6

Are you trying to use it in low light?, that is always a problem with most lenses, especially the cheaper kit ones. I agree with Death, I have switched the Auto Focus off on all of my lenses. After getting used to the old Manual focus lenses on my 35mm SLRs I just don't like using AF anymore. Why don't you give it a try?. .

Answer 7

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Answer 8

A whole can of worms here. May I suggest that you go to a good library and read some basic photography books which I am sure will be of help. Good Luck.

Answer 9

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Answer 10

then use manual focus... :D