EF 90-300mm - Why are my photos blurry?

[TommySharp]

Hey guys,

I'm new to this forum so hopefully I'm asking this question the right way.

I've got a 300D with the standard lense which comes with it and it's working no problem. I recently purchased an EF 90-300mm zoom lense as I wanted to take some wildlife shots and portraits.

I'm having a huge problem with all of my photos being slightly out of focus..... I've got the autofocus feature turned on and even have my camera on a tripod but I can't seem to get my photos dead sharp....

I've even tried playing with the aperature and setting it to f22 to try and get a better depth of field to see if I can get a better focus.

In the attached photo I had the duck locked with the camera's automatic focus system?

Could it be a problem that all of my photos are pretty much at the 300mm end of the zoom?

Any help or suggestions would be greatly appreciated....

Tommy

[henleg]

That's the beauty of digital: the cost efficiency of mistakes!

I find the same. It really is a matter of playing with the camera, and getting to learn how it "thinks". A few pointers (from a beginner) are:

1) Try selecting the auto focus point, bearing in mind that you have 7 to choose from, and so does the camera! so by selecting which one to use, the camera doesn't have to do as much thinking...

2) Use manual focus

3) If you don't have any restrictions on battery life, preview the picture, and zoom in on it as far as possible. You still won't see the truest image, but you'll see if it's badly out of focus.

The best thing you can do is PRACTICE!!! You have a digital, so don't be afraid of it!

Good lucj,
Henny

[tim]

If the duck's moving you'll need to use AI servo to keep it in focus. I looked around for reviews of the 90-300mm lenses to see if it had a reputation of being soft, but neither of the places I go for reviews had one. It's a consumer lens so a little softness at 300mm wouldn't be unusual.

[TommySharp]

Thanks for the advice guys.

I overode the 7 camera auto focus points so that it only used the centre sensor for focusing. I then foucsed on the duck with just that centre focus point. And I still got these results.

I even tried focusing manually but I can't quite get it to be nice and crisp clear.

[Ikinaa]

Googling around, I found that the 90-300 is a rather cheap zoom, even cheaper than the 75-300, which is rather soft at 300 and wide open.
What helps with the 75-300 is stopping it down to about f/11.
You'll loose 2 stops of light compared to f/5.6. If that's a problem, try compensating with a higher ISO.
f/22 isn't necessary sharper.
Most lenses are sharpest 2 stops down, sharpness decreases beyond again...

Make a more scientific try :
Put a ruler in front of your cam but at an angle of 45 degrees, your cam on a tripod.
Now focus (manually) on the middle of the ruler.
Take shots from the greatest to the smallest aperture, review the pics on the computer screen and decide which pic is the sharpest.
From now on, shoot at that focal with that aperture and your pics will be better.
I know that takes some time, but i did the same with my 75-300 and now the pics are sharp for the money the lens is worth...

[TommySharp]

Thanks for that info Ilkinaa, I'll do your ruler trick when I get some spare time.....

You say most lenses are more clearer 2 stops down..... I'm new to photography so could you explain a little?

I've got my head around the whole aperature and shutter relation now...

[Ikinaa]

I don't know why the lenses are sharper when stopped down, it must be some physics/optics thing, perhaps one of the scientists on this board can deliver an explanation.
But I noticed this fact with all my lenses, with some lenses, it is really visible (like the 75-300), with others it's less visible, but you notice it when looking close (like the 28-135)

[CyberPet]

Maybe I'm just seeing things, but it looks like the reflection of the bird is sharper than the bird itself. Could the lens suffer from front focus while shooting with AF? If I'm not totally mistaken, try to manually focus, and see if you get better results and get the sharpness where you want it. If the Manual focus work, then I think it's time to send the lens in for a calibration of the AF.

Sorry, I might be totally wrong here... but my recent problems with my Tamron has made me aware of the fact that the AF *can* be off and it's neither user error or lack of DOF.