Jump to content

50 Mm 1.4 Lens Focus Problem.


Tibbiemax71
 Share

Recommended Posts

I took some pics of a friends Bull Terrier at a show today, this is how it came out, obviously the dog is not sharp but if you zoom in and go to the very bottom edge of the pics, the grass is very sharp, which is probably about 6 inches this side of the dog toward the camera. I had the middle focus point selected, the focus point is just in front of the flank on the dogs last few ribs. It was taken on a Canon 50 D, f/ 2, Shutter 1/4000 sec, AF mode was AI Servo.

Have I done something wrong? I am finding this is happening a bit with this lens, don't get any probs with my 18 - 200 mm lense, I did some googleing and some said it has a "front focus" problem? If I bump the f/stop up I find its fine to, but I was trying to get nice bokeh today and its annoying as it could be very sharp at f/2 if it was focusing where it says it is.

DPP_0007.jpg

Link to comment
Share on other sites

I took some pics of a friends Bull Terrier at a show today, this is how it came out, obviously the dog is not sharp but if you zoom in and go to the very bottom edge of the pics, the grass is very sharp, which is probably about 6 inches this side of the dog toward the camera. I had the middle focus point selected, the focus point is just in front of the flank on the dogs last few ribs. It was taken on a Canon 50 D, f/ 2, Shutter 1/4000 sec, AF mode was AI Servo.

Have I done something wrong? I am finding this is happening a bit with this lens, don't get any probs with my 18 - 200 mm lense, I did some googleing and some said it has a "front focus" problem? If I bump the f/stop up I find its fine to, but I was trying to get nice bokeh today and its annoying as it could be very sharp at f/2 if it was focusing where it says it is.

DPP_0007.jpg

adjust your aperture until the dog is crisp, if you have it set to auto focus it won't always work out the way you want it

Link to comment
Share on other sites

Your lens may front focus slightly. It's common enough that Canon built in a feature on the newer models to fix it.

Download a focus test strip (google it as i don't have the link right now) and set the test up as per the instructions. See what your results are.

If you are finding front or back focus and your camera has a micro adjust feature, follow the directions in your manual to dial the lens in.

If your body does not have this feature, send body and lens in to Canon for calibration.

If the test shows your lens is spot on, then it's a technique issue.

I don't know how you would have consistently gotten the eye in focus with the middle point selected and f2 here - better to move your point to the outer corner as focus and recompose with a shallow depth of field is very hit or miss.

Edited by kja
Link to comment
Share on other sites

Thanks guys. Will do that now KJA, yes I realised that I should have set the focus point off the left, on the eye, or course I realize this after I got home from taking pics :)

Happens to everyone - and usually on those frames that you really really want LOL

Link to comment
Share on other sites

  • 4 weeks later...

OK, I finally got the chance to do this the other day, I think I got the angle of the camera to paper right (45 degrees) from what I can tell, it is focusing as it should be, so I must be the problem, I wonder what I did wrong though :laugh: Maybe I just need to use it more, the more I practise with it the better results I will get I guess.

focus.jpg

Link to comment
Share on other sites

I notice you used AI servo when you took the pic of the dog. Since he was standing still you might have been better with using one shot to lock on focus. Dont be too disheartened just yet.

Thanks Kirislin, AI Servo is for moving subjects isnt it? I normaly leave my camera on that, so will make sure I change it to the One Shot instead :laugh: Think I had on one shot for the focus test thing, will have to check.

Link to comment
Share on other sites

Practice practice practice.

And remember to take more than one frame if you are shooting wide open or almost wide open. That depth of field is a biatch. Check out this Depth of Field calculator - it's a little shocking when you do the math :)

Just keep at it - you'll get there. And not every shot has to be shot wide open, stopping down a bit can still give you the nice isolation but make your life easier.

Link to comment
Share on other sites

I got a 50mm 1.8 and I also battle with the focus, need more practice!!

They are a bugger arnt they!! I go to use mine then think, nah will go with my 18 - 200mm just in case I stuff it up, but I really need to get the 50mm out more and have a go with it.

Link to comment
Share on other sites

Lots of lenses don't work as well at their extremes and this is particularly so of the 50mm (1.4 and 1.8)

Personally, I try and avoid shooting my 1.4 lens at less than 2.2 if I can help it. It just isn't as sharp as I like when I'm shooting wide open. I've seen many people say the things on various forums so it isn't just my own observations.

Link to comment
Share on other sites

I know someone with a 50mm 1.4 that feels she always has to use it at 1.4. Then asks why her photos are out of focus. Drives me nuts. If you can use it that wide open, then good on you, but it's way too challenging for me :p

With practice, you will find your favourite range. Mine is 2.2 - 2.8. I very rarely use it out of that range, unless I have the flash on.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...