Is it me or my lens?

[brake79]

Firstly, I'm relatively new to dSLR, so I know I'm still making lots of very normal newbie mistakes.

However, how do I know if I have a miscalibrated or bad lens?

I bought a Canon 70-200 f/4L IS USM. I also own a 60mm macro that I just adore, and I started out with a 18-55mm IS kit lens that went with my Rebel Xsi.

About 85% of my photos with the 70-200 lens are slighly out of focus. Now half of those are probably my fault. However the other half of the time I get sparkling crisp sharp beautiful *grass*, but my subject is still out of focus. It feels like the AF, especially on the AI setting loves to front focus, where I get 3/4 of the depth of field right in front of the subject.

Today I was shooting outside, partly cloudy. 1/640, 400 ISO, F/8 of my dog playing in the backyard about 25 ft away. Half the shots he was in the back 1/4 of the depth of field (so some part of his body was totaly out of the field), about 25% he was totally out of it, and about 25% he was in the back 1/3. Only 1 shot was he centered in the depth of field, based on the focus plane of the grass. Most of the time I focused on the dog while he was not moving (much), then kept the finger halfway down then took the picture when ready while continuing to track the moving target.

Is this a me problem, having no clue on how to photograph a moving subject, or is this a lens or camera issue? Most of the test images today I had the dog mostly sitting or hopping in place, trying to learn to freeze motion (which if not for the depth of field problem would have been great). OUt of 20 shots I only got 2 that were halfway decent, and they were definately not tack sharp. I was using the IS on mode 2, handholding either standing or sitting down. My assistant who was playing with the dog, and not moving nearly so much suffered from the same "blur", so I don't think it was all motion blur of the dog. I got some *great* pictures of grass blades though...

Suggestions please? thanks so much!

[AndrewCCM]

OMG.

That sounds like my Mark III syndrome after 2 trips to Canon.

[Gart]

My advice and take it for what it is worth.

Since you have said that you are fairly new to this, what you can try to do is to experiment with the lens and camera.

Find an object to photograph that has some length to it (ex. a car parked in the street). Set your camera and lens on a tripod so you are always shooting from the same spot. Now take the time and go through the settings on the camera as far as how many focus points you are using. If you are using the single center one, focus (MF or AF) on the front of the car. Write down what you did. Now change to more focus points (or less) and focus the center point on the same spot. Write down what you did. Experiment with this while taking notes.

Another thing to do in the same set up is to work with your aperture setting. Many people buy a new lens and try to take great pictures with it at the maximum aperture (lowest number). This produces such a thin DOF that they end up with out of focus pictures. It isn't the lens that is bad, it is more of what you are trying to do and you do not have the experience to do it (yet). Work with the f-stops and write down what you did. Again focus on the same spot of your subject.

With moving objects like your dog, that will come with time. If you are zooming real close to the dog, that is possibly why you are getting out of focus shots. Try panning moving objects like cars in the street. Not just snapshots, but get used to flowing with your subject. Again, don't zoom in real tight. You want to have some of the background in a slightly blurred state.

One doesn't become an expert overnight. The more you shoot, the better you will get. I recommend the note taking so when you review the photos, you can see what was right or what was wrong.

Keep at it.

Edit - A few other things: In your notes, write down how far away you were from the object for future reference. Try varying the amount of zoom. Try it on the wide side (take notes), zoom to about 1/3rd of what you have, then 2/3rd's, then full zoom if able (still take notes on what you are doing). As you review them, take a look at how much of the subject is in focus. Do you have the right amount? Too much? Too little?

janetg has a good point. If you can look at your pictures side by side it will allow you to determine if you are getting what you want. You can see what worked and what didn't.

[janetg]

also - if you can download a copy of breezebrowser - you will see where your focus points are - relative to what is in focus - it's interesting

[Patti Edens]

Here's a simple experiment you can do that will take out a lot of the guess work...

1. Set up a tripod in your yard. Mount the camera and lens on the tripod.

2. Put a yardstick or some graduated ruler (I used a metal tape measure stretched out straight) angled slightly up and away from where the tripod is and 20 feet or so away. Experiment with the distance based on your focal length.

3. Autofocus on one spot on the ruler and take the shot. Do this at several different apertures.

4. Repeat all this, but manually focus instead of using autofocus.

I did this for my 100-400 IS lens and found that it was back focusing. Canon fixed it for a large chunk of change. So, if your equipment is still under warranty, make sure you resolve this before it goes out.

My Results: The 100-400 actually focused behind the point where I had the focus point when used in "autofocus", but it focused correctly when manually focused. My 400 prime lens autofocused at exactly the right spot in all cases using the same experiment.

Here's the final shot sent to Canon with the lens... I erased some of the info...

[Chop249]

Great info here. I'm going to be checking my lenses.

[Lexie]

Patti, I am so glad to see your experiment! This certainly clears up questions that I had about a lens that I rented. I have not noticed any problem with the lenses I own but, I'm going to be checking them anyway.

You always have great information to share. And speaking of 'clearing up' my SensorKlear LensPen is on the way!! Thanks

[brake79]

Thanks for all the helpful information!

Trying the "ruler test" at 70mm didn't show any autofocus problems, but I didn't test out other focal lengths. I've also started using the center point more, instead of all 9 points which seem to not always pick what I want in focus...

I did do a test subject (a TV dish on the neighbors roof), at 200mm at several f stops. everything under f8 did look a bit soft (but in focus), while >f 8 looked quite sharp.

So I'm guessing what I am experiencing is a combination of needing alot more practice and using smaller f numbers outside of its "sweet spot" and in an unforgiving DOF.

I bought myself a monopod today too, so that should help a bit with stability I hope! I have to say the folks at Houston Camera Exchange were very nice to a novice like me!

Thanks for all the kind suggestions! I know "mentally" that one does not get good at this overnight, but gee I can be impatient at times!! hah!

[studiocygnet]

Many different manufacturers are seeing this problem. Here is a link to a discussion of dSLR focus problems, including a little chart you can use. It's from a Nikon forum, but I think it would apply to any camera.
http://www.FocusTestChart.com/chart.html

[mdparthum]

Great link! Thanks.

[David Whatley]

Its a bad lens, so bite the bullet and sell it to me for 150.oo
Want me to pay pal the funds?
:)

[AndrewCCM]

http://www.openphotographyforums.com...ead.php?t=4708

Interesting way of using your LCD to calibrate. I used it and the ruler test and the focus chart and the 45 degree test, etc etc etc...

Bottomline (for me), testing and adjusting using controlled environments and test charts did not equal real life shooting and focal distance/lens combos. I ended up having to do some on-the-fly micro adjustments to my Mark III and various lens combos to get something within my satisfaction. Throw up a test chart or tape measure and calibrate to that did nothing for my real world results...unfortunately.

For prime lenses, it can work well. But for zooms...there was too much descrepancy between lets say adjusting at 70mm then adjusting at 200mm.. I had to find the FL that I used most and adjust to it.

[heiyoulianglaohu]

Originally Posted by brake79

I bought a Canon 70-200 f/4L IS USM. I also own a 60mm macro that I just adore, and I started out with a 18-55mm IS kit lens that went with my Rebel Xsi.

You know.. I'm not sure but I can suggest something simple.
I'm not real knowledgeable about Canon but with Nikon there is VR (instead of Canon's "IS"). It's made to reduce a shaky or blurry appearance, but if you use it when the image is steady and it's not needed (like on a tripod) it will CAUSE your image to become blurry... Just a stab at guessing. Don't take my word for it.

[brake79]

You know.. I'm not sure but I can suggest something simple.
I'm not real knowledgeable about Canon but with Nikon there is VR (instead of Canon's "IS"). It's made to reduce a shaky or blurry appearance, but if you use it when the image is steady and it's not needed (like on a tripod) it will CAUSE your image to become blurry... Just a stab at guessing. Don't take my word for it.

Yes. IS on while on a tripod can make an image blurry. I "found" a friend help me out with the lens. He thought the IS might be out of calibration and since the lens was new, I sent it back for a new copy rather than send a new lens to Canon already. So I hope the next one will be better!

In the meantime I've been using my 60mm macro as a walkaround lens. Caught some very pretty shots of spring! This shot was cropped at about 80%. Can't wait to get my 70-200mm back for the extra reach! (At least I know the issues weren't the camera!) Thank you everyone for the suggestions! Its been an education! I'm glad to have found a friendly and helpful community here!

[AndrewCCM]

IS while on tripod only causes issues with certain lenses...Not all. Many implementations of IS are tripod aware...You'll want to check your manual. I believe the 70-200 IS is tripod aware... Need to double check on that.