Focus tracking

[vikkiolds]

<p>Hi,<br>

I am trying to learn about focus tracking but I'm having some trouble and maybe someone could help me figure out where I've gone wrong. I watched a tutorial video on the web to start learning this focus technique but I am doing something wrong and I can't figure it out. It looked really simple in the video...lock the focus on a subject and then recompose and take the shot.<br>

Camera: Canon EOS 7D Mark II<br>

Lens: Canon 50mm<br>

My manual says that I can use One Shot AF for still subjects to lock focus and then recompose. It was a little windy for the daffodil shot but I thought I handled that with such a high shutter speed.<br>

I started practicing with a daffodil.<br>

ISO 100<br />f 1.4<br />shutter speed 1/1600<br>

http://www.photo.net/photo/17994640<br>

I locked the focus on the stem just below the flower and then recomposed on the flower. As you can see I ended up with an out of focus stem and the center of the flower is also out of focus but the petals behind the main flower are in focus.<br>

I then tried with a dandelion, a different lens and different settings.<br>

Canon Lens: 55-250mm<br>

ISO 100<br />f 5.6<br />shutter 1/160<br>

http://www.photo.net/photo/17994641<br>

I focused on the juniper berry on the left of the flower and then recomposed. The juniper berry is out of focus, the outside edges of the petals of the flower are out of focus but some of the blades of grass around the edges are in focus.<br>

I was trying to get a nice out of focus background and then a clear focus on the berry and the flower. What would make the juniper berry be blurry but the blades of grass in focus? Was it because the grass might have been closer to the lens and the juniper berry further even though I thought I locked the focus on the berry?</p>

[Jochen_S]

<p>I'm not familiar with Canon. Did you hold the shutter pressed or let the AF button go after locking focus? If you consult an online DOF calculator you'll notice that f1.4 grants someting pretty close to zero DOF wise at your chosen working distance for the flower shot. It is very likely that you or the flower in the wind moved a wee bit during your reframing attempt.<br>

Just as an example: if I am trying to reproduce a slightly crumpled letter (view finder filling) with my handheld 50mm macro lens I set it to f8 to make sure i get the entire page within DOF. And I can't take a handheld manually focused sharp format filling 1:1 reproduction of printed paper to safe my live, even at f16.<br>

If you really want to shoot flowers at f1.4 rely on your outer AF spots, fire as soon as you hear focus confirmation and do 3 attempts to be on the safe side. Your camera has a lot of mega pixels so if you are trying the insanely narrow DOF stuff its OK and better to crop an image later in post processing instead of getting it OOF while you are trying to reframe it. This sounds dirty but cuts the cake.<br>

Pardon my confusion & 2nd language. Isn't "focus tracking" a camera feature locking AF in continous mode on some face running towards the photographer?<br>

Anyhow: Focus & reframe seem to work only when you have a bit of DOF buffer to make camera and subject movements during the reframing irrelevant.</p>

[danmarchant]

<p>1. As mentioned by Jochen "focus tracking" is not the same thing as focus and recompose. In fact it is almost the opposite as it requires the camera to constantly adjust the focus in order to keep a moving subject in focus. <br>

2. Your focus problem is almost certainly due to a number of issues. First you locked focus using One Shot mode and then moved the camera to recompose. Second the subject moved slightly due to wind and third you were shooting with very narrow depth of field due to wide aperture. Even tiny amounts of movement will throw focus off when shooting close up with a wide aperture.<br>

<br />Solution<br>

Don't focus and recompose. The 7DII has Canon's latest and greatest AF system. There are plenty of AF points so you should be able to position one over whichever part of the scene you want to focus on and just take the shot, without needing to focus/recompose. If the subject is moving due to wind use AI Servo AF mode so that the camera keeps re-focusing to keep the subject in focus.</p>

[vikkiolds]

<p>Thank you Jochen and Dan. Yes, I got my terminology wrong.<br>

First it sounds like I should be using a tripod at f1.4 and not handheld and it sounds like I need a subject that is not influenced by wind/movement when attempting to shoot at that aperture. <br>

I was under the impression for some reason that increasing my shutter speed would make up for camera/subject movement and didn't realize that it wouldn't help with such a wide aperture. <br>

I'll look up AI Servo AF in the manual, do some reading on that today and I'll get deeper into the AF system to learn more about setting other AF points. <br>

I will practice with both of your suggestions today. Thank you again for such detailed answers. They make sense and are extremely helpful.</p>

[Jochen_S]

<p>Vikki, a tripod might not always be helpful with reframing after focusing either. You have 4mm of DOF at 45cm & f1.4. When I look at my ballhead (a big one made by Linhof) the hinge is far away from the image center. OK rotating the camera downwards as you did with the daffodil In portrait orientation will have no impact but paning it will result in a slightly out of focus image. - These things get tricky.</p>

[kerry_grim]

For general photography, I will use the center focus point and then recompose. This works fine unless I press the shutter before recomposing. But that is not your problem.

 

However, if I am out in the woods and doing closeups of salamanders, I will change my focus point so that I can focus on the eye and NOT recompose. In other words, when you recompose at a very close distance you will very likely move the focus out of the depth of field.

 

if I were to take a butterfly photo and the flower or the wings of the butterfly are moving, I would use AI-Servo. It would not work with One-shot as I would very likely be out of the depth of field area. To be fair, I use macro flash at f16, so the motion is stopped and there is a much larger depth of field.

 

As others said, f1.4 has virtually no depth of field. If you do a considerable amount of close-up work, a macro lens is great.

 

Hand-held photography of flowers is not easy. Try to do it when flowers are not moving due to the wind (good luck there!). Do your composure and select the correct focus point. Just as the flower settles with out wind, press the shutter button. Keep in mind you may need to try it many times and then select the best ones. Also, try to use something like f5.6 as that may be just enough depth of field to get the area of focus you are looking for.

 

I can successfully take a dozen photos very close of say, frogs or salamanders and all will be in focus. When I try flowers, the success rate is pretty low. So just keep practicing and studying your results. You will get better.

 

Lastly, a macro lens is better if you intend on photographing close-up more than just occasionally. I've been updating to the newer Canon lenses. My favorite is the 100 2.8IS lens, but there are times I use the ancient 50 compact macro as it is produces excellent results. I will never get rid of this lens, old or not. It is something like a 1987 design, sharpness is absolutely excellent and I would recommend a used one for someone dabbling with close-up photography. Truce macro lenses are corrected for close-up and you will have a flat plane of focus, which something like a 50 f1.4 does not have.

[vikkiolds]

<p>Kerry, I have put that 100 2.8IS lens on my wish list. It looks awesome.<br>

<br /> Jochen the tripod did help but as you mentioned panning doesn't work so well for what I was trying to do. Moving my aperture up a few stops got me almost to where I wanted to be.<br>

<br /> Sorry it has taken me so long to respond. I've been studying everything all of you have mentioned and have learned quite a bit. Had to come back here several times to really get it all to sink in.<br>

<br /> I am embarrassed to say when I viewed the video about recomposing I missed some very important points. One of them, the most important, is that you only get one main focus point unless there are other things at the same distance which explains why the grass blades have some focus. The parts that were in focus were at the same distance as the dandelion. For some reason when I watched the video I got the mistaken impression that if I set focus on one object and then recomposed that both subjects would be in focus and I would also get a nice bokeh for the background because of the aperture setting. Of course I have learned now that is not the case.<br>

<br /> Recomposing is for setting focus on your main subject and then composing the final image with the subject for the rule of thirds or at least recomposing to balance everything in the full image nicely.<br /> I thank you all again for taking the time to explain and I'm still practicing on all the things you've said.</p>