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Author Topic: 7D focusing question??  (Read 38891 times)

unfocused

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Re: 7D focusing question??
« Reply #30 on: May 07, 2011, 11:35:42 PM »
My personal opinion is that this is a depth of field issue. One shot in focus, one shot just slightly out of focus. Or more accurately, one shot slightly mis-focused.

I note that you were shooting wide open (2.8 at 1/1000) I'd bet that if you shot it at 1/250th at 5.6 her entire face would be in focus. It's hard to get autofocus perfect since the camera has to pick something to focus on and the camera can't really tell the difference between a nose and an eye. Practicing will help, but under real-world conditions, it's still hard to get it perfect every time.

Good news is that the only person who will notice will be you and only when you pixel-peep. Give them a print and it will look perfect.

One way to feel better about this problem. Go take a look at Robert Frank's "The Americans" and see how many of his pictures were tack sharp. Didn't stop him from producing what may be the most significant photo book of the 20th century.
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Re: 7D focusing question??
« Reply #30 on: May 07, 2011, 11:35:42 PM »

Orangutan

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Re: 7D focusing question??
« Reply #31 on: May 08, 2011, 09:15:00 AM »
My personal opinion is that this is a depth of field issue.

Agreed.  You need to perform basic tests for front/back focus to assure yourself that there's nothing wrong.

Can anyone suggest a good testing methodology?  A quick Google search yielded two:

http://www.focustestchart.com/focus21.pdf
http://www.leongoodman.com/d70focusnew.html

They're written for Nikon, but should work fine for your 7D.


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Re: 7D focusing question??
« Reply #32 on: May 08, 2011, 09:56:20 AM »
Cool.. I will keep practicing and see where I get to. Thanks again all of ya.

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Re: 7D focusing question??
« Reply #33 on: May 08, 2011, 01:49:41 PM »
You will find some good ideas and a workable autofocus microadjust chart here.

http://regex.info/blog/photo-tech/focus-chart

Be sure to read the article first, understanding how the test chart works with your camera will help you get the best results.  One of the many things to think about when testing autofocus is knowing exactly where your camera is going to focus.  Unfortunately, some test charts cause people to have difficulty because their camera may not focus in the right spot.  Then, we here complaints about erratic focus.

Focus can definitely be erratic, but make sure its not the test chart or subject causing it.

chriswatters

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Re: 7D focusing question??
« Reply #34 on: May 09, 2011, 11:51:03 AM »
When using a lens with a large aperture, and therefore a shallow depth of field, I have gotten similar results when my camera (a T2i) is set for One Shot AF. I suspect that my problem is that I do not fully release the shutter between shots. Any small change in distance can put the subject out of focus. Adjusting the zoom can also affect focus. Because the camera has already locked focus, it does not refocus until I fully release the shutter. To solve this problem, I either use Servo AI or make sure that I fully release the shutter between shots.

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Re: 7D focusing question??
« Reply #35 on: May 09, 2011, 04:46:42 PM »
When using a lens with a large aperture, and therefore a shallow depth of field, I have gotten similar results when my camera (a T2i) is set for One Shot AF. I suspect that my problem is that I do not fully release the shutter between shots. Any small change in distance can put the subject out of focus. Adjusting the zoom can also affect focus. Because the camera has already locked focus, it does not refocus until I fully release the shutter. To solve this problem, I either use Servo AI or make sure that I fully release the shutter between shots.

Using a tripod will help immensely.  You are trying to get the sharpest possible image, so any movement at all should be minimized.

chriswatters

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Re: 7D focusing question??
« Reply #36 on: May 09, 2011, 06:46:45 PM »
Using a tripod will help immensely.  You are trying to get the sharpest possible image, so any movement at all should be minimized.
A tripod might help in many situations, but it would be counter productive in mine. Most of the motion is on the part of the subject, and that requires more mobility on the part of the camera. 7 month old badies don't sit very still, even when you ask them nicely.  ;)

Shutter speed is effective in freezing motion in the X and Y directions. The focus problems comes from motion in the Z direction. The methods that I mentioned seem to be helping in my case, but I am open to other suggestions.

I also realize that the problem could be avoided by increasing the depth of field, but an out-of-focus background is also desirable. Compromises must be made. Improvements in technique help in balancing those compromises.
« Last Edit: May 09, 2011, 06:51:18 PM by chriswatters »

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Re: 7D focusing question??
« Reply #36 on: May 09, 2011, 06:46:45 PM »

maharzan

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Re: 7D focusing question??
« Reply #37 on: May 09, 2011, 09:55:52 PM »
Yea  I have tried micro adjusting only to later disable it all. It seems to focus right. The only thing I am concerned is sometimes it focuses great sometimes not. And then, I have to yet to get sharpest of images like I see on flickr or other forums with the same gear/settings. :) I guess people use more lights. Thats the only thing I think I am missing.

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Re: 7D focusing question??
« Reply #38 on: May 12, 2011, 05:41:16 PM »
The only thing I am concerned is sometimes it focuses great sometimes not. And then, I have to yet to get sharpest of images like I see on flickr or other forums with the same gear/settings.

Welcome to the world of the 7D.  See my post here.  And these articles here, and here, and here, and here.   Then cry when you realize you're outside of your return window.  But there's always warranty service if you want to start down that road.

Best of luck on your search for 7D sharp focus. 

 :'(

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Re: 7D focusing question??
« Reply #39 on: May 12, 2011, 08:47:51 PM »
The only thing I am concerned is sometimes it focuses great sometimes not. And then, I have to yet to get sharpest of images like I see on flickr or other forums with the same gear/settings.

Welcome to the world of the 7D.  See my post here.  And these articles here, and here, and here, and here.   Then cry when you realize you're outside of your return window.  But there's always warranty service if you want to start down that road.

Best of luck on your search for 7D sharp focus. 

 :'(

I've heard others comment about the accuracy of focus for the 7D.  I did not have the issue with mine once I learned to use it, but at first, half my images were out. 

Still, it seems that others see the same issue.

Here is a link to some analysis.  The data used for the analysis is pretty thin, and carrying out a analysis based on a trickle of data is a bit suspect, but, there may be something there.

For the most part, the data shows that the lens and not the camera determines accuracy of focus.

http://nikonrumors.com/2011/03/28/auto-focus-accuracy-a-scientific-cross-brand-analysis-guest-post.aspx

mogud

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Re: 7D focusing question??
« Reply #40 on: May 12, 2011, 10:02:08 PM »
This topic seems to be, along with the "wait or bite" 7DII question, the most frequent topic/problem regarding the 7d.  Not trying to generalize any here, but I get the impression that most OOF questions come from users who have graduated from Rebel models to the 7d.  These cameras are completely different beasts with the 7D being "the" beast.  I used the 50d for quite a while and got very frustrated with the 9 point system.  Before the 50d, I shot manual focus film cameras with no IS.  The 7d is not an automatic point and shoot camera.  As a matter of fact, I think it's a pretty poor PS camera.  It's also not a great center focus camera IMHO.  The focusing system in the 7d is amazing and once mastered, images are very sharp.  I needed to MA my 24-105 by -1.  I've never had an OOF shot and the camera is very consistent.  I move the focus point where I want it to be for every shot I take.  I've disabled zone and auto 19 pt focusing.  If the OP has not read and re-read the manual completely and understood and practiced using the camera, then this camera will give you soft images all the time.  Hopefully, the OP's problem with the camera can be resolved - best of luck.
« Last Edit: May 12, 2011, 10:05:13 PM by mogud »

marcm1

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Re: 7D focusing question??
« Reply #41 on: May 12, 2011, 11:36:27 PM »
We'll seeing how I started this question LOL,

I shoot photos of my daughters doing cheerlaeding which has to be the worst sport to have to take pictures at due to bad lighting and quick speeds needed and also not allowed to use a flash at all. I try to stay above 500 shutter speed, My 70-200 2.8 is usually wide open at 2.8 and the ISO I try to keep low but alot of times 2000 to 6400 if needed for exposure. I have it set to center point auto focus, AI servo, and low speed continous shooting. I haven't tried changing any other settings down in the menu due to not really knowing what they do. Is there some other main settings that would really help with taking pictures such harsh places to take pictures. I usually try to adjust my pictures by trying to keep the exposure level indicator in the middle and make any adjustments with ISO, aperture or shutter speed if needed last option to keep above or at 500 speed to keep n motion blurr down.

Any suggestions would be GREAT !!!!!

Thanks.
« Last Edit: May 12, 2011, 11:49:53 PM by marcm1 »

neuroanatomist

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Re: 7D focusing question??
« Reply #42 on: May 13, 2011, 07:51:00 AM »
I shoot photos of my daughters doing cheerlaeding which has to be the worst sport to have to take pictures at due to bad lighting and quick speeds needed and also not allowed to use a flash at all. ...My 70-200 2.8 is usually wide open at 2.8 and the ISO I try to keep low but alot of times 2000 to 6400 if needed for exposure. I have it set to center point auto focus, AI servo, and low speed continous shooting. I haven't tried changing any other settings down in the menu due to not really knowing what they do. Is there some other main settings that would really help with taking pictures such harsh places to take pictures.

One thing that would help would be a faster lens.  The 135mm f/2L is often recommended for low-light sports shooting, if 100mm would work there's also the much less expensive 100mm f/2. 

In terms of settings, AI Servo is best.  You might consider AF point expansion (if the camera can't focus using the selected AF point, for example if the whole AF point is covered by a monochromatic part of a jersey), adjacent points will be used.  If you have a fast CF card, you might consider high-speed continuous, as it will likely increase the chance of capturing a good facial expression, etc., at the cost of having more pics to sort through.  The other AF settings to explore are the tracking sensitivity (C.Fn III-1) and tracking method (C.Fn III-3).  How you set those depends on how you shoot.  If your primary objective is to capture images of your daughters, setting sensitivity to slow and method to 1: continuous AF tracking priority.  Those settings will result in the 7D trying to maintain focus on the initial subject, ignoring other cheerleaders who move into the frame or pass in front of your subject.

If you don't already, consider shooting in RAW.  Although your buffer will fill faster (fewer shots in a burst), you'll have much more flexibility to adjust exposure in post processing, and noise reduction (important if you're going that high with ISO on a relatively noisy camera like the 7D) will be better.  Consider DxO for post processing - IMO, it does a much better job of noise reduction than DPP.
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Re: 7D focusing question??
« Reply #42 on: May 13, 2011, 07:51:00 AM »

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Re: 7D focusing question??
« Reply #43 on: May 13, 2011, 08:46:26 AM »
As far as using DPP for noise reduction I totally agree Neuroanatomist. In fact I'd go further - it is also poor at sharpening in my opinion. I love it for RAW conversion and refuse to use anything else, but I have third party Photoshop plug-ins for both noise reduction and sharpening.

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Re: 7D focusing question??
« Reply #44 on: May 13, 2011, 09:03:23 AM »
As far as using DPP for noise reduction I totally agree Neuroanatomist. In fact I'd go further - it is also poor at sharpening in my opinion. I love it for RAW conversion and refuse to use anything else, but I have third party Photoshop plug-ins for both noise reduction and sharpening.

You convert your RAW images to JPGs using DPP, and then you open the JPGs in Photoshop and perform NR and sharpening?  If so, that's not really optimal - NR works better on the RAW image.  That's one main reason I use DxO for RAW conversions (another is the lens-specific corrections that are based on empirical testing of specific lens+body combinations).  If you're interested, I previously posted a comparison of DPP vs. DxO
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Re: 7D focusing question??
« Reply #44 on: May 13, 2011, 09:03:23 AM »