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Is focus soft?
  
 
Merlin_AZ
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p.1 #1 · Is focus soft?


Hi. I've been reading through these threads and I've learned so much.
I think I might have an issue and would like your opinions.
I have an SL1 with the 18-55 kit lens, and a 17-55.
We went on a trip recently, and many photos using the kit looked soft to me. I didn't have the 17-55 yet, so I haven't really taken a lot of shots with it yet.
I used Bob Atkins' sheet to focus on a window at slightly over 50 x 35mm Focal length with both lenses. I had the center focus point on the 1.8 cross marks using a 2 second timer on a tripod with the IS off.
How can I tell looking at these whether or not there is a calibration issue?
I'm concerned there may be an issue since many shots from the trip were softer than I'd expect with still subjects, and SS over 1/100 of a second with good technique.
The uploaded images are with the 18-55 using the OVF and LV, and also the 17-55.
Thanks.
17-55 LV





17-55 OVF





18-55 LV





18-55 OVF







Jul 13, 2013 at 06:56 PM
jcolwell
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p.1 #2 · Is focus soft?


When you say LV, do you mean that you're using magnified manual focus in LiveView mode, or AF in LV mode? If it's AF, which mode? For OVF, are you using One-Shot, AI Servo, or AI Focus mode?

Those images look more-or-less sharp, but it's difficult to tell unless you look at 100% crops. In any case, they won't tell you if your're front focused, back focused, or dead on focus.

You can learn a lot about focus testing in this thread,

http://www.fredmiranda.com/forum/topic/1187247/0

...but, from what I can see in the manual, it looks like the SL1 doesn't have AF microadjustment, and so there's nothing you can do about it yourself, anyway.



Jul 13, 2013 at 08:29 PM
Merlin_AZ
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p.1 #3 · Is focus soft?


Thanks for the response.
The LV shots were AF single, not manual focus.
The OVF shots were one shot.
No, the SL1 doesn't have AFMA.
If there is a focus issue causing the shots to look soft to me, I know I need to send it in to have it calibrated.
I'm just trying to get some opinions of people that know more about these things than me (not hard to do) to decide what if anything needs to be done.



Jul 13, 2013 at 08:36 PM
Jeff Nolten
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p.1 #4 · Is focus soft?


I recently purchased an SL1 and did a comparison of the kit 18-55 with both a 17-40 and 15-85. The 18-55 looked almost as sharp in the center but very soft at the horizontal edges compared to the other two lenses. I don't have a 17-55 to compare, so I can't judge your samples. I was disappointed with the 18-55's performance and will be donating it with an old body as a starter kit to a relative. Its light weight would have been nice but I don't think I'd get enough usable images for my needs. I found a different story with the 55-250 which while somewhat softer than the 70-200 or 100-400 is still acceptable enough to justify its light weight.

No substitute for good glass. BTW, I compared the SL1 to my 7D at the same time and found the imagery essetially identical. Note, however, that I didn't push ISO above 800 or really compare the AF abilities of the two cameras. I did spend some time shooting bees in my Palo Verde tree at the long end of the 55-250 and got equivalent results.



Jul 13, 2013 at 09:05 PM
 

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Merlin_AZ
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p.1 #5 · Is focus soft?


Thanks Jeff.
The issue I'm having is that I have no reference to compare my shots to, other than what I see posted online, and I'm not sure whether or not I'm having a calibration/focus issue.
Things just look softer to me than I think they should be.
I've read that using a focus chart on a flat surface is the place to start.
That's why I posted the shots that I did, looking for recommendations.
If I knew there was an issue, I'd send it to Canon and have them look at it since it doesn't have AFMA.



Jul 13, 2013 at 09:25 PM
Jeff Nolten
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p.1 #6 · Is focus soft?


Focus calibration issues occur when the camera thinks its in focus but consistantly positions the lens focus in front or in back of the target. You could test that by shooting a yard stick at a shallow angle with the lens wide open to see if the focus is centered on your chosen mark. As jcolwell says, the SL1 has no adjustment for this. The 18-55 is a fairly slow lens compared to the 17-55 so calibration would be less critical on it.

Were your soft images just soft, or were there sharply focused areas slightly ahead or behind what you thought you focused on? If just plain soft thats either motion blur or the lens. I have a low opinion of the 18-55 so I would suggest sticking with the better 17-55 f2.8 and live with the extra weight. That's what I'm doing with my 15-85.




Jul 13, 2013 at 10:55 PM
Merlin_AZ
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p.1 #7 · Is focus soft?


Hard to tell if they were sharply focused ahead or behind.
I focused on the eyes in portrait shots, and I just think they are softer than they should be.
There's a Canon authorized store in town that also does repairs about a 40-minute ride away.
I'll see if they do in-warranty testing/calibration.



Jul 14, 2013 at 12:37 AM





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