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02-14-2016, 08:45 AM   #1
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Autofocus blurry when "macro"

Hi,

I just got my first DSLR (I was really into film photography years ago and have much experience with SLRs and developing/printing, but never got into DSLRs until now). After much research, I chose the K3, which just arrived last week. I've started experimenting with it to understand its capabilities and I've run into a snag. I'm not sure if it's an issue with the camera, or just good old user error (likely).

Here's my issue:

I'm using the 18-135mm lens that I bought with the camera body and Autofocus/green mode. When I adjust the lens so that I'm as up close as possible, the image that I'm focused on appears slightly blurry, but the environment immediately around the object will be in focus. I'm not doing extreme close ups (in fact, from the same distance, I'm able to focus on the same thing just fine with an iPhone camera, so I don't think I'm asking too much of this camera/lens).

I had this issue with two pictures: one of flowers outside in soft shade, the other of an avocado on my kitchen counter.

I just tried right now with a bottle of olive oil on my counter. I still have the K3 set to AF/green mode. When I push the button to take the picture, several times it struggled to autofocus, then settled on having the background in focus with the olive oil (which is centered and dominates the picture) out of focus. Even after the camera focused on the background instead of my 'subject', it refused to take the picture. I had to push the button several times before it would even shoot the picture, and what I ended up with was a blurry bottle of oil.

I'm assuming I'm doing something very wrong here, but I just can't figure out what. Thanks to anyone who offers some troubleshooting advice!

02-14-2016, 08:58 AM   #2
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QuoteOriginally posted by StringerBell Quote
I'm not doing extreme close ups (in fact, from the same distance, I'm able to focus on the same thing just fine with an iPhone camera, so I don't think I'm asking too much of this camera/lens.
Smartphones are a bad comparison. They can focus much closer than your average DSLR rig. I don't have the 18-135mm, but a quick check of its specs says that the minimum focusing distance is 1.3'. Are you working outside that limit?
02-14-2016, 08:59 AM   #3
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You're too close to the object, if you want to get closer you need a macro lens.

Try zooming to 135 and stepping back a bit
02-14-2016, 09:10 AM   #4
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QuoteOriginally posted by StringerBell Quote
When I adjust the lens so that I'm as up close as possible, the image that I'm focused on appears slightly blurry, but the environment immediately around the object will be in focus.
I assume you are too close. Sample photos would be a big help. What I suggest you do is select P mode, then Manual focus, zoom lens to 135mm, twist focus away from infinity, all the way to closest focus. Now turn on live view and focus peaking. Place camera on table or something (use 2 sec timer if camera is placed on stable surface, this helps avoid mirror slap shake for 100% sharpness), and move it closer to the subject, until focus peaking shows it as illuminated/in focus. I think that lens' minimum focus distance is around 40cm (measured from the camera sensor, so 4.5 cm behind the camera mount to the in-focus subject).
QuoteOriginally posted by StringerBell Quote
(in fact, from the same distance, I'm able to focus on the same thing just fine with an iPhone camera, so I don't think I'm asking too much of this camera/lens).
Unfortunately that doesn't say much. Completely different sensor format. lens design, and so on. In fact, many phones are quite good at "near focus" because they need that feature for video conferences and selfies.

Other things to check: - make sure lens is clean, especially the back lens element (inside the lens mount). IF you decide to clean it, be careful, read up on it. But a finger print on the backside of the lens can cause blur.
- update camera firmware; probably won't do much, maybe you already have the latest version, but in the past some firmware updates included small AF optimizations.
- Macro is usually done in manual focus, not autofocus, because you always get max magnification at nearest focus. Then you just move camera forward and back to get things in focus.
- Check aperture. The closer you focus, the more shallow the DoF will be. At minimum focus, using f4 or lower f-number will have super shallow DoF, making the photo appear to be soft
- Check shutter speed. Macro magnification requires a lot of light and a very steady hand. Using a tripod or at least a stable base with 2 sec timer can dramatically improve the shots.
QuoteOriginally posted by StringerBell Quote
Even after the camera focused on the background instead of my 'subject', it refused to take the picture. I had to push the button several times before it would even shoot the picture, and what I ended up with was a blurry bottle of oil.
You probably have Focus priority enabled. If you go into Menu you can switch it to Shutter priority. Once you do that, the camera will take the shot when you press the button regardless of whether the AF locked or is in motion or whatever. Focus priority is usually better for beginners, so they don't trigger the shutter too soon, before the AF completes. You can also de-couple AF and shutter button and map the AF to be another button. Lots of people do this so they can take photos without re-starting the AF action. There are threads about this (think the main one is called "perfect focus every time" or something similar)

02-14-2016, 09:35 AM   #5
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What you did was close focus, not macro.
02-14-2016, 09:39 AM   #6
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By the way, welcome to the forum! There's no shortage of help from members here!
02-14-2016, 10:02 AM   #7
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If I remember right minimum focus distance on that lens is 16 inches or thereabouts. That is from the sensor plane so if you are closer than that you will not be able to focus.
Check the lens database here to get the specs on your lens or any other lens you might be interested in.
02-14-2016, 11:24 AM   #8
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Also, the K-3 has 27 autofocus points to choose from. If you allow it to choose automatically, the camera may choose oddly. An avocado is dark, curved and has few high-contrast details. The AF system might ignore that if it finds something behind the avocado that is an easier target. You have some options to select a particular AF point on your camera to force the system to focus on your subject. You can tell the camera to use the center point only to see how the rest of the system works, without the variable of choosing points.

02-14-2016, 05:33 PM   #9
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Your camera and lens combination might be backfocusing. Here's how to test that:

1) Put the camera on a tripod (or firmly resting on a rock, table, chair, etc.) so the testing is done at a consistent distance.
2) Turn off shake reduction (you only want SR when handholding)
3) Set autofocus to only use the center point
3) Test manual focus. Zoom in using liveview to confirm you get focus. If you can't reach focus focus you are under the minimum focusing distance; back up.
4) Test autofocus with liveview on (contrast detect AF).
5) Test autofocus through the viewfinder with liveview off (phase detect AF).

If 3 & 4 focus well and 5 seems to focus slightly behind your target, it could be backfocus. The K-3 has a menu item to microadjust the autofocus system.

---------- Post added 02-14-16 at 07:39 PM ----------

QuoteOriginally posted by StringerBell Quote
SNIP...bottle of olive oil...SNIP
Are you focusing on the label or on a section of the bottle with no label? The label has details that give AF something to lock onto; good. The sides of the bottle without a label might not have enough details for AF.
02-15-2016, 06:58 AM   #10
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QuoteOriginally posted by jatrax Quote
If I remember right minimum focus distance on that lens is 16 inches or thereabouts. That is from the sensor plane so if you are closer than that you will not be able to focus.
Check the lens database here to get the specs on your lens or any other lens you might be interested in.

This is my first thought as well. Minimum focus distance is something to remember.
02-15-2016, 10:47 AM   #11
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QuoteOriginally posted by TER-OR Quote
Minimum focus distance is something to remember.
My wife does a lot of food photography with the 18-135 and she has a tendency to keep moving in as she is shooting. Quite often she gets to the point the camera will not focus any more. This is then followed by inappropriate language and a lens change to her 35mm macro. So. I'm confident this is the OPs issue as well. I see it almost every day in our studio
02-16-2016, 06:58 AM   #12
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Thanks to everyone for such thoughtful responses - I'm going to spend some time today reviewing every one and testing out all the suggestions. I'm really amazed at how helpful you all are, thank you so much!
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