Thinking about jumping ship due to poor AF. Any help?

Started Apr 28, 2014 | Discussions thread
viking79 Forum Pro • Posts: 14,137
Re: Thinking about jumping ship due to poor AF. Any help?

GabrielFFontes wrote:

Hey guys!

I'm a brazilian Pentaxian, and i have a Pentax K-30 and 9 lenses.

Most importantly, what type of shooting are you doing?

I've been thinking about jumping ship to Canon/Nikon/Sony or even mirrorless (Olympus) because i've been facing problems with AF. I feel it's simply too slow and inconsistent (as in i spend hours doing af fine adjust, but sometimes it will simply, randomly focus incorrectly).

I will say I started with Pentax, and my K20d forced me to learn about focus issues with DSLR cameras.  All DSLR cameras have these, even "pro" level cameras.  It is how the AF system works, it is two separate paths that have to be calibrated to the micro-meter.

Some cameras are more stable than others.  The 5DIII appears very good, but with any you can have issues.  Also, PDAF works best with center focus point (it measures the phase difference of light for the same point from each side of the lens, if you are off to one side this is less accurate).

Since moving to mirrorless I have been 100 times happier with good light focus performance, especially with large aperture lenses.  Many fewer shots out of focus.  This is because light used to focus is on the same path as the sensor sees so there is no calibration necessary.  Most focus issues with mirrorless are user error (not understanding they focus on highest contrast point in focus box) or a bug in the camera focus software.

The trade off is low light focus is worse.  The system will fail earlier than SLR, and require some sort of focus assist light.  Since the system requires contrast a focus assist light on the camera is terrible and provides little contrast so doesn't really speed things up.  Best bet is technique to put some contrast on the subject.  However, My K-5 was terrible in low light, but this should be rectified by now with K-3 or K-5II(s).

Do you guys think i would see improvement switching to a Nikon D7000?

Not necessarily.  I saw improvement going from K-5 to D7000, but don't think K-5II or newer would be any worse.  You will still miss shots.  Most importantly you need to learn how the AF system responds.  It took me a while to learn that the periphery sensors on the D7000 are horizontal edge sensitive and not vertical edge sensitive.  As soon as I learned that my focus improved dramtically.

With Pentax you need to learn that the focus sensors are very large in older models and might be grabbing something you don't want them to be focusing on.

The lens is a very important aspect as well.  To get great focus on the D7000 you are probably going to need a newer lens.

What about a Canon? 60d, 7d? (but i guess i would lose in image quality)

Same as D7000 I would guess.

Any help? It would be tough to get a K-3 here because it's not so easy to get Pentax items here, and by jumping ship i would be able to sell all my lenses and invest in the camera and new equipment...getting a K-3, i wouldn't want to sell lenses.


Mirrorless cameras require a different mindset, you should turn off image review since you already know what image is going to look like before taking shot (with some cameras that always show live preview by default), and the review image blocks the EVF or monitor from showing the live feed.  If you do this blackout time is comparable to DSLR.

Also, it takes time to get used to differences in focus behavior.  Be sure to focus on high contrast area (catchlight in hair often wants to grab focus above ears), For this reason need adjustable focus point size you can make smaller or larger depending on situation.

For action shots, you often use AF-S and press shutter fully so it snaps image almost instantly after focus is achieved.  This is useful on cameras with short shutter lag and electronic first shutters.  This means you can usually get first shot in focus.

Mirrorless cameras are rapidly catching up in AF-C performance.  Sony A6000 seems to be leading the charge here, but your telephoto lens selection is pretty minimal (seems to be the area you would want this feature most).

Bottom line is before jumping to a mirrorless camera make sure the system offers the lenses you would want to use, and available today (or shortly).  I am done with DSLRs and don't regret my decision to do so.  I still am fond of Pentax, but they don't make what I want to buy today.

Mirrorless cameras aren't better or worse, they are just another tool to do the job.  The bottom line is you shouldn't have to fight your tool to get the job done and so get something that works for you.  If Pentax isn't working for you don't hesitate to change, but knowing more about your specific situation might help.


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