RX10iv Focus Test & False Statement in Sony Help Guide

Started Dec 15, 2017 | Discussions thread
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Horacecoker Senior Member • Posts: 2,077
RX10iv Focus Test & False Statement in Sony Help Guide

When I started my first focusing thread on the RX10iv and explained that the camera passed my branch test with flying colours in AF-C, somebody asked me to post some photos to help illustrate what I was talking about. I think he said a picture is worth a thousand words. I did as he asked and it did indeed make more sense when folk could see what I was doing. But now I've taken it a step further and done three short videos. If a picture is worth a thousand words a video is worth a million!

I'm no expert with videos as you'll see. I took them with my RX100iii pointing at the LCD screen of my RX10iv.

The first video shows how the RX10iv fails to focus on my test branch in AF-S mode. The second video shows the dramatic difference when shooting on AF-C mode, the camera can now focus on the branch quite easily. This is what convinced me that the camera does not use PDAF in AF-S mode. In AF-S mode it behaves exactly the same as my RX10iii used to do and it's why I needed to upgrade. These two videos clearly show that I'd set the aperture to F4 as it can be seen on the LCD screen. I also set the focus area to Expand Flexible Spot as it's the only mode that can nail the branch even in AF-C.

I have set the F-value to F11 in the third video (still shooting in AF-C) as you will see this makes a mockery of this statement in the help guide:-

When the F-value is larger than F8, Phase Detection AF cannot be used. Only Contrast AF is available.

The third video proves that the statement is false.

It does take slightly longer to focus at F11 than it does at F4 but this is because it is opening the aperture to F4 to nail the focus then closing it back down to F11 when focus is achieved. I can actually hear it doing this and it can be seen that the branch goes more blurred momentarily when it opens the lens to maximum due to the much less depth of field.

I know the test at F11 is mostly irrelevant because most of us wouldn't even consider using the camera at F11 or F16 due to diffraction. I never go beyond F5.6. But I've done it because folk mention Sony's statement then wonder why they can still see the PDAF points working merrily as intended at F-values greater than F8.

So to recap

This first video shows the RX10iv failing to focus in AF-S due to lack of contrast on the subject and the fact that it is only using CDAF.


Second video same test in AF-C showing camera can now focus on the branch due to the fact it is using PDAF & CADF.


Third video same as above video but camera now on F11 proving false statement in help guide.



 Horacecoker's gear list:Horacecoker's gear list
Sony RX100 III Sony RX10 IV Sony a7R III Sony FE 55mm F1.8 Sony FE 28mm F2
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