More thoughts on the RX10iv focusing system.

Started 11 months ago | Discussions thread
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Horacecoker Senior Member • Posts: 1,987
More thoughts on the RX10iv focusing system.

This a follow up thread to my initial ramblings on the focusing ability of the new RX10iv.

Re reading my initial thread it seems to me it should have thrown up some questions that never got asked. The main one being this:-

Why will the camera not use PDAF when set on AF-S?

That’s a very simple question but Googling it gets me nothing. Perhaps I’ve not looked deep enough but all I find is stuff relating to PDAF in SLRs and no mention of PDAF not working on any camera in AF-S. If there is anybody out there who can answer this for me I’ll be very grateful.

The fact that the RX10iv doesn’t use PDAF on AF-S literally means that for folk who seldom use anything else other than AF-S (which certainly included me with the RX10iii) they will see absolutely no difference in focusing ability with the iv over the iii and it would be a waste of money to upgrade unless you think it’s worth it for 24fps shooting or a limited touch screen, neither of which I care for, 10fps is plenty enough for me. Oh, but I do love the new 3fps shooting mode on the RX10iv because I can now keep it on that most of the time and still take single shots or a burst of two or three shots if need be. (Quite difficult to take single shots on the RX10iii in its lowest burst mode.)

By trial and error, I got the PDAF to work to my liking but only on AF-C with Expand Flexible Spot. I was so staggered by the resultant improvement in speed and acquisition, I used the word delighted in the title of my first thread. (Don’t forget, in my test with the branch the camera wouldn’t focus at all on AF-S!!) I’m still delighted but there are certain considerations and subtle differences that I now realise I’ll have to adopt in future.

Like most folk with an interest in photography, I like to have a certain amount of control with any camera I own and that’s why I don’t normally use wide focus area. It has its place, for instance coupled with AF-C and PDAF, I can envisage wide focus area being very good for nailing birds in flight. Especially smaller birds that by no means fill the frame. But other than that, it’s centre focusing for me and a quick recompose if need be if I don’t want what I’ve focused on to be in the middle of the frame.

So, here’s the scenario: using AF-C and Expand Flexible Spot, I’m photographing an obliging bird perched in a tree (sorry to keep parroting (pun intended) about birds but it’s the same for most subjects) I’ve pinned the focus on the birds head with the help of the brilliant PDAF but I don’t want the birds head in the centre of the frame so I recompose but now, because I’m on AF-C, the focus has moved to whatever is now in the centre of the frame. There’s a simple remedy for this and some of you might have already guessed it – simply press the focus hold switch before recomposing. To be honest I never used the focus hold switch on the RX10iii but now it will be a vital part of my picture taking.

The new AF-A mode (A for automatic) looks good on paper but it only induces AF-C (and so brings in PDAF) in wide focussing area, how crazy is that? Why is that the case? Because of this, as I’m a centre focusing type of chap, that position on the switch is redundant. Also redundant is the AF-S position at the telephoto end of the lens due to no PDAF which instantly kills lens hunting. Am I likely to keep switching from AF-S to AF-C while I zoom the lens, not a chance! So, for me, until I can think of something I may have missed, my RX10iv stays on AF-C and Expand flexible Spot.

Like I’ve said in another post. Straight out of the box the camera has no advantage focusing wise to the RX10iii. On AF-S you don’t get the all singing all dancing PDAF focusing system which leads me back to my initial question – why?

Not let’s see if the reviews tell you what I’ve found out. It certainly isn’t stated that there is no PDAF when you are in AF-S for the DPReview of the RX100v. This is only reference to it in the entire review: -

The RX100 V gains a 315-point phase detection autofocus system, which is a first on any 1"-sensor compact that's ever been released (or shipped, anyway). You may not notice a huge change when shooting stills in Single AF, but it makes a noticeable difference when shooting with continuous autofocus.

The part of the sentence in bold should really read “You will not notice any change when shooting in Single AF” because as we now know, there is no difference, as the camera doesn’t use PDAF in AF-S.


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