Bought the original I RX100, but he wants to upgrade it to IV which is f/1.8-f/2.8, as oppose to f/1.8-f/4.9 (version 1) it seems to have better video, but I don't need that. I take pictures of everyday life (no landscape), events and food. Which version should I get?
Found a chart, but I have very little idea what it means. We went for a point and shoot rather than a mirrorless so we don't have to buy more than one lens/switch them at events.
Mirrorless gives you option to switch lenses, but does not force you to do it. You can buy a mirrorless camera with one zoom lens only and never (or rarely) remove it. The advantage is that in future when you are more experienced you can buy a special lens, and sometimes use it. Removable lens also gives you access to the sensor inside the camera and allows it to be cleaned when some dust lands on it. Here is another good comparison: http://www.cameralabs.com/reviews/Sony_Cyber-shot_RX100_V/ve…
f/1.8-f/2.8, as oppose to f/1.8-f/4.9 (version 1)
The lower the number, the wider the aperture, which lets more light in and is better for low-light shots. (i.e, the lower number is better)
The Mk3 is a good choice if you're not shooting much video. It can't do 4K, but it's still pretty decent if you do decide to do some video. However, I think it all depends on the price. When I got my Mk3, the Mk4 was around $400 more, and I couldn't justify spending that much extra on 4K recording which I wouldn't really use.
I got mine from digiDirect earlier this year, and if I were to get one now, I would probably go with the Mk4 (at their current 10% off sale, since the difference isn't a lot, and Mk4 has a newer sensor).
The aperture of 2.8 at the end means that you get more light when using the zoom (less need for high ISO or slower shutter speeds). When taking pictures at wide-angle they should be the same in terms of light gathering.