ISO vs Shutter Speed

Discussion in 'Sony RX100 Forum' started by Nick Hope, Dec 28, 2012.

  1. Nick Hope

    Nick Hope New to SC

    Dec 28, 2012
    Hi RX100 users.

    So I've waded through the whole RX100 user guide over the past few days but I'm confused about ISO...

    I have ISO set to auto, and I'm in P mode. I dial in an aperture of F4.0 and the camera gives me a shutter of 1/6 and an ISO of 200. Shouldn't it automatically be giving me a much higher ISO so that my shutter can be faster? Obviously I can't hold 1/6 steady. Am I doing something wrong?

    Further to that, what mode do you guys shoot in for general walkabout stuff and how do you set your ISO?

  2. Crsnydertx

    Crsnydertx SC Top Veteran Subscribing Member

    Jan 21, 2011
    Houston, TX
    Nick, hello and welcome! I'm not a Sony owner, but I did a search and found that there is no way to set a minimum shutter speed on the RX100. S mode is the only way to get full control of the shutter speed.

    I'm a little confused about one thing in your post: you say you're in P mode, then you dial in an aperture. That sounds like maybe you're overriding the choice the camera made in P mode, which may be something like f 1.4 and 1/30 second. Is that what you're doing? If that's the case, the override may be taking the original choice by the camera and simply upping the f stop and lowering the shutter speed in tandem without adjusting the ISO.

    What if you set the camera to A mode and f4? What shutter speed and ISO does the camera give you?
  3. bartjeej

    bartjeej SC Hall of Famer Subscribing Member

    Nov 12, 2010
    ^ yup, sounds like that's what happening (camera only changing around aperture and shutter speed without touching ISO). But it does sound like it's not ideal, because 1/6th is pretty slow indeed!

    I'm not a Sony RX100 owner either, but for walkaround, I think you'll find many enthusiasts using Aperture mode, because so long as the shutter speed isn't too slow to give sharp photos and the ISO isn't too high to give good quality, aperture is the only variable that really changes your end result by varying the depth of field. That is, ofcourse, unless the shot you want to take requires either unusually fast shutter speeds (to stop lots of motion) or unusually slow shutter speeds (to introduce motion or for shots of the stars for instance), in which case many people will use S or M.
  4. Crsnydertx

    Crsnydertx SC Top Veteran Subscribing Member

    Jan 21, 2011
    Houston, TX
    By the way, another finding of my "research" is that Sony cameras don't allow the use of Auto ISO in M mode. Thought you might be able to force the higher shutter speed at desired aperture in that way, but not so.
  5. Nick Hope

    Nick Hope New to SC

    Dec 28, 2012
    Thanks very much for the replies. I'm starting to get my head around this now. I was indeed overriding the combination that the camera had decided on in P mode, by turning the rear dial. By doing that I entered "Program Shift" mode, whereby the shutter and aperture both adjust to maintain the exposure. However the ISO stays at whatever value it started at, hence the very slow shutter. I don't think I'll be using Program or Program Shift modes. Can't see a lot of use in them. If you want to go that automated it seems one may as well use Intelligent Auto or Superior Auto mode.

    What I'm finding in Aperture Priority mode, with auto ISO, is that as I reduce the aperture, it pushes the shutter speed to 1/30, then gradually increases the ISO to 3200, then gradually slows the shutter again. Seems pretty logical, although perhaps I'd prefer it to start increasing ISO when the shutter reaches 1/60 rather than 1/30. For example in some circumstances aperture priority will give 1/30 - f1.8 - ISO 125 when I think that 1/60 - f1.8 - ISO 200 might be more sensible.... or is it reasonable to expect to control handheld shake at 1/30?

    Chuck, you are right that ISO cannot be set to auto in M mode.

    So another question to those users who shoot typically in aperture priority... Do you typically leave ISO on auto or set it manually?
  6. Panut

    Panut SC Regular

    May 8, 2012

    Sure, I can control camera shake at 1/30, often even at 1/10 if I can stabilize myself with a wall or something. At the widest zoom setting, I mean. For me, the dynamic range and gamut of lowest ISO is also often more important than sharpness, that's why I'll rather have a little bit of shake, or take several shots to have more likely a steady one.
    But in general, I would suggest you try yourself, that's how you find out. :)

    About auto ISO, I use auto if I zoom in, or photograph something which is even slightly moving.
    But zoomed out, steady subject, I set it manually because I can support slower than 1/30.

  7. Luke

    Luke Super Moderator Subscribing Member

    Nov 11, 2011
    Milwaukee, WI USA
    Here's yet another non RX100 user weighing in. When I shoot with smaller sensor cameras, I generally don't concern myself with controlling DOF since the effects are less obvious. So I would shoot in Shutter Priority mode and set it at whatever you think you need to avoid handshake motion blur or what speed you might need to freeze the action (if that is what you are after) and let the camera choose the aperture and ISO. The cool thing is that there are just those 3 variables for exposure so control what you need to for a given shot and let the camera take care of the rest.
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  8. Nick Hope

    Nick Hope New to SC

    Dec 28, 2012
    Thank you for the feedback.

    Interesting to hear that Panuk. It shifts my thinking about 1/30 shutter.

    Luke, I understand what you're saying with regard to normal compacts, but isn't one of the benefits of the RX100 that the sensor is so much bigger than other compacts, that one can do some shallow DOF work at wide apertures? I've already managed some reasonably blurred backgrounds at f1.8. Hence aperture priority is more relevant with the RX100?
  9. norman shearer

    norman shearer SC Veteran

    A 1" sensor still has a huge dof and for normal use changing apertures will have little impact. Shutter speed on the other hand can make or break a photo with a small sensor. So I'd agree with Luke but add the proviso that if you want shallow dof then switch to aperture priority and open her up. The only disadvantage to shooting in shutter priority that I can see is watch you don't have that iso too high or your camera might select an aperture so small that diffraction kicks in. I've not read any reviews on the Sony Rx100 but I know with my Nikon V1 you generally get the sharpest images wide open or no more than a few stops down.

    Another way is aperture priority with the lens pretty much wide open and adjust the iso to a level that raises your shutter speed to approximately where you want it. That way you can rule out diffraction, get a shallower dof and hopefully the shutter speed will not drift too far out.
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