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I'd like to change aperture and keep the exposure consistent while taking multiple photos of one scene. I am aware of the exposure triangle. I know I need to increase ISO or decrease shutter speed by a stop if I decrease aperture by a stop.

I would meter for exposure and set it in a way that I like. For example ISO 200, F/2.8 and a shutter speed of 1/4000. Now, the scene changes and I want to use a smaller aperture, so I stop down to F/5.6, two stops down. I'd need to change my shutter speed to 1/1000 to keep the same exposure.

The scene sometimes changes very rapidly, so I want to do this in as little actions as possible. I'd like the shutter speed to automatically adjust when I twist the aperture wheel.

What I've found so far:

  • I can set ISO, aperture and shutter time on a value using the dials, which is manual mode, but then I need to change both aperture and shutter time. The goal is to change just one and keep similar exposure.
  • Program mode activates if I put ISO, aperture and shutter speed on A for auto, but this keeps metering for individual photos on. I would like to achieve a consistent look for all my photos and for ISO not to change (unless I want it to for HDR shots, but I can limit auto ISO to 800, so that's not an issue).
  • ISO priority actives if I put the ISO on a value (for example 200). This gets me closer to the effect I want, but metering is still on.
  • If I flip the aperture switch to manual and keep shutter speed on auto, the shutter speed will adjust, but I still do not have the same consistency in exposure throughout my photos.

(How) can I achieve consistent exposure through a shoot, with the camera automatically adjusting shutter time if I adjust aperture?

  • 1
    Your question is a bit ambiguous. What do you call "consistent exposure"? Does it means : a) a part of the scene is rendered with the same level of grey as long as it gets the same lighting either if the lighting of the other parts of the scene change? b) a part of the scene is rendered with the same level of grey either if it gets a different lighting? c) on the whole the average grey level remains the same? – hpchavaz May 29 '18 at 19:49
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    @hpchavaz I’m not sure I get what you mean. Nor what’s ambiguous. I don’t want any gray levels to stay the same. I want my pictures to look consistent and be shot at the same exposure, so the same result of ISO+shutter speed+aperture. A shutter speed of 1/500s with an aperture of f/2.8 achieves the same exposure as a shutter speed of 1/1000s and an aperture of f/2, to my knowledge. – Belle-Sophie May 29 '18 at 20:22
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Sounds like you want exposure lock (AE-L).

On my Sony, if I am in A (aperture priority mode) and with ISO not set to Auto, as the scene changes the camera adjusts the shutter speed to maintain a "correct" exposure. If now I lock the exposure, the camera does not change any of the exposure settings even as the scene changes (that's what exposure lock is for). And if I change the aperture while the exposure is locked, the camera adjusts the shutter speed so that the exposure is unchanged. Of course, unlocking the exposure will again allow the camera to adjust the shutter speed so that the exposure is again "correct".

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    -sudden clarity- That is what that mysterious button does! I just needed to change the setting for the button to "AE/AF‑LOCK MODE" as explained in the manual. – Belle-Sophie May 22 '18 at 9:53
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Based on a cursory look at the Fuji XT-2 Owner's Manual, I'd suggest trying the following:

  • Place the camera in 'Mode P: Program AE' (p.60 of the Manual)
  • Set the [Exposure Compensation] dial to 'C' so that you can use the front command dial to select up to +/-5 stops of EC. (p.89 of the Manual)
  • Half-press the shutter button to meter the scene. Use the front command dial to adjust EC to the exposure you want (p.89), then use the rear command dial to "shift" the same exposure value to your desired aperture (p.61).
  • Once you have the desired aperture and shutter time, press the [AE-L] button.
  • Use the rear command dial to "shift" the Av and Tv at the same exposure value as desired.

If your camera has an option for the [AE-L] button to hold until pressed again, you can release the [AE-L] button and you're set until you press it again.

  • Let's forget about PSAM modes: even if the manual describes them, it is best to forget them on the Fuji X-T2 and for the main part the other Fujifilm X cameras. – hpchavaz May 29 '18 at 19:50
  • Why do some users insist on putting their answers to a question in comments to another answer instead of in their own answer? – Michael C May 29 '18 at 19:53
  • Michael, If your previous comment is upon the previous mine. the latter was not a reply to the question, but a reaction to yours that I thought more appropriate to write as a comment than a reply. – hpchavaz May 31 '18 at 9:11
  • @hpchavaz You wrote a rather lengthy answer that opened with the exact same sentence, then deleted it. Users with +20,000 rep can see deleted answers. Although you say to "forget" the PASM modes, the rest of your answer describes using "A" mode. – Michael C May 31 '18 at 9:13
  • What is the problem, II wrote an answer, then delete it because after reflexion a previous answer seemed a better one to the question. – hpchavaz Jun 2 '18 at 17:14

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