AETTR bug when change F-stop in 650d

Issue #2374 new
Bank Thanat created an issue

Hi. My name is Bank.

I've been using ML for a while. Thank you guys for such a great work!

today I found a bug with AETTR. I went for taking macro pictures with my camera mount in a tripod. when I shot at fully open fstop everything seem right. The camera provide a great picture because AETTR. unless DOF of this pic is a little blur more than I want. So I increased f stop number. The thing is AETTR doesn't change shutter speed to compensate increasing of f-stop. it using shutter speed that used when fully fstop open. (I'm using press set btn to activate) no matter how many times I tried to restart camera or pressed set button. So I shot it as It is. the pic went a little underexposed. Then I have to lower shutter speed myself by I looking in histogram and got it as I want.

650D 1.0.4 ef 18-135 stm


My AETTR Settings are - Trigger mode : Press set

  • Slowest Shutter : 10"

  • exposure target :-1ev

  • Highlight ignore : 0.1%

  • Allow chipping : OFF

  • Midtone : 6ev

  • Shadow : 2 ev

  • Link to canon shutter : OFF

  • Link to dual ISO : OFF

camera setting M mode iso 100 f widest at 3.5 and increase it to 8 then found this.

So, Can I assume it as a bug? or AETTR only work with fully open aperture?

Thanks in advance B

Comments (9)

  1. Walter Schulz

    Unable to reproduce. No 18-135 STM around and my lenses work well with ETTR module. Are you able to test with another lens type (non-STM preferred)?

  2. Bank Thanat reporter

    I just ran a AETTR test with a 50 1.8 II lens. (the old one non STM)

    AETTR work correctly from f1.8-f7 stop by stop untill f8 the problem occur. also the higher f.

    Speed shutter went down to the Slowest Shutter (10 sec as I mention before)and it boost ISO up from 100 to 800 so that shot overexposed as live view displayed. I don't know what's up with f8 and the upper.

  3. Alex

    If the metering was done in LiveView, it's probably related to exposure simulation and its limitations (it's hard to meter a long exposure from a 1/30s LiveView frame). For long exposures, it's best to meter outside LiveView, from the captured images. For example, take a 1-second test image, and the second (or the third) frame should be exposed correctly.

  4. Bank Thanat reporter

    No, I didn't taking any long exposure. in f7 speed shutter just 1/5 or something at ISO 100. and then f8 shutter speed gone too far. it's reached 10" and boost ISO to 800 and the LiveView is overexposed.

  5. Alex

    Got it. Can you capture a silent picture from the overexposed LiveView? (not a full-res one).

    I assume once you reach f/8, the aperture used for ExpSim gets changed, and the LiveView preview appears underexposed to the ETTR algorithm.

    A possible workaround: enable both ExpSim and Expo Override. It might work, but I'm not sure.

  6. Bank Thanat reporter

    In 18-135 stm lens aperture stay fully open and it will narrow down to chosen f-number only when taking a shot or press DOF check. (photo mode and LiveView)

    but in 50mm 1.8 II aperture narrow down or open up by f-stop number. (only in LiveView)

    But both of it have f8 problem

    That's why I don't know what's up with f8 and higher.

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