Macro ETTR strangeness

[garry23]

I have been trying to work out what is going on with my 5DIII and my F2.8L 100mm Macro lens.

I have Exp Sim on, Global Draw on All, and am using ETTR to get a base exposure.

At F2.8 the exposure looks OK.

When I try and ETTR at F/16, the ETTR does not 'correct' for the smaller aperture, ie the shutter stays at the F/2.8 value.

This is confusing me, as I thought ETTR used the actual sensor data, ie irrespective of what the lens optics are doing, hence ETTR works with manual aperture lenses.

Can anyone educate me?

Cheers

[a1ex]

Check the slowest shutter setting.

If it's not this, take a screenshot of your LiveView screen, and the ETTR settings.

[garry23]

Alex

When it started playing up I checked the slowest, it was 16s.

Have played around some more and what I see is this. BTW I've tried my 25-105 f/4 as well.

The ETTR exposure shutter speed does change, but it has this strangeness to it:

I set the aperture to F/4 and press SET, shutter changes to 1/40

I change to F/22 and press SET, shutter speed remains at 1/40

I press SET again and shutter changes to correct value, ie 0.8s.

I can repeat this over and over.

[a1ex]

Can you record a video of the camera screen?

I just tried the above scenario with a manual lens and worked just fine. The issue happens only with a Canon lens? (I don't have one right now with me to try)

[garry23]

This is even stranger!

I put on my manual 12mm fisheye and ETTR seemed ok as a dialed between the aperture extremes.

Put my 100mm macro back on and now that seems to respond appropriately.

I'll monitor the situation and report if I have any update.

Please don't waste your time anymore at the moment :-)

Cheers

Garry

[Walter Schulz]

 Used 7D and EF 100/2.8 L. Have inconclusive results here, too. Most of the time it works just fine. Will try to hunt it down tomorrow.

[Walter Schulz]

Have to postpone testing. Hope to come back with results later this week.

[garry23]

Have continued to test and strangeness is repeatable.

That is grab an ETTR with my 100mm macro at say F2.8 and it seems ok.

Change aperture to say F22 press SET and shutter time doesn't change.

Repeat the above but press SET before adjusting aperture to F22 and things are ok.

It seems you need to insert a SET before adjusting aperture.

[Walter Schulz]

Sorry, unable to give it a try last days. Time consuming tests for +40 GByte MLV recording and seamless recording +23:59:59.