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EOS R + TTL flash + fast SIgma non-Art lens (<F2.0)

Started Mar 18, 2019 | Discussions thread
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random.lt New Member • Posts: 8
EOS R + TTL flash + fast SIgma non-Art lens (<F2.0)

Hi,

Could anyone try to replicate my problem with E-TTL?

I'm using flash (580EXII, bounced or not - doesn't matter) and if aperture is less than F2.0 (i.e. 1.8/1.6/1.4) TTL is not metering right and pictures come out VERY dark. Most visible when focused far than near.
Tried with 2 different flash units, I'm also using "control" adapter.
I narrowed it down to this behaviour:
When the aperture is set to lower than F2.0 then:
- if ISO set to AUTO, then during flash exposure ISO drops dramatically (e.g. from 1600 to 250) and then goes back again
- if ISO set to some value, ISO doesn't drop but exposure is still too dark (flash output is considerably lower)

Basically I cannot get properly exposed shot with flash and aperture lower than F2.0

I found that 'phenomenon' occurs with non-Art Sigma 50 ant 85mm lenses. 35mm Art Sigma is working OK.

P.S. It works flawlessly on 5D mark III / mark III used that setup for years

#EOSR #ETTL #Sigma

So if anyone has older (non-Art) Sigma 1.4 lens - could you check for it's behaviour?

 random.lt's gear list:random.lt's gear list
Olympus XZ-1 Canon EOS 5D Mark II Canon EOS 30D Canon EOS 5D Mark III Sony a6000 +2 more
Canon EOS R Sigma 50mm F1.4 EX DG HSM Sigma 85mm F1.4 EX DG HSM
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