Archive 2016 · Sony 90mm f/2.8 Macro G OSS - is this normal behavior?

smpetty
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p.1 #1 · p.1 #1 · Sony 90mm f/2.8 Macro G OSS - is this normal behavior?

I have the 90 macro and an A7RII. I am struggling with focusing this lens.

Settings:

Focus Area - Lock-on AF Center
Focus Mode - AF-C
Face Detect - Off
Drive Mode - Continuous (slow)
Pre-AF - Off
Phase Detect Area - On
Aperture Priority

The image sort of bounces, pulsing in and out rapidly, when I try to focus. Sometimes the focusing settles in and behaves, but most of the time it bounces and never achieves good focus. This is happening in full sun or bright overcast - plenty of light. Setting the lens focus range (0 - infinite, 0.5m - infinite, or 0.28m - 0.5m) makes little difference.

Is this normal behavior? Am I doing something wrong?

Thanks,

Scott

Aug 06, 2016 at 04:27 PM

virtualrain
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p.1 #2 · p.1 #2 · Sony 90mm f/2.8 Macro G OSS - is this normal behavior?

I've seen this once or twice with the 85GM when shooting at apertures smaller than f/8. Try opening the aperture and see if it goes away. I think it may have something to do with the camera only using CDAF at small apertures. I could see this being a PITA with macro. But when I saw it the light was really bright so lighting might be a factor.

Aug 06, 2016 at 06:20 PM

AGeoJO
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p.1 #3 · p.1 #3 · Sony 90mm f/2.8 Macro G OSS - is this normal behavior?

I am not saying one way or the other but if you are working in the macro range or very close up range, I would rather focus manually. Sometimes it is easier and more convenient to set the focus on a certain distance on the lens, be if at the minimum focusing distance or whatever you want it to be, and you adjust to get the object in focus by moving the whole gear (your camera and lens) further away or closer to the target for getting the object in focus. That's why they have a macro rail for that purpose.

Aug 06, 2016 at 06:48 PM

chrisd999
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p.1 #4 · p.1 #4 · Sony 90mm f/2.8 Macro G OSS - is this normal behavior?

The AF-C or continuous focus is causing the weird behaviour. It's normal under some conditions. Just switch to AF-S or focus manually.

Aug 06, 2016 at 07:56 PM

smpetty
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p.1 #5 · p.1 #5 · Sony 90mm f/2.8 Macro G OSS - is this normal behavior?

Thanks to all -

I'll check and see if the behavior happens at f8 or below.
I'll try AF-S instead f AF-C.

I'm happy to MF in certain circumstances, but for what I paid this lens should do a far better job automatically focusing. At times, it wouldn't even focus on large flowers, my shoes, or my dogs.

Scott

Aug 06, 2016 at 10:42 PM

DavidBM
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p.1 #6 · p.1 #6 · Sony 90mm f/2.8 Macro G OSS - is this normal behavior?

smpetty wrote:
I have the 90 macro and an A7RII. I am struggling with focusing this lens.

Settings:

Focus Area - Lock-on AF Center
Focus Mode - AF-C
Face Detect - Off
Drive Mode - Continuous (slow)
Pre-AF - Off
Phase Detect Area - On
Aperture Priority

The image sort of bounces, pulsing in and out rapidly, when I try to focus. Sometimes the focusing settles in and behaves, but most of the time it bounces and never achieves good focus. This is happening in full sun or bright overcast - plenty of light. Setting the lens focus range (0 - infinite, 0.5m - infinite, or 0.28m - 0.5m) makes...Show more →

This happens with continuous AF and relatively close focussing distances with a number of lenses.

Think of it this way: Continuous is always trying to adjust the focus. If something is close to you, the slightest hand tremor will get you out of focus, so it has to adjust. But by the time it's adjusted, it has to do it again.
Can be made worse by low light (because each adjustment takes longer) or small apertures (because effectively less light and the the camera is less good at telling if it needs to readjust)

Single AF will take it away: but of course what you can tell is that you may not get exact focus this way, because by the time you take the exposure you may be a few mm closer or further away from the subject. Of course it is likely OK; but this phenomenon is a kind of warning that even if you have the shutter speed for hand held, for ideal sharpness you need a tripod.

Aug 06, 2016 at 10:46 PM

bowens
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p.1 #7 · p.1 #7 · Sony 90mm f/2.8 Macro G OSS - is this normal behavior?

Switching to AF-S in those situations should take care of the issue.

Aug 06, 2016 at 10:54 PM

smpetty
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p.1 #8 · p.1 #8 · Sony 90mm f/2.8 Macro G OSS - is this normal behavior?

Thanks - I will give AF-S a try today. I really appreciate everyone's suggestions.

Aug 07, 2016 at 08:22 AM

Viramati
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p.1 #9 · p.1 #9 · Sony 90mm f/2.8 Macro G OSS - is this normal behavior?

If your shooting at f8 or lower aperture the camera will switch to contrast detect and this is what you could be seeing. f2.8 -f8 is phase detect and you shouldn't get this

Aug 07, 2016 at 04:45 PM

smpetty
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p.1 #10 · p.1 #10 · Sony 90mm f/2.8 Macro G OSS - is this normal behavior?

Thanks to everyone - I had much better success yesterday keeping at f8 or wider. I also found a better success rate with AF-C and expand flexible spot in the center of the frame.

Aug 08, 2016 at 08:04 AM


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