Sony A1 Alpha 1 menu setting for Aperture Drive in AF"

[GracieAllen]

Sony Alpha 1:
Can someone explain what the AF/MF menu item “Aperture Drive in AF” is doing? I have it set to “Focus Priority” for everything currently, but why would the guide say "the continuous shooting speed may become slower or the screen may flicker"? And in what circumstances would I change the value to “Standard”?

The guide also says “Focus during continuous shooting is locked to the setting of the first shot when the parameter for [Aperture Drive in AF] is set to[Standard] or [Silent Priority], and the F-value is greater than F22”. They mean if you have a REALLY SMALL aperture - f25 or higher, right? They don't mean an aperture that's "greater" like f11?

 

[AlphaWorld]

The key thing about "Aperture Drive in AF" is that it opens up the aperture while it's focusing. Just like DSLRs used to do. Means that the camera gets more light to use to focus; also means that it is working with a smaller depth of field.

I find it particularly useful when shooting in a studio.

Sorry, I can't help you with an interpretation of that part of the documentation.

 

[-ST-]

Sony Alpha 1:
Can someone explain what the AF/MF menu item “Aperture Drive in AF” is doing? I have it set to “Focus Priority” for everything currently, but why would the guide say "the continuous shooting speed may become slower or the screen may flicker"? And in what circumstances would I change the value to “Standard”?

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The guide also says “Focus during continuous shooting is locked to the setting of the first shot when the parameter for [Aperture Drive in AF] is set to[Standard] or [Silent Priority], and the F-value is greater than F22”. They mean if you have a REALLY SMALL aperture - f25 or higher, right? They don't mean an aperture that's "greater" like f11?

In this article, read the footnotes.

Does the camera continuously adjust the focus while in Continuous Shooting or Speed Priority Continuous focus mode?​

You'll see the same reference to F22 for the A1. However, for older models, the aperture value where the limitation kicks in is at values like F8. I think you're right with this interpretation "They mean if you have a REALLY SMALL aperture - f25 or higher, right?"

For example
For the A1

13. The camera may not be able to maintain focus on a subject using AF during continuous shooting in the following situations:

• When the subject is outside of the phase-detection AF sensor area.
• When shooting in dark surroundings.
• When the contrast of the subject is low, such as a blue sky or a white wall.
• When the aperture value is greater than F22.

For the A9 and A9 II

10. Can't track AF when shooting in a dark environment. The camera won't focus:

• If the subject is outside the range of the Phase-Detection AF sensor.
• If the aperture value is more than F16.

 

[GracieAllen]

Thanks for the replies. Now it makes more sense... For "normal" things I should have it in Focus Priority 'cause I don't CARE if the focus motors make noise - I've actually never heard the Sony motors make noise.

Cool. Another thing I can set and not have to mess with, even when I switch to silent shutter!

 

[AlphaWorld]

Oh, I think I know what that reference to f/22 and f/16 is about - it's the point where PDAF stops working.

On a DSLR the phase detect auto focus sensor was much smaller, and required a comparatively large aperture to work - a lot of DSLRs could not auto-focus below f/5.6, and even top of the line DSLRs like the 1Ds Mark III and 1D Mark IV could not (reliably) auto-focus below f/8 - they simply couldn't get enough angle for phase detect.

On a mirrorless camera the PD sensels are embedded in the sensor, so they can be spread much wider, and that's how we can get PDAF on smaller apertures.

If you turn Aperture Drive in AF off, the AF works at the shooting aperture, which means that if you are shooting at f/16 (cue people screaming "diffraction limiting!") then you may be dropping back to CDAF only (which is much slower) because you are below the aperture where PDAF can work, unless your camera is an A1 or A9 (or another body with support for PDAF at tiny apertures).

Does that make sense?

So why might you turn off Aperture Drive in AF? There are some lenses which focus differently at different apertures. The one I recall most readily is the Canon EF 50mm f/1.2L (because I owned one) - there was a range of apertures (around f/1.6 to about f/2, from memory, focussing on a fairly nearby subject) where the centre AF point would mis-focus the lens (off-centre points were still accurate). This was because it would focus at f/1.2, then set the shooting aperture, and the result would be that the lens was not focused on the subject. So using a lens like that one, and focusing at the shooting aperture, the mirrorless camera would always be in focus.

NOTE: I am not certain that this deduction is the whole truth, but it makes sense to me.

 

[GracieAllen]

I never realized that could even be a problem... Fortunately, it sounds like I can leave the setting alone at "Focus Priority" and it'll work fine.

 

[AlphaWorld]

I never realized that could even be a problem... Fortunately, it sounds like I can leave the setting alone at "Focus Priority" and it'll work fine.

And that's why we talk to each other. We learn more. And when something weird happens we can remember something someone mentioned a year or two ago and say "oh, yeah, I think I know what might be happening!".

Like someone mentioning that DRO could cause an image on the back of the camera to look nice, and the RAW to look horribly dim - I had that problem, but I remembered someone mentioned evil DRO, turned it off, and happiness ensued!

Stop learning, started dying

 

[AlphaWorld]

Didn't you get an RV? I'm betting that model will AF at pretty small apertures. The 7IV will go to 22, which, I might add, is twice as much as going to 11!

I can't see Sony going backwards on their low-light AF. As much as they seem to like to cripple features on lower priced cameras, this is an industry thing.

Excellent explanation of the Aperture AF. Not sure I understood it fully before.

Took my A7RV out into the exact opposite of dim light yesterday Zero clouds, bright noon-time Australian summer sunshine (don't forget the factor 50 sunscreen!). The new AF is extraordinary. Working with the same sensor are the A7RIV, with its known 1/10 second to read the entire sensor, and needing that data to do subject recognition, and I'm trying to photograph birds in flight. I missed a lot because it's hard to keep them in frame, but when they slow down a bit to come into land I got some perfect focus, even with the bird small in the frame (I cropped one image to 4 megapixels out of 60).

I had a quick try in dim light a few weeks ago in a nocturnal animals exhibit (negative EV and very difficult to see anything), but I will try again in slightly less extreme conditions.

I am so very much looking forward to getting this new AF in an A1 mark II - if it's this good on a slow sensor... Actually, that makes me wonder - will we get a new overheating problem? Will we need air-conditioning in the A1 mark II to keep the AI AF components cool? Or will they de-tune them to reduce heat generation? I guess the A1 mark II might be well able to resist freezing conditions Can't give up my day job yet - I have cameras to purchase!