RF 100mm f2.8L Macro IS USM SA control ring not working

[MarjonM]

Last week I used the SA control ring on the macro lens for the first time. (in combination with an R6). I found the effect interesting.

Today I wanted to continue practicing with this effect. Now the SA control ring suddenly stops working. The effect is shown in the preview, but when I take a photo, the effect is not present on the photo.

In the meantime I had gone from firmware version 1.6 to 1.8. As a test went back to 1.6 but unfortunately this did not help.

Does anyone else have this problem?

[FloridaDrafter · Accepted solution]

I use it on an R5, although I also have an R6, I didn't update to 1.8 so I can't say if that messed with spherical aberration (SA).

As mentioned, aperture plays a big part in the effect SA has on the image. I suspect what you are seeing in the viewfinder is its effect at f/2.8. Your camera focuses at f/2.8 (or wide open) to maximize AF, no mater what aperture you have set, then when you take the shot the aperture you have selected is used. I don't think exposure simulation would work for SA, at least that is the way I understand it, and besides, ES is only available in live viewing from the rear LCD.

Attached are some "down n dirty" tests that I just shot with SA at -2. and varying apertures.

F/2.8 with no SA.

 F/2.8 - No SA.

F/2.8 and -2 SA.

F/2.8 - Negative 2 SA.

F/4 and -2 SA.F/4 - Negative 2 SA.

F/6.2 and -2 SA.

F/6.3 - Negative 2 SA.

Note that there is very little change in the subject itself from f/2.8 no SA and f/6.2 -2 SA, however, the background is effected. If I had pulled back a little, you would see a more dramatic effect in bokeh at f/6.2.

I hope this helps.

Newton

[rs-eos]

Excellent work on showing the effect on this, Newton.  And great callout about the lens always being at it's widest aperture before the shot is taken.  That would explain what the OP is experiencing.

[FloridaDrafter]

Thanks, Ricky and Rick!

Newton

[MarjonM]

Thank you for your answer FloridaDrafter!. I never knew that what you see in the viewfinder is always shown with aperture 2.8. I'm going to continue practicing with the SA ring.

[FloridaDrafter]

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@MarjonM wrote:

Thank you for your answer FloridaDrafter!. I never knew that what you see in the viewfinder is always shown with aperture 2.8. I'm going to continue practicing with the SA ring.

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You are very welcome. I've been shooting for a long time with DSLR's, and it [AF wide open] was unknown to me as well until I bought MILC's a few years ago. I didn't think about it, I just knew what worked when it came to exposure, LOL!

I don't use SA that often because almost all of my shots with the RF 100mm macro are straight up macro, including focus stacking (Depth compositing). But I did practice using it so I would know its possibilities. Personally, although I don't use it a lot, I think it's a nice feature. Yes, you can create a similar effect in a good post editor, but IMHO, anything that speeds up my post editing is a benefit 🙂

Newton

[shadowsports]

This sounds very likely. 👍 

Excellent Newton!