FE SEL24-105 soft focus

Started 7 months ago | Discussions
FingerPainter Forum Pro • Posts: 10,954
Re: FE SEL24-105 soft focus

JERumball wrote:

It was definitely not too dark in the arena.

No too dark for what? Typically an arena like this will have lighting about 8 stops darker than sunny 16 light. It is evidently too dark to focus accurately using the AF mode you were in with the subject distance and framing you had, because the image is obviously front-focussed. Can you not see that it is front-focused?

I could plainly see the player

So what?

and the green focus lock on the back screen before exposure.

Yes, the camera thought it had focus. Do the results indicted that it was right?

Whether it used face or eye is inconsequential because where the focus target is, at f8, the face eyes and hair should be tack sharp and it definitely is not.

That assumes that it actually focussed at the distance the focus target would make you think it focussed at. The results in the photo indicated it actually focused closer than that. Things will only be "tack sharp" right on the actual plane of focus - the subject plane. Even if the eyes and hair are still within the normally calculated DOF, they will not be as sharp as things on the actual subject plane. But be aware that the normal calculation of DOF uses a CoC that assumes you are viewing a 20cm x 25cm print from about 30cm away. When you pixel peep this camera's images at 100% on a typical HD screen, you need to use a COC of about 0.004mm, not the 0.03mm used in standard DOF calculations. With such a COC, if you miss focus by 10cm, the eyes will be outside the DOF. I'd say your actual subject plane is at least 10cm in front of the eyes, and that's why they aren't sharp enough when you pixel peep.

One way you can improve your chances of getting accurate focus using eye or face detect is to frame tighter. Your subject is only taking 2/3 the height of the frame. There is no need for all the empty space around him. Get closer and make it 9/10 of the frame.

Another way is to get more light on the subject before the strobes fire.

The sample you showed using a video light was much better-focused. It had much more light on the subject while focussing, and was much more tightly framed.

JERumball
OP JERumball Junior Member • Posts: 26
Re: FE SEL24-105 soft focus

OK thanks.

I will try tighter crops next time, but I am trying keep everything the same for all players because these are all getting cut out and made into a composite.  I need to leave room for the taller players.

On the topic of front focussing, I think this lens is indeed front focussing at F8, but not at F4.  I did a little test just now where I focused on the middle of 5 batteries with flexible spot small. One shot is at F4 the other is at F8. The focus appears to shift forward at F8.  These were all shot at 105mm,, auto ISO, 1/250s.  Would you agree that the lens should be sent back or am I misinterpreting the results?

SQLGuy
SQLGuy Forum Pro • Posts: 11,871
Re: FE SEL24-105 soft focus

What's the aperture drive in AF setting?

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CaliforniaDave Senior Member • Posts: 2,337
Re: FE SEL24-105 soft focus
2

JERumball wrote:

Ok thanks... I will do some more testing when I get a chance and see what I can discover.

Thanks agian.

It has been pointed out that you were using AF-S for the hockey player photo, and you mentioned that you had the camera on a tripod, so presumably the camera didn't move. But if you partially pressed the shutter, which would lock focus at that instant in time on the face (since you were in AF-S), and the player then moved a little before you fully depressed the shutter and triggered the flash, the camera would still be focused on where the face was, and not where the face is when the flash fires. This would explain your result. AF-S should not have a problem if the camera is stationary and the subject is stationary, but if the subject moves, there is a chance the subject would be at the wrong location when the image is taken. I would think that using AF-C would eliminate this potential problem.

JERumball
OP JERumball Junior Member • Posts: 26
Re: FE SEL24-105 soft focus

Um... not sure what you're asking.  Drive mode was single shooting. I was using AF-S with back-button (AEL) focusing. Does that answer your question?

JERumball
OP JERumball Junior Member • Posts: 26
Re: FE SEL24-105 soft focus

It was on the outside of his left eye on his face.

JERumball
OP JERumball Junior Member • Posts: 26
Re: FE SEL24-105 soft focus

Yes... when its off on the lens, its also off on the body.

FingerPainter Forum Pro • Posts: 10,954
Re: FE SEL24-105 soft focus
1

JERumball wrote:

OK thanks.

I will try tighter crops next time, but I am trying keep everything the same for all players because these are all getting cut out and made into a composite. I need to leave room for the taller players.

I guess that means shooting the tallest player first and framing to ~95% vertical fill for him.

On the topic of front focussing, I think this lens is indeed front focussing at F8, but not at F4. I did a little test just now where I focused on the middle of 5 batteries with flexible spot small. One shot is at F4 the other is at F8. The focus appears to shift forward at F8.

Were these done from a tripod with remote release? If so, it does look like it is focusing closer at f/8 than at f/4. (I'd put the arrows nearly half a position to the right in each frame). Personally I'd want to test larger targets at distances more typical of my use of the lens. Such close focus distances may cause anomalous results. I'd also want to be shooting targets in light good enough that I could use ISO 100 without flash. I'd also want to test a different lens on the same camera, and possibly the same lens on a different camera. As it is, we don't know whether the focus issue is due to the lens or the camera.

These were all shot at 105mm, auto ISO, 1/250s. Would you agree that the lens should be sent back

I don't think we know enough yet to blame the lens, and if it is the lens we don't know whether it is the specific copy of the lens or if this is a characteristic of the lens model.

or am I misinterpreting the results?

SQLGuy
SQLGuy Forum Pro • Posts: 11,871
Re: FE SEL24-105 soft focus
1

JERumball wrote:

Um... not sure what you're asking. Drive mode was single shooting. I was using AF-S with back-button (AEL) focusing. Does that answer your question?

https://helpguide.sony.net/ilc/1710/v1/en/contents/TP0001979556.html?search=aperture%20drive

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JERumball
OP JERumball Junior Member • Posts: 26
Re: FE SEL24-105 soft focus
1

It’s greyed out, therefor not compatible/applicable to my lens.

VisionLight
VisionLight Veteran Member • Posts: 6,146
Re: FE SEL24-105 soft focus
1

JERumball wrote:

It was on the outside of his left eye on his face.

Thanks for the reply. I've been following this thread, so I'm aware of where you currently are in finding an answer. One thing I will note is that when using this lens (on my A7R IV) and shooting portraits, I use CAF because it tends to give me a higher on eye hit rate than when using SAF. I also keep the ambient lighting just high enough to allow the focus to easily find the eye without affecting the final lighting scheme. You can test this by shooting images without firing the lights. They'll probably be a bit dark, but still be able to show the focus point. Adjust accordingly.

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havoc315 Veteran Member • Posts: 5,040
Re: FE SEL24-105 soft focus
1

JERumball wrote:

OK thanks.

I will try tighter crops next time, but I am trying keep everything the same for all players because these are all getting cut out and made into a composite. I need to leave room for the taller players.

On the topic of front focussing, I think this lens is indeed front focussing at F8, but not at F4. I did a little test just now where I focused on the middle of 5 batteries with flexible spot small. One shot is at F4 the other is at F8. The focus appears to shift forward at F8. These were all shot at 105mm,, auto ISO, 1/250s. Would you agree that the lens should be sent back or am I misinterpreting the results?

Focus shift is a normal effect, nothing wrong with the lens. The solution is shooting AF-C or DMF

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havoc315 Veteran Member • Posts: 5,040
Re: FE SEL24-105 soft focus
1

havoc315 wrote:

JERumball wrote:

OK thanks.

I will try tighter crops next time, but I am trying keep everything the same for all players because these are all getting cut out and made into a composite. I need to leave room for the taller players.

On the topic of front focussing, I think this lens is indeed front focussing at F8, but not at F4. I did a little test just now where I focused on the middle of 5 batteries with flexible spot small. One shot is at F4 the other is at F8. The focus appears to shift forward at F8. These were all shot at 105mm,, auto ISO, 1/250s. Would you agree that the lens should be sent back or am I misinterpreting the results?

Focus shift is a normal effect, nothing wrong with the lens. The solution is shooting AF-C or DMF

Actually.. did you buy your lens new or used?

I just remembered..... When released, a batch of the Sony 24-105 has an abnormally significant focus shift issue, Sony offered a repair for the lenses that fell within a certain serial number range.

https://www.imaging-resource.com/news/2018/02/13/sony-announces-potential-focusing-issue-with-new-24-105mm-f-4-g-oss-lens

Any newer 24-105 lens shouldn't be having the issue, at least to an abnormal degree.

Some level of focus shift is unfortunately, quite common. The solution is to focus with the aperture stopped down. On Sony cameras, that means focusing in AF-C, or in DMF.

Focusing in AF-S will lean to focus shift issues.

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JERumball
OP JERumball Junior Member • Posts: 26
Re: FE SEL24-105 soft focus

Thanks for sharing that… someone else did as well (at least I think it was the same issue) and when I checked, my lens wasn’t affected. It’s brand new… had it only a week or so.

ok, well I’ll stick with AF-C then and see how that goes.

Thanks again.

moficera Contributing Member • Posts: 873
Re: FE SEL24-105 soft focus

havoc315 wrote:

JERumball wrote:

OK thanks.

I will try tighter crops next time, but I am trying keep everything the same for all players because these are all getting cut out and made into a composite. I need to leave room for the taller players.

On the topic of front focussing, I think this lens is indeed front focussing at F8, but not at F4. I did a little test just now where I focused on the middle of 5 batteries with flexible spot small. One shot is at F4 the other is at F8. The focus appears to shift forward at F8. These were all shot at 105mm,, auto ISO, 1/250s. Would you agree that the lens should be sent back or am I misinterpreting the results?

Focus shift is a normal effect, nothing wrong with the lens. The solution is shooting AF-C or DMF

Yes, I can confirm, mine does the same, seems to be normal for the lens to have some focus shift.

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William Curtindale
William Curtindale Veteran Member • Posts: 9,510
Re: FE SEL24-105 soft focus

moficera wrote:

havoc315 wrote:

JERumball wrote:

OK thanks.

I will try tighter crops next time, but I am trying keep everything the same for all players because these are all getting cut out and made into a composite. I need to leave room for the taller players.

On the topic of front focussing, I think this lens is indeed front focussing at F8, but not at F4. I did a little test just now where I focused on the middle of 5 batteries with flexible spot small. One shot is at F4 the other is at F8. The focus appears to shift forward at F8. These were all shot at 105mm,, auto ISO, 1/250s. Would you agree that the lens should be sent back or am I misinterpreting the results?

Focus shift is a normal effect, nothing wrong with the lens. The solution is shooting AF-C or DMF

Yes, I can confirm, mine does the same, seems to be normal for the lens to have some focus shift.

Did the two of you do the same test using AF-C and see the shift or only tested with AF-S?

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JERumball
OP JERumball Junior Member • Posts: 26
Re: FE SEL24-105 soft focus

William Curtindale wrote:

moficera wrote:

havoc315 wrote:

JERumball wrote:

OK thanks.

I will try tighter crops next time, but I am trying keep everything the same for all players because these are all getting cut out and made into a composite. I need to leave room for the taller players.

On the topic of front focussing, I think this lens is indeed front focussing at F8, but not at F4. I did a little test just now where I focused on the middle of 5 batteries with flexible spot small. One shot is at F4 the other is at F8. The focus appears to shift forward at F8. These were all shot at 105mm,, auto ISO, 1/250s. Would you agree that the lens should be sent back or am I misinterpreting the results?

Focus shift is a normal effect, nothing wrong with the lens. The solution is shooting AF-C or DMF

Yes, I can confirm, mine does the same, seems to be normal for the lens to have some focus shift.

Did the two of you do the same test using AF-C and see the shift or only tested with AF-S?

Yes… just tried it without changing anything else except AF-S to AF-C

DMF did not exhibit this problem however… guess that is expected.

Not sure what to make of this.

LenRivers Senior Member • Posts: 3,675
Re: FE SEL24-105 soft focus

Turn stabilization on, does that make a difference

is your shutter speed high enough.
what focus mode are you using

lots can give this not so good result.

moficera Contributing Member • Posts: 873
Re: FE SEL24-105 soft focus

William Curtindale wrote:

moficera wrote:

havoc315 wrote:

JERumball wrote:

OK thanks.

I will try tighter crops next time, but I am trying keep everything the same for all players because these are all getting cut out and made into a composite. I need to leave room for the taller players.

On the topic of front focussing, I think this lens is indeed front focussing at F8, but not at F4. I did a little test just now where I focused on the middle of 5 batteries with flexible spot small. One shot is at F4 the other is at F8. The focus appears to shift forward at F8. These were all shot at 105mm,, auto ISO, 1/250s. Would you agree that the lens should be sent back or am I misinterpreting the results?

Focus shift is a normal effect, nothing wrong with the lens. The solution is shooting AF-C or DMF

Yes, I can confirm, mine does the same, seems to be normal for the lens to have some focus shift.

Did the two of you do the same test using AF-C and see the shift or only tested with AF-S?

AF-C was spot on as it focused at f8 while AF-S focuses wide open and stops down afterwards that introduces focus shift.

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William Curtindale
William Curtindale Veteran Member • Posts: 9,510
Re: FE SEL24-105 soft focus (or focus shift)
1

This has been a very interesting and informative thread.

I was not aware of a focus shift at higher f-stops and AF-S with the FE 24-105mm f/4 G.

I generally shoot between f/4 to f/6.1 with AF-C and don't experience focus shift. Although, what I now believe after reading through this thread is that if using AF-S with a higher f-stop setting I could experience a slight focus shift (with AF-S the lens focuses wide open and closes down for the exposure).

While using AF-C the lens focuses and exposes the image at the chosen aperture (no shift). Although, an issue could arise when shooting in low light with AF-C and a closed down f-stop. I don't know for sure but expect in low light a closed down f-stop with AF-C my run into technical limitation for accurate focusing.

IMHO, in the end I believe the issue is not a soft lens at 150mm but a slight focus shift with AF-S and higher f-stop setting (solution may be eye-AF w/ AF-C).

Thanks to the OP for the thread and all the great information.

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