Nikon Z8 - Does not focus with Speedlight in lowlight

Thom Hogan · Aug 31, 2023

batleys said:
vockman said:

One thing is sure: While the Z cameras are optimized to focus around F5.6, IN GOOD LIGHT.

Click to expand...

Where did you get this from and what do you mean 'optimised'.

This may be a carry-over in thought from the DSLRs, though the number is wrong. In the DSLR world, focus worked best at about an aperture of f/4. A lot of that had to do with the way light is transmitted through to the AF system.

wjan · Aug 31, 2023

I do not have such problems on Z6II while photographing events.

I mostly use F1.4-2.8, continuous AF and wide-area AF (L-people) area. The camera focuses in 9 out of 10 cases even in such a low light, that I can't see my subjects properly. But it needs some contrast elements to hold on to. I had big problems once with a completely black cat walking in a shadow of a table in a badly lit hall for example. The only contrast element were its eyes. As soon, as the cat was turning its head away, camera were losing focus and grappling on something else in the background

Also consider suggestions from LTheWafflePWN.

Bennvdm · Aug 31, 2023

This issue appears to effect all mirrorless camera’s or at least Sony, Nikon, Canon, Fuji. Just google mirrorless af assist not working. Sony A1, Canon R5 & nikon Z’s.

No 3rd party flash maker like Prophoto or Godox or any camera manufacturer has brought out a new flash with green af assist light as some have suggested. There must be a technical reason that this cannot work or someone would be making a killing by being the 1st.
The light might have to be to harsh to potentially harm subjects eyes etc. The bayer filtering appears to make light transsission seen by af sensor on mirrorless much less than on dslr filter and can see nothing in infrared spectrum. Red af assist appear to contain some visible red and ir mixture, but differs between flashes.

Here is some articles.

https://www.dpreview.com/articles/0...-pro-feature-that-no-mirrorless-camera-offers

https://fstoppers.com/originals/why-mirrorless-autofocus-means-trade-offs-390040

https://neilvn.com/tangents/finding...low-light-auto-focus-with-mirrorless-cameras/

Nicely explained in post #2

https://photography-on-the.net/forum/showthread.php?t=1525026

astirusty · Aug 31, 2023

Bob A L said:
Sounds like another reason that DSLR's are unlikely to completely go away at least for the immediate future. It's hard to believe Nikon missed this one. Did other manufacturers do the same? Will no one's new mirrorless focus in really dark situations, or just Nikon?

It is a problem with virtually every mirrorless camera brand / model.

However, it does not excuse Nikon. Nikon should have produced a RF Wireless Flash and controller with a Green AF assist lights. Or Nikon should have found a way to AF the Z cameras in low light.

camerosity · Aug 31, 2023

astirusty said:
camerosity said:

RedRob said:

Hello,

Hoping some folks can share how shoot with a Z8 in very low light with a speedlight.

I shoot a lot of receptions/weddings. I'm finding that the Z8 is almost completely unusable in a somewhat dark room when trying to use a speedlight. I was recently photographing a party and every time that I'd approach a group to shoot a grip and grin, I ended up awkwardly standing there as I waited for the camera to search for focus.....which it never found at times. Totally embarrassing! If people are moving around on a dim dance floor, forget it. I'll miss almost every shot. I've been having to switch to my DSLR in these situations because the focus is instant. I've been shooting events for 15 years or so and never had this issue....even with old DSLR's.

I understand that mirrorless cameras do not trigger the red assist beam that speedlights are equipped with.

How are people working through this problem?

Click to expand...

I remember in the old days shooting wedding receptions in a dimly lit room we'd just set the 35mm lens to f5.6.5 and preset focus and shoot away. Never missed a shot!

Click to expand...

I can remember in the old days of setting camera's aperture to guide-number vs. range in distance. A few moons later, using the ultra advanced auto-flashes such as Vivtar 283 with it's adjustable return flash power sensor. :-D

Yep! We had Vivitar 283's and I had a 285, set it to Purple!

Born2Code · Aug 31, 2023

Thom Hogan said:
sirhawkeye64 said:

Thom Hogan said:

Custom Setting #D8 > Show effects of settings > Only when flash is not used

Click to expand...

To be honest, I don't know this option improves AF accuracy or speed -- I think it's mainly for ease of viewing the scene in the EVF when a trigger or flash is attached.

Click to expand...

Focusing on the Z's is always done from the EVF stream. Thus, if the EVF stream is brightened, the camera will focus better ;~).

I just tried this with my Z8.

I set D8 to "Show effects of settings" and "Only when flash is not used".

I set exposure mode to M and underexposed to simulate a dim room, so the view in the EVF was pretty dark.

I set AF-C and set the AF area mode to Wide Area - Small with subject detection turned on for people.

Then I tried focusing on a needlework picture of two people (it's all I have to test with at the moment.)

With the flash turned off, it focused quickly, but didn't detect any faces. When I turned the flash on, the EVF brightened considerably and the AF system found faces and eyes.

Not entirely scientific, but I think this confirms Thom's assertion that the AF runs off of the EVF stream. Its isn't that I would have guessed offhand, but it is what it is.

KevinAC · Aug 31, 2023

Not a problem I typically have because I just turn the modeling light on the strobe.

Would putting it in Starlight mode do anything useful?

sirhawkeye64 · Sep 1, 2023

KevinAC said:
Not a problem I typically have because I just turn the modeling light on the strobe.

Would putting it in Starlight mode do anything useful?

I think it's been mentioned before that it wouldn't help much given the OP's situation . Thom seemed to have probably the best solution and adjust D8 in the menu (the setting to adjust the EVF for viewing when using a strobe, which he says will improve AF, but I'm still not sure about this myself, partially in that he states it uses the EVF feed for AF, which doesn't really make sense to me, but maybe it does -- I would think it would use the processing feed though for AF).

--
NOTE: If I don't reply to a direct comment in the forums, it's likely I unsubscribed from the thread/article..

Thom Hogan · Sep 1, 2023

sirhawkeye64 said:
Thom seemed to have probably the best solution and adjust D8 in the menu (the setting to adjust the EVF for viewing when using a strobe, which he says will improve AF,

There's another solution, as well: exposure compensation. Program a +3EV into the Recall Shooting Function customization. Press the button, acquire Back Button AF, let go of the button, photograph.

just Tony · Sep 1, 2023

Bennvdm said:
just Tony said:

Bennvdm said:

what aperture are you shooting at as Z uses set aperture up to f5.6 and f5.6 thereafter. Dslr always does af with lens wide open

Click to expand...

Actually not as it turns out. The AF modules are internally masked down to f/5.6 so there is zero advantage to faster lenses. DSLRs and MLs are on level ground so far…

I’m making a reasonable sounding guess here: DSLRs have an advantage of larger sensing elements in the AF modules vs pixels within imaging sensors, therefore they have a better signal level to work with. Likewise the Z6 AF sensing pixels are larger than those in the 45 MP Z bodies so they have a slight low light focusing advantage over their brothers.

Bennvdm said:

and only stops down to set aperture for shutter release. Ie shoot f1.8 lens at f4, af is done at f4 on nikon Z.

Click to expand...

Click to expand...

Please list your source for internally stopped down to f5.6.

Marianne Oelund, a Titan of the Nikon full frame DSLR forum.

Search for her landmark thread containing her deep analysis. It’s on the short list for the best dpr thread ever, in any forum.

[EDIT] Here it is. Sadly, it's already a victim of Web Rot... key images are now missing. Perhaps they once linked to Marianne's dpr Gallery.

https://www.dpreview.com/forums/post/54211961

But she references her conclusion here in the title of this reply:

https://www.dpreview.com/forums/post/50074383

If you block the central f/5.6 cone of the image path you will have no AF. Here is how you can replicate the work by yourself:

https://www.dpreview.com/forums/post/50073569

Bennvdm said:
per Thom Hogan Z8 and z6 ii guide, it works as I listed.

I suspect that he would concur with Marianne.

Bennvdm said:
Nikon’s own AF spec listing measuring range is with a f1.2 lens, so fast lens must have better detection range.

Yes AF works when such a lens is mounted but since you will be focusing with an f/5.6 image path you risk getting blindsided by focus shift when exposing at wider apertures. During a rental of the AF-S 85mm f/1.4 I discovered that I needed a different AF Fine Tune setting for shooting at f/1.4 than for f/5.6 and beyond. Simply put, the AF module receives a different wavefront than the imaging sensor. That rental convinced me to not buy a copy of that lens.

Bennvdm said:
Z8

-7 to +19 EV (-9 to +19 EV with starlight view Detection range (ISO 100, f/1.2 lens, 20 °C/68 °F using single servo AF (AF-S)

z6 ii

-4.5 to +19 EV (-6 to +19 EV with low-light AF)
Detection range (ISO 100, f/2.0 lens, 20 °C/68 °F)

Z6 ii range appear much worse, but was with a F2 lens. Z8 with fastest glass appears much better, but likely due to quoted with f1.2 lens

olyflyer · Sep 1, 2023

Bennvdm said:
Sb5000 also has IR/ red af assist light, so does not work on Z8.

Not IR, if it was IR it would not work at all and you would not be able to see it. IR light is used in TV remotes. If you have one you can try to have a look while pushing a button. You will see that you don't see it flashing. Now aim your phone camera at it and you will see it flashing through the camera. If it would be IR it would need to be very powerful and the lens would be out of focus when the camera would be locking in focus. Only visible light can be used for focusing.

olyflyer · Sep 1, 2023

RedRob said:
Hello,

Hoping some folks can share how shoot with a Z8 in very low light with a speedlight.

I shoot a lot of receptions/weddings. I'm finding that the Z8 is almost completely unusable in a somewhat dark room when trying to use a speedlight. I was recently photographing a party and every time that I'd approach a group to shoot a grip and grin, I ended up awkwardly standing there as I waited for the camera to search for focus.....which it never found at times. Totally embarrassing! If people are moving around on a dim dance floor, forget it. I'll miss almost every shot. I've been having to switch to my DSLR in these situations because the focus is instant. I've been shooting events for 15 years or so and never had this issue....even with old DSLR's.

I understand that mirrorless cameras do not trigger the red assist beam that speedlights are equipped with.

How are people working through this problem?

What AF modes are you using (still getting used to different AF modes as I've always been a back button, center focus, reframe kinda shooter...but that's another thread)

The bright green assist lamp is ok at times but is very noticeable and disrupts the shot.

I didn't realize this would be a problem until after I purchased the camera. I contacted Nikon with my concern and the only response I got was this:

"The SB-5000 has AF-assist illumination for multi-point AF. Please see the specifications in the link below for more information."

I have an SB900, SB910 and some third party flashes. Is the SB-5000 really any better in these situations?

The Z8 is great in well lit situation but it's really screwing me up where I really need the speed and accuracy.

Your only option today is this solution:

https://adapting-camera.blogspot.com/2022/05/auto-focus-light-extender-for.html

It may not be the most beautiful thing on the earth, but there is nothing better at the moment. Your other options are modelling light or some other type of constant light sources, none of them are usable anywhere else than in a studio in my opinion.

Thom Hogan · Sep 1, 2023

I think you're missing some of Marianne's points. Moreover, her statements you're quoting don't explain why you can autofocus to f/8 (and sometimes beyond) on most of the current DSLRs ;~)

just Tony said:
I suspect that he [Thom Hogan] would concur with Marianne.

I absolutely concur with Marianne's work. She's a brilliant and very careful engineer. I offered to make her set of articles more permanent on my site if she wished when it appeared that dpreview was biting the big one.

just Tony said:
just Tony said:

Nikon’s own AF spec listing measuring range is with a f1.2 lens, so fast lens must have better detection range.

Click to expand...

Yes AF works when such a lens is mounted but since you will be focusing with an f/5.6 image path you risk getting blindsided by focus shift when exposing at wider apertures.

I think you're conflating two things. I've not seen any such focus shift issues with even the f/1.2 lenses. Yes, the individual phase detect unit is still only seeing the innermost light from the image circle to determine phase. No, that's not the equivalent to stopping the lens down to f/5.6.

Bennvdm · Sep 1, 2023

I did not mean output only IR light. I agree that would be invisible to the naked eye. I did not test this myself and are only quoting dpreview and f-stoppers articles that I provided links to in previous post.

Per those articles red af assist have light in visible red spectrum and in near infrared spectrum, with some lights being more biased to the one side than others. Godox x1t comes recommended as is more biased towards visible red spectrum.

I cannot vouch for accuracy and testing methods used by the authors of those articles, but makes a lot of sense as to why it works on dslrs and not on mirrorless.

Canon dual pixel af appears to have pd af capibility on all color filtered sub pixels, whilst nikon and sony mirrorless only appear to have it on green for reasons unknown.
Canon’s also suffer from this issue, so there must be something more than just the color of the af assist lamp making this hard for mirrorless to see.

just Tony · Sep 1, 2023

Thom Hogan said:
I think you're missing some of Marianne's points. Moreover, her statements you're quoting don't explain why you can autofocus to f/8 (and sometimes beyond) on most of the current DSLRs ;~)

I’m not sure how we wouldn’t actually be seeing eye to eye here. Inside every f/5.6 wavefront is an f/8 one, so we know it gets right in and the module is free to respond to it if it can. I didn’t say anything negative about anything narrower than 5.6. If there’s good subject acutance and good light that could be a “go for it” combination that moves the boundary a bit.

Thom Hogan said:
Thom Hogan said:

I suspect that he [Thom Hogan] would concur with Marianne.

Click to expand...

I absolutely concur with Marianne's work. She's a brilliant and very careful engineer. I offered to make her set of articles more permanent on my site if she wished when it appeared that dpreview was biting the big one.

Thom Hogan said:

Thom Hogan said:

Nikon’s own AF spec listing measuring range is with a f1.2 lens, so fast lens must have better detection range.

Click to expand...

Yes AF works when such a lens is mounted but since you will be focusing with an f/5.6 image path you risk getting blindsided by focus shift when exposing at wider apertures.

Click to expand...

I think you're conflating two things. I've not seen any such focus shift issues with even the f/1.2 lenses.

I was still in the context of F mount but I can see how that might not have been clear. Apologies.

Where I myself have been blindsided was with a rented 1.4 lens on a D800. The AFFT value that let me make focused images at 5.6 and narrower was clearly off for 1.4, and vice versa. I’m glad I rented that lens instead of purchasing.

I tried to find the specific entry at Jim Kasson’s blog that I intended to link to that was the watershed event for me in DSLR vs ML. He focused once then shot at several apertures. The graph of the size of the circle of confusion vs aperture setting was horrifically sloped at low f/# for the DSLR in viewfinder PDAF mode but basically level for the ML.

Thom Hogan said:
Yes, the individual phase detect unit is still only seeing the innermost light from the image circle to determine phase. No, that's not the equivalent to stopping the lens down to f/5.6

Similar to a first approximation anyway. I’m thinking that you’re thinking about how complex the wavefront can be along the 3D pathway?

--
Wag more; bark less.

RedRob · Sep 1, 2023

LTheWafflePWN said:
RedRob said:

Hello,

Hoping some folks can share how shoot with a Z8 in very low light with a speedlight.

I shoot a lot of receptions/weddings. I'm finding that the Z8 is almost completely unusable in a somewhat dark room when trying to use a speedlight. I was recently photographing a party and every time that I'd approach a group to shoot a grip and grin, I ended up awkwardly standing there as I waited for the camera to search for focus.....which it never found at times. Totally embarrassing! If people are moving around on a dim dance floor, forget it. I'll miss almost every shot. I've been having to switch to my DSLR in these situations because the focus is instant. I've been shooting events for 15 years or so and never had this issue....even with old DSLR's.

I understand that mirrorless cameras do not trigger the red assist beam that speedlights are equipped with.

How are people working through this problem?

Click to expand...

I'm sorry to hear this RedRob. I am also a wedding/event photographer, but I suppose I don't seem to have this issue. I know others here seem to as well, and I'm not doubting you or that this is a very real dilemma.

What works for me usually is either Single-Point or Dynamic mode, but placed on a contrast-y part of a subject. Sometimes that's a face, but other times that's a shirt collar, with perhaps some tie in it. Unlike the others here though, I am almost always in AF-C mode, and virtually never switch to AF-S. When I find focus I just let go of the back button, I do not use the shutter button for focus.

That is pretty much how I focus only with AF-S. I also use the back button but have been considering going back to the top button due to my clumsy thumb knocking into the focus select lever. (Not being able to lock that really bugs me.)

I'll have to try AF-C a bit more as I pretty much only use that when something fast is headed toward me.

LTheWafflePWN said:
I typically also use faster lenses, at or near wide-open for these scenarios. When I'm using a 24-70mm f/2.8, I'm very often at f/2.8. For a grip-and-grin, I'm usually at or wider than 35mm, or 10 feet or further away, so I figure I only need to stop down for large groups because I should have a good amount in focus even at f/2.8.

Will also try this more. I'm usually using a 24-70 at F4 for grip and grins.

LTheWafflePWN said:
With my Z8 I don't usually have to leave Wide Area AF Small with auto-Subject detection.

Saying that, from using Z6/Z7/Z7ii cameras for weddings and receptions, I found that Dynamic mode works very, very well for low light. In the handful of times the Z8 seemed to be struggling with Wide Area Small - Subject Detection, I switched it over to the Dynamic (Small) and it worked better. I generally don't focus-and-recompose much anymore, but I do find myself doing it from time to time.

Hard habit to break! Something to work on. Honestly, I've always done things so stripped down and rarely take advantage custom settings or fancy features....just manually change shutter/f-stop/ISO/flash power according to the situation, focus, quickly adjust composition and fire.

LTheWafflePWN said:
LTheWafflePWN said:

The transition from DSLR to mirrorless, in general, can be a bit of a learning curve. Most people anticipate the EVF being the biggest change, but for me it was using autofocus. I came from a D500, and I'll be honest I struggled at first getting anything working in low-light on the Z6 and Z7. I eventually got it though, and I know you will too with the Z8.

Click to expand...

I got to liking the EVF pretty quick. Hopefully I'll work out the AF issues soon. This is my first mirrorless camera and have only had it for a few weeks. Had to upgrade from a dying D750 and it seemed silly to buy another DSLR. Had a bought another D850, everything would be real nice and smooth but I guess you gotta step outta the comfort zone at some point.

I do have to say that I shot an event in a real dark bar the other night. Still had AF issues with flash and my adapted 24-70 on the Z8 but switched to a 50mm 1.8 Z lens for ambient candid shots and it was stellar. For now I'm doing a lot of shuffling and swapping of lenses as I'm shooting with both a D850 and a Z8 at events.

LTheWafflePWN said:
One other tip/feature, have you tried Focus Peaking? If you have it on, and are in AF-C mode, you can hold down the focus button (back button for me, should work with shutter half press too) and just turn the lens's focus ring a tiny bit. Your camera should the illuminate everything that it thinks is in focus, and if it's off you can quickly just manually focus and get the shot. -I don't use this much anymore, but it's something that helped me out tremendously in my Z6/Z7 days when I was learning the ways of mirrorless. Whenever I do use this now, it's usually in daylight when shooting large 40+ person family group photos. This saves me from taking a shot, chimping all over my screen to see if I got everyone at f/whatever, taking another shot, repeating, etc. Cool feature, even if you don't end up using it.

Didn't know about Focus Peaking. Another thing to check out.

Thanks for all of the tips!

LTheWafflePWN said:
Good luck!

astirusty · Sep 1, 2023

astirusty said:
One company is making LIDAR system for Blackmagic video cameras. Maybe the company will make a LIDAR system which can AF Nikon Z cameras & lenses.

Wonder if Nikon Z's AF system would function with blue to ultraviolet light provided by AF assist. We know Z's AF system works with green light provided by AF assist. Blue to UV would not be as annoying to people's eyes in low-light as Green.

With a bare Z 24-70mm f/2.8 lens, Z7ii set to Aperture of f/5.6 & ISO 800; tried boosting natural light at night hitting a leafy green tree; with a near ultraviolet light. It did not help AF. Killing off any hope of using a UV light source for AF assist which would not be noticed by human eyes. :-(

In the dark places, DSLR is king. ;-)

Bennvdm · Sep 1, 2023

The uv/ ir cut filter is over the sensor on both dslr and mirrorless, but dslr has seperate af module that gets light from seperate secondary prism. As af sensor is part of image sensor on mirrorless, these frequencies are blocked from view by af detectors on mirrorless.

For astro photography there is an h-alpha filter mod that increase the sensitivity of the sensor for deep reds for hydrogen nebulae as normal filter has a steep sensity falloff on red in this frequency range. It would be interesting to test a h-alpha modded camera with red af assist list on canon mirrorless that have pd af on red filtered pixels. Nikon & Sony appear to only have pd af sensors on green for some or other obscure reason.

just Tony · Sep 1, 2023

just Tony said:
Thom Hogan said:

I think you're missing some of Marianne's points. Moreover, her statements you're quoting don't explain why you can autofocus to f/8 (and sometimes beyond) on most of the current DSLRs ;~)

Click to expand...

I’m not sure how we wouldn’t actually be seeing eye to eye here. Inside every f/5.6 wavefront is an f/8 one, so we know it gets right in and the module is free to respond to it if it can. I didn’t say anything negative about anything narrower than 5.6. If there’s good subject acutance and good light that could be a “go for it” combination that moves the boundary a bit.

And then I found this posting by Marianne. I'm not sure of the context for her statement that AF isn't possible at f/8 (which she wrote in 2017):

https://www.dpreview.com/forums/post/60260772

just Tony said:
just Tony said:

just Tony said:

I suspect that he [Thom Hogan] would concur with Marianne.

Click to expand...

I absolutely concur with Marianne's work. She's a brilliant and very careful engineer. I offered to make her set of articles more permanent on my site if she wished when it appeared that dpreview was biting the big one.

just Tony said:

just Tony said:

Nikon’s own AF spec listing measuring range is with a f1.2 lens, so fast lens must have better detection range.

Click to expand...

Yes AF works when such a lens is mounted but since you will be focusing with an f/5.6 image path you risk getting blindsided by focus shift when exposing at wider apertures.

Click to expand...

I think you're conflating two things. I've not seen any such focus shift issues with even the f/1.2 lenses.

Click to expand...

I was still in the context of F mount but I can see how that might not have been clear. Apologies.

Where I myself have been blindsided was with a rented 1.4 lens on a D800. The AFFT value that let me make focused images at 5.6 and narrower was clearly off for 1.4, and vice versa. I’m glad I rented that lens instead of purchasing.

That posting I linked above talks about how Nikon incorporated some sort of predictive algorithm for focus shift in cameras introduced after 2014, which excludes the D800 that so frustrated me with the 85/1.4 AF-S. So my statements about blindsiding that I phrased without qualification wouldn't apply to models introduced after my troublesome D800. As it turned out I replaced it with a D810 and had better focusing generally.

But I'm even happier nowadays, DSLR-free.

just Tony said:
I tried to find the specific entry at Jim Kasson’s blog that I intended to link to that was the watershed event for me in DSLR vs ML. He focused once then shot at several apertures. The graph of the size of the circle of confusion vs aperture setting was horrifically sloped at low f/# for the DSLR in viewfinder PDAF mode but basically level for the ML.

just Tony said:

Yes, the individual phase detect unit is still only seeing the innermost light from the image circle to determine phase. No, that's not the equivalent to stopping the lens down to f/5.6

Click to expand...

Similar to a first approximation anyway. I’m thinking that you’re thinking about how complex the wavefront can be along the 3D pathway?

--
Wag more; bark less.

Nepeta · Sep 2, 2023

vockman said:
When a flash is turned on a Z body, "apply settings to live view" automatically switches off, and the camera defaults to focusing around F5.6 no matter what aperture is set and the EVF ISO is boosted resulting in the grainy, laggy EVF struggling to focus.

I tried to replicate this with my Z6ii and SB-500. With the flash on, aperture is unchanged even if set to wider than f/5.6. Maybe I'm missing something.

Nikon Z8 - Does not focus with Speedlight in lowlight

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