FV Lock isn't working as expected on my Nikon Z8.

[David H. Hartman]

FV Lock (Flash Value) isn't working on my Z8 as expected...

I've loved the FV Lock feature fond on my DSLR(s) D2H to D850 but it doesn't work as expected on my Z8. Nikon DSLR(s) have a dedicated flash sensor in the mirror box for TTL flash exposure. A mirrorless camera would need to create the same feature in software I'd guess. Maybe I'm missing something.

The way the FV Lock works on all my DSLR(s) is you press a dedicated button and the flash emits a monitor pre-flash. The flash exposure is automatically locked in. You can recompose and you can fire off several shots and the flash exposure will be the same in all shots. You do have to maintain the flash to subject distance to have correct exposure. To cancel the FV lock you press the dedicated button again. It's a toggle on, toggle off feature.

The way I've used this feature is in a PJ, PR, "Paparazzi" style of on camera flash. I put paparazzi in quotes because I don't badger subjects. At an event say a wedding reception I select a subject or subjects. The place is swarming with people taking photos so it's not a big deal. Subjects typically pose with a "say cheese" smile and when the monitor pre-flash fires they relax and give a natural smile. Then I'll fire a couple of actual photos and move on. If the subjects clown for the camera I'll take a few more. This technique works especially well with kids.

Now the Z8 is different as to how auto flash works and as yet I don't understand it. What is happening is I'm getting consistent over exposure of maybe 2 stops. So far I'm finding my FV lock, PR/PJ technique useless with my Z8.

Maybe someone here understands how TTL auto flash works on a Nikon Z camera. I hope someone here has suggestions.

Thank's for considering this!

Dave

I was experimenting with an SB-400. Just now I tried with an SB-800 and the results are the same. I'm also finding that the SB-800 doesn't expose correctly in the [TTL] mode, only the [TTL][BL] mode where [TTL][BL] is balanced TTL fill flash and [TTL] is standard iTTL flash that ignores the ambient light.

Asking here is probably a long shot as not much is disgust about flash here. There are several groups on Flickr that in years past would be a good place to ask this question but these days one needs a familiar spirit to bring up the dead to get a question answered.

[Ilkka Nissilä]

Do you also get overexposure when using the SB-800 on the Z8 without using FV lock?

I haven't had any issues using the SB-5000 on the Z8, but with one third-party flash the results at higher than sync speeds (Elinchrom THREE with Skyport Pro) have been not what I would have expected.

[Akira]

According to the manual of Z8 for FV lock function with SB-800:

Available only in i‑TTL flash control mode or when the flash is configured to emit monitor preflashes in Auto Aperture or Non-TTL Auto flash control mode.

The source:

https://onlinemanual.nikonimglib.com/z8/en/compatible_flash_units_377.html


Hope this would be of any help.

[David H. Hartman]

Do you also get overexposure when using the SB-800 on the Z8 without using FV lock?

No, the SB-800, SB-700 and the SB-400 all produce expected results when the FV lock is not used.

[David H. Hartman]

Available only in i‑TTL flash control mode or when the flash is configured to...

Aira, thanks for the link. I'll check it out tomorrow afternoon.

Dave

[David H. Hartman]

According to the manual of Z8 for FV lock function with SB-800:

Available only in i‑TTL flash control mode or when the flash is configured to emit monitor preflashes in Auto Aperture or Non-TTL Auto flash control mode.

The source:

https://onlinemanual.nikonimglib.com/z8/en/compatible_flash_units_377.html


Hope this would be of any help.

OK, the SB-800 performs correctly with the Z8 and FV lock in AA mode with monitor pre-flash but not in iTTL or iTTL BL so I've learn that much.

The SB-400 has a limited feature set offering iTTL BL or manual in from 1/1 to 1/128 in 1/3 stops. It's small and light, easy to carry but lacks the power for single shots in rapid succession.

Maybe FV Lock has lost it's usefulness with Nikon mirrorless cameras?

Yes, the link was helpful.

Dave

I don't care for the SB-700. I bought it because the D-800 had no popup flash to use as a Master or Controller and the SB-800 was discontinued. At the time I bought the SB-700, used SB-800(s) sold for $435.00 used where they SB-800 had recently closed out a $320.00. The SB-700 is almost identical to the SB-800 in size and weight but has about 1 ~ 1 1/3 stop less power compared to the SB-800. Further the SB-700 has 4 channels but only groups A & B. I think the latter is Nikon jerking around its customers.

The SU-800 is long in the tooth and does not offer 1/3 increments in manual mode.

---

Maybe in a year I can look into the SB-5000?

[Ilkka Nissilä]

OK, the SB-800 performs correctly with the Z8 and FV lock in AA mode with monitor pre-flash but not in iTTL or iTTL BL so I've learn that much.

The SB-400 has a limited feature set offering iTTL BL or manual in from 1/1 to 1/128 in 1/3 stops. It's small and light, easy to carry but lacks the power for single shots in rapid succession.

Maybe FV Lock has lost it's usefulness with Nikon mirrorless cameras?

Yes, the link was helpful.

Dave

I don't care for the SB-700. I bought it because the D-800 had no popup flash to use as a Master or Controller and the SB-800 was discontinued. At the time I bought the SB-700, used SB-800(s) sold for $435.00 used where they SB-800 had recently closed out a $320.00. The SB-700 is almost identical to the SB-800 in size and weight but has about 1 ~ 1 1/3 stop less power compared to the SB-800. Further the SB-700 has 4 channels but only groups A & B. I think the latter is Nikon jerking around its customers.

The SU-800 is long in the tooth and does not offer 1/3 increments in manual mode.

---

Maybe in a year I can look into the SB-5000?

It seems like there is a bug. I can check how FV lock behaves on my Z8 and SB-5000; I have not used this feature in recent years. In the early DSLR years I felt the preflashes were timed so that they caused a lot of eye closures at the time of the actual exposure, at least with the less expensive camera models, and so I would use FV lock to get the preflashes out of the way, wait for a moment and then get some real shots without eye blinks. However, in the higher-end DSLRs the delay between the preflashes and main exposure was so short that eye blinks were not a common issue for me (though they could still happen) but in the past decade or so, most of my flash work has been with Elinchrom flashes mostly in manual mode so I haven't had as much recent experience with this.

I am happy to do some testing if it helps to identify the problem. I think you should report to Nikon on their contact web page, give as much information as you can, and they will pass the information to Japan.

[David H. Hartman]

The only SB-800 mode that functions as expected with the FV(lock) and Nikon Z8 is [AA] or Auto Aperture which uses the sensor on the front of the SB-800 rather than the image sensor in the camera. Perhaps FV (lock) is just not compatible without a separate sensor such as the ones in the D850's finder. I have some ideas why FV (lock) may be fundamentally incompatible with the image sensor in a digital camera, DSLR or mirrorless. Now I'm wondering if there is a way to lock in the exposure after taking a shot: shutter, aperture and flash duration. Also the same problem I'm having with the SB-800 is the same with the SB-400 and SB-700.

I'll talk to Nikon but last time I did whoever I talked to thought the *.nxd and *.nka files were presets rather than potentially unique to a single image.

Dave

[Ilkka Nissilä]

The only SB-800 mode that functions as expected with the FV(lock) and Nikon Z8 is [AA] or Auto Aperture which uses the sensor on the front of the SB-800 rather than the image sensor in the camera. Perhaps FV (lock) is just not compatible without a separate sensor such as the ones in the D850's finder. I have some ideas why FV (lock) may be fundamentally incompatible with the image sensor in a digital camera, DSLR or mirrorless. Now I'm wondering if there is a way to lock in the exposure after taking a shot: shutter, aperture and flash duration. Also the same problem I'm having with the SB-800 is the same with the SB-400 and SB-700.

I'll talk to Nikon but last time I did whoever I talked to thought the *.nxd and *.nka files were presets rather than potentially unique to a single image.

Dave

FV lock works correctly (in the expected way, familiar from DSLRs) in my Z8 when a Z 50 mm f/1.8 S and SB-5000 are mounted on the hot shoe. Manual mode was selected for ambient exposure and TTL for flash.

I did a bunch of tests and the flash output was clearly locked by the FV lock functionality (assigned to Fn1 button) and a second press of the button released it.

[David H. Hartman]

Ilkka,

The FV (lock) (assigned to the Fn2 button), functions to the extent that it fires preflashes and locks the flash exposure but the resulting flash exposure blows out the subject. I'm guessing about 2 to 2.5 stops of over exposure.

I've tried everything I can think of: [TTL][BL], [TTL], manual exposure, aperture preferred, programed mode. I've tried Matrix and Center Weighted metering. I tried spot meter with the SB-400 and SB-700 which is supposed to force Standard iTTL. I've tried turning off flicker control, etc. Again this is with an SB-400, SB-700 and SB-800. The only mode that doesn't cause over-exposure is [AA], Auto Aperture with preflash which with my speedlights is only available with the SB-800. [AA] uses the sensor on the face of the SB-800.

The flash exposure I get with the Z8 without FV (lock) are as expected with all my speedlights. There was only one reply that didn't solve that person's problem.

I know there are compatibility issues with the SB-800 and Godox/Flashpoint triggers and receivers that are not present with the SB-700. I got gross under exposures with the SB-800 in iTTL mode unless I used FV (lock) with my D850. With FV (lock) the exposures were fine. If framing and focus remain constant I should get the same flash exposure with and without FV (lock). With a DSLR I found flash exposure consistent with FV (lock) followed by recomposing and that I believe is one of the prime reasons for FV (lock). Maybe there are compatibility issues with my speedlights that are solved with the SB-5000.

I read on Dpreview someone having the same over exposure problem with a Z8 and FV (lock).

Dave

[Ilkka Nissilä]

I did not get overexposed results with my setup with or without FV lock. I don't have an SB-800 to test.

[David H. Hartman]

I did not get overexposed results with my setup with or without FV lock. I don't have an SB-800 to test.

The SB-800 did not expose correctly with a Godox/Flashpoint set of a trigger and receivers in iTTL mode unless curiously I used FV (lock) whereas my SB-700 did. This setup worked perfectly in manual flash mode and the exposures were great with the SB-800 and iTTL but only with the use of the FV (lock). The camera was a D850.

At some point I'll have to get an SB-5000 or twoj but until I get a mid range zoom in Z mount.

The SB-800 is an interesting speedlight. I believe it is compatible all the way back to the FE2 but it is showing its age.

Dave

[David H. Hartman]

Just for the hell of it I put my Nikon SB-24 on my Nikon Z8...

I set Z8 to manual exposure mode 1/200th f/8 and manual ISO 200. The SB-24 was set to A (Auto Thyristor mode as we called it), f/8.0, ISO 200 and Zoomed to 85mm. The lens was a 100/2.8 Z MC.The results were over exposure of about 2 stops??

To get proper exposures I had to set ISO 800 on the SB-24 while the Z8 remained at ISO 200 neither of which should effect the meter in the Z8.

To double check that the Z8 was really in full manual I turned the SB-24's head 180 degrees so no light from the SB-24 would hit the subject. The subject was under exposed as expected and the SB-24 fired at full power also as expected.

Finally the Z8 cycles on and off it the Z8 is turned on and the SB-24 is in the hot shoe weather the SB-24 is set to Standby or On.

Conclusion: The SB-24 can be used on the Z8 in an emergency provided that the ISO is set two stops faster on the SB-24 than on the Z8. The Z8 must be in full manual mode including ISO. Standby on the Z8 will not function correctly so if the Z8 will not be used for a time, it as well as the SB-24 must be turned off.

Dave

I'm keeping the SB-24 as I still own FE2(s), an F3 with AS-17 and an F5.