Flash Triggering With Nikon D850 and EFCS

[mawyatt]

"Since the actual exposure is started with the 2nd trigger which uses EFCS, the vibration effects shouldn't be an issue"

Mike, I know you are aware of this, but I just want to remind new readers again that even though the second-curtain vibrations are not an issue for the current photo, those vibrations can slightly move the subject, and thus ruin the next photo's alignment with the previous one....especially if the subject is a specimen in liquid.

Lou,

Yes thanks. I forgot about subjects that can actually move and not return to the original position under vibration. Here the D850 fully electronic shutter Silent Live View mode is required, since absolutely no vibration nor sound is involved, but the hot shoe is blocked (which we have a work around with my delay circuit and Peter's better (MJKZZ) new controller with a digitally programmable delay. Very nice stacking controller BTW, with programmable motor parameters and well as flash trigger delay and works with just about every focus stacking setup I have

Thanks for pointing this out,

Best,

[mawyatt]

Peter,

I always use manual flash mode for macro and have the Adorama R2 trigger set as such, also the strobes I use for macro Adorama AC 300 (Godox SK300II) don't support TTL.

Not sure how Robert has his Godox X1 RF trigger set though.

Best,

I think Robert's X1-T-N (the N is for Nikon?) is a TTL trigger, so from what he described, it seems TTL mode works but not other manual ones.

Peter,

As far as I know the Godox X1 is the same as the Adorama R2 RF TTL trigger. Yes the "N" is for Nikon as these triggers are camera brand specific.

Robert is using the Godox Speedlights, which support TTL, I am using the Adorama AC 300 (SK300II) studio strobes which do not support TTL. So this could be something to consider regarding the flash behavior.

Maybe Robert will report soon.

Best,

[RobertOToole]

I think Robert's X1-T-N (the N is for Nikon?) is a TTL trigger, so from what he described, it seems TTL mode works but not other manual ones.

I use Manual, but that is a good idea, I should check all the other modes!

Thanks

Robert

[mjkzz]

I think Robert's X1-T-N (the N is for Nikon?) is a TTL trigger, so from what he described, it seems TTL mode works but not other manual ones.

I use Manual, but that is a good idea, I should check all the other modes!

Thanks

Robert

OK, I see Manual Mode 1/160, I thought that is camera setting.

Nikon camera can sense the presence of TTL capable device (via extra pins on its hotshoe) and determines if it is capable of being TTL master. As far as I know, most high end Nikon flashes are capable, but not the prosumer SB-600 (which I have). Your trigger have to be master mode (at least the transmitter). On the receiving end, if the flash attached to the receiver is TTL capable, it will behave like one and obey commands sent from wireless link.

It is interesting to see if you can set your SB-800 into master mode and put it on the hotshoe. If it fires in master mode, it will confirm the idea that TTL flash will work.

But I am very surprised about that DeBao SU-800 which is suppose to be a TTL master, which in turn should trigger the SB-800 in slave mode.

So maybe take a note whether the SU-800 or other TTL flashes is in slave mode or in MANUAL mode (where it is simply a dumb flash)

Thanks for sharing.

Regards
Peter

[RobertOToole]

Thanks for your input on this Peter, I appreciate it.

OK, I see Manual Mode 1/160, I thought that is camera setting.

Should have been more clear on that.

Godox flash in Manual mode 1/128th power.
Godox transmitter in manual and master mode.
D850 also in manual mode at 1/160th shutter speed.

Nikon camera can sense the presence of TTL capable device (via extra pins on its hotshoe) and determines if it is capable of being TTL master. As far as I know, most high end Nikon flashes are capable, but not the prosumer SB-600 (which I have). Your trigger have to be master mode (at least the transmitter). On the receiving end, if the flash attached to the receiver is TTL capable, it will behave like one and obey commands sent from wireless link.

It is interesting to see if you can set your SB-800 into master mode and put it on the hotshoe. If it fires in master mode, it will confirm the idea that TTL flash will work.
But I am very surprised about that DeBao SU-800 which is suppose to be a TTL master, which in turn should trigger the SB-800 in slave mode.

So maybe take a note whether the SU-800 or other TTL flashes is in slave mode or in MANUAL mode (where it is simply a dumb flash)

Great points Peter!

So this is what I get:

Nikon D850
Godox X1T-N Wireless Trigger in the hotshoe
Godox TT350n Flash
Live View On
EFCS Enabled
Godox flash in Manual mode 1/128th power or TTL mode!
Godox transmitter in manual and master mode.
D850 also in manual mode at 1/160th shutter speed.
d5: exposure delay mode on or off

Flash fires!

Nikon D850
Live View On
EFCS Enabled
Debao SU-800 manual mode
Nikon SBR-200 flash manual mode
D850 also in manual mode at 1/160th shutter speed.
d5: exposure delay mode on

Flash fires!

Nikon D850
Live View On
EFCS Enabled
Debao SU-800 TTL mode
Nikon SBR-200 flash TTL mode
D850 also in manual mode at 1/160th shutter speed.
d5: exposure delay mode on

No flash

Nikon D850
Live View On
EFCS Enabled or off
Debao SU-800 TTL
Nikon SBR-200 flash TTL
D850 also in manual mode at 1/160th shutter speed.
d5: exposure delay mode OFF

Flash fires!

The Godox will fire with EFCS and d5 delay ON in TTL or M mode.

The Debao SU-800 would fire in M mode with EFCS with enabled and d5 delay ON or in TTL mode with d5: OFF.

This is an important news for me even though its not full electronic shutter its still good to know and makes working with flash easier for sure.

Will try the Nikon SU-800 when I get a chance.

Robert

[RobertOToole]

"Since the actual exposure is started with the 2nd trigger which uses EFCS, the vibration effects shouldn't be an issue"

Mike, I know you are aware of this, but I just want to remind new readers again that even though the second-curtain vibrations are not an issue for the current photo, those vibrations can slightly move the subject, and thus ruin the next photo's alignment with the previous one....especially if the subject is a specimen in liquid.

Very good point Lou, thanks for mentioning that!

This is good reason to have the subject on a separate stand/base to isolate vibrations from the main rig.

Robert

[mjkzz]

Thanks Robert! I will try something on my D5200 and SB-600, just curious about the difference between high end D850 and D5200 :-)

[mawyatt]

"Since the actual exposure is started with the 2nd trigger which uses EFCS, the vibration effects shouldn't be an issue"

Mike, I know you are aware of this, but I just want to remind new readers again that even though the second-curtain vibrations are not an issue for the current photo, those vibrations can slightly move the subject, and thus ruin the next photo's alignment with the previous one....especially if the subject is a specimen in liquid.

Very good point Lou, thanks for mentioning that!

This is good reason to have the subject on a separate stand/base to isolate vibrations from the main rig.

Robert

Robert,

It's not that simple in general and depends on subject. With subjects like Lou mentioned, then a separate stand/base for the subject might be a good option to "isolate" the camera induced vibration from the subject.

However, with subjects that don't change position after vibration has subsided (like your Silicon wafers), then having the subject and camera/lens rigidly connected may be the better approach. This is because the rigid connection will allow the subject and camera/lens "system" to move in unison with the camera induced vibration, at least somewhat so and reduce the induced vibration blur image degradation.

It's called Common Mode and isn't quite a simple as I have shown. The movement of this "System" is approximately governed by 2nd order dynamics which involve position, frequency, time delay and phase shift and can get somewhat complicated, but the lower frequency components of vibration do fall in unison between the camera (sensor) and subject which helps reduce vibration induced blur. BTW this also helps with external vibration effects, so generally a good idea for the stationary subjects mentioned.

Best,

[mjkzz]

"Since the actual exposure is started with the 2nd trigger which uses EFCS, the vibration effects shouldn't be an issue"

Mike, I know you are aware of this, but I just want to remind new readers again that even though the second-curtain vibrations are not an issue for the current photo, those vibrations can slightly move the subject, and thus ruin the next photo's alignment with the previous one....especially if the subject is a specimen in liquid.

Very good point Lou, thanks for mentioning that!

This is good reason to have the subject on a separate stand/base to isolate vibrations from the main rig.

Robert

Robert,

It's not that simple in general and depends on subject. With subjects like Lou mentioned, then a separate stand/base for the subject might be a good option to "isolate" the camera induced vibration from the subject.

However, with subjects that don't change position after vibration has subsided (like your Silicon wafers), then having the subject and camera/lens rigidly connected may be the better approach. This is because the rigid connection will allow the subject and camera/lens "system" to move in unison with the camera induced vibration, at least somewhat so and reduce the induced vibration blur image degradation.

It's called Common Mode and isn't quite a simple as I have shown. The movement of this "System" is approximately governed by 2nd order dynamics which involve position, frequency, time delay and phase shift and can get somewhat complicated, but the lower frequency components of vibration do fall in unison between the camera (sensor) and subject which helps reduce vibration induced blur. BTW this also helps with external vibration effects, so generally a good idea for the stationary subjects mentioned.

Best,

Great analysis and I have been doing this all along, but by hunch. However, for stuff in liquid, it might be troublesome.

[Lou Jost]

Yes, the goals of stabilization are quite different depending on whether the subject is in liquid or not. For dry rigid subjects, the most important thing is to make the subject and camera move in unison. Hanging a granite block from the ceiling with bungee cords might be a reasonable thing to do for such subjects. For liquids, though, there is an extra requirement, that there be no movement of any kind (with respect to the earth).

[mawyatt]

Peter,

Thanks, you have good intuition

Yes, the subjects in liquid as Lou mentioned are probably better isolated from the camera/lens.

Here's some MIT lecture notes on 2nd Order Mechanical Systems. The camera induced vibration from mirror flop and/or shutter curtains can be reasonably approximated as an impulse function excited 2nd order system.

As such note equation 1.67 and figures 1.25 & 1.26. These illustrate the vibration induced behavior well and aren't too complex. Note that the system stiffness causes the natural frequency to increase, and nicely illustrated in figure 1.25.

Here's a quote from the notes.

"Thus, the mass with initial velocity 1 “runs into” a stiffer system, and is returned to rest more rapidly"

https://ocw.mit.edu/courses/mechanical- ... lment2.pdf

Best,

[mjkzz]

Mike, too complicated for me, so I will take your word for it

[mawyatt]

Peter, Lou,

If you want to model the subject in a liquid situation, this could be a pair of coupled 2nd order systems. One system, the camera/lens setup, excites the second system, the subject in a liquid. The second system (subject in liquid) will have a much lower natural frequency and be highly underdamped, while the first system (camera/lens) will have a much higher natural frequency and somewhat higher damping.

Figure 1.25 in the notes shows how each of the behave independently, but not coupled together.

This can get much more complicated when multiple coupled 2nd order systems are involved but with widely varying natural frequencies as is the case here, the result is that both systems will "ring" at their natural frequencies and as Figure 1.25 shows the lower natural frequency system (subject in liquid) will "ring" much longer in time.

So Lou's solution is to not couple the two systems together (or very weakly couple them) and not excite the low natural frequency and low damped subject in liquid system, that works

Note however, that with the systems not coupled the camera sensor doesn't move with the subject in unison but independently which has it's own set of issues (exposure period) to deal with.

BTW there is an optimal coupling between theses systems for a desired given response but this is well beyond the scope of our discussions and quite complex.

Here's more information on 2nd order systems for those interested.

http://web.mit.edu/2.151/www/Handouts/F ... dOrder.pdf

Best,

[mawyatt]

Mike, too complicated for me, so I will take your word for it

Peter,

Well, your intuition has certainly lead you down the right path

Actually it's not that complicated once you get the "hang" of what's going on.

Best

[mawyatt]

Mike, too complicated for me, so I will take your word for it

Peter,

Another way think about all this is that as the system gets stiffer the natural frequency increases, this causes the system energy to dissipated quicker since energy dissipation increases with increasing frequency.

So the subject in the liquid will "oscillate" a long time as the liquid sloshes around (low natural frequency and low damping), so you don't want to instill any kind of starting energy (think of water in a bath tub sloshing around when you drop a bar of soap in).

Whereas the camera/lens is a much stiffer connection with a much higher natural frequency and higher damping (hopefully). Play around with different setups while you "ping" (impulse) the camera in Live View and watch the response under high magnification. If you loosen the camerra/lens/setup connection the system stiffness is lower and so is the natural frequency, thus taking longer to subside and with higher initial amplitude (again Figure 1.25).

Another good example is the long macro lenses we use, they are like a cantilever beams (complete 2nd order system themselves). Ping the camera and watch the response, then add the clamps you & Robert use which increase the stiffness & natural frequency. That's why they work so well

Best,