Exposure issues with Nikon flash - advice needed. Ta!

[duff photographer]

Howdo all,

I'm at my wits end!

My problem is getting the correct exposure with my Nikon D2Xs or D300S and SB600 and/or SB800 flash units for my macro work. When in manual, which I use most, if I need to expose a 1/3 stop more, it exposes 2-3 stops more. If I need to under-expose by say 2/3rd stop it under-exposes by, say, 3 stops. On many occasions I have not even been able to get the correct exposure at all (it either under-exposes or over-exposes, never in between). This happens no matter what mode I use. I have applied every single change to try and solve the problem. Everything from exposing in manual/aperture priority/P; TTL/manual on the flash; changing exposure on the camera either through shutter speed/ISO/aperture; distance of flash from subject; power of flash; etc., etc. Other times it works okay(ish) and usually first time (I just need to adjust shutter speed up or down to get the right exposure, and usually down when the batteries begin to fade!). At such times, I do get the correct exposure, usually in manual mode on the camera and manual mode on the flash, but invariably get some under-exposed (because the flash hasn't had time to re-charge) and over-exposed (no idea why). I've used the system in wireless and wired. Batteries are fully charged and I either use rechargeable AA's or Quantum battery(ies).

I run a Nikon system for my macro work. I either use two SB600 flashes in tandem or a single SB800 for fill-in, both outdoors or indoors.

Please assume that I at least know the basics of using my flash - I've read the manuals backwards as well as the more in-depth accounts on-line and have had five frustrating years of using them. I don't normally use flash but there are circumstances, i.e., freezing the motion of a moving insect or filling in the shadows in direct sunlight, where I need it. Sadly I have lost some money-earning shots through the variance in flash exposure and it's been getting me down lately.

If I've left out any important information you need to help suss out the problem, please do say so.

If anyone can help pinpoint the problem I would be very, very appreciative as would my hair, half of which has already been pulled out.

Many thanks.

Cheers,
Steve.

 

[Sirius Glass]

This crosses over the the bailiwick of DPUG.org and I do not believe that APUG is the best place for this question.

Welcome to APUG

 

[ic-racer]

Which camera are you using? This is posted in the 35mm section.

 

[BrianShaw]

Sounds to me like the perfect application for a flash meter - whether analog or digital!

 

[CGW]

Save yourself the trouble and scoldings and ask at photo.net. DPUG isn't that active.

 

[duff photographer]

Save yourself the trouble and scoldings and ask at photo.net. DPUG isn't that active.

Thanks, I will.

I assumed that because it was an issue which would occur with both analogue and digital (I do both) I might get a working reply. My mistake.

..apologies to all for posting in the wrong bit.

 

[Les Sarile]

I assumed that because it was an issue which would occur with both analogue and digital (I do both) I might get a working reply. My mistake.

SB16 TTL works perfectly fine on my FM3A & F3 and of course with C41's latitude you have more than enough for post work.

 

[PhotoJim]

Digital fill flash works a lot differently than film fill flash, since most TTL flash systems on film cameras measure light reflection from the emulsion and that is simply not possible on digital. For that reason, and arguably, film TTL fill flash still works better than it does on digital cameras.

Debugging the problem will be digital-specific most likely, since the problem will be based on completely different hardware methods than we see on film cameras.

 

[duff photographer]

Digital fill flash works a lot differently than film fill flash, since most TTL flash systems on film cameras measure light reflection from the emulsion and that is simply not possible on digital. For that reason, and arguably, film TTL fill flash still works better than it does on digital cameras.

Debugging the problem will be digital-specific most likely, since the problem will be based on completely different hardware methods than we see on film cameras.

This makes a bit of sense.

PS. I should have posted on DPUG not APUG but my brain was only half working so...

 

[David A. Goldfarb]

I'll agree with Brian Shaw--analogue or digital, this is simple with a flash meter. Use the meter to determine the base exposure, and then add any fillter factor and the magnification factor for macro to determine the actual exposure using the table attached to the following post:

(there was a url link here which no longer exists)

and then add reciprocity factor, if that's something you have to worry about.

How to do this in an automated way with Nikon's TTL gizmos? Beats the heck out of me. I have a flash meter and a table, and I'm good--any camera, any format.

 

[Chan Tran]

I'll agree with Brian Shaw--analogue or digital, this is simple with a flash meter. Use the meter to determine the base exposure, and then add any fillter factor and the magnification factor for macro to determine the actual exposure using the table attached to the following post:

(there was a url link here which no longer exists)

and then add reciprocity factor, if that's something you have to worry about.

How to do this in an automated way with Nikon's TTL gizmos? Beats the heck out of me. I have a flash meter and a table, and I'm good--any camera, any format.

Very true! The OP has digicam so may be the flash meter isn't even needed. Just set everything in manual, take a test shot and then adjust. The new Nikon TTL or CLS doesn't work. I watched 2 hours plus instruction video from Nikon and all they show is how to adjust after the taking test shots.

 

[grahamp]

I think I would need to see a diagram of your subject/lens/flash arrangement. At macro distances, the flash to subject distance is important, but there is also loss due to off-axis illumination - often more than 45 degrees to the lens axis. Add in the effective f number at extension, and triggering multiple flash units, and automation often fails. When I used to do this sort of thing, I worked out the flash levels by experiment, set the magnification of the set up, and them moved the whole unit to focus. On a totally manual system.

 

[Dismayed]

This crosses over the the bailiwick of DPUG.org and I do not believe that APUG is the best place for this question.

Welcome to APUG

Why? Does light not pertain to film photography? Would it be relevant if he were using flash powder?

 

[tkamiya]

Film or digital, I don't have a lot of faith in TTL. When exposures are critical, they often let me down.

I kind of wonder if the issue really is equipment setup. I also wonder the usage because OP mentions changing shutter speed.... When ambient light isn't really a factor, the shutter speed is usually fixed at sync speed or lower - and doesn't affect exposure based on flash output. What's important is the output of the flash itself, aperture, and the distance.

At macro distance where lens and the subject is really close, getting a good angle of light from flash isn't easily possible unless the flash lamp is mounted on or near the lens - such as ring flash or SB200 type setup.

Another thing I wonder about is OP talks about adjusting the shutter speed up and down and getting the right exposure. This tells me he is really shooting with ambient light. So the situation is even more complicated. OP also said he is changing ISO. This tells me he could possibly be raising ISO rating so that ambient is becoming more of a factor. At macro distance, any flash has more than ample output at base ISO.

Long story short, I'm not sure how to help this OP without seeing his setup and seeing how he shoots.

Yeah, everyone is right because light is light no matter the medium. At the same time, this is hugely equipment dependent which APUG charter won't really let us into suggesting digi setups. I wish I can be more of a help. I can't for more reason than APUG policy.

 

[duff photographer]

Howdo all,

I had a private discussion with an APUG member and have come to the conclusion it's an issue with going 'High Speed', in other words beyond the normal sync' speed of the flash/camera. It appears that high speed flash is considered 'unreliable' by other users away from APUG.

However, I'll give an example set-up to better explain my issue.

Camera: Nikon D300s (yes I know it's digi', sorry)
Lens: Schneider 120mm Apo-Digitar
Bellows: Novoflex (extendable up to 150mm)
Flash units: Two SB 600's placed on double bracket, one either side of the camera. Both have Lastolite soft 'boxes' to diffuse the light.

The above is just an example - I use up to three macro lenses, an SB800 singly, vary the position of the flashes to get the illumination I require, etc. Despite the variation in set-up, the issue remains.

I use the flash manually (set as M1/1 full power) and set the camera to manual and set the shutter speed as required to freeze the moving insect, e.g., 1/4000th second.

Using the flash/camera in High Speed requires a lot of power. This has implications after taking a few shots in that I have to reduce shutter speed to mirror the drop in battery power. Working this way and in manual usually works after taking a few test shots to ascertain the optimum flash, and as long as the flash battery(ies) last.

However, while doing this and in all other possible modes on flash and camera (including TTL), I sometimes, and in some cases nearly all the time, adjust the shutter speed but say 2/3rd stops to compensate for under-exposure it over-exposes by a significant margin, i.e., a lot more than 2/3rd stop. Even making equivalent adjustments to the ISO and/or aperture does not change things. Equally, if the image is over-exposed and I drop by the merest 1/3rd stop, it under-exposes by a lot more than that (e.g. 3 to 6 stops). This is the problem I'm having. This under- or over-exposure is consistent, e.g., if it over-exposes by 3 stops it continues to do so unless I change a setting but never gets anywhere near the exposure I require. This occurs at any shutter range setting I make on the camera.

Common sense says if the flash output remains the same then a change to the camera setting by a 1/3 stop to over-expose will let in a 1/3rd of a stop more flash light. All things being manual. I should add that this is independent of the ambient light available.

I hope that explains the problem more clearly.

As I said in the first paragraph, it may be a problem with going beyond the camera/flash normal ('natural') flash sync' but while this may account for the variation in the final exposure I'm not sure how it would not allow me to manually adjust the settings to get at least some shots just right instead of going 3 stops over or 3 stops under, for example. I should add I don't have issues when used at the normal flash sync' range (up to 1/320 for this particular camera). It does seem to be a FP/High Speed issue but if anyone knows better then I'm all eyes...

Thanks to all those who've responded constructively, and again if you require further clarification just shout.

Cheers,
Steve.

 

[MattKing]

Steve:

With some exceptions, changing the shutter speed should have no effect on the exposure if your light source is flash.

If ambient light isn't involved, the only ways to change exposure are:
1) with filtration (e.g. neutral density);
2a) by changing the aperture;
2b) by changing the magnification (because it effectively changes the aperture);
3) by changing the number of times the flash fires; and
4) by adjusting the output of the flash.

It may be that moving the shutter speed outside its recommended range disables the flash metering function, or modifies it in unexpected ways.

Are you sure the TTl flash metering functions are compatible with macro bellows work? At least with film TTl, there is a film surface to measure the light reflectance off of.

 

[rolleiman]

Having used D1's & D2's in my professional years, I can tell you that dedicated flash with these digital cameras (and possibly others) of that era was an absolute pain,. particularly fill in, it was hopelessly erratic. Complaints to Nikon got no-where...yet it was common knowledge there was a problem.
Thankfully I'm no longer a pro., and have returned to using Nikon film cameras.

 

[Sirius Glass]

Why? Does light not pertain to film photography? Would it be relevant if he were using flash powder?

1. Read the FAQ on the main page. It is well covered there.
2. Electronic sensors do not behave the same way film does.

 

[duff photographer]

Hello Matt,

Yes, it could be that macro work is not suited to flash in this case. The way I set the flash up is that flash operates at full power no matter what is set on the camera (although obviously I can adjust the output on the flash but I usually need it at full power to get the shutter speed I need to freeze the movements of the twitchy insect). I just adjust the aperture, shutter speed, etc. to match up to the flash output. The camera/flash system can nowadays be operated to go beyond normal sync speed but it appears that the results are very hit and miss even with today's technological advances.

As Rolleiman points out (thanks Rollei') it appears that digital is a real pain to use with flash. I've had similar feedback today from a couple of other pro's on this matter who have said the same and now work with continuous light when shooting digital.

As it may be a flash/digital issue (rather than just a simple flash problem) then this topic has gone beyond the remit of APUG I guess. I'm also now satisfied that I haven't been doing anything wrong other than forgetting to make the necessary inputs and adjustments on camera and flash now and then.

Think I'll go back to a continuous light set-up in a studio environment for my macro shots.

Anyway, thanks to all for pitching in with their learned thoughts - it's been much appreciated.

All the best,
Steve.

PS. My next thread will be film related - honest!

 

[Chan Tran]

Is it possible for you to shoot at 1/250? I never think the FP flash (first introduced by Olympus for the OM-4Ti) is a good idea. It wastes so much flash power and I never have enough flash power.

 

[duff photographer]

Is it possible for you to shoot at 1/250? I never think the FP flash (first introduced by Olympus for the OM-4Ti) is a good idea. It wastes so much flash power and I never have enough flash power.

Yes, I'll continue shoot at this speed where I need fill-in flash for example but sadly it won't work to freeze rapid movement (which of course is magnified when using macro).

...and you're right about flash power. I have a seperate Quantum battery for each SB600 flash and I only get about 100-150 flashes beofre power dies off completely - rather annoying.

 

[tkamiya]

I think you are going about this the wrong way....

You said "I use the flash manually (set as M1/1 full power) and set the camera to manual and set the shutter speed as required to freeze the moving insect, e.g., 1/4000th second."

What happens is, if you set your flash manually and go "boof", the flash tube starts to illuminate and stops illuminating while the shutter is only partially open. In such a high speed of shutter setup, you have a small slit going across your frame. So only portion of the exposure is lit by the flash. The "FP" mode causes the flash to pulsate for duration. I don't think this works if you set it in manual mode. You told the flash to go full power all at once and you told the camera to go 1/4000.

If what you want to do is to stop motion, why not set the shutter speed at or below SYNC, close the aperture as much as you can so ambient won't be a factor, then let the very short duration of flash itself be the exposure? It will stop the motion because flash is only "on" for no longer than 1/1000 seconds, more like 1/4000 as you want it.

I agree, this isn't a digital/analog issue. It's a lighting and using flash issue.

 

[Bob-D659]

Well seeing as the Nikon F6 film camera supports Nikon's newest iTTL flash system, there is really no difference between it and a newer type electronic capture cameras in discussions of macro flash technique.
See http://www.vistek.ca/pdfs/nikonf6.pdf , the F6 supports X-sync to 1/8000 sec in Auto FP mode.

 

[PhotoJim]

Well seeing as the Nikon F6 film camera supports Nikon's newest iTTL flash system, there is really no difference between it and a newer type electronic capture cameras in discussions of macro flash technique.

I wonder if the F6 supports iTTL combined with off-the-film measurement. I expect not.

If not, is the F6 still compatible with the older-style film TTL which is really superior?

The iTTL compatibility is nice because the F6 properly supports modern Nikon flash units, so you can at least use newer flashes in TTL mode, but from what I understand, you may get better results (and certainly never worse) with the older through-the-lens and off-the-film TTL.

 

[Chan Tran]

i-TTL is not off the film even with the F6. But I think F6 can use other TTL mode.