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.
I feel, therefore I photograph.
Why? Does light not pertain to film photography? Would it be relevant if he were using flash powder?
Originally Posted by Sirius Glass
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.
Develop, stop, fix.... wait.... where's my film?
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.
Last edited by duff photographer; 07-02-2012 at 12:49 PM. Click to view previous post history.
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.
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2
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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.
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,
PS. My next thread will be film related - honest!
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.
Originally Posted by Chan Tran
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.
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.
Develop, stop, fix.... wait.... where's my film?