Handheld Macro BG control basics

Charles Glatzer said:

Hey Robert,

Flash and f/stop are linked together...change one of these variables and you have to change the other ie; cut down the flash pwr in manual mode and you will have to open the f/stop or bring the flash closer to the subject.

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Agreed and ISO is another variable in regards to exposure and flash.

Charles Glatzer said:

Shutter-speed is independent. Think of flash and ambient as two separate entities.

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I think of shutter speed as being independent since the flash output and short duration (1/1000 to 1/8000th) usually has the greatest effect on the subject. Shutter speed does have an effect if the the ambient exposure is close enough to the flash exposure to cause ghosting.

Charles Glatzer said:

Ghosting occurs when the flash and ambient exposures are close.

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Yes, I find that in high light levels with medium apertures anything less than 1/200th or so will give you ghosting with macro photography. Sometimes this just shows up as a haze or smearing.

Charles Glatzer said:

Moreover, high-speed syn ( above 1/250) reduces the flash pwr, making it necessary to increase the flash output or move the unit closer to the subject to maintain the same f/stop.

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Yes agree once again. Flash output or reach is reduced in FP/HSS. Reach or output is usually not a problem with Macro flash since you are usually shooting at low power but I see your point if you are moving into FP/HSS speed territory.

Dont forget some DSLRs like the old Canon 1D and the Nikon D70 (there are others) sync up to 1/500. Also there are ways to get strobes to sync up to 1/1000th with normal use and full output (with the proper trigger method).

Thanks,

Robert

Hi Robert. Thanks for posting this thread. I struggle with flash. I need to spend some time studying this discussion - and then head outside and try these techniques.

Good to hear Steve, if you need any advice or have any questions, just post/PM/email me anytime.

Robert

I too struggle with flash, how much, etc.....My brain hurts just reading this thread.

Thanks Robert. I'm going to have to work on this. ut it'll be fun work!

Robert I am very interested in this thread. I use a 550 EX Gun and a Stofen Omnibounce. I used to set aperture and shutter speed manually to about 1/60 and f16 for insect photography and let the flash do the rest. when i went digital I started trying to use ambient light as much as possible using flash more as fill in.
Currently I set the 550 ex to High speed sync and at -1 stop, I generally set the camera to ISO 200 and in AV mode to about f11 through to f16 depending upon subject and brightness of day. My latest post in the macro forum is an example. Can you suggest how else I may use the gun to ensure consistently sharp images or improve upon the natural lighting effect. I am not sure if I can set the gun to 1/8th power.
Jon

Hi Jon,

Sounds like you are on the right track. Diffusing the flash is good, I would recommend placing the flash as close to possible to the subject, right near the end of the lens. The closer the flash is to the subject the softer the light and the less power you need.
Also try manual flash, and experiment with different settings. -1 and AV will work okay too but manual will give you fine control over the output to give you the exact amount of light and in effect the image look that you are looking for.

Robert

Thanks Robert I will have another go today. At first you surpised me when you say put the flash as close as possible to the subject - the inverse square law dictates more fall out, but your method is not primarily of course for lighting it is merely to stop movement. The shutter speed and aperture will of course take care of the ambient light. ..........I will post any success!!
Jon

Inconsistent flash results - usually underexposed

Robert I have been doing a little more macro with flash photography. I have had some good results with flash at 1/8 power and the camera in AV mode (Canon 20D & 100mm macro lens).
I have noticed however that many shots come out underexposed if the ambient light is not bright. The other thing I have noticed is that all my shots have a shutter speed of 1/250 sec. This is the sync speed on the camera and yet I set AV fully expecting the shutter speed to be in the region of 1/60 to 1/25 sec - obviously varying with aperture and ambient light.. When I use AV mode and the flash gun on high speed flash at -1 stop I note the shutter speed varies with the ambient light. The problem of course is most noticeable when the background if further away or when in shade
Given that I want natural lighting I am wondering why the manual flash setting is dictating the shutter speed. Perhaps I should set the camera to manual say 1/125 at for example f11 and try the flash again on manual at 1/8 power.
The AV mode with auto flash at -1 was working but I appreciate that you are more likely to get a stadardised burst of flash in manual mode.
Do you or anyone else have any comments please or have you had a similar experience?
Jon

Jonathan Michael Ashton said:

Robert I have been doing a little more macro with flash photography. I have had some good results with flash at 1/8 power and the camera in AV mode (Canon 20D & 100mm macro lens).
I have noticed however that many shots come out underexposed if the ambient light is not bright.

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Canon flash use auto fill reduction, sort of like auto flash comp. Try setting CF 14.1 to disable auto fill-in flash reduction. This may help.

Jonathan Michael Ashton said:

The other thing I have noticed is that all my shots have a shutter speed of 1/250 sec. This is the sync speed on the camera and yet I set AV fully expecting the shutter speed to be in the region of 1/60 to 1/25 sec - obviously varying with aperture and ambient light.. When I use AV mode and the flash gun on high speed flash at -1 stop I note the shutter speed varies with the ambient light. The problem of course is most noticeable when the background if further away or when in shade
Given that I want natural lighting I am wondering why the manual flash setting is dictating the shutter speed. Perhaps I should set the camera to manual say 1/125 at for example f11 and try the flash again on manual at 1/8 power.
The AV mode with auto flash at -1 was working but I appreciate that you are more likely to get a stadardised burst of flash in manual mode.
Do you or anyone else have any comments please or have you had a similar experience?

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Sounds like the 1/250 SS is a limit and not a setting. The camera body is limiting your SS since it is not in H speed sync mode maybe.
I prefer to use manual mode with flash for more consistent results. Remember with Canon based on ambient levels and SS the camera will go from balanced fill flash to flash as main light.

Hope this helps

Robert

Canon C.Fn mode

Jon, If I'm reading your message right, it sounds like you have the C.Fn I - 7 (custom function for flash sync speed in AV mode) set to 1/250th (fixed). (That is the custom function number on my 40D anyway, your 20D may be different)..you'll need to set it to Auto so that the camera will set the shutter speed for your chosen aperture based on a correct exposure.


P.S. Great thread Robert, thanks for posting it and answering questions...I have lots to learn about macro flash and this helps a lot.

Cheers!
Bruce

Thanks Robert & Bruce, Custon Function 14 is probably for the EOS 1, the 20D doesn't appear to have such a setting. The flash sync in AV mode was set to Auto - honest!
I will try a few shots with every thing . i.e. camera and flash on manual.
Jon

Many thanks Robert for all the info. There is so much to learn and I appreciate your time and efforts .

Very cool Robert!

would this help for for macro???

Canon MR-24EX Macro Ring Lite



with a macro 100 2.8 lens???

Renate Arzonetti said:

would this help for for macro???

Canon MR-24EX Macro Ring Lite



with a macro 100 2.8 lens???

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I a not too sure if that ring light is for non digital cameras, and the digital cameras now use a twin flash unit. If you already have a conventional gun I would recommend using that with a diffuser, it gives great natural looking results.
Jon

Thanks for all the info here! I have recently gone from not knowing anything about using my flash unit except how to turn it on (!!) to finally learning what the settings are/do, how to figure power level, etc. I have huge amounts of learning to do to know how to successfully use flash and this tutorial will be very helpful!

Robert, thanks for this educational post. Are you using multiple SB R200s or a single unit???

Hey Jason,

Thanks!
I use a single diffused SBR200.
I run the single for a few reasons:
-Dont like more than one catchlight.
-I am using the flash in manual on low power as it is so I dont have a need for more power right now.
-Dont need the extra bulk, its hard enough with one flash hanging on branchs and twigs all the time as is.
-I like the single light effect, its your basic 45 Deg high front lighting. more than one light looks really flat, I am not a ring light fan.

Robert