Using Flash with Macros

[Loupey]

Now that you’ve mastered the 4 Basics, here is a really easy technique to add to your arsenal.

First of all, let me say that I think it is a “mistake” (in a friendly, disagreement-over-a-pint-of-beer-kind-of-way) to think that a flash, no matter how powerful, should be considered the main light source. Instead, I think that flash for macros should be carefully balanced with the ambient light so as to make it look as natural as possible while, at the same time, adding just enough detail in the shadows.

The general method here is:

1. meter on the background
2. set your exposure (in manual mode)
3. set your flash to underexpose

The key is to use manual mode (see, there is a method to my madness here) to lock in your basic exposure. Since you all have taken great pains to control the light coming in to your camera, you’ve got to be equally careful of the light coming out of your camera.

For those of you using the built-in pop-up flash (me), set the exposure compensation anywhere from –2 to –1 . This will force your camera to try to underexpose the shot and the only way it can do that is by reducing the intensity of the flash (since you’ve got the shutter/aperture locked in manual mode). Try different levels until you get the look you’re after.

For those of you using an external flash (I recommend getting an off-camera extension cable or wireless transmitter), you can do the same thing if your flash has a variable output mode. The Canon 430EX can be brought down to 1/64th of its full power. Again, play with the setting until you get the balance for the given circumstance.

Because subject distance is so critical with flash and the ambient light levels are always fluctuating, there is a fair amount of trial and error with this technique. But this technique is easy to master and quick to deploy with practice.

[Loupey]

OK, so here's the scene: you're shooting from the shadow side on a bright, mid-afternoon day. Image #1 is my test shot WITHOUT flash. Exposure set for the background (ISO 400, 1/250s, f/9.5) with my 300mm + Tube.

Image #2 are what I can get with my Pop-Up flash using (1 ~ 3: no flash, flash/exposure compensation at -2, and flash/exposure compensation at -1).

Image #3 are what I can get with my 430EX flash using (1 ~ 5: 1/64 power, 1/32 power, 1/16 power, 1/8 power, 1/4 power).

Notice the background hardly changes? That's because in all of these images, my shutter/aperture combination has not changed. Only the flash output power. I was very careful here in that post-processing has handled identically in all images.

[Loupey]

Here are 5 examples from last year using only the pop-up flash on my old 10D. All with the 300mm + tubes.

That reminds me of another reason why I love the 300mm+tubes: its about the only combination that allows enough working distance for the pop-up flash to clear the end of the lens.

Some of these are easier to detect the flash than others. For those which are difficult to detect, I consider it a success! As I hope you can see, the pop-up need not / should not be so powerful for macro work.

I will temporarily make this thread a sticky. If it helps, I'd love for you guys and gals to post image pairs to it (no flash/flashed with this technique) so that other people can learn from your application.

Thanks for looking!

[payn817]

Good thread Loupey. This is basically the same technique I use, just slightly different equipment. Of course my results aren't as good as yours. At 1:1 on smaller insects, this technique is a bit more difficult and the light seems to fall off quick and leave a black (or very dark) background. Is that the same for you or could it be something I am doing wrong?

Just to show some more examples, here's a few. Most (if not all) have been posted before. I don't have any examples without flash, so cannot show the difference as Loupey did. Basically, I use Aperture priority and meter a gray card or something 18% gray, and lock the exposure (AEL button). Then adjust the flash to -1 or -2 depending on the goal. The softbox I swear by cuts the light by another 1.5 stops.

Remember, I am new to photography and especially macro, so be easy on me.

[Loupey]

At 1:1 on smaller insects, this technique is a bit more difficult and the light seems to fall off quick and leave a black (or very dark) background.

Even at higher magnifications, as long as you are exposing for the background and locking in on it, it will not (can not) go to dark. The fall-off is common when the flash becomes the main light source instead of just fill. The trick in this case is to hold just the flash as far back as possible. Then the difference in distances of the subject and its background becomes negligible so fall-off becomes negligible. That is why you see it more in higher magnification shots - your flash is closer to the subject which enhances the problem.

By you using the AEL button along with aperture priority, you are doing the same thing as shooting manually as long as you are reading the gray card without firing the flash.

Nice pixs by the way

[Loupey]

Using manual mode to expose for the ambient light has another BIG advantage. You can shoot away without flash as you normally do; then, when you need a little fill light, you just deploy the pop-up without making any other change/adjustment. Very quick and easy.

You leave the exposure compensation adjustment unchanged. Without the flash, it will be telling you to underexpose but you're shooting manual so ignore it. With the flash deployed, it now uses the exposure compensation setting for the flash output which you've already pre-selected.

Two images of the same butterfly taken moments apart. Same basic exposure for both (1/180s at f/8 without flash on the left, 1/250s at f/6.7 with flash on the right).

[WsW-WYATT-EARP]

This is another great tutorial from you loupey ... never cease to amaze !!!

[Bevb]

Yes thanks Loupey for taking up your time to do this, its a great help and have already learned from what you have posted. I will post some examples as soon as i can but at the present time we are having extremely strong westerly winds, im finding it hard to stay still, let alone a macro subject!

[Old Timer]

Great explanation on using the flash with macro. Love your step by step. I have used flash with macro in the past with good results but after a lot of experimentation. Your tutorial will definitely cut down on a lot of the trial and error. Thanks once again.

[Bevb]

Well here are good examples of really bad flash attempts, i was trying to go by your instructions above Loupey but i was obviously failing miserably.
well the first image is when i used flash, settings : 1/180, @f22, ISO200, @50mm.
#2 is using no flash, settings: 1/90, @f8, ISO200 @ 50mm. Built in flash on 20D.

I had a right job getting the right settings and after fighting with the wind and at first illuminating the whole subject, it makes me realise theres more to flash photography than you think, although i am still more of a fan of natural light.

[WsW-WYATT-EARP]

I am no expert ... but from reading loupeys *instructions* and viewing your settings ...

1 - your first image your settings aren't for background exposure (small aperature and fast shutter speed) - I do like how well the web shows though -- too bad the spider is blown out

2 - you seem to have the correct settings here for the background ..... now as he explained just a matter of dropping down the power on the flash and filling in the spider with a bit more light ....

I am sure he will chime in ... but from his directions this is what I am getting out of it

[Loupey]

Ben is correct - your exposure changed drastically between the two shots. Because the difference in exposure is 2 full stops, your background became severely underexposed in #1.

In this example, BOTH shots should have been at 1/90s at f/8 in manual mode. That way, the background remains looking natural and will remain unaffected by the small output of the flash. Remember, as long as you lock in the basic exposure in manual mode (or AE-Lock), it is IMPOSSIBLE for your background to go darker.

Thanks for posting these as I'm sure others may have the same results. I hope that helps some.

[Bevb]

Thanks Ben & Loupey i am going to have to go and practise this tomorrow.

[Copy_Kot]

I ordered the Canon 430EX flash today (been meaning to get it for a while) along with some macro goodies... be prepared to be barraged with tons of macro images and macro questions

Thanks for taking the time with this thread Loupey.

Practise pics coming soon

[Bevb]

Right, here are my second goes at macro with flash/no flash.


#1 (NO flash) 1/45 f8 ISO200 @ 50mm
#2 (Flash) 1/60 f11 IO200 @50mm

20D, 50mm 1.8 with 36mm tube, pop up flash.

[Loupey]

Pretty good, Bev You took an overcast shot and made it appear as if it was shot in direct sunlight (in a natural kind of way).

From your specs, you lost 1 1/2 stops in the background. Yet, the background in #2 doesn't look too bad - like natural shadows on a bright day.

This technique is like an HDR merge in photoshop. You take a normally exposed ambient light shot and simultaneously merge it with unbalanced flash shot which has the foreground slightly overexposed but with the background severely underexposed. The resulting merge lightens the shadows of the subject yet does not change the background.

[Bevb]

Thanks for this advice Loupey its helping no doubt, but i am still struggling to get that "just right" balance from using, to not using flash and getting the metering right, but its practice again that makes things better so when this torrential rain stops il be out again!

[payn817]

Worked on this one a little today. Here's a couple...

The light on the black hopper was actually the sun. The light was extremely harsh, and it's armor picked it up. If I can find it again, I'll post the one w/o flash.

[Loupey]

Very nice, Payn - the ladybug and fly look very natural.

[Loupey]

Another example from this afternoon. Dark woods during a light rain with only a 300mm (no extension tubes, no support ).

First image is no flash and lighter and more contrasty than the original scene. Full frame at the closest focusing distance of the 300mm.

The comparison cropped images are both at the same exposure: ISO 1600, 1/90s, f/5.6 (did I mention it was dark ).

Thanks for looking.

[WsW-WYATT-EARP]

Loupey - question with your tutorial here .... I am using my speedlight with a wireless transmitter ... I dropped the exposure down to 1/64th ...

now do you just mess with the distance from the subject ? and the angle to the subject with the speedlight ? basically you are just trying to fill in the subject with the flash while having a bright background ?

in your post #6 in this thread you show a butterfly with a black bg and then again with a bright green bg ... I am guessing that the exposure settings were the same just a different angle with the flash ???

THANKS MUCH !!!

[Loupey]

Ben, thanks for asking. Yeah, that butterfly example is a confusing one. I was just trying to show how incrementally small the fill flash can be. The background is different only because I shot the one without flash at an angle with a void behind the butterfly.

Getting back to your question: with a wireless or cable, you surely can adjust the flash-to-subject distance as well as the angle to suit your needs. Think of the distance as fine tuning the output of the flash. So if 1/64 power is just a bit too weak, you can hold the flash just a bit closer.

However, keep in mind that the closer you are to the subject, the greater the effects of moving the flash will be. Because light falls off at the inverse squared law and f-stops are a measure of lens diameter (through which light passes with the same inverse squared law of the diameter), you can think of flash-to-subject distance in terms of f-stops. Here are two quick examples if one is using the flash as the MAIN source of light (as opposed to fill flash):

Scenario 1: you are getting a proper flash exposure with a subject that is 8' away.

Without making any changes, if you move the flash to a distance of 5.6' from the subject, it will be exactly 1 stop overexposed. Moving the flash to 9.5' would make it 1/2 stop underexposed. So anything in between would give you infinite variations.


Scenario 2: you are shooting macro and getting proper flash exposure at 400cm

Now, inside your shot, foregrounds which are 200cm are blown out by a whopping 2 stops while backgrounds which are 800cm are 2 stops underexposed! So inside this shot, there would be a total range of 5 stops (f/2, f/2.8, f/4, f/5.6, f/8 corresponding to 200cm, 280cm, 400cm, 560cm, and 800cm) - an impossibly difficult image to process.

This is why so many flash images have that dark background. And it is also why it is so pronounced the closer you work with your subject.

I hope this doesn't sound like jibberish. Too many beers

[WsW-WYATT-EARP]

not jibberish .. just need to read a few times to understand ....

appreciate the time you took to write that ....

I was playing around with this technique with the flower shots due to the harsh shadows from the mid afternoon sun ... trying to fill them in some without blowing out the flower ... as you said its alot of trial and error before getting it right ...

but on the other hand with 3 tubes you know how close the lens is to the subject so getting the flash to it is difficult ... especially getting in close to a big flower ....

still having fun doing it so....


thanks again for the time !!!

[Loupey]

Time to let this thread go Un-sticked.

[SenorNikonMan]

Very interesting and informative thread. Thanks to all who have contributed to it. I plan on trying this technique soon. I'll post the results here (whether good or bad).