Flash sync for Macro work

[cliffcalhoun]

I've done a search of this forum, without success.

 

If looking for a camera primarily for macro work, is it desirable to

have a flash sync speed of 1/250, 1/125, or does it matter? In other

words, what advantage is 1/250 flash sync over 1/125, or 1/60, or

does it matter?

 

My guess is that 1/250 is great for freezing movement for flowers,

insects, etc., but under certain conditions one might have problems

with dark backgrounds at 1/250.

 

So, is it handy to have the option of 1/250 flash sync?

 

Thanks.

[paul_purcell]

Having a higher synch speed means you can stay away from using ambient light in more situations. John Shaw recommends using only flash in macro work, and it works in most instances.

[alan_yeo1]

You are right about the higher flash sync freezing movement. But this will also darken the background significantly unless in very bright conditions. If you prefer this type of images, good for you. Although I admire the work of John Shaw very much, I would much prefer to shoot with ambient light using only fill flash. IMO, only subjects which are nocturnal by nature are treated with a black background - not always though.

[robert_p._boner]

If you have flash sync at 1/250, you can always use a slower sync speed. If you don't, you can never use flash at 1/250. I have kept one EOS 1n rather than upgrading to EOS 3 for just that reason.

[paul_purcell]

According to Shaw, and I've found it true in most cases myself, once you get close enough there is no background falloff to speak of, and the settings you will need to blend ambient and flash will almost guarantee blur. At this distance flash by itself provides light and sharpness.

[yuri_huta]

True, 1/250 can render your background underexposed, but you still have the capability of using a slower shutter speed, while the opposite is not true if your flash sync speed is only 1/60.

1/250 flash sync speed can be advantageous when the light conditions are high and you need to retain shallow depth of field or freeze motion at the same time as having a well exposed background.

 

For example, shooting a butterfly with a cluttered background on a very sunny day. I want to maintain depth of field shallow enough to throw green background out of focus, lets say f/5.6. At f/5.6, the correct ambient exposure for my film would be 1/250 of a second. If the flash sync on my camera is maxed out at 1/125, then I will have a background that is 1 stop overexposed, or I will have to stop down to f/8.0 to maintain proper exposure of the background (this will give more depth of field and 'show' more of the cluttered, distracting background in focus). Having a camera that has a higher flash sync, 1/250 would give me the depth of field I want, while maintaining proper exposure for my nicely out of focus background.

 

Another exmple is using it to help stop action. For example, a bird flying back to its nest. The flash will freeze the bird, but now you have to worry about the ghosting effect of the ambient exposure of the same bird. For arguments sake, lets say the flash duration for this situation was 1/5000 th of a second, plenty to freeze action. However, with a maximum flash sync of only 1/60, there is definite bird motion recorded on your image. Having a camera with a faster flash sync speed, reduces the bird motion, or if it is fast enough for the situation, can eliminate it altogether.

 

Why not give it a try? Go shoot with a flash at different shutter speeds and see if your type of photography will be affected.

 

Even though I have made this sound complicated or something that would be rarely used, it is a selling point for me.

[kurt_heintzelman]

I believe that in general, the faster the max. synch speed of a camera, the better. [Furthermore, certain Canon EOS flashes and Certain EOS cameras provide for high speed "FP" or "focal plane" flash in which flash can be used (within certain constraints) at all shutter speeds >1/250].

 

Suppose you wish to photograph a portrait of someone in relatively bright ambient light with 100 ISO slide film, and you want to use a touch of fill flash to open up facial shadows. Suppose further that you want to use a wider aperture to blur and effectively neutralize distracting background elements that would otherwise ruin your portrait. If your max. synch speed is only, say, 1/125, it may well force you to use a smaller than desired aperture if you intend to avoid over-exposure from the ambient light. In this example, the camera can't synchronize to the flash with a shutter speed greater than 1/125, which means that you can't further increase (make faster) the shutter speed in order to compensate for a larger aperture. If you ignore this constraint and deliberately set a wide aperture in the above example, the result will be an over-exposed picture. For example, let's say that without a flash attached, you manually meter the exposure at 1/750 sec. at f3.5. Now attach the flash, and you would see your in-camera light meter warning of over-exposure, because now your exposure values would be 1/125 at f3.5 for the same amount of ambient light! Assuming you chose not to hassle with neutral density filters and perhaps slower film, the only practical way you can avoid over-exposure (aside from not using fill flash at all) would be to begin stepping through progressively smaller apertures until you find the correct aperture to achieve proper exposure with respect to the max synch speed of 1/125; and, at that small aperture, you can forget about achieving shallow depth of field, right?

 

I do quite a bit of macro photography (currently using the EOS 100/2.8 macro lens), and although the parameters for typical macro shots may vary widely from the above general example, I usually employ some degree of fill flash from an EOS 550 EX flash (even in bright ambient light), and a fast synch. speed is always nice to have available when needed.

 

FWIW, I happen to often prefer using a B+W Schneider KR 3 (~ an 81c) warming filter on my macro lens when also using flash, as it helps to warm-up the look of electronic flash. Also, I suggest you invest in an off-camera shoe cord for the flash, and also consider a macro flash mounting bracket if you plan to use more than one flash for your macro photography.

[kurt_heintzelman]

It looks like Yuri beat me to the punch while I was slowly pecking at my keyboard!

[cliffcalhoun]

Thanks to everyone. I finally have this matter resolved in my mind.

 

1/250 flash sync is nice to have if you can get it.

 

Now I have to get shooting!!!

[marshall_black]

Slightly off the point but perhaps useful.

 

In some circumstances it's possible to give yourself some help with fill flash for small subjects on bright days.

 

1 Meter the ambient exposure for flash synch speed (mine's 1/125th) or slower, and set the aperture.

2 Hold the flash on a off-camera cord to light the subject, holding a grey card (or similar) against the back of the flash to shade the subject from the sun.

3 Make the exposure by TTL or a tested exposure/distance value.

 

As the flash is between the sun and subject you'll get a similar light angle as your view of the subject, and shading the subject cuts the subject exposure value and reduces the possibility of ghost images.

 

I find this most useful with small plants (say fly or bee orchid blooms) bobbing about in the wind, with the camera on a tripod. It's still best to wait for as little movement as possible of course.

[tom_thurston]

Since John Shaw has been cited a couple of times, I think it would be useful to quote from his latest book, "John Shaw's Nature Photography Field Guide". On page 133, in the chapter on closeup flash, he says:

 

"You can use any shutter speed you want up to the flash synchronization speed, which on most modern camers is 1/250 sec. ... However, you don't have to use this top sync speed. In fact I would urge you to slow it down a stop or two, depending on the film you're using. First of all, it should be obvious that you're not going to use fast film in this situation. Suppose you want to shoot an ISO 400 speed film. Proper bright sunlight exposure is 1/400 sec. at f/16. But you can't use 1/400 shutter speed as the camera's top sync speed is 1/250 sec. Change to 1/250 sec. and f/22, mostly likely the smallest f-stop on your lens, and you're still at bright sunlight exposure. You'll end up recording ghost images, both an ambient light image and a flash image. Go to slow-speed film and the problem is solved. Let's say you an ISO 50 film. If that camera is set at f/16 and 1/250 sec. shutter speed, you're already two stops away from recording a bright daylight image. Even in blazing sunlight, the flash still functions as the primary light source, exactly what you want to happen. Now when you slow the shutter speed a stop [to 1/125], you'll let some daylight record on the film."

 

It appears that he recommends using 1/125 sync for macro flash even if 1/250 is available.

[rollin_verlinde]

Maybe I overlooked something but sync-speed is not necessarely used to freeze movement. That's done by the duration of the flash, between 1/500 and 1/25.000 s for normal computerflashes. You can make a picture with a speed of 1/2 s of a flying moth and it will be sharp if the flash is short enough. Of course, this is only so if the ambient light is (very)low.

Rollin

[paul_purcell]

That's right Rollin, the flash stops the action. The high synch shutter speed is just to reduce the ambient, which could blur the shot, as one thing that has not been mentioned comes into play at near life-size magnifications: a macro lens, close up, no longer follows the "sunny 16" rule, but requires much more light. This has been covered in other threads here before.

 

If you are close enough, the exposure will likely be too long to prevent blur, and as well, very close up, the flash exposes the background as correctly as it exposes the subject, which was a main part of the original question. So using flash covers several bases.

 

You can have just about whatever depth of field you want: it's called personal preference and learning how to use the aperture control. Depends on whether you want to show the context of the subject, or isolate it for more esoteric purposes. Set the synch high to block the ambient, set the aperture for the desired depth of field, and the flash will provide the correct amount of light.