Wednesday, April 7, 2010

As promised in the last post, here comes the final appearance of ED. It is used as a fully manual flash. In our last experiment we found that it has a Guide number of about 11.2. I wanted to verify this with a flat surface.

I moved the set up as described in the last experiment in front of the house and took some shots of the garage door with the 50mm 1.4 lens. The camera was 6 m from the Garage and set to ISO 100 to make the calculation easier. I shot all the apertures from f1.4 to f16 but I will not post all the shots as it might be unhealthy, if you fall asleep in front of your computer and your head hits something hard.

1/4s f1.4 flash ISO100
The shot is a bit too bright.

1/4s f2 flash ISO100
The shot is just a little on the bright side in the highlights but basically OK. Calculation 6m* Aperture 2 = Guide Number 12
Close enough.

1/4s f2.8 flash ISO100
This is clearly too dark. It demonstrates another reason why we want automatic flash. A full stop or even a half or third stop can make a relatively large difference in your pictures. Automatic flash can be any value in between and be therefore much more precise.

I was already in front of the house so I took a couple more shots. First just to see how the old little ED would light a large area.With the guide number only about 11-12 I took the ISO right up to 3200. That gives a good working aperture and the exposure times are not so long.

I set up across the road and determined with a couple of test shots that f8 would give a pleasing flash exposure not too overpowering. Then I made some more test shots without flash to establish that 1/4s will give a nice warm light to the house. However the street was quite dark. Below you see two of the shots for comparison:
1/4s f8 flash ISO 3200
The garage door is slightly lit by the flash, and you see that it is white as the ugly yellow light of the street lantern is overpowered.
The House is nice and warm and inviting in its light. The big dark gray blob of street in the foreground gets some structure. Not at all bad result for the little flash. 

1/4s f8 no flash ISO 3200

The same shot without flash for comparison.

Cross check calculation: I was about 18m from the Garage door. ISO was 4.5 times up - remember doubling of guide number needs quadrupling of ISO. ISO 400 is double the guide number of ISO 100, ISO 1600 is double of ISO 400, two times double is 4 times multiplied by an additional times 1.5 to come from 1600 to 3200. 12 (GN) * 6 (ISO adjustment) = 72 (adjusted GN). And 72/18m = f4.

Uh??? f4?  That is 2 stops off? What went wrong? Nothing!!

Maybe you noted that I used above the words "pleasing" instead of correct. When it comes to light it is all in the mix. In this specific situation I found it pleasing that the flash contributes to some problem-areas of the picture, however you notice that there is still a bit warm light in the garage door. A "correct" picture which would completely overpower ambient light would have been flat and plain ugly. "Underexposure" of 2 stops was the best solution in my eyes.
Now you will understand why manual flash with guide number calculation was such a p*** in the a** in the old film days. Making a series of test shots to zero in on your exposure and light setting mix was only practiced by highly paid professionals with Polaroid backs on their Hasselblads. For everyone else it was trial and error with many many more errors than keepers. That is also the reason why millions and billions of bad flash pictures where produced in the film days. (And I had my fair share in it.)
There are some situation where I still use film for nostalgic reasons, however I currently will not use film in complicated and mixed lighting situations with arranged lights, as the immediate feedback on your LCD is invaluable. I feel that these are the most interesting situations as flat predictable lighting is safe but boring.
To further illustrate the point I made a fast forward to today's technology. The following two pictures are taken with the D300s and the SB-900 in the hot shoe. (ED already relegated to the reserve forces.)

1/30s f5.6 flash ISO 400
That extremely ugly shot is the "safe" variant. The settings are: (S) Time Priority 1/30s, Daylight WB, Flash i-TTL BL.
Take a a good look at the harsh ugly and flat light. Many many years most flash pictures looked like that.

0.8s f5.6 flash ISO 400

Same camera and Flash combo only set to P and i-TTL BL to get the long exposure time. Impressive what the little computer can do out of the box. In my personal taste I would dial the flash back a third stop so that it looks more like ED's last picture above.

So what's the verdict: Is it possible to make good use of manual flash? Definitely Yes! Would I do it voluntarily given today's available technology? Definitely No! Rest in peace ED you will most probably not be used again for a long long time.

Next I will write a shot piece on CAT more or less the first automated flash system. (No experiments.) And then we will move on quickly to the Computer-Automatic-Electronic Flash Revolution (the third one) with the introduction of the German-Uberblitz-Wunder Metz 45!

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