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!

Testing ED's Flash Guide Number

Now the test pictures. For the set-up see here.
All pictures are taken with ISO 400 and the camera set in manual mode.
1/30s Aperture f2.8 flash
In all pictures with 1/30s only the flash contributes to the exposure. At f2.8 "Snoopy" is overexposed and the garden wall looks about right.





1/30s Aperture f4 flash
"It's OK! Leave it! Good Boy!"
Wolfi looks about right, Snoopy is a bit to bright because he is white. That is near the right Aperture.




1/30s Aperture f5.6 flash
Now at f5.6 Snoopy is about right, but you see a strong fall off of light behind him. The Garden wall is now quite underexposed.
Guide number check: ISO 400 gives a double factor to the guide number compared to ISO 100. The calculation is distance 4m x Aperture f5.6 / 2 for the ISO and results in Guide number 11.2. It is rated 14 which is close enough and after all ED has already 33 years working life behind him.

1/30s Aperture f8 flash
With 8 Snoopy is clearly underexposed. You can also see that the garden is very dark. looking through the viewfinder I could basically see nothing. Auto Focus does also not work.
David recommended in his Seminar to use a torch light for situations like this. It is critical to keep the Auto Focus in manual at the lens and at the Camera. Otherwise the AF starts hunting when you want to take your flash picture.
I wanted to make a couple of picture with the torch light placed on the floor, ("Wolfi! Noooooo!") to get a mix between an ambient light and flash and to show the relation between time and aperture. First I tried a couple of shots without flash.

4s Aperture f4 no flash
The torch lights Snoopy OK, but the garden is black.






8s Aperture f4 no flash
Garden still black, Snoopy a bit overexposed.






15s Aperture f4 no flash
Snoopy nuked, lawn very dark, the wall and plants in the back show up.






15s Aperture f4 flash
So now I bring the flash back on. With Aperture f4 the garden is really bright, however Snoopy is still nuked by torch and flash.
The shadow of Snoopy is nice and could be a bit more emphasised by reducing the overall background brightness.



8s Aperture f4 flash
I bring the time down one stop so that the torch light is reduced. Still way too bright.





8s Aperture f5.6 flash
I also want to reduce the flash. Therefore I need to close the aperture one more stop. Aperture cuts ALL light that contributes to exposure. Remember: Time cuts ambient light, Aperture cuts flash and ambient.

The shadow becomes more visible. But Snoopy is still a bit too bright.



8s Aperture f8 flash
One more Aperture down. Now the middle ground is quite dark. The shadow stands out and Snoopy is kind of OK, if not a bit on the bright side.





15s Aperture f8 flash
Bringing the time up one stop again brings some detail into the middle ground, but Snoopy is much too bright again.






30s Aperture 8 flash
"Enough attention for Snoopy! That is MY toy!"






You might ask so what's the point? After all we could not find a satisfactory lighting with the torch and the flash. I wanted to illustrate a few points by the strobe experiments ( i have to keep repeating the title from time to time).
1) We tested the guide number of ED. It seems to be between 11 and 12 rather than 14. Good to know for me. You also know now how to test for the guide number of your flash. It would have been much better to use a grey card leaned against snoopy for a more exact result.
2) By varying aperture and time you can see how such changes influence the picture result. Aperture is the only way to regulated a manual flash. BUT it also changes the ambient light level at the same time. The time setting only changes ambient light.
3) It is really desirable to be able to vary the power of your light sources. A flash with only full power and a torchlight with only one power setting are both less than ideal. Basically they stink! Even with a stationary setting. Theoretically you could "regulate" both by moving them closer or further away. Such an approach has practical limits in the space that is behind you when you move it away and the fact that you do not want either in the picture when you move them nearer.
4) In this set-up I wanted to also show the light fall off. I placed ED deliberately low so that the grass shows nicely the different light levels. A typical (bad) flash picture is normally quite overexposed in the foreground bright in the middle and pitch dark in the background.
So what's next? We want an automatic, we want to be able to vary our light sources. Before that one last session with ED. Above we see the shortcomings of flash when lighting an extended space. So what about a flat object? A large flat object should be lighted perfect at the right aperture?
Also never trust only one experiment you might have got something wrong without noticing.
Stay tuned for the last appearance of ED (in a leading role) in the up coming "ED and the garage door".