Hasselblad flash issue

[David J]

I have the Hasselblad D-40 flash unit. It puts out the energy of a small atomic bomb, which seems to overpower my photos and give an overexposed look. Is there any way to tone it down a bit? Bouncing it off the ceiling works well, but there's not always a ceiling when you need one.

 

[Sirius Glass]

I have the Hasselblad D-40 flash unit. It puts out the energy of a small atomic bomb, which seems to overpower my photos and give an overexposed look. Is there any way to tone it down a bit? Bouncing it off the ceiling works well, but there's not always a ceiling when you need one.

Increasing the Guide Number results in a smaller aperture [larger f-number].

So if the Guide Number is 100 increasing it by 1.4 (square root of 2) changes the aperture by one stop. If the Guide Number is 100 increasing it by 2 changes the aperture by two stops.

At 9 ft GN 100 => f11
At 9 ft GN 141 => f16
At 9 ft GN 200 => f22
​

Steve

 

[David J]

By "guide number" do you mean the little flash selector dial on the side of the camera? There is nothing on the flash unit that looks like a guide number.

 

[Sirius Glass]

By "guide number" do you mean the little flash selector dial on the side of the camera? There is nothing on the flash unit that looks like a guide number.

Is there an ASA/DIN/ISO dial? Set it for a faster speed film.

Steve

 

[dentkimterry]

What camera are you using the D40 on? It will only flash meter on Hasselblads with flash metering in the body, such as 503 cw, cx, and cxi. Also the 500elx, 553elx and 555eld. All the 200 series support it also. If you don't have one of these bodies the flash will go off full power every time. The are no adjustments on the flash. It is TTL only.

Terry

 

[Ira Rush]

David,

In addition to the previously posted comments, regarding "what body are you using" as only certain bodies are capable of TTL flash, and if you are not using one of these bodies, you really can't do much....

Another issue is is "What film are you using".

Even though a films box speed may be "100", or "400" Hasselblad suggests you alter the film speed on the camera bodies "film speed selector dial" as per the D40 manual. This again will only apply to certain bodies.

See the link I've attached. Download the pdf file, hope this helps


http://www.hasselbladhistorical.eu/PDF/HasManuals/D_Flash.pdf

 

[David J]

I have a 503cw, so there is a dial on the side of the camera. Sounds like I'm in luck for toning down the power of the flash. I'll try setting the dial to 400 with 100 speed film and see what that does. Previously, I've just been setting the dial to whatever speed film I happen to be using. Thank you everyone for your help!

 

[John Koehrer]

Guide number is a measurement of power for the flash. Usually a marketing tool they are approximate measurements.
In the US they're most often seen using ISO 100. To find the ISO of a given flash, set ISO to 100, look at 10' on the distance scale, and the aperture recommended, for example: f8.
Multiply f8 by 10 and that's the guide number(80) for that flash/film combination.
a guide number is only a starting point just like the box ISO of a film you can tailor it by giving a little more or less exposure.

 

[Q.G.]

With the unit hooked up to the TTL-sensor in the 503 CW, using the ISO dial will indeed provide the necessary control over output.

Remember that the results of OTF flash also vary with film reflectivity. Though as the table in the manual shows, not so much when using the 503, it is 'clouding' the Guide Number issue by adding a variable not incorporated into the concept of GNs.