BetterPhoto Q&A
Category: Best Photographic Equipment to Buy : Choosing the Right Camera Flashes

Photography Question 
Paul K. 

Flash Equipment

I have retired and now have time to follow my interests. I have a Minolta SRT-101 (1974) and the flash unit I purchased with it will not charge.

I guess I'm looking for a suggestion on what flash to get (new or used). The Minolta is match needle and there is neither automatic focus nor auto exposure - only a hot-shoe mount.

Therefore I guess my flash needs are pretty simple - although I think I've forgotten everything I once new about guide numbers. Thanks

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6/14/2003 11:27:00 AM

Jon Close
BetterPhoto Member Since: 5/18/2000
  You don't need/can't use a dedicated TTL flash, just get a good manual or auto via built-in sensor. Fitting this category:

Vivitar 2800 is a nice basic inexpensive unit. More powerful and more manual modes are the Vivitar 283 and 285HV. Sunpak 383 is similarly powerful, and allows head to swivel as well as tilt, so you can bounce flash with the camera held vertically. I'm not as familiar with Metz's line, but they are also highly regarded.

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6/14/2003 1:51:45 PM

Paul K.    Thank you very much, Jon C, for your helpful answer. I'm very glad I found this site.

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6/14/2003 6:45:30 PM

John A. Lind
BetterPhoto Member Since: 9/27/2001
  Jon mentions all three of the standard, basic, shoe mounted auto flashes that have withstood the test of time, and they're among the most powerful on the market.

IMO, the Vivitar 285HV is a better buy than the Vivitar 383. The 285HV comes with some features that are accesories to the 283 and must be purchased separately. Add up the cost of a 283 plus these accessories and it's more than the price of a 285HV.

Metz is a German company that makes an enormous line of superb flash units. They're reliable, very durable and the upper half of their line caters to professionals. Well known in Europe and among professionals in the U.S., most non-pros in the U.S. have never heard the name. The design, build quality, and durability of their pro-grade flashes spill downward into the lower half of their line that caters to the consumer market. Within the Metz line for the SRT-101, the "32 Z-1" and slightly less powerful "36 C-2" are their basic auto-flashes. Between the two, the 32 Z-1 is more powerful (in spite of its model number). Both have a manual zoom head that tilt. The 32 Z-1 also swivels. Between the two, my recommendation is the 32 Z-1. More expensive new compared to the Vivitar 285HV or Sunpak 383, they can be found used in very excellent condition for about the price of a new Vivitar or Sunpak. The English version of Metz' web site with their Mecablitz flash products:

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6/15/2003 6:49:40 AM

Maynard  McKillen   Dear Paul:
If I write a few sentences I suspect you'll quickly recall everything you may have forgotton about guide numbers.
Current "auto" flash units are so quick and easy to use that fewer photographers use a flash in manual, which is where it helps to know the guide number. With the flash set to manual, you focus the lens, read the subject-to-camera distance off the lens, and divide the guide number by that distance. The number that results is the f/stop you will use. If you give it a moment's thought, you probably realize that the f/stop number you get as an answer will not always be one you recognize, or one that appears on the f/stop ring of the lens. It may, in fact, be some intermediate value, in which case you might round it to the nearest full f/stop, or half stop, and depend on the exposure latitude of the film to cover the slight discrepancy.
All of the flash units mentioned in the responses above will also have some sort of graph, scale or display on the back or side of the unit that indicates which f/stop should be used for a given distance and film speed. Purist practitioners of manual flash will tell you to be wary of these scales or displays: They argue, often accurately, that the guide number assigned by the manufacturer to a given model is often, well, "generous."
Of course, you can use the auto flash settings these flash units also have, which work just fine for an SRT-101. A thyristor circuit in the flash will quench output when it detects enough light has reflected off the subject to provide correct exposure. A scale or chart on the flash tells you which f/stop to use. In auto flash mode, an f/stop will provide correct exposure over a range of distances, say, five to fifteen feet, not just one specific distance, which is the case in manual mode. Auto flash is convenient, to say the least.
Sometimes auto flash circuitry can be fooled by very light or very dark subjects, just the way the camera's built-in meter can sometimes be fooled, but as someone who has used almost every one of those flash units mentioned above, in auto, I can say that auto flash is accurate for a wide variety of situations. (Again, the exposure latitude of current films can often help you obtain satisfactory results in those situations where auto flash might be fooled.)
Well, once again I've managed to write more than anybody cared to know on a topic. I'll have to rig a timer or a lock-out on this keyboard...

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6/15/2003 6:09:53 PM

John A. Lind
BetterPhoto Member Since: 9/27/2001
  Maynard remembered the GN math correctly . . . divide GN by subject distance for aperture setting. However, the GN for nearly all electronic flash units is ONLY given for ISO 100 film. A flash's GN changes with film speed. For something other than ISO 100 film, here's the conversion formula for a GN given for any film speed to another film speed:

GN[new] = GN[old] * squareroot(ISO[new]/ISO[old])

If the GN for a flash is given in the specs as 120 for ISO 100 film, in feet, and you wish to use Kodachrome 64, the new GN becomes:
GN[new] = 120 * squareroot(64 / 100)
GN[new] = 120 * squareroot(0.64)
GN[new] = 120 * 0.8
GN[new] = 96
Now load up a roll of Royal Gold 200 and calculate the new GN:
GN[new] = 120 * squareroot(200 / 100)
GN[new] = 120 * squareroot(2)
GN[new] ~= 120 * 1.414
GN[new] ~= 170

Do this in the comfort of your home using a calculator and write the guide numbers for a list of different film speeds for your flash onto a 3x5 card. Stuff the card into the camera bag . . . or tape it to the flash (if taping things to your equipment doesn't bother you). This beats carrying around a calculator and trying to remember the equation to use.

-- John

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6/15/2003 9:20:17 PM

Paul K.    Thanks again to Jon, John and Maynard. You guys have been great. I am going to start looking for a flash this week.

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6/15/2003 9:40:50 PM

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