Which is more powerful

[mishmatta]

Adorama universal flashes:
DL-82ABSZ Adorama Auto Bounce Flash, Non-Dedicated Flash with a GN of 82 ft (ISO100)

screw in slave flashes:
ACMS Adorama AC Master Slave with PC Connection, Guide Number of 90 at ISO 100.

I'm "guessing" the adorama flash" is stronger, but I don't know how to determine that to be sure.

I'm looking for the best solution to light a background.

I have an alien bee 800. That's my main light. If I'm using a white background, I'd like the best possible way to blow out the background. I've only used the screw-in slaves to accomplish this. It's not horrible, but it still takes some post processing work to get it pure white. The reason I haven't used the adorama flashes yet is that I have to buy some kind of optical slave trigger to make them work, as I have no other way of firing them as a slave to determine which is stronger.

So I thought I'd ask some input before I fork out $40 to find out they're not much stronger than my screw in slaves?

[zona5101]

guide number tells you the power. 90>82

but these two units are apple and oranges as far as functionality... with a major difference that one plugs into a lightbulb socket and the other works off batteries...

As far as blowing out the background - either will work but you will probably need 2 of either to get the job done. Plus you will most likely need a light modifier to spread and control the light (umbrella) or a flag of some type to control any flare.

[mishmatta]

Originally Posted by zona5101

guide number tells you the power. 90>82

Good to know. Thanks for the input. Exactly what I needed.

Originally Posted by zona5101

As far as blowing out the background - either will work but you will probably need 2 of either to get the job done. Plus you will most likely need a light modifier to spread and control the light (umbrella) or a flag of some type to control any flare.

Got 2 of each, and use them on an stand with the AC adapter/umbrella holder with a white shoot through umbrella pointing at the background from either side.

Thanks! You saved me $40.

[zona5101]

np.
you will find shoot throughs are light bombs. They will throw as much light forward as they will backwards. This will increase your chance of undesired light on your subject or lens flare. You can use flags to help control it or try a silver bounce umbrella. good luck have fun. ps: i wouldn't go out and buy a new set of umbrellas until i knew whether the shoot thrus were causing a problem.

[mishmatta]

Originally Posted by zona5101

np.
you will find shoot throughs are light bombs. They will throw as much light forward as they will backwards. This will increase your chance of undesired light on your subject or lens flare. You can use flags to help control it or tray a silver bounce umbrella. good luck have fun. ps: i wouldn't go out and buy a new set of umbrellas until i knew whether the shoot thrus were causing a problem.

Thanks! I do have some reflective umbrellas, black with white removables. I'll try those instead of the white shoot throughs.

[ccting]

Originally Posted by zona5101

np.
you will find shoot throughs are light bombs. They will throw as much light forward as they will backwards. This will increase your chance of undesired light on your subject or lens flare. You can use flags to help control it or try a silver bounce umbrella. good luck have fun. ps: i wouldn't go out and buy a new set of umbrellas until i knew whether the shoot thrus were causing a problem.

that means use only shot-through umbrella outdoors or huge hall?

[Doug Sundseth]

Originally Posted by ccting

that means use only shot-through umbrella outdoors or huge hall?

No, not really. Sometimes a light grenade is exactly what you want.

Shoot-through umbrellas make great fill lights in many cases. Since the light is going everywhere, you get a nice base exposure for the shadows. You can then add a key light to get nice shape definition without losing detail where the key light isn't. For this use, you want to keep the illumination from the fill 1-2 stops below that from the key light.

Also, sometimes you just want really even light (some sorts of product photography, for instance. If the walls and ceiling in your studio are a neutral color, they can act to give you very even bounce lighting when you use a shoot-through.

It's important to understand what will happen though, because sometimes you'll find that light everywhere is causing you problems. Then you need to know where the problem is coming from so you can fix it.

[zona5101]

exactly as Doug has said and in reference to the OP, he was wishing to "blow out" the background and make it white... That means he needs the background to be one, or more likely, two stops brighter than the main light...running your background light through a shoot-thru umbrella at +2 stops is going to be a problem because you will have a lot of light contaminating the rest of the shot. Using a reflective umbrella will keep the light more contains and directed onto the background and not all over the room.

[ccting]

The reflected light from umbrella looks more intense than the transmitted light..

What is the relationship between The quality of fill light on subject by light generade vs distance (between light source vs subject) in

a) Small room?
b) huge hall?
c) open space?

d) Do we have product like below but inverse material to solve the light generade? It looks like a softbox for me rather than an umbrella.. Anyone inverse the black cover and white transmitter?





Thanks again.

[zona5101]

for any given reflector/light modifier, the farther away the light is from the subject the more the light acts like a point source light giving sharper shadows and more contrasty light.

The size of the room will interact with the spill - the uncontrolled/undesired light ("spill" like spilling a glass of milk, it no longer stays where you want and goes everywhere). In a smaller room, the spill will bounce off the walls and have more impact on your exposure. In a large room or out side that spill may just go off and not make any difference. It depends on which light is doing the spilling. A fill light off to camera left may not have any affect. Spill coming off the background light could give you flare or other undesirable effects.

I have not seen an inverse of the umbrella you posted (one with a translucent dome but a black cover. Someone probably makes one... buy why not use a softbox...then you can control the front edges? Or just use a shoot through and know that you have to account for the spill? There is nothing wrong with a shoot through umbrella, they give great light, just need to use them in locations where the spill isn't doing more harm than good.