Need help about lighting....

[kalodighi]

Hi.. I am totally new to this forum. I really need a help with lighting things as i am feeling so frustrated now.

anyway, the thing is, i have bought a pair of strobe (150w each) with umbrella and 2 light stands. Problem is - i was trying to take some pictures using one of this strobe. but all pics were underexposed.

my camera setting was 1/60 - 1/90 and f5.7 .....

is anything wrong with my strobe? i am so upset .. i cant afford to buy anything else.. i have money problem. i started to think that i have wasted my money already.

can anyone help me pls by pointing out what is wrong and how to fix it?

thank you so much...

 

[tirediron]

First of all, you NEED the bible of lighting (it's available on Amazon.ca, that was the first link that came up). Next: How are you triggering your strobes, and what modifiers are you using? Shutter speed doesn't necessarily play a role in the exposure, so I wouldn't worry too much about that; aperture is the important factor. Can you post some of the images (with full EXIF data) for "forensic analysis" as well as sketch, with distances of your set-up?

There are a few issues that could be causing the problem: How far away from the subject are the lights? When I use my old Sunpak hammerhead speedlights (similar light output), I will typically fire them on about 1/2 to 2/3 power through a large soft-box with a shutter speed of 1/250 and an aperture of f8 and the lights 3-4' from the subject. They may not be aimed correctly. As long as you see them firing, chances are they're working, and it's you, not them.

 

[Derrel]

I have a feeling that maybe the strobes are not hooked up to your camera properly. Just a guess. Please feel free to ask for additional help. Somebody ought to be around to help you.

There are two common ways to hook up a strobe. First is using a "PC cord", from the strobe to the camera's PC outlet. This is an easy way to hook up.

The second way is by using a low-output flash fired by the camera, which causes a photo cell or "slave trigger" on the strobes to fire, when the slave is set to ON position. Now, this slave is very sensitive, so "automatic TTL" flash on the camera can cause mis-timing of the strobes. When the camera's flash is in TTL mode, it fires a microscopic pre-flash, so tiny and so fast the human eye can hardly see it; that pre-flash will FIRE the strobes, and only a few milliseconds later, the camera's shutter will open, but the strobes will have already fired.

SO, when using a slave set-up, the camera flash needs to be set to a MANUAL flash mode, which has no pre-flash.

 

[Patrice]

When you say strobe do you mean monolight as in studio flash which runs on A/C (you power from a wall plug)? Which kind?

150 w/s lights would likely have a guide number of 110 (ft) at ISO 100 or so at full power. To set the aperture of your camera you divide the guide number by the distance between the flash and the subject. So 10 ft means f/11. You might lose 2 stops from the umbrella so now your aperture would be f/5.6.

Next you need to find a reliable way to fire your flash when you press the shutter. The cheapest way is to use a PC sync cable from your camera to your flash. The second flash should slave itself to the first one if it has an optical slave feature and you have enabled it. If you don't have a sync cable then you should be able to optically slave both lights from the popup flash on your camera.

The best simplest way to use studio lights is to go full manual on your camera and use a light meter to determine your aperture. But you can also go ahead with trial and error. Start with one flash only with no modifier (umbrella) and learn how to use the guide number. Then add the umbrella and learn how it affects the light output and distribution. Takes a bit of practice but it's really not very difficult.

Your first order of business though is to figure out how to sync your monolights with your camera.

(Your second order of business might be to fix your shift key. It shows a bit of respect to the membership from whom your are seeking help when you take the time to at least try.)


edit: Derrel beat me to it. Pay attention, he knows about stuff. So does tirediron.

 

[kalodighi]

dear tirediron... thank you so much for your quick reply.. unfortunately i have deleted those pics.. so i cant post those for analysis.. but next time i will keep them.. i was just soooo frustrated..
but for your estimation.. the light was 2.5 -3 ft away from the subject.. camera was 5-6ft away..shutter speed was 1/60 - 1/90 & aperture was 5.6...

i fired the light with my popup camera flash.. (it worked) .. first i used the umbrella, then when i saw those pics are underexposed then i didnt use any modifier.. but not much improved.. i am afraid that if anything wrong with the light...

thank you so much once again..

 

[kalodighi]

I have a feeling that maybe the strobes are not hooked up to your camera properly. Just a guess. Please feel free to ask for additional help. Somebody ought to be around to help you.

There are two common ways to hook up a strobe. First is using a "PC cord", from the strobe to the camera's PC outlet. This is an easy way to hook up.

The second way is by using a low-output flash fired by the camera, which causes a photo cell or "slave trigger" on the strobes to fire, when the slave is set to ON position. Now, this slave is very sensitive, so "automatic TTL" flash on the camera can cause mis-timing of the strobes. When the camera's flash is in TTL mode, it fires a microscopic pre-flash, so tiny and so fast the human eye can hardly see it; that pre-flash will FIRE the strobes, and only a few milliseconds later, the camera's shutter will open, but the strobes will have already fired.

SO, when using a slave set-up, the camera flash needs to be set to a MANUAL flash mode, which has no pre-flash.

Dear Derrel..

thank you so much for your reply.. i am glad that you have given your time to me.

well, i used my camera's pop up flash to fire the light.. i will do this again.. thank you so much once again...

 

[kalodighi]

When you say strobe do you mean monolight as in studio flash which runs on A/C (you power from a wall plug)? Which kind?

150 w/s lights would likely have a guide number of 110 (ft) at ISO 100 or so at full power. To set the aperture of your camera you divide the guide number by the distance between the flash and the subject. So 10 ft means f/11. You might lose 2 stops from the umbrella so now your aperture would be f/5.6.

Next you need to find a reliable way to fire your flash when you press the shutter. The cheapest way is to use a PC sync cable from your camera to your flash. The second flash should slave itself to the first one if it has an optical slave feature and you have enabled it. If you don't have a sync cable then you should be able to optically slave both lights from the popup flash on your camera.

The best simplest way to use studio lights is to go full manual on your camera and use a light meter to determine your aperture. But you can also go ahead with trial and error. Start with one flash only with no modifier (umbrella) and learn how to use the guide number. Then add the umbrella and learn how it affects the light output and distribution. Takes a bit of practice but it's really not very difficult.

Your first order of business though is to figure out how to sync your monolights with your camera.

(Your second order of business might be to fix your shift key. It shows a bit of respect to the membership from whom your are seeking help when you take the time to at least try.)


edit: Derrel beat me to it. Pay attention, he knows about stuff. So does tirediron.

Dear Patrice..

it is so nice to get your reply. thank you so much.. i am so grateful.

yes, i am using studio monolight. this time i used one light, fired by my camera popup flash. it was plugged in wall. A/C. once with the umbrella and then without the umbrella.. result was same.. feeling upset.. but thank you so much for your advice .. it gave me little hope now... i will try the way you told..

 

[Sw1tchFX]

Hi.. I am totally new to this forum. I really need a help with lighting things as i am feeling so frustrated now.

anyway, the thing is, i have bought a pair of strobe (150w each) with umbrella and 2 light stands. Problem is - i was trying to take some pictures using one of this strobe. but all pics were underexposed.

my camera setting was 1/60 - 1/90 and f5.7 .....

is anything wrong with my strobe? i am so upset .. i cant afford to buy anything else.. i have money problem. i started to think that i have wasted my money already.

can anyone help me pls by pointing out what is wrong and how to fix it?

thank you so much...

Unless you're shooting tabletop, I'd be shocked if you could crank 5.6 out of a 150 w/s light at ISO 100 through any modifier.


BUT YOU SAID 150W.....which suggest continuous light.... Do they even flash? if not, than congrats. You just bought yourself lights that are no brighter than whats lighting your living room!


If they're strobes, open the aperture to 2.8-ish, shutter speed at 1/125th, and ISO about 100-800. Than you should be cookin' with fire. The crappy thing about using lights that are only 150w/s (speedlights crank out more power than that!) is that you'll have unbelievably little control over blocking out ambient light. 150 w/s is shockingly little light. For context, the standard for a basic studio is the ballpark of 1200-2400 w/s!

 

[OLaA]

Unless you're shooting tabletop, I'd be shocked if you could crank 5.6 out of a 150 w/s light at ISO 100 through any modifier.

BUT YOU SAID 150W.....which suggest continuous light.... Do they even flash? if not, than congrats. You just bought yourself lights that are no brighter than whats lighting your living room!

If they're strobes, open the aperture to 2.8-ish, shutter speed at 1/125th, and ISO about 100-800. Than you should be cookin' with fire. The crappy thing about using lights that are only 150w/s (speedlights crank out more power than that!) is that you'll have unbelievably little control over blocking out ambient light. 150 w/s is shockingly little light. For context, the standard for a basic studio is the ballpark of 1200-2400 w/s!

The OP already stated right above your post that they were moonlights and he was trying to fire them with on camera flash. I'm assuming the issue is the pre flash as already suggested. Hopefully we get an update when he reshoots.