maybe someone can help, or point to me help. flash/sync/aperture/DOF...

[matt62485]

so, I've jumped into a simple strobe setup. flashpoint dg600/battery pack with an umbrella setup and a reflector set. my wife is pregnant and i wanna do some beach maternity shots, but after reading some strobist/lighting 101 stuff, i still am baffled by a few things.

1. flash sync speed- this is the FASTEST shutter speed you can shoot without "losing" light or having blacked out portions of you're image. slowing down the shutter speed will essentially affect the portion of the image you are exposing the strobe to correct? lets say you are shooting on a bright beach and the sky needs to be exposed down... sync at 1/250 and adjust the aperture accordlingly for the sky/sand and adjust flash power/distance for subject exposure?

2. aperture- lets say the same situation as above but you want to shoot with a 50/1.8 close to wide open to acheive a nice DOF, is this even possible since your defeating the whole purpose of what i said in (1.), is this when filters come in to play to stop down the background?

I'm trying to work on it some this weekend, but want to make sure i have a decent understanding of what to do before i go out there wasting a ton of time with a pregnant/uncomfortable wife and not get any photos to make it worth the while.

 

[480sparky]

so, I've jumped into a simple strobe setup. flashpoint dg600/battery pack with an umbrella setup and a reflector set. my wife is pregnant and i wanna do some beach maternity shots, but after reading some strobist/lighting 101 stuff, i still am baffled by a few things.

1. flash sync speed- this is the FASTEST shutter speed you can shoot without "losing" light or having blacked out portions of you're image.

Yep.

slowing down the shutter speed will essentially affect the portion of the image you are exposing the strobe to correct?

Nope. It will affect ambient light.

lets say you are shooting on a bright beach and the sky needs to be exposed down... sync at 1/250 and adjust the aperture accordlingly for the sky/sand and adjust flash power/distance for subject exposure?

Yes, but you'll need a powerful enough strobe to be 'correctly' exposed for the set aperture, given the distance between the strobe and the subject. If you were in a dark room and you need f/4 to expose the strobe correctly, shooting at the beach at 1/250 at f/16 won't show the effect of the flash much.

2. aperture- lets say the same situation as above but you want to shoot with a 50/1.8 close to wide open to acheive a nice DOF, is this even possible since your defeating the whole purpose of what i said in (1.), is this when filters come in to play to stop down the background?

Not sure how filters would be the answer, unless you're referring to filters on the flash itself.

I'm trying to work on it some this weekend, but want to make sure i have a decent understanding of what to do before i go out there wasting a ton of time with a pregnant/uncomfortable wife and not get any photos to make it worth the while.

Try some test shots of an inanimate object in your yard first.

 

[Big Mike]

1. flash sync speed- this is the FASTEST shutter speed you can shoot without "losing" light or having blacked out portions of you're image. slowing down the shutter speed will essentially affect the portion of the image you are exposing the strobe to correct? lets say you are shooting on a bright beach and the sky needs to be exposed down... sync at 1/250 and adjust the aperture accordlingly for the sky/sand and adjust flash power/distance for subject exposure?

Above the camera's max sync speed, the shutter is never fully open, so whenever the flash fires, it could not illuminate the whole scene (as seen by the sensor).
So yes, in that situation, you would use your fastest sync speed, lowest ISO and then find what aperture will be needed to get the exposure you want. But as you go to smaller and smaller apertures, you will need more light from your flash. So keeping the flash as close as possible to the subject will help and ditching any modifier or diffusion material will also help.

2. aperture- lets say the same situation as above but you want to shoot with a 50/1.8 close to wide open to acheive a nice DOF, is this even possible since your defeating the whole purpose of what i said in (1.), is this when filters come in to play to stop down the background?

If you want to do that, you would need to use High Speed Sync (Nikon calls it Auto FP, I think). You would need a Nikon flash unit, slaved to the camera/master though. This mode pulses the flash so that it covers the whole scene, even if the shutter is only open a little bit at a time. But it greatly reduces your flash's range, so it's not always going to work.

You mentioned that you have a reflector, this may be the solution that works best. You can use it to light up your subject, and by cutting out the flash, you are free to use any shutter speed (thus any aperture).

 

[matt62485]

so, I've jumped into a simple strobe setup. flashpoint dg600/battery pack with an umbrella setup and a reflector set. my wife is pregnant and i wanna do some beach maternity shots, but after reading some strobist/lighting 101 stuff, i still am baffled by a few things.

1. flash sync speed- this is the FASTEST shutter speed you can shoot without "losing" light or having blacked out portions of you're image.

Yep.

slowing down the shutter speed will essentially affect the portion of the image you are exposing the strobe to correct?

Nope. It will affect ambient light.

ok thanks, this is where i was like "wtf", ambient makes more sense. the verbage on some stuff i read lead me to believe otherwise though.



Yes, but you'll need a powerful enough strobe to be 'correctly' exposed for the set aperture, given the distance between the strobe and the subject. If you were in a dark room and you need f/4 to expose the strobe correctly, shooting at the beach at 1/250 at f/16 won't show the effect of the flash much.

makes sense. the dg600 has 300w/s, so hopefully enough to get me started. plus, i plan to use the reflector as much as possible, but want to have the "know how" for this monolight.

2. aperture- lets say the same situation as above but you want to shoot with a 50/1.8 close to wide open to acheive a nice DOF, is this even possible since your defeating the whole purpose of what i said in (1.), is this when filters come in to play to stop down the background?

Not sure how filters would be the answer, unless you're referring to filters on the flash itself.

i'm not sure. i was referring to polarizers for toning down the sky. no idea, just was thinking out loud.

I'm trying to work on it some this weekend, but want to make sure i have a decent understanding of what to do before i go out there wasting a ton of time with a pregnant/uncomfortable wife and not get any photos to make it worth the while.

Try some test shots of an inanimate object in your yard first.

good idea, thanks.

1. flash sync speed- this is the FASTEST shutter speed you can shoot without "losing" light or having blacked out portions of you're image. slowing down the shutter speed will essentially affect the portion of the image you are exposing the strobe to correct? lets say you are shooting on a bright beach and the sky needs to be exposed down... sync at 1/250 and adjust the aperture accordlingly for the sky/sand and adjust flash power/distance for subject exposure?

Above the camera's max sync speed, the shutter is never fully open, so whenever the flash fires, it could not illuminate the whole scene (as seen by the sensor).
So yes, in that situation, you would use your fastest sync speed, lowest ISO and then find what aperture will be needed to get the exposure you want. But as you go to smaller and smaller apertures, you will need more light from your flash. So keeping the flash as close as possible to the subject will help and ditching any modifier or diffusion material will also help.

i see, makes sense. i'll tinker with it and hopefully get some results decent enough for C&C

2. aperture- lets say the same situation as above but you want to shoot with a 50/1.8 close to wide open to acheive a nice DOF, is this even possible since your defeating the whole purpose of what i said in (1.), is this when filters come in to play to stop down the background?

If you want to do that, you would need to use High Speed Sync (Nikon calls it Auto FP, I think). You would need a Nikon flash unit, slaved to the camera/master though. This mode pulses the flash so that it covers the whole scene, even if the shutter is only open a little bit at a time. But it greatly reduces your flash's range, so it's not always going to work.

You mentioned that you have a reflector, this may be the solution that works best. You can use it to light up your subject, and by cutting out the flash, you are free to use any shutter speed (thus any aperture).

yea, i plan to use it as much as possible, but wanna play with the lighting as well. i have a few "ideas" i wanna try, but not sure i can execute them.



thanks for yalls help. that explains a lot.

 

[gsgary]

When shooting ambient and flash, shutter speed and ISO control ambient exposure, aperture controls flash exposure

 

[480sparky]

Matching ambient light (especially sunlight) and a strobe can be viewed as a math problem.

All light is subject to the Inverse Square Law when it comes to the reduction of light in relationship to the distance from it's source.

The sun, while at a great distance, is pumping out a HUGE amount of light. The ISL reduction of light in a sunlit scene here on Earth is nothing more than a mathematical anomaly that can only be calculated... it has no bearing on photographing a scene. What I mean is, let's say you're taking a photo of someone and the sun is at your back. If the subject is 5 feet away, they are receiving a set amount of light from the sun. Now, move the subject to 5 miles away. Mathematically, less sunlight is falling on them, but you really can't tell the difference because it's such a miniscule amount.

Man-made strobes, however, are a different story. Although much closer than the sun, their light output is absolutely dismal compared to the huge yellow nuclear reaction in the sky. And being so close, the light fall-off due to ISL is much more noticable. Moving the subject a few feet towards or away from the strobe can cause over- or under-exposure.

So the trick is.... to find the distance from the strobe the subject needs to be in order to be correctly exposed given the aperture and ISO chosen in the camera, and matching that exposure the sun gives you for ambient light with the same aperture and ISO, and throw the shutter speed in for a swift kick in the pants.


Now, let's bring up the subject of color temperature, shall we?