Question on calculating light output from strobe

[sirhawkeye64]

I'm thinking I may have the answer to this already but thought I'd ask anyway.

So if I get a 400ws strobe that has an adjustment of up to 5 stops, can one calculate the lowest power setting simply by dividing each increment in half, like you do when calculating general exposure in stops?

So for example, a 400ws strobe with 5-stops of adjustment:

400ws (full power), 200ws (1/2 power), 100ws (1/4), 50ws (1/8), 25ws (1/16 power).

does it work like this or not, or am I missing something?

(I'm looking to get a 300ws or 400ws light but need to figure out how many stops of adjustment I will probably want/need. The studios I plan to shoot in vary in size, although most of the setups and configurations I plan on doing will only be about the size of 10x10 at most--mainly for portraiture and model photography of 1-3 people). I will be buying a second light probably but I want to get this figured out before I buy anything.

 

[Brooke Meyer]

You have it right. As examples:

Buff Einsteins have 9 stops, Digi Bees 7 stops Alien Bees 6 stops

YN560 IIIs have 8 stops: Full, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64 and 1/128th.

You'd be fine with a pair of used AB800's for about $200 ea. . If budget allows, DB800's new with their dimmable 400w equivalent LED Modeling light ares very flexible.

In most use cases and on a limited budget , these would also work okay Neewer Vision 4

 

[BAK]

Theory and fact.

Yes in theory, no in reality, as far as the math gies, But a 300 watt second or 400 watt second strobe wii work fine for, 1, 2, or 3 people in a 10 x 12 space.

BAK

 

[sirhawkeye64]

Theory and fact.

Yes in theory, no in reality, as far as the math gies, But a 300 watt second or 400 watt second strobe wii work fine for, 1, 2, or 3 people in a 10 x 12 space.

BAK

OK but I figured around 5 stops is somewhat what I would need. Obviously it's probably not exact, as flashes themselves probably aren't exact halving or doubling of light (when going up/down a stop) but at least it gives me an idea, as it seems some can only go down about 4 stops but others can go farther. I just want to see about getting/having the maximum flexibility as I don't have a particular style that I do (like it's not all low-key or high-key lighting but various types of shoots/lighting).

 

[Sailor Blue]

Always be careful when discussing the number of stops of light control for a strobe.

The range of the power adjustment is what really tells you about how useful the light is.

Manufactures will tell you how many stops, which is one less than the range of stops. The reason is obvious, more sounds better.

What you gave is undoubtedly what a manufacturer would say, five stops, but in fact the range is only four stops - from full to 1/2, 1/2 to 1/4, 1/4 to 1/8, and 1/8 to 1/16. A 5-stop range would take you to 1/32 and 6-stops takes you to 1/64.

The PCB DigiBees have "7 f-stop range (full to 1/64 power)" according to their specifications. It is incorrect, it is a 6-stop range strobe.

The higher the range of stops the better, especially with higher powered lights.

I can shoot from f/2.8 to f/16 at ISO 100 with my 300Ws strobes and a 40" softbox by varying the power of my 5-stop range strobes and changing the distance. As far as I'm concerned that covers all the f stop range I am interested in.

If I had a 4-stop range I could still cover down to f/2.8 by adding a layer of white translucent nylon or Dacron fabric to the front of the softbox to reduce the light output another stop.

 

[sirhawkeye64]

Always be careful when discussing the number of stops of light control for a strobe.

The range of the power adjustment is what really tells you about how useful the light is.

Manufactures will tell you how many stops, which is one less than the range of stops. The reason is obvious, more sounds better.

What you gave is undoubtedly what a manufacturer would say, five stops, but in fact the range is only four stops - from full to 1/2, 1/2 to 1/4, 1/4 to 1/8, and 1/8 to 1/16. A 5-stop range would take you to 1/32 and 6-stops takes you to 1/64.

Yeah I guess that makes sense, especially if they consider 1/1 (full power) a stop in the advertised "5-stop" range. (I'm currently looking at an Elinchrom D-Lite system).

The PCB DigiBees have "7 f-stop range (full to 1/64 power)" according to their specifications. It is incorrect, it is a 6-stop range strobe.

The higher the range of stops the better, especially with higher powered lights.

I can shoot from f/2.8 to f/16 at ISO 100 with my 300Ws strobes and a 40" softbox by varying the power of my 5-stop range strobes and changing the distance. As far as I'm concerned that covers all the f stop range I am interested in.

If I had a 4-stop range I could still cover down to f/2.8 by adding a layer of white translucent nylon or Dacron fabric to the front of the softbox to reduce the light output another stop.

Yes I will be using a softbox most of the time for this, so yeah that would probably work for me as well if I needed an extra stop of light.

 

[sungphoto]

I think you're overthinking things a bit.

Calculating light output might make sense on paper, but all those calculations tend to go out the window when you're actually shooting, as there's so many variables in play - distance to subject, whether you're aiming it directly at the subject or feathering it, efficiency of modifier, how much diffusion you're using, light absorption properties of the subject, etc.

Also, we are spoiled for choices now in terms of off camera lighting that has a broad power range - from profoto to godox, so I wouldn't overthink your strobe decision from a power adjustability standpoint. I highly recommend the Godox AD200. I have profoto D1s, B1s, and B2s, but for when I want to travel light and don't want to worry about carrying thousands of dollars in strobes with me, I throw a couple AD200s in my bag.

 

[BAK]

What does this mean? >> OK but I figured around 5 stops is somewhat what I would need. <<

Let's say you want to photograph a 12 year old sitting on a stool.Can you tell us how you set the controls?

Thanks.

BAK

 

[Klaus dk]

Always be careful when discussing the number of stops of light control for a strobe.

The range of the power adjustment is what really tells you about how useful the light is.

Manufactures will tell you how many stops, which is one less than the range of stops. The reason is obvious, more sounds better.

What you gave is undoubtedly what a manufacturer would say, five stops, but in fact the range is only four stops - from full to 1/2, 1/2 to 1/4, 1/4 to 1/8, and 1/8 to 1/16. A 5-stop range would take you to 1/32 and 6-stops takes you to 1/64.

Yeah I guess that makes sense, especially if they consider 1/1 (full power) a stop in the advertised "5-stop" range. (I'm currently looking at an Elinchrom D-Lite system).

The PCB DigiBees have "7 f-stop range (full to 1/64 power)" according to their specifications. It is incorrect, it is a 6-stop range strobe.

The higher the range of stops the better, especially with higher powered lights.

I can shoot from f/2.8 to f/16 at ISO 100 with my 300Ws strobes and a 40" softbox by varying the power of my 5-stop range strobes and changing the distance. As far as I'm concerned that covers all the f stop range I am interested in.

If I had a 4-stop range I could still cover down to f/2.8 by adding a layer of white translucent nylon or Dacron fabric to the front of the softbox to reduce the light output another stop.

Yes I will be using a softbox most of the time for this, so yeah that would probably work for me as well if I needed an extra stop of light.

I have four Godox AD600. They are 600Ws and are variable from 1/1 to 1/256. Shooting head and shoulders portraits at f/5.6 and ISO 100, I rarely go above 1/8 for the main light in a 90cm softbox, and sometimes I have trouble with rim lights or hair lights being too bright at 1/256.

Running all four on full blast I can light 150 people at f/8.

I prefer to have the same Wattage on all my lights. Using extra diffusion material or ND gels is possible, but not ideal in a portrait session. To me it's a question of staying in flow with as few distractions from the gear as possible.

 

[sungphoto]

I have four Godox AD600. They are 600Ws and are variable from 1/1 to 1/256. Shooting head and shoulders portraits at f/5.6 and ISO 100, I rarely go above 1/8 for the main light in a 90cm softbox, and sometimes I have trouble with rim lights or hair lights being too bright at 1/256.

Running all four on full blast I can light 150 people at f/8.

I prefer to have the same Wattage on all my lights. Using extra diffusion material or ND gels is possible, but not ideal in a portrait session. To me it's a question of staying in flow with as few distractions from the gear as possible.

Highly recommend picking up an AD200 for your hair light if you're having issues with your AD600s being too powerful.

 

[Klaus dk]

I have four Godox AD600. They are 600Ws and are variable from 1/1 to 1/256. Shooting head and shoulders portraits at f/5.6 and ISO 100, I rarely go above 1/8 for the main light in a 90cm softbox, and sometimes I have trouble with rim lights or hair lights being too bright at 1/256.

Running all four on full blast I can light 150 people at f/8.

I prefer to have the same Wattage on all my lights. Using extra diffusion material or ND gels is possible, but not ideal in a portrait session. To me it's a question of staying in flow with as few distractions from the gear as possible.

Highly recommend picking up an AD200 for your hair light if you're having issues with your AD600s being too powerful.

As I write, I prefer to have the same Wattage on all lights. I have a few V860 IIs I could use, but I would probably rather go to f/8 or f/11.

The point of my post is that a narrow power range may seem sufficient, but you sometimes need more than you think.

But thanks anyway.

 

[Ms Bigglesworth]

But for something like, theoretically - 5 stops range.....

That doesn't mean there are only 5 power levels, right? - Ex. either set it to Power 1, 2, 3, 4 or 5.

So what's all the fuss - if you have enough power to light the subject, set a fine tuned amount and you're good - unless you're trying to figure out how to achiever the very lowest power possible?

 

[Simon Barker]

But for something like, theoretically - 5 stops range.....

That doesn't mean there are only 5 power levels, right? - Ex. either set it to Power 1, 2, 3, 4 or 5.

Range describes maximum to minimum power so 100 to 25 is a 3 stop range but only 2 stops of adjustment.

So what's all the fuss - if you have enough power to light the subject, set a fine tuned amount and you're good - unless you're trying to figure out how to achiever the very lowest power possible?

Well if you don't have the benefit of working in the field, being taught or experience then these are the sort of questions you ask when starting.

I personally think it's pretty easy with modern equipment, anything that isn't cheap garbage or ancient should offer a good power range and even if still slightly too much distance or a larger modifier would mean it's not a problem.

 

[sungphoto]

I personally think it's pretty easy with modern equipment, anything that isn't cheap garbage or ancient should offer a good power range and even if still slightly too much distance or a larger modifier would mean it's not a problem.

Agreed. Most modern strobe systems (godox, elinchrom, phottix, profoto, broncolor, etc) will be totally up to the OP's needs.

 

[sirhawkeye64]

But for something like, theoretically - 5 stops range.....

That doesn't mean there are only 5 power levels, right? - Ex. either set it to Power 1, 2, 3, 4 or 5.

So what's all the fuss - if you have enough power to light the subject, set a fine tuned amount and you're good - unless you're trying to figure out how to achiever the very lowest power possible?

Yes I'm trying to see how low of a power setting I can accomplish, but I guess there is no one-size-fits-all answer to this, as it may vary on the light, brand, total output, etc. And I guess in the end, if I'm using a softbox, I can add additional materials (ie. baffles) to reduce light further than what the light itself is capable of being reduced to. I more or less just wanted to make sure that my thinking in terms of power levels and stops was appropriate. Obviously there is some variables that will come into play in the studio that will affect the required power output.

 

[sirhawkeye64]

But for something like, theoretically - 5 stops range.....

That doesn't mean there are only 5 power levels, right? - Ex. either set it to Power 1, 2, 3, 4 or 5.

Range describes maximum to minimum power so 100 to 25 is a 3 stop range but only 2 stops of adjustment.

So what's all the fuss - if you have enough power to light the subject, set a fine tuned amount and you're good - unless you're trying to figure out how to achiever the very lowest power possible?

Well if you don't have the benefit of working in the field, being taught or experience then these are the sort of questions you ask when starting.

This basically is where I'm coming from. I'm sort of new to the studio photography stuff (something I'm wanting to get into more) but am ready to move on from flash units to something else. My goal was to get a better understanding of what I might need to think about when looking at studio strobes as the last thing I want to be doing is exchanging lights a lot. That's not to say I'll get it right on the first go, but at least I'll know what I'm looking for (within a certain range) and can be make a more "educated" purchase. For example, someone mentioned the misconception that 5 stops is not really 5-stops of adjustment, but really 4 (as some mfrs or all of them, consider full power one of those stops of adjustment, which I probably would have missed that if I hadn't asked).

I personally think it's pretty easy with modern equipment, anything that isn't cheap garbage or ancient should offer a good power range and even if still slightly too much distance or a larger modifier would mean it's not a problem.

 

[Sailor Blue]

But for something like, theoretically - 5 stops range.....

That doesn't mean there are only 5 power levels, right? - Ex. either set it to Power 1, 2, 3, 4 or 5.

So what's all the fuss - if you have enough power to light the subject, set a fine tuned amount and you're good - unless you're trying to figure out how to achiever the very lowest power possible?

Range means going from someplace to somewhere else.

A 5-stop strobe would be one where you can set the power at 1, 1/2, 1/4, 1/8, and 1/16th of full power.

A 5-stop range strobe would be one that goes from 1 to 1/2, to 1/4, to 1/8, to 1/16, and to 1/32 of full power.

A 5-stop range is better than only 5-stops.

 

[Sailor Blue]

But for something like, theoretically - 5 stops range.....

That doesn't mean there are only 5 power levels, right? - Ex. either set it to Power 1, 2, 3, 4 or 5.

Range describes maximum to minimum power so 100 to 25 is a 3 stop range but only 2 stops of adjustment.

Nope. Range is how many stops you can change the power.

Going from 100 to 50 is a 1-stop range. Going from 50 to 25 would be the second of a 2-stop range.

So what's all the fuss - if you have enough power to light the subject, set a fine tuned amount and you're good - unless you're trying to figure out how to achiever the very lowest power possible?

Well if you don't have the benefit of working in the field, being taught or experience then these are the sort of questions you ask when starting.

I personally think it's pretty easy with modern equipment, anything that isn't cheap garbage or ancient should offer a good power range and even if still slightly too much distance or a larger modifier would mean it's not a problem.

 

[Sailor Blue]

<snip>

I have four Godox AD600. They are 600Ws and are variable from 1/1 to 1/256. Shooting head and shoulders portraits at f/5.6 and ISO 100, I rarely go above 1/8 for the main light in a 90cm softbox, and sometimes I have trouble with rim lights or hair lights being too bright at 1/256.

Running all four on full blast I can light 150 people at f/8.

I prefer to have the same Wattage on all my lights. Using extra diffusion material or ND gels is possible, but not ideal in a portrait session. To me it's a question of staying in flow with as few distractions from the gear as possible.

Klaus I agree with you, it is best to have all lights the same. This way if one dies you have instant replacements available. All your light modifiers will also work with all your lights.

Like you I hate using something extra to reduce the light output of a strobe but sometimes I do it anyway. There are times that you just have to bow to the inevitable and do something you don't like in order to get the photo.

I'll never use a ND filter in a softbox since it ruins a flash tube if it melts onto it, and there is always a chance that will happen. They are okay in front of a metal bowl reflector.

The added layer of fabric works for a softbox and it really isn't hard to attach one with some clothespins. It may not be pretty but it saves me spending money I don't want to spend for a different light. Since I am an amateur I make do.

If your AD-600 is too strong for an accent/hair light at 1/256 then it is time to think about how to reduce the light output. Most accent lights aren't diffused so I would assume you are using a metal bowl reflector or snoot. A ND filter would work fine for that.

The AD-400 would also let you seamlessly use all your current light modifiers but drop your minimum light output by only about 1/4 of a stop. The AD-200 would require the use of a special holder (AD-B2) to use your current light modifiers but would drop the light output about 1-2/3 stops.

I rarely see any compelling need to shoot below f/4 in the studio but the options are worth considering if you want to be able to shoot at wider apertures than you can now.

--
Living and loving it in Pattaya, Thailand. Canon 7D - See the gear list for the rest.

 

[Simon Barker]

This basically is where I'm coming from. I'm sort of new to the studio photography stuff (something I'm wanting to get into more) but am ready to move on from flash units to something else. My goal was to get a better understanding of what I might need to think about when looking at studio strobes as the last thing I want to be doing is exchanging lights a lot. That's not to say I'll get it right on the first go, but at least I'll know what I'm looking for (within a certain range) and can be make a more "educated" purchase. For example, someone mentioned the misconception that 5 stops is not really 5-stops of adjustment, but really 4 (as some mfrs or all of them, consider full power one of those stops of adjustment, which I probably would have missed that if I hadn't asked).

That's understandable, we all started somewhere and studio lighting is one of the most incestuous businesses out there, it's not a great way for new people to learn.

I would recommend against overthinking this problem, pick a few modern heads and let us know which those are and if one is entirely unsuitable we'll tell you. These days we're spoilt for choice compared to the past, almost easier to get it right rather than wrong with flash.