Light Meter with Distance Laser meter ...

[hjoseph7]

For those who shoot Manual Flash this light Meter might be for you. This light meter(From China)  https://www.rogerlowe.co.uk/laser-light-meter-for-photography/ is actually for Range Finder cameras, but I'm guessing that you can also use it for manual flash. One thing that makes using manual flash a hassle, is that you constantly have to use the formula Guide Number divided by Subject Distance to get the proper Aperture(GN/Distance = F-stop) This can get a little confusing when you are at busy event with people running in and out of your subject's distance. I was thinking about bringing my ENGINDOT Laser Distance Meter to an upcoming event to help me get the right exposure when using manual flash, but this little meter might just do the trick ? One less calculation and no guessing ! I use my Distance Meter to design floor-plans on my Real-Estate photography job BTW...  The only thing is that you don't want to point the laser at your subjects eyes....  Sorry about the video it is really BAD,  but the only one I could find online.    

Edited November 3 by hjoseph7

[BeBu Lamar]

I have no problem with that. The problem is GN doesn't work with bounce flash and I almost always bounce my flash. 

[hjoseph7]

On 11/3/2024 at 4:07 PM, BeBu Lamar said:

I have no problem with that. The problem is GN doesn't work with bounce flash and I almost always bounce my flash. 

True, never thought about that ?

[hjoseph7]

Some flash units like my Metz 58 AF-1 display the subject distance on the back of the LCD. The 58 AF-1 takes into consideration the position of the Zoom-head when making the calculations. This is great if you are shooting head on ! Metz recomends that you place your subject somewhere around a third less than the value displayed on the LCD. For example if the LCD displays 10 feet, then you would place your subject at around 7 feet. My Quantum 5D-r also displays the distance + the guide number, but since the 5D-r does not zoom, it only uses the guide number assigned to the flash at different power settings.

The thing is I wanted to use my Norman 200c that like the Quantum 5D-r  does not depend on the position of the Zoom-head for a particular guide number. The  Norman 200c has 3 guide numbers at ISO 100. At 50W the guide number is (45), at 100W the guide number is (63), at 200W GN=(90).  Just as important the guide number stays the same no matter what focal length lens you use ! That cuts out the calculation where you are trying to figure out the guide number based on the Zoom-head position and lens.  

As far as bouncing, there is no need to bounce with this flash unit because basically it's a portable studio strobe. With the 2DRP(frosted dome) reflector, you get soft even light with hardly any shadows. Talk about wrap-around light, this thing wraps around  up to 10 feet behind the subject.   

Norman 200C 

50W; ISO = 100; 2DRP; max=800 shots(1/1)
-----------------------------
GN   Ft.  f-num 
---------------
45 / 15 = f2.8
45 / 10 = f4.5  
45 /  8 = f5.6
45 /  7 = f6.3 
45 /  6 = f7.5
45 /  5 = f9

100W; ISO = 100; 2DRP; max=400
------------------------------
GN   Ft.  f-num 
---------------
63 / 15 = f4.5
63 / 10 = f6.3  
63 /  8 = f7.5
63 /  7 = f9 
63 /  6 = f10.5
63 /  5 = f13

200W; ISO = 100; 2DRP; max=190
------------------------------
GN   Ft.  f-num 
---------------
90 / 20 = f4.5
90 / 15 = f6.3
90 / 10 = f9  
90 /  8 = f11.2
90 /  7 = f13 
90 /  6 = f15
90 /  5 = f18

GN(guide number)  = f.#(apeture) * Ft(feet)
 

       

Edited November 5 by hjoseph7

[rodeo_joe1]

If I need to use flash I nearly always use 'Auto Aperture' mode, whereby a sensor on the front of the flash switches off the light pulse when it detects a sufficient exposure. In my experience this mode is far more reliable than any supposed 'sophisticated' TTL system, and certainly far, far more reliable than using the flash manufacturer's guide number (which can usually be safely divided by 1.5 to arrive at a sensible real-life exposure!). 

Since the Auto-Aperture sensor always points forward at the subject, this mode works with bounce flash or a diffuser cap equally as well. It's basically a real-time reflection meter. 

I haven't had to use guide-numbers since the days of flashbulbs, and certainly not after AA mode was introduced and flashmeters were invented. 

You simply need to make sure the aperture and ISO set on the flash matches those on the camera. Also not forgetting to make sure the camera shutter is within the X-synch parameters, and not ridiculously slow either. 

On 11/5/2024 at 4:00 PM, hjoseph7 said:

With the 2DRP(frosted dome) reflector, you get soft even light with hardly any shadows.

You'll find that's only true in a lightly-painted reflective environment. Take it outside on a dark night and the light will be as hard as direct sunlight. 

Lighting 101 - a light source is only as soft as its size allows (the bigger the area, the softer), and inversely as soft as it's distance from the subject. 

So that little 2" x 4" - or whatever -dome is a hard light source, no matter how frosted it is. The perception of 'soft' is only because its light is radiated over a 180 degree solid angle; allowing reflection from every available light-coloured surface in the room. The exact same effect is got from putting a cheap translucent plastic diffuser cap on a speedlight. Try it - both indoors and out! 

Edited November 13 by rodeo_joe1

[BeBu Lamar]

On 11/5/2024 at 10:00 AM, hjoseph7 said:

Some flash units like my Metz 58 AF-1 display the subject distance on the back of the LCD. The 58 AF-1 takes into consideration the position of the Zoom-head when making the calculations. This is great if you are shooting head on ! Metz recomends that you place your subject somewhere around a third less than the value displayed on the LCD. For example if the LCD displays 10 feet, then you would place your subject at around 7 feet. My Quantum 5D-r also displays the distance + the guide number, but since the 5D-r does not zoom, it only uses the guide number assigned to the flash at different power settings.

The thing is I wanted to use my Norman 200c that like the Quantum 5D-r  does not depend on the position of the Zoom-head for a particular guide number. The  Norman 200c has 3 guide numbers at ISO 100. At 50W the guide number is (45), at 100W the guide number is (63), at 200W GN=(90).  Just as important the guide number stays the same no matter what focal length lens you use ! That cuts out the calculation where you are trying to figure out the guide number based on the Zoom-head position and lens.  

As far as bouncing, there is no need to bounce with this flash unit because basically it's a portable studio strobe. With the 2DRP(frosted dome) reflector, you get soft even light with hardly any shadows. Talk about wrap-around light, this thing wraps around  up to 10 feet behind the subject.   

Norman 200C 

50W; ISO = 100; 2DRP; max=800 shots(1/1)
-----------------------------
GN   Ft.  f-num 
---------------
45 / 15 = f2.8
45 / 10 = f4.5  
45 /  8 = f5.6
45 /  7 = f6.3 
45 /  6 = f7.5
45 /  5 = f9

100W; ISO = 100; 2DRP; max=400
------------------------------
GN   Ft.  f-num 
---------------
63 / 15 = f4.5
63 / 10 = f6.3  
63 /  8 = f7.5
63 /  7 = f9 
63 /  6 = f10.5
63 /  5 = f13

200W; ISO = 100; 2DRP; max=190
------------------------------
GN   Ft.  f-num 
---------------
90 / 20 = f4.5
90 / 15 = f6.3
90 / 10 = f9  
90 /  8 = f11.2
90 /  7 = f13 
90 /  6 = f15
90 /  5 = f18

GN(guide number)  = f.#(apeture) * Ft(feet)
 

       

You think that reflector is soft enough. I found that umbrella isn't soft enough for me. Although they always overate the GN you can test and find out the true GN. 

[ben_hutcherson]

On 11/15/2024 at 8:25 AM, BeBu Lamar said:

You think that reflector is soft enough. I found that umbrella isn't soft enough for me. Although they always overate the GN you can test and find out the true GN. 

I tend to like the light from a shoot-through umbrella if I'm using bare bulb and especially if I'm close to the ceiling of a light colored room. They've worked great for me in that specific situation-bare bulb lets enough light "out" that basically-again in a light colored room-you're providing ambient and you can use the shoot through to provide some directional fill. Bigger of course is better within reason. On my big Norman lights, if I want to direct it a bit more, I can use a 20" or so reflector, but I wouldn't do that unless I had a big umbrella(like 60", and there are few spaces where I work where I could even manage one that big) and could also put the umbrella far enough away that I'd actually be using most of the area. At that point, though, I'd rather just use a big softbox, which is a lot more predictable.

I've never been happy with reflective umbrellas, although I've never used a really big one. I've seen some with a cover a lot like a shoot-through you can slip over the back, but there again at that point it just seems a backwards way of making a softbox.

[BeBu Lamar]

3 hours ago, ben_hutcherson said:

I tend to like the light from a shoot-through umbrella if I'm using bare bulb and especially if I'm close to the ceiling of a light colored room. They've worked great for me in that specific situation-bare bulb lets enough light "out" that basically-again in a light colored room-you're providing ambient and you can use the shoot through to provide some directional fill. Bigger of course is better within reason. On my big Norman lights, if I want to direct it a bit more, I can use a 20" or so reflector, but I wouldn't do that unless I had a big umbrella(like 60", and there are few spaces where I work where I could even manage one that big) and could also put the umbrella far enough away that I'd actually be using most of the area. At that point, though, I'd rather just use a big softbox, which is a lot more predictable.

I've never been happy with reflective umbrellas, although I've never used a really big one. I've seen some with a cover a lot like a shoot-through you can slip over the back, but there again at that point it just seems a backwards way of making a softbox.

But when you shoot thru an umbrella or even reflected umbrella the GN system no longer works. 

[ben_hutcherson]

On 11/20/2024 at 5:03 PM, BeBu Lamar said:

But when you shoot thru an umbrella or even reflected umbrella the GN system no longer works. 

 

I'd started, but never finished, a second response to the OP about their original discussion of the GN system.

Even with the type of flashes they're talking about, it still really doesn't work. I've not used the Norman portable system, but have used Q-flashes and Lumedynes a lot, and all three systems use the same basic "formula" of a relatively small 4 pin flash tube coupled with-usually-a 4" reflector.

Offhand, Quantum's stated GN for a Q-flash T-series on full power(150 w-s) is 165ft. They're assuming direct flash from the standard 4" dimpled reflector. Quantum and Lumedyne both, and presumably also Norman, have smooth reflectors, larger and smaller reflectors, and other changes. All of these of course will change the GN. The Q flash T and T2 had two reflector positions, one of which would give you more coverage but of course reduce the guide number. Quantum packages frosted panels to fit over the front of the reflector with the Q-flashes. I believe they normally include two, and say that using one cuts output by a stop, and using two cuts by 2 stops. Don't hold me to that.

Lumedyne, at least on the heads I use, only has the single reflector position, and their diffuser looks more like a tupperware lid(for all I know it is...Lumedyne gear is indestructible but not exactly refined) although it does have a a darker area in the center right over the bulb. I don't recall a them saying how much this cuts light, but then I also don't recall seeing Lumedyne publish a guide number. They do catalog 4 different flash tubes and say that each one has a different light distribution. Of course too Lumedyne tubes fit the same socket as Quantum tubes, but are not interchangeable as they trigger on different pins(I suspect intentional as 200 w-s is the lowest powered pack Lumedyne offers, and you can go up to 1200 w-s stacking boosters, where the Q-flash tops at 150 w-s.

In any case, I've used Q-flashes on camera(or rather on a Stroboframe since they don't have shoes). With the right cables, I can get full iTTL w/pre-flash on Nikon using a T5Dr, or of course auto-aperture works with everything. Even with the frosted diffuser in front of the reflector, it still looks like direct flash when pointed straight ahead. The higher position from flash bracket does avoid red-eye and changes the shadow angles from on camera direct flash, but that happens with any light when you put it on a bracket. Long and short of it, I'm bouncing or finding a way to put the flash off-camera with a big modifier if I can. The Q-flash just gives a lot more power on tap compared to a conventional flash for bounce or diffusing...

[BeBu Lamar]

3 hours ago, ben_hutcherson said:

 

I'd started, but never finished, a second response to the OP about their original discussion of the GN system.

Even with the type of flashes they're talking about, it still really doesn't work. I've not used the Norman portable system, but have used Q-flashes and Lumedynes a lot, and all three systems use the same basic "formula" of a relatively small 4 pin flash tube coupled with-usually-a 4" reflector.

Offhand, Quantum's stated GN for a Q-flash T-series on full power(150 w-s) is 165ft. They're assuming direct flash from the standard 4" dimpled reflector. Quantum and Lumedyne both, and presumably also Norman, have smooth reflectors, larger and smaller reflectors, and other changes. All of these of course will change the GN. The Q flash T and T2 had two reflector positions, one of which would give you more coverage but of course reduce the guide number. Quantum packages frosted panels to fit over the front of the reflector with the Q-flashes. I believe they normally include two, and say that using one cuts output by a stop, and using two cuts by 2 stops. Don't hold me to that.

Lumedyne, at least on the heads I use, only has the single reflector position, and their diffuser looks more like a tupperware lid(for all I know it is...Lumedyne gear is indestructible but not exactly refined) although it does have a a darker area in the center right over the bulb. I don't recall a them saying how much this cuts light, but then I also don't recall seeing Lumedyne publish a guide number. They do catalog 4 different flash tubes and say that each one has a different light distribution. Of course too Lumedyne tubes fit the same socket as Quantum tubes, but are not interchangeable as they trigger on different pins(I suspect intentional as 200 w-s is the lowest powered pack Lumedyne offers, and you can go up to 1200 w-s stacking boosters, where the Q-flash tops at 150 w-s.

In any case, I've used Q-flashes on camera(or rather on a Stroboframe since they don't have shoes). With the right cables, I can get full iTTL w/pre-flash on Nikon using a T5Dr, or of course auto-aperture works with everything. Even with the frosted diffuser in front of the reflector, it still looks like direct flash when pointed straight ahead. The higher position from flash bracket does avoid red-eye and changes the shadow angles from on camera direct flash, but that happens with any light when you put it on a bracket. Long and short of it, I'm bouncing or finding a way to put the flash off-camera with a big modifier if I can. The Q-flash just gives a lot more power on tap compared to a conventional flash for bounce or diffusing...

Besides from the light is weaker with large reflector or diffuser you still have the problem that it is no longer the point light source and the inverse square law no longer applied. 

[ben_hutcherson]

5 minutes ago, BeBu Lamar said:

Besides from the light is weaker with large reflector or diffuser you still have the problem that it is no longer the point light source and the inverse square law no longer applied. 

I think at the end of the day this all just shows that there's basically two approaches to "correct" flash exposure...

You can use stationary light at constant power with a relatively constant subject position then camera's exposure to match it, or if your lights and/or subject are moving around you probably want some means of automatically adjusting the light output of the flash for each shot.

The former approach of course has worked well as long as studio strobes have been around(and of course also works with constant lights). I use it when I'm doing product/tabletop type shots or even relatively static portraits. Of course the "proper" way to set exposure is to use a flash meter, although with digital I use the "adjust it until it looks right" approach.

For the latter, that's exactly the situation that auto thyristor(or whatever your flash maker calls it) was developed for, and then later TTL-off film metering and now using a low-intensity preflash. All of those approaches work well, although all have their limitations and require that you at least have some understanding of how the system works.

Guide numbers really do only work if you're doing direct flash, and considering that most will basically only consider it a last resort technique I can't imagine doing it when there's ANY other option available.

[BeBu Lamar]

6 hours ago, ben_hutcherson said:

Guide numbers really do only work if you're doing direct flash, and considering that most will basically only consider it a last resort technique I can't imagine doing it when there's ANY other option available.

The only time that I used the GN was when I was a 10 year old kid using a Petri 7s and a bulb flash. I didn't know any better as that what my father told me to do. Now if the flash is manual only I just guess the exposure. After using the flash for a while you can get pretty close even for ceiling or wall bounce. 

Edited November 22 by BeBu Lamar

[Ken Katz]

"After using the flash for a while you can get pretty close even for ceiling or wall bounce."

When bouncing your flash at a white ceiling, add 2 stops to the exposure calculated for the distance from flash to ceiling and ceiling to subject.  Worked OK when using B&W negative film.  Stopped doing that once I started using a big old Metz 202, which let you tilt the flash head while keeping the sensor pointed at your subject.  Flash head didn't swivel, so verticals were still a big PITA.