Off Camera Softbox Speedlight and underexposed pictures

OK, so I finally am getting my feet wet with off camera flash. Amazon delivered a pair of Neewer NW910 speedlights, a pair of Godox 47" umbrella softbox's, 2 Godox speedlight S-clamps, and have them standing on 10' neewer stands... The wireless is powered by Meike MK-R10N

So, I am thoroughly confused now, I set up one of these at set the height to 5 feet and aimed it down at 45 degree angle with a pair of kids shoes 5 feet from the based (I measured distance from shoes to the softbox panel itself at 5 feet also... no matter what I did I kept getting extremely inconsistent results and became more and more confused as I went through!

When setting the flash to manual 1/1 almost every single shot was just solid black... didn't matter what shutter speed I set it to (I also played around with ISO from 100 to 1600 to no avail) I tested most of the shots at f/8 through f/11 since I expected those would be the apertures I would want to use when doing these kind of shots most likely..

When setting the speedlight to TTL mode the results were interesting as well, at times I would get decently exposed pictures, never properly exposed but usually underexposed but still decent... the only way I got well exposed shots were to put the shoes on a pedestal barely a foot away from the center of the panel... or to bump the ISO up to 800 or 1600....

I tried every shutter speed from 1/60 through 1/200 on my D750 and am flummoxed... was I expecting too much from this speedlight and softbox setup? Should I have setup 2 of them to get a better idea of the lighting?

I know I am all over the map with this right now and have no pictures to show but I am so lost that I thought I should at least ask here since the results for me felt underwhelming! I shall return later to check up on the thread but this weekend will have me shuttling off through several of my daughter's dance, sports, and modeling events... thanks in advance for any helpful hints tips or direction!

You're playing with too many variables.

Firstly set everything manually and within the correct parameters, which means ISO 200 or 400 and a shutter speed of 1/125. Do Not adjust these settings once set. Keep the flash to subject distance fixed too at 4 -6 feet (I'd suggest the nearer end of that)

The only variables you now have are the flash power and aperture. Set f5.6 and half power. You should get something close to correct, adjust aperture or flash power to taste.

Apart from the wild behaviour around all the variables what you failed to understand before you started:
Sync speed - your camera has a fixed flash sync speed where the flash fires when both shutter curtains have cleared the whole frame.
Inverse square law - double the distance from flash to subject and you need 4x the light output.
ETTL - is great for dynamic situations where we're bouncing flash off various surfaces at moving subjects, but adds complications in a static situation - Manual is best in these situations.

The Neewer NM910 is not a particularly powerful flash unit with GN60' at 180mm...in comparison, the lowly Canon 430EX is GN141 at 105mm.

Since I have no access to Neewer documentation I can only make a guess about its light output (what GN) for a 'normal' FL lens coverage angle, the Canon 430EX is GN112 at 50mm coverage, so I would guess the NM910 has GN48. So if you are using f/11, that means the flash can reach only 4.4' as the main source of illumination (or out to 6' as a -1EV fill light).

If we put the typical flash into the typical softbox, we would expect somewhere around 1.5 - 2EV of light loss compared to the same strobe fired, or translated into distance, the flash would reach 2.2' as main illumination or 3' as a -1EV fill.

You already said, "set the height to 5 feet and aimed it down at 45 degree angle with a pair of kids shoes 5 feet from the base"...I interpret that to mean the umbrella front was about 7' from the object being illuminated vs. my previously computed 2.2' max, which results in underexposing things by just under -5EV !

Phil V wrote in post #17990470
You're playing with too many variables.

Firstly set everything manually and within the correct parameters, which means ISO 200 or 400 and a shutter speed of 1/125. Do Not adjust these settings once set. Keep the flash to subject distance fixed too at 4 -6 feet (I'd suggest the nearer end of that)

The only variables you now have are the flash power and aperture. Set f5.6 and half power. You should get something close to correct, adjust aperture or flash power to taste.

Apart from the wild behaviour around all the variables what you failed to understand before you started:
Sync speed - your camera has a fixed flash sync speed where the flash fires when both shutter curtains have cleared the whole frame.
Inverse square law - double the distance from flash to subject and you need 4x the light output.
ETTL - is great for dynamic situations where we're bouncing flash off various surfaces at moving subjects, but adds complications in a static situation - Manual is best in these situations.

Thank you! very nice and simple way to help me understand it. Sounds roughly similar to what I read on strobist the other night but still I was apparently not grasping the idea! Now I know where I can start as a base. My ultimate goal once I get this figured out is to setup a small photo area for my kids birthday party with a cute little back drop- but with it being outdoors I wanted to make sure I have everything properly lit and understood what I was doing first!

Wilt wrote in post #17990516
The Neewer NM910 is not a particularly powerful flash unit with GN60' at 180mm...in comparison, the lowly Canon 430EX is GN141 at 105mm.

Since I have no access to Neewer documentation I can only make a guess about its light output (what GN) for a 'normal' FL lens coverage angle, the Canon 430EX is GN112 at 50mm coverage, so I would guess the NM910 has GN48. So if you are using f/11, that means the flash can reach only 4.4' as the main source of illumination (or out to 6' as a -1EV fill light).

If we put the typical flash into the typical softbox, we would expect somewhere around 1.5 - 2EV of light loss compared to the same strobe fired, or translated into distance, the flash would reach 2.2' as main illumination or 3' as a -1EV fill.

You already said, "set the height to 5 feet and aimed it down at 45 degree angle with a pair of kids shoes 5 feet from the base"...I interpret that to mean the umbrella front was about 7' from the object being illuminated vs. my previously computed 2.2' max, which results in underexposing things by just under -5EV !

Close, the front of the umbrella was about 5'6" away from subject. Wow, yes apparently I need to learn the math much better! Hmmm, so maybe for what I want to do (where subjects might be further than the 5') I may want something more powerful? I could always return the NW910's and purchase some 300w monolight strobes... obviously my purchase was price sensitive since I don't make money off it, but I guess I could find a few decent monolights ar around $120-$150...

Thanks for the quick and well thought out responses - will get back on this later, have to go process some dance performance pictures... all natural light

OK after looking at Guide numbers and sort of grasping what you guys were talking about I figured I may as well plunk some cash down for some strobes and ordered a pair of DG600 Flashpoints... Could have gone cheaper but I want to have enough power to move the umbrellas back if I need to and to be able to stop down as well.

Thanks and hopefully the next update has me going in the right direction

werds wrote in post #17992407
OK after looking at Guide numbers and sort of grasping what you guys were talking about I figured I may as well plunk some cash down for some strobes and ordered a pair of DG600 Flashpoints... Could have gone cheaper but I want to have enough power to move the umbrellas back if I need to and to be able to stop down as well.

Thanks and hopefully the next update has me going in the right direction

Well there's that.

Or frankly get your softbox closer - most amateur first attempts with softboxes are ruined just by the light being too far away..

Again the inverse square law kicks in for size - the further away the light the smaller it's apparent size. The Sun is the largest object you can see with the naked eye, but on a Sunny afternoon it acts as a point light source.

I'm not kidding when I use the phrase 'if the lights not getting in your way, it's not close enough'.

However a speeedlight will have problems 'filling' a 47" softbox, remember that flash tube is surrounded by a little high efficiency reflector whos job is to focus the light into a narrow beam straight ahead, even at it's widest setting it'll struggle to create an even light pattern in a softbox over 30".

You can do some amazing things with a speedlight - but it involves acknowledging and working with their limitations, you can't just stick one in a s type bracket and pretend it's a strobe.

The great thing is though mains strobes are actually a bargain compared to speedlights. Lighting only gets expensive when you want a lot of portable power, or you get really nerdy about the 'quality' of light you expect from your modifiers.

I whole-heartedly agree with Phil. My biggest challenge when doing product shots is keeping the lighting equipment out of the frame. I use a 30" umbrellas and 24" softboxes - relatively small stuff. It is a constant struggle to balance proximity and composition.

You guys are awesome! Thanks for helping me grasp this stuff a little better - some of it should have been pretty obvious to me but for some reason it just didn't take. Yes, the more I looked into what you were talking about the more I decided the price difference after returning the NW910's and getting strobes was negligible, after that I just had to decide how much was too much... I figured DG600 was a little more money but decent bang since the GN goes up to 190/ft or 58/meter at ISO 100. Since I don't NEED the portability and if I ever get to that point I will assume I am getting paid and can afford some battery packs lol.

Maybe I'll pick up some manual speedlites in the future to do some bare flash stuff instead

Also Bassat, thanks for pointing out the constraints you run into - looking at the internet almost all the studio spaces show the softboxes and lighting at a hefty distance from subject so going in I wasn't prepared for how close everything seems to need to be!

werds wrote in post #17992655
You guys are awesome! Thanks for helping me grasp this stuff a little better - some of it should have been pretty obvious to me but for some reason it just didn't take. Yes, the more I looked into what you were talking about the more I decided the price difference after returning the NW910's and getting strobes was negligible, after that I just had to decide how much was too much... I figured DG600 was a little more money but decent bang since the GN goes up to 118/ft. Since I don't NEED the portability and if I ever get to that point I will assume I am getting paid and can afford some battery packs lol.

Maybe I'll pick up some manual speedlites in the future to do some bare flash stuff instead

Also Bassat, thanks for pointing out the constraints you run into - looking at the internet almost all the studio spaces show the softboxes and lighting at a hefty distance from subject so going in I wasn't prepared for how close everything seems to need to be!

Yeah - on another forum I'm a member of we've had a recent discussion about the damn right misleading 'BTS' shots used by even some of the respectable lighting firms. Anyone that can read an image can see Profoto's advertising BTS are just bullshit.

werds wrote in post #17992655
Also Bassat, thanks for pointing out the constraints you run into - looking at the internet almost all the studio spaces show the softboxes and lighting at a hefty distance from subject so going in I wasn't prepared for how close everything seems to need to be!

Peruse the thread called Show us your setup and the final result, which is 650 pages of real BTS. In some of the tabletop examples, the modifiers are just about falling into the subject! Especially for broad light sources, you need to get close to generate the covering angles. If you pull back, the source area and flash power must be scaled exponentially. In the example below, I could barely get a visual on the subject:

RicoTudor wrote in post #17992717
Peruse the thread called Show us your setup and the final result, which is 650 pages of real BTS. In some of the tabletop examples, the modifiers are just about falling into the subject! Especially for broad light sources, you need to get close to generate the covering angles. If you pull back, the source area and flash power must be scaled exponentially. In the example below, I could barely get a visual on the subject:

That is an awesome thread! You just created one hell of a time waster for me now! Ok maybe it isn't wasted time but I will sure be spending a bit in there lol. Thanks! Already saw a few cool setups and results just in the first three pages.

Phil V wrote in post #17992638
However a speeedlight will have problems 'filling' a 47" softbox, remember that flash tube is surrounded by a little high efficiency reflector whose job is to focus the light into a narrow beam straight ahead, even at it's widest setting it'll struggle to create an even light pattern in a softbox over 30"..

With a flash zoom head set for 24mm coverage (FF) you must position it 47" away from the umbrella's surface in order to fill a 47" diameter umbrella.

Which is part of the reason I always deploy my diffuser panel when using umbrellas.

OK, although probably not a question for this thread - it still feels as if it pertains to this thread. I assume a handheld lightmeter would help? I mean from what I understand, I would hold the meter where the subject would be and it reads out the several combinations of required shutter/ f.stop/iso to get a proper exposure right?

How does that work in terms of it assuming the amount of light that will be provided by the lighting setup?

Wilt wrote in post #17992846
With a flash zoom head set for 24mm coverage (FF) you must position it 47" away from the umbrella's surface in order to fill a 47" diameter umbrella.

But he's using a 47" Octa with the flash mounted at the back