Modifier Sizes

[rpcrowe]

When dealing with round (umbrella) or octagon (Octabox) modifiers, it is obvious that at the same distance from the subject, the larger modifiers should provide softer light than the smaller modifiers (given that the modifiers have the same approximate construction). As an example a 47 inch Octabox should provide softer light than a 22 inch Octabox.

When you are using a square modifier (such as a softbox) the larger size modifier (given the same modifier to subject distance) should produce a softer light than a smaller modifier. As an example a 32 inch softbox should produce softer light than an 18 inch softbox.

However when we are considering rectangular modifiers, does the same theory apply. In other words will a 24 x 48 inch softbox produce a softer light than a 24 x 24 inch square softbox.

OR

Will it produce light of the same approximate soft quality but, over a larger area?

[Manfred M]

Two different issues are at play here Richard:

1. Size of the modifier; and

2. Distance from the subject.

Ideally, the modifier will be close to the subject; the closer the better. The light will start to get harder as one pulls further back from the subject and this starts becoming noticeable once the modifier is further than 2x the diameter (for umbrellas or octaboxes) or 2x the diagonal for rectangular modifiers. Most photographers I know try to keep the modifier 1x the diameter or diagonal away from the subject, if at all possible.

What this means is that a small modifier needs to be closer to the subject than a larger one. The biggest mistake I see when people use light modifiers is when they put them too far away from their subjects. Once the move too far away, they become little more than point sources and the light can be quite hard.

I did some shooting with a 6' x 6' butterfly (essentially a scrim) that was just above the subject and light using a boomed softbox. The light was unbelievably soft.

[rpcrowe]

Then the diagonal size of the rectangular modifier is the key, rather than the square area. Or is it that usually a modifier with a greater diagonal is usually of a greater square area? Given of course, that the modifier to subject distance from modifier to subject is the same and, of course that the construction of the modifiers are equivalent.

At a recent presentation, I was very impressed with an octabox which I estimate to have been about 60 inches in diameter which was placed within less than three to four feet of the subject. There was no other lighting involved but, the results were exceptionally soft and quite pleasing. The presentation was a demo of tethering and thus very little information was provided regarding the equipment used for the shooting...

I have just purchased and am waiting for the arrival of a Godox 120cm/47 inch Portable Octagon Softbox. basically a large umbrella with a diffuser on the open side.
https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1


The strobe on a light stand is inserted into the umbrella through an access at the bottom and the umbrella rod is then inserted into the S Bracket of my 360 TTL strobe.

This is a very inexpensive and very light weight way to carry around a rather sizable modifier which is also quick to set up and break down. The total cost of the unit was $26.99 USD including shipping...


I could also use this rig with one to three hot shoe flashes (which I already own) on a 3-flash bracket which I also own.

[Manfred M]

Then the diagonal size of the rectangular modifier is the key, rather than the square area. Or is it that usually a modifier with a greater diagonal is usually of a greater square area? Given of course, that the modifier to subject distance from modifier to subject is the same and, of course that the construction of the modifiers are equivalent.

Just to make sure that we are writing about the same thing, this is essentially all about placing the key light. I find that I handle the other light sources differently and they are often further away, but as their light contribution is lower or concentrated on a particular area of the subject or the scene.

For regular rectangular softboxes I find that the "rule" works reasonably well. I also find it is good for octaboxes, umbrellas and beauty dishes. If I feather my lights, I find that the rule applies, even though the light only hits the subjects obliquely.

As with any "rules of thumb", there are exceptions. For instance, strip boxes are long and narrow and while I rarely use them as key lights, I find that I tend to place them more closely than the "rule" suggests.

Standard reflectors, that I tend to use as accent lights (hair lights, background lights) are so small that the light tends to be hard. This is generally what I am looking for in these instances.

When it comes to octaboxes, the general advantage over rectangular reflectors is the shape of the catch lights; they are round. This makes them a more pleasing shape. The light falls off a bit more irregularly as well,

[Hanginon]

I have just purchased and am waiting for the arrival of a Godox 120cm/47 inch Portable Octagon Softbox. basically a large umbrella with a diffuser on the open side.

For the money, this looks excellent, but how do you access the flash's controls once it's inside, if you have a totally manual flash? You might have to be a contortionist sticking your hand up through the stand hole, and do it by "feel"? Surely, constantly having to remove the velcro front will be a PIA - probably best with a remotely controlled one.

[Manfred M]

For the money, this looks excellent, but how do you access the flash's controls once it's inside, if you have a totally manual flash? You might have to be a contortionist sticking your hand up through the stand hole, and do it by "feel"? Surely, constantly having to remove the velcro front will be a PIA - probably best with a remotely controlled one.

Remote controlled radio triggers are pretty well the only way to go these days. Depending on the brand, they can be quite inexpensive to quite pricey.

Some of the higher end speedlights now come with built in receivers. External receivers that either use the camera's TTL metering system or can be manually controlled are the way to go for some of the older units (whether these are speed lights, studio lights or something in between). These are attached to the flash hot shoe and the camera hot shoe mount.

[rpcrowe]

For the money, this looks excellent, but how do you access the flash's controls once it's inside, if you have a totally manual flash? You might have to be a contortionist sticking your hand up through the stand hole, and do it by "feel"? Surely, constantly having to remove the velcro front will be a PIA - probably best with a remotely controlled one.

I use the Godox (Flashpoint, Cheetahstand, etc.) flashes and remote triggers,

This setup is quite easy to use and is relatively inexpensive (triggers run from around $40 USD for the XT-1 to a bit over $60 USD for the Pro model).

The flashes are also relatively inexpensive and can be had for as little as $60 USD new for the all manual model to $110 for the TTL model. The larger 360 TTL model flash kits (including battery pack, charger and cord) are running for $300 from Adorama and pack a lot power into a lightweight and relatively reasonably inexpensive unit.

All of the Godox (type) flashes have built-in transceivers and can either function as remote slaves or as master transmitters. The flashes can be controlled remotely (either individually or in designated groups) from either a transmitter or from a flash on camera. You can adjust the power manually and/or dial in flash exposure compensation with flashes that are capable of TTL exposure.

They are also capable of HSS and second curtain sync.

The Godox line of flash modifiers also includes a wide range of relatively inexpensive accessories including umbrellas, octaboxes and softboxes. The S Type mount (available at under $20) will enable you to use any hotshoe flash as well as the larger 200 and 360 size Godox flashes with any Godox modifier as well as any modifier from other suppliers that has a Bowens S Mount.