Softbox Questions

Pinto wrote in post #9367646
Am I correct that the PCB box does not have an inner baffle? Wouldn't this be a significant reason for the hot-spot you reference?

There is inner baffle atleast on my PCB strip box.

Pinto wrote in post #9367646
Am I correct that the PCB box does not have an inner baffle? Wouldn't this be a significant reason for the hot-spot you reference?

Certainly the inner baffle is something of a 'hot spot killer' but it simply reduces and doesn't eliminate the hot spot. Different material and thicknesses will determine the amount of light loss from the panel. On the medium to larger modifiers there is light loss from center to edge and corner. That amount will vary and the transition from the hot spot to area surrounding the hot spot will vary.

Thank you for your responses. I don't think a baffle is mentioned in the box description, and with Rob's reference to a hot spot, I guess I made an assumption.

I'm trying to study this as much as I can before committing to purchase, and I see so many comments around the web about PCB boxes being economical and functional, but not built for the long haul. But I don't know how many of these comments refer to PCB's current boxes.

After some time and study, here is my assessment of opinions:
In medium priced boxes, Chimera has a very high overall satisfaction rating.
In the higher end boxes, excluding Profoto, which is prohibitively overpriced, people have a very high opinion of Plume boxes, which brings me to my question. I don't see any discussion, let alone recommendations, for Calumet's Illuma soft boxes, which apparently have a similarity, and relationship to the so-highly-thoughts-of Plume.

Love to hear your thoughts. Thanks.

Pinto wrote in post #9368066
Thank you for your responses. I don't think a baffle is mentioned in the box description, and with Rob's reference to a hot spot, I guess I made an assumption.

I'm trying to study this as much as I can before committing to purchase, and I see so many comments around the web about PCB boxes being economical and functional, but not built for the long haul. But I don't know how many of these comments refer to PCB's current boxes.

After some time and study, here is my assessment of opinions:
In medium priced boxes, Chimera has a very high overall satisfaction rating.
In the higher end boxes, excluding Profoto, which is prohibitively overpriced, people have a very high opinion of Plume boxes, which brings me to my question. I don't see any discussion, let alone recommendations, for Calumet's Illuma soft boxes, which apparently have a similarity, and relationship to the so-highly-thoughts-of Plume.

Love to hear your thoughts. Thanks.

As has been mentioned by many of us, the Photoflex product line is both economically priced as well as well built and excellent performers. There are many other excellent brands not being mentioned. Creative Light, Norman, Westcott, Elinchrom, Hensel, just to name a few.

Photoflex is a direct comparison to PCB, but it appears that Chimera is at the upper end of that price range but better quality than both. Any thought from anyone on Chimera?

Any thoughts on my Calumet Illuma question?

Pinto wrote in post #9368589
Photoflex is a direct comparison to PCB, but it appears that Chimera is at the upper end of that price range but better quality than both. Any thought from anyone on Chimera?

Any thoughts on my Calumet Illuma question?

Chimera is excellent in every way.

I know a lot of Chimera owners and users and they have nothing but great things to say about them.

Construction and materials really is outstanding on the Chimera gear.

TMR Design wrote in post #9368639
Chimera is excellent in every way.

I know a lot of Chimera owners and users and they have nothing but great things to say about them.

Construction and materials really is outstanding on the Chimera gear.

Thanks, Rob. Trying to learn.

Rob,
What would be the most revealing/accurate method of showing what the hot spot would be ? I have the PCB 30x60 and the 47 octa. I could test them with just the outer panel and then again with both the inner and outer in place.

george m w wrote in post #9369061
Rob,
What would be the most revealing/accurate method of showing what the hot spot would be ? I have the PCB 30x60 and the 47 octa. I could test them with just the outer panel and then again with both the inner and outer in place.

Hi George,

If I want to just see the hot spot or evenness or light I just point the modifier at the camera and fire a shot of the face of the modifier. I usually underexpose by about 2 stops first so I can see the hot spot and the falloff to the extreme and then shoot another that's 1 stop underexposed.

Play around with the inner and outer panels as well as no diffusion and check out the differences.

Thanks Rob, will do it. I wasn't sure if I would also need to attempt to take meter readings across the face of it. Sounds like I can do it just by shooting.

george m w wrote in post #9370993
Thanks Rob, will do it. I wasn't sure if I would also need to attempt to take meter readings across the face of it. Sounds like I can do it just by shooting.

If you're underexposing then you can see the hot spot and see the falloff but at times I will take readings to see how much loss there is from center to edge and corner.

When I meter the loss I do it 2 ways as a reference. I measure right against the front diffusion material and then I take a reading 2 feet away. If the loss is minimal at 2 feet then anything further away will be fine and well controlled.

Okay, let's try to quantify what Rob is saying regarding the PCB 30"x60" softbox and the 47" octobox.
I took multiple readings ( Sekonic L-358 ) on the surface and then again 2 feet away. I used power settings of 3/4 power and 1/2 power on an AlienBee B800. I used just one diffusion panel, the outer, then both inner and outer. (All PCB softboxes come with both panels )

In general what I found is this on the 30x60:

one panel, average difference from the hot spot in the middle area to the edge was point 4 stop ( a little under 1/2 of a f/stop ). Some readings were right at 1/2 stop difference. Two panels reduced the difference to an average of point 3 stop. Again, some readings were point 4 of a stop.

on the 47" octa, with both panels, the difference was again on average point 3 ( 1/3 ) stop.

In general testing I have found that all four of my AB B800's vary about point 1 to point 2 stop, pop to pop, so consider that too.
The attached photo might show the hot spot on your screen, maybe not. I can see it on mine.
I have no idea how this compares to other softboxes on the market made by other companies. PCB is the only softboxes I've used.

To the OP, you should probably consider the type of subjects you will be lighting before making a decision. If you are going to be shooting high end product where you need the absolute best control over all aspects of the lighting situation, like for instance where your work is going to be used in the graphics industry to be printed, then your clients are going to demand tight controls over exposure, both in general, and across the frame. They will also likely demand color to be very close to correct, etc. The more demanding your client, the better your gear, and your understanding of how to operate it needs to be. On the other hand, if you are like me, I'm just shooting mostly portrait type stuff, generally for fun, although I sell one or two of them....this AB stuff works fine for me.
Rob is more demanding than I am, because, well, first, he's better at this than I am, and two, he makes his living at this.

So there you go: you pays your money and you takes your choices.

EDIT: the attached photo had both inner and outer diffusion panels in place.

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Great demonstration, George. Thank you. I'm still a little confused about what causes the hot spot. Is it purely a matter of the efficiency of the box or does the strobe design come into play? This comment from Rob about the flash tube and back plate has me confused.

TMR Design wrote in post #9351754
I've never measured evenness of light so I can't comment on the amount of falloff of PCB modifiers. Quality of light is quite good from the PCB box but there is more of a hot spot as a result of the flash tube and back plate on the strobe.

Is this about the strobe, or the way the PCB box is fitted to it?

Maybe this will help. The backing plate is chrome, and as you can see, there is a rim of it showing once the modifier is mounted. On this shot, I increased the contrast a lot to show the difference beteen it ( where the red arrow points ) and the surrounding part of the mount. The difference is not that dramatic when you actually see it. I think what Rob is saying is that he suspects that very shiney surface behind the flashtube is contributing to the hot spot.

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george m w wrote in post #9372354
Maybe this will help. The backing plate is chrome, and as you can see, there is a rim of it showing once the modifier is mounted. On this shot, I increased the contrast a lot to show the difference beteen it ( where the red arrow points ) and the surrounding part of the mount. The difference is not that dramatic when you actually see it. I think what Rob is saying is that he suspects that very shiney surface behind the flashtube is contributing to the hot spot.

Thank you, George, that is very helpful. But if the backplate is to blame, wouldn't it create the same hot spot effect on every brand of box?