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Sat Dec 12, 2009 7:42 am

Joined: Thu Dec 10, 2009 9:38 pm
Posts: 16

Can you describe the light quality and falloff characteristics of soft/octo-boxs vs. PLMs (silver or white) with and without diffuser?

Thanks...JOHN




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Sat Dec 12, 2009 11:41 am

Joined: Wed Dec 09, 2009 11:48 pm
Posts: 28

The white plm would probably be like a slightly more efficient umbrella when used reflected. the silver would be similar to a beauty dish but not as sharp a falloff but extremely similar to a beauty dish! I have 42" version and I have used it extensively now as both a softbox replacement and a large beautydish. The falloff is pretty sharp. The versatility is extreme when you combine the fact that you can add the diffuser fabric to mimic a softbox. The orientation of the fabric however make the light spread out like an ungridded softbox. But its ultra soft ligh with lots of power because the PLM does not appear to waste any light.



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Sun Dec 13, 2009 1:08 pm

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Joined: Tue Dec 08, 2009 11:49 am
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jrsforums wrote:
Can you describe the light quality and falloff characteristics of soft/octo-boxs vs. PLMs (silver or white) with and without diffuser?

Thanks...JOHN

Any modifier with diffusion fabric (softbox, white umbrella, etc) will have a very broad falloff - typically around 150°. The same applies to a white beauty dish.

Silver PLMs have a very focused output, with sharp falloff outside the main pattern, But because of it's size, the main pattern is quite wide in terms of area actually lit. When the white front diffuser is added to PLM it's angle of coverage is vastly increased and is similar to a softbox.

The High Output Silver Beauty Dish has a narrow (45°) central pattern but feathers out to about 100°. Adding the diffusion sock causes it to perform pretty much like a softbox or white BD, with 150° coverage and lower output.



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Tue Jan 25, 2011 1:56 pm

Joined: Tue Jan 25, 2011 1:53 pm
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I was just looking for a large softbox with a 40 degree grid and was wondering if there is a PLM combination that would offer similar light?

Thanks!




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Tue Jan 25, 2011 3:00 pm

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Joined: Tue Dec 08, 2009 10:43 am
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A silver PLM will give you a similar beam spread, but with more contrast and specularity. A white or diffused silver PLM would give you similar "softness", but at a significantly wider beam spread. So, no, there is not a PLM combo that gives exactly the same light as a grided softbox.



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Tue Jan 25, 2011 3:21 pm

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Joined: Tue Dec 08, 2009 11:49 am
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Technical Support wrote:
A silver PLM will give you a similar beam spread, but with more contrast and specularity. A white or diffused silver PLM would give you similar "softness", but at a significantly wider beam spread. So, no, there is not a PLM combo that gives exactly the same light as a grided softbox.


The silver PLM has a much narrower beam and sharper cutoff than a softbox with 40° grid, and about 3 f stops more output.



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Thu Feb 24, 2011 12:21 am

Joined: Mon Feb 21, 2011 8:25 am
Posts: 11
Age: 39

Luap wrote:
Silver PLMs have a very focused output, with sharp falloff outside the main pattern, But because of it's size, the main pattern is quite wide in terms of area actually lit. When the white front diffuser is added to PLM it's angle of coverage is vastly increased and is similar to a softbox.


Based on the articles that I've read and Youtube videos I've seen about the PLM, I get the idea that does the job of most other modifiers of its kind much more efficiently. That job is to increase the effective size of the light source. Instead of diffusing the light as it moves toward the subject as soft- and octaboxes do, it simply reflects the light parabolically (is that a word?) so that the rays are parallel to each other moving toward the subject. The intensity throughout the beam is relatively equal, unlike the other modifiers.

Now given that it has greater efficiency, and you get a similar effect to soft/octaboxes when the PLM is used with a diffuser, is there any reason to use anything other than PLMs? Do grids on those other modifiers really change the light pattern all that much?




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Thu Feb 24, 2011 10:35 pm

Joined: Fri Dec 18, 2009 11:50 am
Posts: 306

frugivore wrote:
Now given that it has greater efficiency, and you get a similar effect to soft/octaboxes when the PLM is used with a diffuser, is there any reason to use anything other than PLMs? Do grids on those other modifiers really change the light pattern all that much?


Yes...controlled soft light. Use it indoors and you'll know why you need controlled light. Outdoors, it matters a lot less.

If there were a grid that could be slipped over a silver PLM w/ diffuser, then you wouldn't need a gridded octabox.




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Fri Feb 25, 2011 12:49 pm

Joined: Sat Dec 12, 2009 3:29 pm
Posts: 15

has anybody tried adapting the 47" octobox grid to a PLM? perhaps by making a deep rim out of coroplast and fitting the grid to the rim. also, does anyone stack multiple grids to get a 25 or 30 degree grid look? i am getting a nice hard edge using two grids on a stripbox.




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Fri Feb 25, 2011 9:46 pm

Joined: Fri Dec 18, 2009 11:50 am
Posts: 306

amplexis wrote:
has anybody tried adapting the 47" octobox grid to a PLM?


I'm fairly sure the 47" octa has less surface area than the 86" PLM....




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