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FORUMS General Gear Talk Flash and Studio Lighting 
Thread started 02 Jul 2015 (Thursday) 05:28
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How much parabolic are parabolic light modifiers ...

 
nixland
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Post edited over 2 years ago by nixland.
     
Jul 02, 2015 05:28 |  #1

I just found this site :

http://onemediacenter.​com/ (external link)

update : the website content of that link has changed. I found other website where you can download the parabola calculator pc app (freeware) here :

http://mscir.tripod.co​m/parabola/ (external link)


where we can draw a parabolic curve with variation parameters.
So I tried to google some of the parabolic modifiers and find a matching curve for each of them.
The black dot in the axis line is the location of focus point (our barebulb strobe).

As you can see in the picture, the Broncolor, PLM and Rime Lite are quite parabolic while the Westcott Zeppelin and Profoto umbrella are not.

I have the Paul Buff PLM, Rime Lite 120cm and Aurora Tera D (same as Westcott Zeppelin).
Though the Aurora is not true parabolic, I like its light output.

Any other parabolic modifiers I should check? :)


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Left ­ Handed ­ Brisket
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Post edited over 3 years ago by Left Handed Brisket. (2 edits in all)
     
Jul 02, 2015 09:06 |  #2

cool project.

I will say that while having a perfect parabola and the resulting light might be important in some cases, having less focused light can also be what is desired. So really all that matters is what is coming off the front of the modifier.

That said, :D see what you can find for this one.

http://www.cheetahstan​d.com/product-p/p7-d.htm (external link)

screen caps from video on that page. The first is probably the best one to use, but I included them both so you can see that it is close to a side profile … it was hard to pause it at exactly the right moment, but you can see that the flash bracket is right at the front of the umbrella.



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PSA: The above post may contain sarcasm, reply at your own risk | Not in gear database: Auto Sears 50mm 2.0 / 3x CL-360, Nikon SB-28, SunPak auto 322 D, Minolta 20

  
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Left ­ Handed ­ Brisket
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Jul 02, 2015 09:51 |  #3

so after posting the screen grabs i went to that website

here's what I came up with, x 260 focus 115:


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PSA: The above post may contain sarcasm, reply at your own risk | Not in gear database: Auto Sears 50mm 2.0 / 3x CL-360, Nikon SB-28, SunPak auto 322 D, Minolta 20

  
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GregDunn
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Jul 02, 2015 10:53 |  #4

Glad to see someone checking the manufacturer claims and giving best-fit results!

Keep in mind that the bulb is also not a point source, so you will get some spread based simply on the fact that some of the light will be emitted both in front of and behind the actual focus.

I have also tested the Quantum QF63 which is a somewhat truncated parabolic, and while it does produce a concentrated beam, the fact that it's really too short causes a lot of "sidelobe" pattern effect. Having a long conic section, even if it's not a perfect parabola, helps concentrate the light. I stuck a "collimator" cone onto the Cheetah/Godox 360 standard reflector and got quite a bit more light in the center at the cost of some unevenness.


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nixland
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Jul 03, 2015 00:51 |  #5

GregDunn wrote in post #17618079 (external link)
Glad to see someone checking the manufacturer claims and giving best-fit results!

Keep in mind that the bulb is also not a point source, so you will get some spread based simply on the fact that some of the light will be emitted both in front of and behind the actual focus.

I have also tested the Quantum QF63 which is a somewhat truncated parabolic, and while it does produce a concentrated beam, the fact that it's really too short causes a lot of "sidelobe" pattern effect. Having a long conic section, even if it's not a perfect parabola, helps concentrate the light. I stuck a "collimator" cone onto the Cheetah/Godox 360 standard reflector and got quite a bit more light in the center at the cost of some unevenness.

Agree. There is a spill when using my PLM, as seen in the picture below.
Not much problem but I am working on making a DIY spill kill plate to solve it (but still have no time to do it right now :) ).

For deep parabolic modifiers I made a DIY rod to reverse the strobe, to eliminate direct light forward. The rod also used as a focusing rod if I want to vary the character of the output. This all inspired by the senior member of this forum, the DIY Master, Dave "tetrode" :).


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RicoTudor
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Jul 04, 2015 11:40 |  #6

Left Handed Brisket wrote in post #17617954 (external link)
I will say that while having a perfect parabola and the resulting light might be important in some cases, having less focused light can also be what is desired. So really all that matters is what is coming off the front of the modifier.

Very true about desirability. The Profoto NarrowBeam reflector is essentially parabolic (a paraboloid), and it images the the bulb when projected onto a wall: very efficient, but not the ideal pattern for your subject! It works better to bounce such light for an indirect purpose. Many stage lights are designed for direct illumination of the subject, and the ellipsoid shape is preferred to generate a less precise, but still directional, pool of light.


Canon, Nikon, Contax, Leica, Sony, Profoto.

  
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abbadon31
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Post edited over 3 years ago by abbadon31.
     
Jul 04, 2015 12:53 |  #7

Some bracket inspired by master shom ;)

IMAGE: https://farm1.staticflickr.com/473/18791946543_507d9258ce_z.jpg

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windpig
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Jul 04, 2015 15:44 |  #8

abbadon31 wrote in post #17620505 (external link)
Some bracket inspired by master shom ;)

IMAGE NOT FOUND
| Byte size: ZERO | Content warning: NOT AN IMAGE

Uh, MacGyver has nuttin' on you.:-P


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I'm accross the canal just south of Ballard, the town Seattle usurped in 1907.

  
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jmaher
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Jul 04, 2015 16:06 as a reply to  @ abbadon31's post |  #9

I am confident that these are all great. However a quick look at them and it seems like a display for medial weapons, mace morning star, etc that you might see in a museum :)




  
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GregDunn
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Jul 04, 2015 20:06 |  #10

The Quantum QF63 reflector appears to be designed for long range illumination, not necessarily light quality. Interestingly, it does seem to do a pretty good job at projecting light while not wasting too much at the edges for such a small unit. I took a couple of shots last night with mine pointing at a wall 30 feet away, with and without the bulb extender. With the extender, it does a 30-degree beam with about 1-stop falloff outside that width. Incidentally, the center is overexposed on purpose - I set the nominal exposure based on the standard 5" reflector to see how much "gain" I got with the QF63. It's roughly 2 stops, as claimed.


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Canon 1Dx | 5D3 | 7D2 | 6D | 70-200L f/2.8IS | 70-200L f/4 | 24-70L f/2.8 | 24-105L f/4IS | 100-400L f/4.5-5.6IS | 17-55 f/2.8IS | 50 f/1.8 | 28-105 f/3.5-4.5 | 4x Godox AD360

  
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abbadon31
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Jul 04, 2015 20:48 |  #11

Quantum QF63 reflector w/ Extender at about 50 feet awesome compact reflector with high output. This and Greg's post clearly shows that it all about bulb placement in the modifier.


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nixland
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Post edited over 3 years ago by nixland.
     
Jul 04, 2015 22:32 |  #12

abbadon31 wrote in post #17620505 (external link)
Some bracket inspired by master shom ;)

QUOTED IMAGE

Whoah, awesome!

This is my poor unprofessional focusing rod ..haha:)
The strobe to rod adapter is too long. I still find time to make the new improved one.


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nixland
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Jul 04, 2015 22:41 as a reply to  @ abbadon31's post |  #13

By the way, does this Quantum reflector fit Witstro AD head slot?




  
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abbadon31
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Jul 04, 2015 22:51 |  #14

nixland wrote in post #17620916 (external link)
By the way, does this Quantum reflector fit Witstro AD head slot?

Quantum QF63B - Deep Parabolic Telefoto Reflector will fit all the godox 180 /360 the flash extender ( depends on which version you get) that is needed may and my not fit the 360, but works on the 180s just fine.

The version I have fits both 180/360


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GregDunn
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Jul 05, 2015 00:55 |  #15

Yes, my photos are using a CL360. The bulb extender needed to have 2 of its pins sanded down a bit to fit the CL360 socket. Everything else was perfect.


Canon 1Dx | 5D3 | 7D2 | 6D | 70-200L f/2.8IS | 70-200L f/4 | 24-70L f/2.8 | 24-105L f/4IS | 100-400L f/4.5-5.6IS | 17-55 f/2.8IS | 50 f/1.8 | 28-105 f/3.5-4.5 | 4x Godox AD360

  
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How much parabolic are parabolic light modifiers ...
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