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Archive 2011 · Macro Ring Flash Distance and Brightness
  
 
kakomu
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p.1 #1 · p.1 #1 · Macro Ring Flash Distance and Brightness


I want to start photographing surfaces to use for texturing in 3D applications such as Maya. This typically involves setting a camera such that the film plane is parallel to the surface and using a long lens in order to minimize perspective (and with a macro lens, minimize barrel or pincushion distortion). For use in 3D applications, you typically want the texture to be evenly lit with no shadows (such that you can light the scene yourself and create your own shadows).

I could achieve a diffuse, evenly lit photograph if I were using some flashes with umbrellas, soft boxes or using a scrim, but I was hoping to carry around a minimal amount of gear. I can also photograph during a cloudy or overcast day, but waiting for that day could take a while and possibly mean rain (or snow).

I was thinking about ring lights.The vast majority of photographs I see with ring lights are either macro photos or in-your-face portraits with all of the telltale ring light artifacts.

However, I'm curious if ring lights can effectively be used to evenly light a subject from a distance. If I were to stand around 30 feet away from a brick wall with a ring flash, would it conceivably be powerful enough to light a wall? Or are ring flashes geared mostly toward photographing at close distances?



Dec 29, 2011 at 06:27 PM
jcolwell
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p.1 #2 · p.1 #2 · Macro Ring Flash Distance and Brightness


Ring lights are devised to give even lighting in the near field, as you need for macro. For a subject distance of 30 feet, a typical ring flash will apear to be a small point source, like a single 580EX, but less powerful.

For portable remote lighting, I have two 580EX, one 580EX II, and a pair of 420EX. I'd probably use all five flash for this task. I'd use a 580EX on the camera as master, with two of the others sitting on the ground (on their little plastic feet), and two others mounted on light-weight stands at about head height. I use the legs and posts for sheet music stands as my light-weight flash support stands. They're really inexpensive at music stores that supply school bands. You can use thin fibreglass tent poles (secured by gaffer's tape) to extend the raised flash to higher heights - the poles fit inside the music stand posts. You'll also need something to mount the raised flash on. I use a cold shoe attached to a DIY bracket that fits over the angled top-tube of the music-stand post. FWIW.


Edited on Dec 29, 2011 at 09:20 PM · View previous versions



Dec 29, 2011 at 09:00 PM
M Vers
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p.1 #3 · p.1 #3 · Macro Ring Flash Distance and Brightness


You do not need a tele lens to minimize distortion, a lens like the 50cm or, if you shoot APS-C, the EF-S 60 are both excellent in regards to distortion control. In terms of lighting, I'd agree with the above or you could go with two small strobes.


Dec 29, 2011 at 09:19 PM
jcolwell
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p.1 #4 · p.1 #4 · Macro Ring Flash Distance and Brightness


M Vers wrote:
You do not need a tele lens to minimize distortion,...


True. I'd probably use a tilt-shift lens for this; Canon TS-E 24/3.5L II, or a Mamiya M645 55mm or 80mm on Mirex adapter, depending.



Dec 29, 2011 at 09:28 PM
kakomu
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p.1 #5 · p.1 #5 · Macro Ring Flash Distance and Brightness


M Vers wrote:
You do not need a tele lens to minimize distortion, a lens like the 50cm or, if you shoot APS-C, the EF-S 60 are both excellent in regards to distortion control. In terms of lighting, I'd agree with the above or you could go with two small strobes.


Optical distortions aren't the only issue. 50-60mm on a crop camera still shows a fair amount of perspective, which is why I would opt to go for longer. It may not be readily noticeable as-is, but as soon as you start tiling the texture, the perspective on the opposite sides of the frame would become readily noticeable. 24mm especially would show perspective. I would prefer to shoot longer at 150mm-200mm, but the distance needed to shoot at that focal length would probably be prohibitive.

Also note the 2nd paragraph. I know I can evenly light a surface with several flashes (and accessories), but I want to attempt to shoot surfaces with as little gear as possible. If I wanted to photograph several surfaces in a city, walking around with a bunch of gear gets old fast.



Dec 29, 2011 at 09:43 PM
jcolwell
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p.1 #6 · p.1 #6 · Macro Ring Flash Distance and Brightness


kakomu wrote:
Also note the 2nd paragraph. I know I can evenly light a surface with several flashes (and accessories), but I want to attempt to shoot surfaces with as little gear as possible. If I wanted to photograph several surfaces in a city, walking around with a bunch of gear gets old fast.


Noted. That's why I posted what I posted. You mentioned many kinds of light modifiers. My suggestion included no modifiers or accessories.

Of course, you may have already made up your mind on what to use. In which case, why did you make the post? Perhaps you're looking for a spell; 'illumanitis maximus'.

P.S. If you want the best telephoto lens for high resolution and lack of distortion, then you should consider a Mamiya M645 A 200/2.8 APO. Unless of course, you already know what you want to use...


Edited on Dec 29, 2011 at 10:30 PM · View previous versions



Dec 29, 2011 at 10:17 PM
 

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BrianO
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p.1 #7 · p.1 #7 · Macro Ring Flash Distance and Brightness


kakomu wrote:
...I know I can evenly light a surface with several flashes (and accessories), but I want to attempt to shoot surfaces with as little gear as possible. If I wanted to photograph several surfaces in a city, walking around with a bunch of gear gets old fast.


From 30 feet or more, a single Speedlite on camera would be virtually shadowless on a flat, textured surface.

A macro-oriented ring flash wouldn't have much power to light from 30+ feet. If you do want to buy a ring flash, then you need something with more oomph; an Alien Bees ABR, for example. The least expensive option would be a Speedlite ringflash attachment like an Orbis or Rayflash.

http://www.ray-flash.com/rayflash/index.php

http://www.orbisflash.com/



Dec 29, 2011 at 10:30 PM
M Vers
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p.1 #8 · p.1 #8 · Macro Ring Flash Distance and Brightness


kakomu wrote:
Optical distortions aren't the only issue. 50-60mm on a crop camera still shows a fair amount of perspective, which is why I would opt to go for longer. It may not be readily noticeable as-is, but as soon as you start tiling the texture, the perspective on the opposite sides of the frame would become readily noticeable. 24mm especially would show perspective. I would prefer to shoot longer at 150mm-200mm, but the distance needed to shoot at that focal length would probably be prohibitive.

Also note the 2nd paragraph. I know I can evenly light a surface with several flashes (and
...Show more

I honestly don't think you'll notice any distortion at all using either of the lenses I suggested, just make sure you're shooting dead square/level to the surface to avoid any pp correction. It seems you want to light a large surface evenly with only one light source without any light fall off...if this is the case and you're expecting to accomplish that goal from 30ft away I'd imagine you would have difficulty doing so, particularly when using a single on camera speedlite/ringlite. Of course this also depends on ambient light.

On another note, have you thought of an AB ring flash? It'll give you more power in case you need it....

EDIT: Just noticed Brian already beat me to it...



Dec 29, 2011 at 10:53 PM
kakomu
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p.1 #9 · p.1 #9 · Macro Ring Flash Distance and Brightness


jcolwell wrote:
Noted. That's why I posted what I posted. You mentioned many kinds of light modifiers. My suggestion included no modifiers or accessories.

Of course, you may have already made up your mind on what to use. In which case, why did you make the post? Perhaps you're looking for a spell; 'illumanitis maximus'.

P.S. If you want the best telephoto lens for high resolution and lack of distortion, then you should consider a Mamiya M645 A 200/2.8 APO. Unless of course, you already know what you want to use...


i have no preconceived decision, nor am i looking to justify a decision. i am mostly looking to travel as light as possible and make the process of photographing surfaces as easy as possible.

as to 200mm, i think it would be prohibitively long (and probably too expensive).

M Vers wrote:
I honestly don't think you'll notice any distortion at all using either of the lenses I suggested, just make sure you're shooting dead square/level to the surface to avoid any pp correction. It seems you want to light a large surface evenly with only one light source without any light fall off...if this is the case and you're expecting to accomplish that goal from 30ft away I'd imagine you would have difficulty doing so, particularly when using a single on camera speedlite/ringlite. Of course this also depends on ambient light.

On another note, have you thought of an AB ring
...Show more

with shorter focal lengths, you'll notice objects start to lean toward the edges. i agree that it's probably not a big deal as an image (eg brick wall tests), but while it's subtle as a regular image, it sticks out like a sore thumb while tiling, much like keystoning to an architectural photog. i'll run some tests later to compare 50mm to 100mm, but i'm fairly sure it won't turn out well as a tileable asset.

as to the AB ringlight, i was under the impression that it requires an external battery to function, which sounds rather bulky to be honest. i already have a dual flash rig i can use, but was hoping i could use something much smaller.



Dec 29, 2011 at 11:33 PM
M Vers
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p.1 #10 · p.1 #10 · Macro Ring Flash Distance and Brightness


kakomu wrote:
with shorter focal lengths, you'll notice objects start to lean toward the edges.


Which is precisely why I mentioned that you must be completely square/level to the surface. A tripod would help with this.

as to the AB ringlight, i was under the impression that it requires an external battery to function, which sounds rather bulky to be honest. i already have a dual flash rig i can use, but was hoping i could use something much smaller.

The vagabond II is very light and compact, but it alongside the ABR is probably not as light and compact as a dual flash setup and more expensive as well.



Dec 29, 2011 at 11:52 PM
wilt
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p.1 #11 · p.1 #11 · Macro Ring Flash Distance and Brightness


The Canon MR-14EX macro ring flash has a full power Guide Number of 46' at ISO 100.
At ISO 400, that would be GN92'. From 30' away, that distance would require f/3.0



Jan 03, 2012 at 10:25 PM





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