:: View topic - Christmas LED
 Forum Index
An online community devoted to the practices of photomacrography and amateur microscopy..
 
New! Photomacrography2.net
 
This site is no longer available for posting or registering new members.
 FAQFAQ   SearchSearch     UsergroupsUsergroups   
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Christmas LED

 
This forum is locked: you cannot post, reply to, or edit topics.   This topic is locked: you cannot edit posts or make replies.     Forum Index -> Macro and Close-up Photography Gallery
View previous topic :: View next topic  
Author Message
rjlittlefield



Joined: 06 May 2005
Posts: 727
Location: Richland, WA, USA

PostPosted: Fri Dec 23, 2005 11:29 pm    Post subject: Christmas LED Reply with quote

Combining some of our favorite topics, I have made a Christmas LED macro for you Very Happy



Cropped more tightly (and not blinking Wink )


LED's are very cool devices, if you will pardon the pun. Through some high technology that I don't really understand, they convert electric current directly to light. You can find gobs of info about them on the web. For a particularly tongue-in-cheek treatment, see this one. Cool

What you see here is a single LED, viewed simultaneously from two angles by looking through the top and side faces of its transparent plastic case.

As I understand it, the light is actually emitted from the rather thin junction between two types of semiconductors, which I guess must lie just below the top of the translucent cube where the band of brightest red is. The cube sits inside what appears to be a parabolic reflector, which I presume is designed to direct the light outward so it can be seen.

You may be amused by the various hoops that I had to jump through to make these pictures.

For starters, the standard plastic cases of these LED's have matte surfaces, great for diffusing the emitted light but not so great for imaging through. My first thought was to polish the plastic. But plastic polishing is not one of my best skills. I worked down from 600-grit cloth to rubbing compound to rouge, but still the surface was too rough. I applied several coats of a lacquer-like plastic finish. Still too rough. Finally I uttered a mild obscenity and decided to oil the dang thing. Olive, extra light. That worked great!

Then I started taking pictures. But you know (duh...), LED's are really bright! They normally operate on 20 milliamps of current. But there was no way that I could illuminate the supporting structure and still see the LED at anything approaching that brightness. So I threw in a large variable resistor and started cranking the current down.

Things were going pretty well...until one of the bare wires touched the clip vise I was using...and shorted out the limiting resistor...which made the LED draw a whole lot of current...which really did generate some heat...apparently quite a lot of heat, in fact...because then I had these funny little bubbles on the surface of the plastic case, right over all the metal parts.

No problem, I said...I have a lot more of these cheap little things in the junk box. And indeed I did. So I sanded another one smooth, slapped on a coat of oil (olive, extra light)...and discovered that the new LED's plastic was translucent, not transparent. Back to the junk box (sigh). Fortunately, I had another one (of 10) that actually had transparent plastic -- apparently I had grabbed a transparent one the first time by accident. OK then, back to business!

Things went relatively well after that.

The final pictures were shot in raw mode with my Canon Digital Rebel, 55mm lens reversed on bellows to give 3X onto the sensor. (The LED case is 4.9mm wide.) ISO 100, F/11 setting, 1/3 second. LED current 0.6ma, fill illumination from a 45W flood 4" from the case. In Photoshop, some color "corrections" to neutralize some of the unremittingly red appearance, and some sharpening to compensate for, well, I don't really know what but it looked better sharpened. The flashing image was done by photographing with the LED on and off, and rendering through Adobe ImageReady to an animated GIF.

I hope you enjoy this, and that it finds you well and having Happy Holidays! Very Happy Very Happy

--Rik
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Ken Ramos
Site Admin


Joined: 04 May 2004
Posts: 4809
Location: Western North Carolina

PostPosted: Sat Dec 24, 2005 3:29 am    Post subject: Reply with quote

Pretty neat post Rik! I have occassionally wondered about what makes and LED tick. Pretty cool, especially GIF and Happy Holidays to you too! Surprised
_________________
Site Admin.
Kenneth Ramos
Rutherfordton, North Carolina
Kens Microscopy
Reposts of my images within the galleries are welcome, as are constructive critical critiques.
Back to top
View user's profile Send private message
S. Alden
Site Admin


Joined: 29 Apr 2004
Posts: 2780
Location: Pennsylvania, USA

PostPosted: Sat Dec 24, 2005 4:11 am    Post subject: Reply with quote

This is so neat Very Happy . Love the gif too. Thanks for posting and Happy Holidays to you as well.
_________________
Sue Alden
Administrator
Repost of my images are welcome
Back to top
View user's profile Send private message Send e-mail Visit poster's website
rjlittlefield



Joined: 06 May 2005
Posts: 727
Location: Richland, WA, USA

PostPosted: Sat Dec 24, 2005 10:40 am    Post subject: Reply with quote

For the unusually curious[*], here's the setup.


[*] People often call me "curious". Sometimes they mean "inquisitive", sometimes they don't. Think Very Happy

That spring-loaded parallelogram thing is an old enlarger stand, modified for fine height adjustment. It's described in detail at http://www.janrik.net/PhotoAdapters/index.html. The green thing with the vise sitting on it is a two-axis milling table, see the discussion here.

--Rik
Back to top
View user's profile Send private message Send e-mail Visit poster's website
MikeBinOKlahoma



Joined: 20 Nov 2004
Posts: 1491
Location: Umm....Could it be Oklahoma?

PostPosted: Mon Dec 26, 2005 8:55 pm    Post subject: Reply with quote

rjlittlefield wrote:

[*] People often call me "curious". Sometimes they mean "inquisitive", sometimes they don't. Think Very Happy


When I get that way, people usually just call me nosey! Very Happy

What a neat animation in the original shot. Thanks for sharing it.
_________________
Mike Broderick
_____________________________________________________________
"I must obey the inscrutable exhortations of my soul.....My mandate includes weird bugs."--Calvin

(reposts on this site of my images for critique or instruction are welcome)
Back to top
View user's profile Send private message
pwiles1968



Joined: 18 Dec 2004
Posts: 307
Location: Leicestershire. UK.

PostPosted: Thu Dec 29, 2005 1:51 am    Post subject: Reply with quote

Interesting Post, you appear to have adequate illumination so why did you need the "Extra Light" Idea does that work in a similar way to the LED Laughing
_________________
Paul - Everywhere you look there is something to see.
My Gallery It's not much but it's Mine.
Back to top
View user's profile Send private message Send e-mail Visit poster's website
rjlittlefield



Joined: 06 May 2005
Posts: 727
Location: Richland, WA, USA

PostPosted: Thu Dec 29, 2005 10:45 pm    Post subject: Reply with quote

Paul,

The floodlamp was not to increase light level, but to control light direction.

The shot was actually made with room lights turned off, to avoid numerous distracting reflections from the LED faces.

Positioning the flood close to the LED made it easier to light up the shiny metal supports as I wanted.

Having less dark[*] was helpful, but not critical. With just the room lights, exposure time would have been 10 seconds instead of 1/3 second, still easily doable.

--Rik

[*] Have you read what I called the "tongue-in-cheek treatment"?
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Display posts from previous:   
This forum is locked: you cannot post, reply to, or edit topics.   This topic is locked: you cannot edit posts or make replies.     Forum Index -> Macro and Close-up Photography Gallery All times are GMT - 7 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB 2.0.6 © 2001, 2002 phpBB Group