Let's talk about Lighting

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Let's talk about Lighting

Postby DonnaA » 28 Nov 2010, 05:09

Hi all,
I would like to start a topic specifically about lighting for DIY book scanners. LED lights, fluorescent lights, CFL lights -- what have you tried, what have you measured, and what works for you?

-- DonnaA
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Re: Let's talk about Lighting

Postby DonnaA » 28 Nov 2010, 05:11

Has anyone checked out this newest Zebralight headlamp?

http://www.zebralight.com/H51-Headlamp- ... _p_37.html


LED: Cree XP-G Cool White (color temperature 6100-6500 K)
User Selectable Levels: 3 main level (High, Medium and Low). Each main level can be configured to one of its two sub-levels. The second sub-level of the High can be further configured to different brightness levels or strobes.
Light Output
High: H1 200 Lm (0.9 hrs) or H2 140 Lm (1.7 hrs) / 100 Lm (2.4 hrs) / 4Hz Strobe
Medium: M1 30 Lm (12 hrs) or M2 8 Lm (39 hrs)
Low: L1 2.5 Lm (3 days) or L2 0.2 Lm (16 days)
Light output are out the front (OTF) values. Runtime tests are done using Sanyo 2000mAh Eneloop AA batteries.
200, 140, 30, 8 and 2.5 Lumen output are current regulated. 100 and 0.2 Lumen output are PWM generated.
Voltages: 0.7V - 2.5V
Battery: One 1.5V AA (NiMH, lithium or alkaline). 14500 Li-ion batteries are not supported. Batteries are not included in the package.
Parasitic Drain: Negligible (equivalent to 16 years)
Beam Type
80° spill beam spread
11° (3.8 feet at 20 feet) hot spot
Dimensions
Diameter: 0.90 inch (23 mm)
Length: 3.2 inch (81 mm)
Weight
1.2 oz (35.8 gram)
2.2 oz (61.9 gram) with an Eneloop AA
3.0 oz (84.9 gram) with an Eneloop AA and headband
Features
Electronic soft-touch switch, with a 200,000 cycle operating life
Smart user interface provides fast and easy access to all brightness levels
Precision machined unibody casing from premium grade Alcoa aluminum bar stock
Proprietary heat sinking design bonds the LED board directly to the unibody aluminum casing, providing unblocked thermal paths to over 94% of the surface area.
Durable natural hard anodized finish (Type III Class I)
SCHOTT ultra clear lens with anti-reflection coatings on both sides
Orange peel textured reflector
Glow In The Dark (GITD) silicone ring near the tail cap
Battery power can be locked out by slightly unscrewing the tailcap to prevent unwanted activations or parasitic drain
Waterproof to IPX8 (1 meter 30 minutes)
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Re: Let's talk about Lighting

Postby Moonboy242 » 28 Nov 2010, 10:27

I'm certin there are a whole bunch of technical details that I don't know, but...

"Lighting. Though not archivally appropriate, I prefer the brightness of floody daylight halogens. Get Edison "Reveal" or other daylight halogen Par38 bulbs with bubbly lens. Quantity: 2."

The best way I know to sum this up is that really good quality lighting helps produce really good quality photos of your subject. Lots of clear, well aligned, well focused photos do not require a whole lot of individual correction and result in faster processing and output times. Garbage in = garbage out. :) I personally use halogen bulbs in a darkened room for my scanning.

As for portable scanning rigs... I don't have one. I do know that there are a whole slew of flashlights out there that can produce serious lumens. The question is a matter of how long will the battery last, and how long will the lens, body, and LCD circuit board withstand the high temperatures that high peformance lights put out. I personally prefer flashlights that use AA or AAA batteries to the more exotic "CR" type batteries due to price and availablity (particularly when the Zombie Apocalypse comes ;) ). My guess would be that a portable scanning rig is best served by bringing along some smaller sized clamp lights that use standard high output light bulbs.

Hope that helps.
iPad: Over it. Android FTW.
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Re: Let's talk about Lighting

Postby ceeann1 » 28 Nov 2010, 14:47

I think this thread is applicable:
viewtopic.php?f=1&t=40&start=0
It is,"LED lighting systems for book scanning."

Inside the above mentioned thread is a note about xenon HID high intensity discharge arc lamps. The one pictured by turtle is a car headlight bulb. A well vetted and proven illumination technology.

Cabe has remarked a bit further along in that thread that there are some problems with that tech in that it can give off UV light and that it would require a ballast to start the light.

I propose using these lights indirectly with a reflector and a diffuser to get high intensity light in a package that will fold (that should take care of UV and protection). Although these lights need some real electrical engineering it seems to have been done long ago in cars. The rest should be a straight forward if not an easy task.

My real concern is whether this type of bulb will produce light in the range of the sorts of cameras most popularly used for scanners here on this forum. Can someone answer that question?
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Re: Let's talk about Lighting

Postby ceeann1 » 28 Nov 2010, 15:29

I came across this while looking for a circuit that would work for HID lighting. I think this is slick. The maker, Wangtrirat says,”This is my Home Made Super Cheap Metal Halide Ballast and Igniter can use on Mercury vapor or High pressure Sodium Lamp too.This is Super Cheap System i've made about $33.33 and A Lamp i've bought for $14.54 (all that currency transform from Thai Baht).

This system can power up a 150W Metal Halide lamp by using 4 40W Fluorescent Ballast and ignite with 12V fluorescent ballast for a car that produce about 700V to make the lamp arc over and after that it will power on all ballast and turn off igniter,That's it it's works.All of fluorescent ballast is get hot as it normally use no problem while using.”

The video is low quality but is interesting:
http://www.youtube.com/watch?v=3I20K1zYmJw

I have included the circuit diagram he posted:
Metal Halide DIY Ballast.gif
Metal Halide DIY Ballast.gif (29.63 KiB) Viewed 8084 times
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Re: Let's talk about Lighting

Postby will1384 » 28 Nov 2010, 17:18

ceeann1 wrote:I came across this while looking for a circuit that would work for HID lighting. I think this is slick. The maker, Wangtrirat says,”This is my Home Made Super Cheap Metal Halide Ballast and Igniter can use on Mercury vapor or High pressure Sodium Lamp too.This is Super Cheap System i've made about $33.33 and A Lamp i've bought for $14.54 (all that currency transform from Thai Baht).

This system can power up a 150W Metal Halide lamp by using 4 40W Fluorescent Ballast and ignite with 12V fluorescent ballast for a car that produce about 700V to make the lamp arc over and after that it will power on all ballast and turn off igniter,That's it it's works.All of fluorescent ballast is get hot as it normally use no problem while using.”

The video is low quality but is interesting:
http://www.youtube.com/watch?v=3I20K1zYmJw

I have included the circuit diagram he posted:
Metal Halide DIY Ballast.gif


A few things, I learned from my DIY projector days

(1) Years ago I got a 150w Metal Halide electronic ballast for $75 on eBay, so you might want to check eBay
(2) Metal Halide lamps are close to, and some are, brighter than the sun is in the sky, so you need eye protection
also they put out UV, lots of it, even the lamps that have UV shielding will give you a sun tan
(3) Skin oil, from you touching the lamp will make it explode, use cotton gloves when handling the Lamp
(4) The lamp gets hot, real hot, the 250w one I had in a DIY projector put a constant amount of heat
around that of a blow drier on max, I used it to heat my room in the winter, touching a lit lamp will
not only remove a huge chunk of skin burning you in the process but cause the lamp to explode, likey
causing more injury with flying super-heated glass shards
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Re: Let's talk about Lighting

Postby ceeann1 » 29 Nov 2010, 02:05

UV is going to be produced. No doubt about it. Very little of the UVA band will penetrate the diffuser. I believe the correct diffuser, a combination of glass and plastic, would allow a very tiny amount of UVA to leak through. Sorry just am not concerned about that problem.

Of bigger concern is design around the heat production. But really is it a lot worse than two flood lamps? Ducted vents and a fan in a metal enclosure sounds right.

The remaining concerns are proper use of equiptment. I appreciate the tips and they are very well put! Thanks!

My biggest concern is money and space. This looks like the most expensive and space eating option. Sigh... The ballests, electrical needs, and enclosure are genuinely the largest needed of several options. Not the best option for a machine that is supposed to fold flat.

This is also a high amperage option. In what I have explored today the start up ignition can take over 15 amps and 3 amps to maintain. Seems a bit much to light a book.

It seems I have been barking up the wrong tree. I am also exporing another option with LED and will also look into plain old tungsten. I doubt the heat problems will be worse.

This seems a bit of a hodge podge of statements but its late... gnite all.
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Re: Let's talk about Lighting

Postby daniel_reetz » 29 Nov 2010, 02:07

I am of the opinion that LED is the only way to go for portable scanners. For all other designs, all other lighting options are alright, but for portables, nothing beats the cost, size, and weight savings of LED. But they should be power LEDs, like Cree Q5s.
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Re: Let's talk about Lighting

Postby vitorio » 29 Nov 2010, 02:51

Moonboy242 wrote:Though not archivally appropriate, I prefer the brightness of floody daylight halogens.


What is considered archivally-appropriate lighting?
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Re: Let's talk about Lighting

Postby Misty » 29 Nov 2010, 10:34

vitorio wrote:
Moonboy242 wrote:Though not archivally appropriate, I prefer the brightness of floody daylight halogens.


What is considered archivally-appropriate lighting?


UV-shielded lights. The exact type doesn't matter too very much, but avoiding UV exposure to documents is important. UV is bad for documents because even relatively short-term exposure causes some level of irreversible ageing to the paper which builds up over time. UV exposure is what causes the brittle paper and colour shifts you're probably familiar with from old paper. It helps to avoid lights which are known to release lots of UV (sunlight, halogen), though an effective UV filter over the light reduces the risk. You also need to be careful of heat from light sources like halogen. If you're interested in knowing more on that, the Canadian Council for Archives's "Red Book" is a good resource.

Aside from that, archivally speaking you also want a light with a predictable, solid colour temperature. Getting correct colours on your image depends in part on getting a correct white balance, and the best way to do that with minimum work is to know the temperature of your light before you get started. You want to make sure the light is one that can be relied on to stay at that colour longterm as well, since many lights drift in brightness and temperature over time.
The opinions expressed in this post are my own and do not necessarily represent those of the Canadian Museum for Human Rights.
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