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New Product Announcement - Nitecore MT06MD 180 Lumen Nichia 219B LED Penlight

NitecoreStore

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Nitecore MT06MD 180 Lumen Nichia 219B LED Penlight

180 lumen with three brightness settings
High CRI, neutral white output
Operates on 2x AAA batteries
Weighs 0.78 ounces before battery installation

15% OFF with CPF15OFF Coupon Code
Purchase at NITECORESTORE.COM








15% OFF with CPF15OFF Coupon Code
Purchase at NITECORESTORE.COM










15% OFF with CPF15OFF Coupon Code
Purchase at NITECORESTORE.COM

 
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Zak

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I really appreciate that Nitecore is making and actively promoting a significant number of high-CRI lights. Outside of dedicated throwers, pretty much anything that comes in to my hands with a CRI under 80 gets an emitter swap.

I do see one issue with the intended use case: 4 lumens from a 219B with a reflector is a bit much to have shined directly into the eyes from a close distance. That will produce 19 candela from this light. A lower low, between 0.1 and 1 lumens would be nicer.
 

Lumencrazy

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That would be total candela. But I do not think that medical practitioners place the lens of the flashlight directly on the eye. Less that 25% of the light will likely be reaching the pupil. If they specify it for medical personnel maybe they actually did the trial work. Lights for examining the pupil have been made for decades. No need to guess at the candela requirements, the data is already out there.
 
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Zak

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No need to guess at the candela requirements, the data is already out there.

Is it? I couldn't find it in a few minutes of searching Google. The best I came up with were anecdotes in CPF threads. One says the Liteflux LF2XT is too bright for his patients' eyes on the low setting, but Preons aren't "concentrated" enough. Selfbuilt's review of the LF2XT says low is 0.12 lumens, high is 50 lumens and he measured 310 candela on NiMH. That gives us 0.74cd for low. Selfbuilt's reviews for Preons around the same era show 46cd for a 1xAAA Preon. So that's a bit contradictory and not at all helpful.

If you know where to find an actual controlled study, that would be awesome. Barring that, even an instrumented test of a light that has been popular for examining the pupil for decades would be very helpful.
 

Lumencrazy

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The medical industry does not resort to candlepower forums for technical advice. This is a consumer forum.
 

Zak

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I've seen a fair number of posts here and on reddit saying "I'm a doctor/nurse/paramedic/etc... and I want a pen light suitable for pupillary checks", and I have not found medical journal articles talking about any photometrics for flashlights for use for this purpose. So yes, it does look like at least on occasion, people working in the medical industry do resort to consumer forums for advice on flashlights.

The fact that something is common practice in a profession, even a sciency one like medicine doesn't necessarily mean that it has been studied in detail. If the data is out there, by all means, we should compare it to Nitecore's product. I'd like to do that, but I can't find it and I suspect the data might not be out there. If you know about actual data on this subject being out there, please share with the group.
 

Lumencrazy

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What I cannot find is the word "sciency" in any dictionary:). If you have not had any training I would suggest that you do not start shining lights into peoples eyes (especially LED. The harmful effects are known and not knowing is no defense in a court of law). That would be very irresponsible and could get you into a lot of trouble if you injured someone.

Nevertheless here
is a place to start. From here you can work back and get to the real science. It gets very advanced very quickly. .http://www.ledsmagazine.com/article...logical-safety-standards-part-2-magazine.html Notice, that in Europe there are even legal requirements, so I am surprised you could not find any info. This information goes back more than 7 years.

Just a simple snippet "...In viewing a source, the eye collects light within a given solid angle set by the diameter of the pupil, and projects an image of the source onto the retina. As the pupil dilates (or contracts) according to the level of visual stimulus, or luminance, of the source, the retinal irradiance of the image increases (or decreases).The law of conservation of radiance states that radiance cannot be increased by passive optical systems such as the lens of the eye. The retinal irradiance is therefore determined from the source radiance and the solid angle subtended by the pupil (2-7-mm diameter) at the retina (17-mm distant) in the reverse of the determination of radiance from irradiance, given below.," and etc.

The standard provides specific guidance on the geometrical conditions under which these measurements should be made to take into account biophysical phenomena, such as the effect of eye movements on retinal irradiation. The spectral range over which radiance should be considered is reduced to 300-1400 nm, since the retina is essentially protected outside this range due to the transmission characteristics of the lens. Table 1 indicates the required measurement (radiance or irradiance) for different hazards. And so on!

Look Up IEC62471:2006 standard "Photobiological Safety of Lamps and Lamp Systems"
From here you can work back by doing a thorough literature review (scientific articles not opinion blogs or Reddit). If you are well versed in doing scientific literature searches (Not Google.Yahoo, Bing, Safari and etc.) you will discover that there is a whole other world out there where scientists and specialists go for and publish information. Unfortunately most of these search engines are highly specialized and are paid services since they are very specific in nature and are not funded by advertisements.



Photochem Photobiol.
2000 Feb;71(2):225-9.
Transmission spectra of light to the mammalian retina.

Dillon J1, Zheng L, Merriam JC, Gaillard ER.
Author information



Abstract

A simple method has been developed to determine the optical properties of the anterior segment of the intact eye. This consists of a probe that is inserted into the posterior sclera and detects light passing through the anterior segment. The probe is connected to a charge-coupled device spectrophotometer via a fiber optic bundle. It was determined that the young rat anterior segment transmits light down to 300 nm, whereas calf and rabbit eyes transmit no UVB and only part of the UVA to the posterior segment. The absorbing species in these animals is most likely NAD(P)H, which has an absorption maximum at approximately 345 nm and is associated with zeta-crystallin. A young primate anterior segment transmits almost no UV with a steep increase in transmission at CA 400 nm. Because some experiments employed a light tube that is used to illuminate the retina during vitrectomies, this method can be used to determine the transmission spectra of the anterior segment of humans in vivo.

There are literally hundreds of research papers!


PMID: 10687398

 
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Johnnyh

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Well...it looks like a nice penlight even if you're not an EMT or medical pro. The high CRI would make it great for wiring or machinery inspection.
 

Lumencrazy

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Isn't technology great. AAA batteries high CRI in a compact light. No longer have to carry around a 2 pound flashlight with 10 D-Cell batteries as a back up just for the evening.
 

Zak

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I can find information on what kind of light sources will cause eye injury, but that's not what I was asking about here. I'm asking whether there is anything published anywhere other than flashlight forum posts about the ideal intensity of a flashlight for pupillary examinations. Most such posts talk about patient comfort as a primary concern. More formal sources I can find on the subject, such as this medical textbook do not discuss the characteristics of the light to be used.

Google Scholar is a reasonably effective way to find scientific research, though not necessarily to read it since so many journal articles are behind paywalls. A couple searches there did not reveal articles that appeared likely to contain any research on the ideal light source intensity or desired illuminance hitting the pupil to conduct a pupillary examination. I do not believe the data is out there. If it is, please say where.
 

Lumencrazy

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Johnnyh

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Looking at the Nitecore site, no PMW as well. I like it more...have seen some complain of the predecessor (MT06) low mode PWM and weak clip. Maybe they fixed both?
 

Lumencrazy

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Looking at the Nitecore site, no PMW as well. I like it more...have seen some complain of the predecessor (MT06) low mode PWM and weak clip. Maybe they fixed both?

I only fear that if something happens to me, my wife will sell all my sh*t for what I told her I paid for it.:oops:
 

Zak

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Honestly, did you read the IEC standard and inquire about the RGO rating and go from there?


In fact, I did. I found limits for UV, IR and blue light exposure, as well as guidelines for estimating blue light risk groups based on the color temperature and illuminance of white light. A light source can put several thousand lux of warm white light on someone's eye and still be RG0. Again, we're talking about risk of eye injury here, not whether it will work well for a pupillary examination.

Have you considered asking manufacturers of eye examination equipment. Many of them out there too.
http://www.ophthalmologyweb.com/Opht...and-Equipment/


I looked for other handheld lights specifically marketed for medical use. Your link doesn't appear to have any, but there are some, like the Welch Allyn Penlite, which uses a halogen incandescent source. I found intensity measurements of 17 and 22 candela for different versions of it in CPF posts. The manufacturer does not state its intensity. It is not marketed specifically for performing pupillary examinations and most discussion I've seen from people using lights for that purpose thought other lights that produced similar intensity were too bright.

So my assertion remains that the data isn't out there, and the minimum mode of Nitecore's new light is a little high for its advertised purpose.
 

Zak

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PWM is pulse width modulation, a means of adjusting brightness by blinking the light rapidly and varying the length of the blinks. It's easy for a driver designer to use, but when it's too slow, the flicker is visible. Even when it's fast, it can create artifacts in photos taken with an electronic rolling shutter, like a smartphone.
 

Timothybil

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My sister is a trauma rated RN in a Level 2 trauma center. I have offered to buy her a light like the MT06MD, but she declined. She says they have more than enough penlights from the sales reps giving them away. Back in the incan days I saw a couple of those, and they were dim enough that I am sure they would work just fine. As far as I am concerned, I don't feel any pain from a retinal exam, but the bright light is just disturbing. Of course, just looking at a birthday candle for a little bit will produce an afterimage, so I will be the first to admit to a rather uneducated position on the topic, and let the more pedantic duke it out.
 

krutone

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So my assertion remains that the data isn't out there, and the minimum mode of Nitecore's new light is a little high for its advertised purpose.

Nitecore and other medical optics manufacturers could easily identify the correct intensity through testing. The data generated from this type of testing is valuable and a trade secret, and can't be Googled.

A physician tested the mt06md on Jon M's review on youtube and said the intensity was bright enough to be used in a lit room, but dark enough to not cause temporary blindness.
 
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5S8Zh5

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There is lots of useable light well outside of the hotspot to test someone's pupil dilation without directly shining a light at someone's eyeball.
 
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