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Light meter recommendation for checking absolute lux/lumens?

7K views 23 replies 10 participants last post by  nathan_h 
#1 ·
Hey guys,

What’s the least expensive light meter that you guys would trust for checking the absolute nits/lumens from a projector? I’ve got a JVC projector with a lamp that I suspect is outputting below spec brightness, but Mike G has informed me that the cheapo $35 meter I’m using isn’t sufficiently reliable for that purpose. It’d be nice to have something reliable to setting proper aperture values etc as well.

Alternatively, would a colorimeter like the i1Display PRO be sufficiently accurate for what I’m talking about?
 
#2 ·
Hey guys,

What’s the least expensive light meter that you guys would trust for checking the absolute nits/lumens from a projector? I’ve got a JVC projector with a lamp that I suspect is outputting below spec brightness, but Mike G has informed me that the cheapo $35 meter I’m using isn’t sufficiently reliable for that purpose. It’d be nice to have something reliable to setting proper aperture values etc as well.

Alternatively, would a colorimeter like the i1Display PRO be sufficiently accurate for what I’m talking about?
Hi, I have tested several of the under $100 meters, I would recommend spending the extra $$ and getting a quality meter like the AEMC-CA813. it's been used by forum members for over 10 years and is the closest accuracy I've seen compared to my calibrated Minolta T10 ($1000+) which is a reference light meter.

https://www.amazon.com/AEMC-CA813-Function-Lightmeter-Resolution/dp/B008S0AHSY

 
#3 ·
The LX1330b was the worst one if that is the one you owned, it is worse than the LX1010b. LX1010b are fairly accurate, sometimes, but cannot say how consistent they are (you have to buy the one with the larger sensor). Sekonics are usually better than the AEMC one, if you can find a recent model used. That AEMC one can be accurate, but I've seen some people say it's off by up to 15%. The used Extech's are usually accurate, but again I cannot speak to consistency, as only owned 2.

Klein Tools has a light meter for $70 on Amazon, not sure if it's any good, but their other stuff is really good (like their volt meters).
https://www.amazon.com/Digital-Ligh...klein+tools+light+meter&qid=1579366221&sr=8-1
 
#4 ·
I've got one of these - https://www.certifiedmtp.com/sper-s...=c29a3091f4f87305e3197d7c887dff9a&fo_s=gplaus

SPER SCIENTIFIC 840020 LIGHT METER LUX/FC

I also got it with the Certificate of Calibration Traceable to N.I.S.T.
Select "Add NIST Traceable Certificate of Calibration" above to receive an additional NIST certificate of calibration that specifies that the standards against which the product has been certified or calibrated were themselves calibrated by the National Institute of Standards and Technology (N.I.S.T.), or with N.I.S.T. calibrated equipment under conditions specified by N.I.S.T.

Not too expensive but seems more accurate that the old AEMC - which I still have.
 
#5 ·
I've got one of these - https://www.certifiedmtp.com/sper-s...=c29a3091f4f87305e3197d7c887dff9a&fo_s=gplaus

SPER SCIENTIFIC 840020 LIGHT METER LUX/FC

I also got it with the Certificate of Calibration Traceable to N.I.S.T.
Select "Add NIST Traceable Certificate of Calibration" above to receive an additional NIST certificate of calibration that specifies that the standards against which the product has been certified or calibrated were themselves calibrated by the National Institute of Standards and Technology (N.I.S.T.), or with N.I.S.T. calibrated equipment under conditions specified by N.I.S.T.

Not too expensive but seems more accurate that the old AEMC - which I still have.
That looks like a good option since it has the calibration cert. I send my T10 out ~2 years for a recal. it's an expensive meter but still one of very few that can do accurate JVC contrast measurements.
 
#9 ·
Sekonic and Extech are the current industry leaders, but the Sekonics are real expensive. I had one before I sold it. Extech is just behind Sekonic, you can get Extech NIST certified too, but they are around $250+.

See this Top 10 list, 7 of 10 are Sekonic or Extech.
https://wiki.ezvid.com/best-light-m...9RhvlpFUMejXZakgJr30V9fhKFlr5FwoaAoGyEALw_wcB

However, the cheapest light meter with a NIST cert is probably the best deal, most likely...
 
#12 ·
#11 · (Edited)
#13 ·
You can get the same meter without the NIST from Walmart.com for $80, just FYI if trying to save money, but if you want to ensure accuracy, you need the NIST cert'd one...

https://www.walmart.com/ip/Light-Me...mLiQ5x5anM3ZH__dM-h6sDLJC1_rNkYsaAlQGEALw_wcB

That said, most of the light meters that have the NIST option are better than the ones without the NIST option, even if they are not NIST cert'd. However, may not apply in all situations.
 
#14 ·
Can we go back to the question about using a colorimeter like an i1 for this? Just about every calibration software package can read out in lux when the diffuser cover is in place. Aren't these values pretty reliable?


The OP just wants a lux meter, I get it, but since we're talking about saving money, surely the cheapest lux meter is 'don't buy a lux meter' which is an option if you have a colorimeter.


Obviously I'm talking about basic measurements of full white at the screen. If I needed to hold the thing two inches from the lens or needed accurate readings near black then yes I understand an i1 doesn't work.
 
#15 · (Edited)
Can we go back to the question about using a colorimeter like an i1 for this? Just about every calibration software package can read out in lux when the diffuser cover is in place. Aren't these values pretty reliable?

The OP just wants a lux meter, I get it, but since we're talking about saving money, surely the cheapest lux meter is 'don't buy a lux meter' which is an option if you have a colorimeter.
Yes and no, it can be depending on your screen uniformity, projector uniformity, screen material, gain, projected angle, and a bunch of other factors. Depends on the meter too, some are off at different color temperatures. Some colorimeters are too sensitive to angle and perfect positioning.'

As far as using the diffuser, I don't think it's accurate for a projector.
 
#16 ·
To be more specific, if I recall correctly, the Spyder4/5/X diffuser might work somewhat for lumens with a projector, since it can work for auto-cal. This would be a bit difficult and inconvenient to measure though, and you'd have to keep moving it to get the best result, then do the conversion calculations correctly. However, I believe the i1 and i1 Display Pro meters (2 and 3) series diffusers were not generally used for front projection due to inaccuracy.

Haven't tested it myself though...

The i1 Display Pro can take a relatively accurate reading off the screen though, which is only going to work well for a 1.0 gain uniform screen. Now this I have tested, it was pretty accurate, within about 10% or so.
 
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#21 · (Edited)
As a result of Craig’s use and recommendation of the Sper 840020C, was about to order. I called Sper to check stock, and while doing so asked about a model with more features (though unneeded) and a bit better form factor/button layout the 850006C model. I realize the 840020C has an option for LED color compensation as well, but this can be turned off, which then makes it essentially an 840020C. Sper said the accuracy is the same, but when looking at the data chart in each model’s user manual (under downloads/instruction manual) the data is a bit different, namely the range, resolution and accuracy parameters. On a follow up call, Sper told me that the lower the Resolution for a given Range the better for the application.

If any of you that know how to read the details of the charts, could compare the two models, and give feedback, that would be great. The 850006C is on sale for the same price as the 840020C presently, hence my interest.

After comparing the 2 charts, are both meters equally good to measure theater projector‘s light Lux/FC... to Lumens/Nits?

Thanks

840020C (see user manual for detailed spec chart)



850006C (see user manual for detailed spec chart)

 
#24 ·
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