WTS: Calibration lights for DIY integrating spheres / lumen tubes - 67 € -

garrybunk · 2020-02-06T17:09:53.000Z

hcanning:

Hi guys,

After a little break from the lumen measuring game, I have binned the crappy old lumen tube I made, and built myself an integrating sphere.

One 25cm polystyrene ball from Amazon and about an hour of my time later, and this is what I have crafted:

What the photos don’t show is some paper over the inside of the entry holes to bring the light level down a bit, as higher powered torches were saturating my meter.

It does appear that my meter’s accuracy is biased toward cool white as previously discussed, but when using the correction factor from my calibration S2+ for CW lights the figures appear spot on:

Olight M2R NW - 18800 lux - 0.08 cf - 1504lm
Olight X7R - 132000 lux - 0.08cf - 10560lm
Astrolux C8 - 14100 lux - 0.08 cf - 1128lm
BLF A6 w/ spring bypass - 20300 lux - 0.08cf - 1624lm

For warmer lights the correction factor from my calibration BLF 348 (0.07) was too low. I have considered a few lights which have consistent “known” lumen outputs and decided that a CF of 0.094 appears to work for now. This gives me the following:

Emisar D4s (XP-L HD 3D) - 51300lux - 4822lm
Emisar D4v2 (SST-20 5000k) - 45300lux - 4258lm
Emisar D18 (SST-20 5000k) - 148600lux - 13968lm
BLF FW3A (XPL HI 7A) - 28600lux - 2688lm
BLF Q8 (XPL HD 3D, bypassed springs, brass screws) - 66100lux - 6213lm

I know this is all going to give rough figures but I believe at this point I can at least be fairly accurate with my readings?

Is there anything I’m doing wrong or particularly need to improve?

Thanks!

Hi hcanning, how is your sphere performing, specifically at higher output levels? Reason I ask is that I am seeing inconsistency with mine between lower lumen levels and higher lumen levels as posted here. I see your sphere has a complete opening at the luxmeter rather than just being pressed up against the foam like mine is (see pics of mine posted here). I also am not using any diffusion material in mine, nor am I blocking the entrance hole with anything other than the light itself (and maybe part of my hand at times. I need to figure out what I’ve done wrong with my sphere and how to correct it for more trustworthy results.

Thanks,
-Garry

maukka · 2020-07-12T08:12:25.000Z

One more set of 2x Convoy S2+, XM-L2 (low CRI, cool white) and SST20 (high CRI, neutral white) available from the latest batch. Price for the kit is still 67 € including international shipping.

TimMc · 2020-08-22T05:28:36.000Z

Interested

pol77 · 2020-10-07T15:24:45.000Z

I need to purchase a calibration kit please, as soon as you can manage. I am located in London.

I am interested in measuring all kind of lights, from 2000K 95+ CRI to 7500K 70 CRI. What calibration kit would you recommend for me? Do you think the CW low CRI + NW high CRI will work well?

maukka · 2020-10-07T15:44:59.000Z

Unfortunately I don’t have any lights in stock right now. There hasn’t been much interest lately and I don’t know when I will order the next batch.

pol77 · 2020-10-07T15:47:38.000Z

I can order what lights you need and have them delivered to your preferred address. Would that work for you?

maukka · 2020-10-07T16:45:25.000Z

That’ll work. I’ll hit you with a PM.

pol77 · 2020-10-07T16:57:04.000Z

Thanks. Let me know the details and I will make arrangements at once

maukka · 2021-01-10T16:59:39.000Z

After rummaging my stock I’ve found one S2+ & BLF348 kit for sale if someone’s interested.

edit: this is now reserved

TimMc · 2021-01-12T09:32:03.000Z

Lights arrived. Thanks!

maukka · 2021-01-12T09:41:13.000Z

Haha, goot to hear! What was that, 3-4 months?

TimMc · 2021-01-16T08:36:06.000Z

maukka:

What was that, 3-4 months?

Yeah, about 4 months. I thought it may have been lost :partying_face:

ArtieT59 · 2021-03-12T15:19:56.000Z

Is it possible to buy calibrated lights anywhere atm? Or does anyone recommend an off the shelf light that can be used? Thank tou!

beam0 · 2021-10-03T14:56:37.000Z

ArtieT59:

Is it possible to buy calibrated lights anywhere atm? Or does anyone recommend an off the shelf light that can be used? Thank tou!

I recently got back into flashlights and set up my tube the other day, it seems quite accurate but I’m thinking a calibration light would be a good idea.

So although it’s been 7 months here with no reply, I’d like to know this too!

Tom_E · 2021-10-03T14:58:46.000Z

You would have to ask maukka - oops, he hasn't been on for 6 months, or find an owner willing to sell. What I and couple others did was mail the lights around so I had one shot at using them.

ArtieT59 · 2021-10-03T15:13:58.000Z

Tom E:

You would have to ask maukka - oops, he hasn't been on for 6 months, or find an owner willing to sell. What I and couple others did was mail the lights around so I had one shot at using them.

I was thinking, if one was able to "borrow" some calibrating lights, and you set up your lumen tube with them. Could you then find 3 lights in your collection that are as stable as possible (one light around 300-500lm, one thrower, and one high power 3000-4000lm) and then take their calibrated measurements. then you would send the calibration lights on their way and know that you have 3 lights that are your "standards" to calibrate the lights off of moving forward. is that a good idea? or not as simple as it sounds?

ToyKeeper · 2021-10-03T15:33:17.000Z

ArtieT59:

if one was able to “borrow” some calibrating lights, and you set up your lumen tube with them. Could you then find 3 lights in your collection that are as stable as possible (one light around 300-500lm, one thrower, and one high power 3000-4000lm) and then take their calibrated measurements. then you would send the calibration lights on their way and know that you have 3 lights that are your “standards” to calibrate the lights off of moving forward. is that a good idea? or not as simple as it sounds?

Yes, it works fairly well, and it’s a good idea. You’ll probably need to calibrate your light box / tube more than once. Like, it’s usually good to check the calibration before each measurement session. Things can change between, like if the sensor moves even a little bit, it can throw off future readings. But verifying calibration frequently can help avoid that.

Just be sure the reference lights you choose are truly stable… because something needs to be stable to make any of this work.

Tom_E · 2021-10-03T16:15:51.000Z

Agree, could work

chops728 · 2021-10-03T17:04:19.000Z

you could reverse this option —mail a regulated light you own to some one with a calibrated Tube — they could give you some real readings on a light you already own — just a thought

Lumencraft-Matt · 2023-08-25T15:20:41.491Z

Maukka have you ever used your integrating sphere to measure UV?