Greetings peeps, this post will serve two intents, one to review the Photone app (with the diffuser), and the other to compare it's output to that from my el cheapo so called "par meter".
This is the par meter that I have been using for a couple years:
Ignore the cord wrap around the wire, the unit has never been damaged in any way, I put that on simply to support the cord where it would otherwise be bent back and forth. There are various versions of this meter available online, I expect that they are all similar in quality, but can't confirm that.
As a result of the recent symptoms, I finally did more homework and tried the Photone app (available in the Apple app store, or Google play for Android users) Initial tests with a paper diffuser suggested that my par meter was underestimating light intensity roughly by 30% or so. However, paper diffusers vary, so to make sure that I was using the app to its full potential I ordered the proprietary diffuser. It arrived well packed as well as early early relative to expectations. Here are pictures of the diffuser and the stuff that came with it.
The small storage bag was included so that the diffuser is kept clean. Keeping it clean is needed to ensure the effectiveness of the calibration.
Comparative Results:
I tested both the par meter and the photone setup with four different light sources, three in my 'drobe in varying positions under my grow lights, and one under a ceiling fluorescent. I purchased the app add on which calibrates to full spectrum LED, and know that this would potentially make the fluorescent reading incorrect, but threw that test in just to see how the comparison varies between different light types. Each comparative reading was done with the two meters reading in exactly the same position. I made certain that the Photone app was set to diffuser accessory, and full spectrum LED calibration.
The four readings were 207,195, 339 and 96 (flourescent) for the Photone app, and 184,168, 303, and 88 respectively for the par meter. Averaged across all tests, the par meter was ~13% too high. Not as bad as the paper diffuser suggested, but still potentially a problem. Given the persistent symptoms that I have been dealing with, I suspect that at least for my lights, the overestimate by the par meter was at least this much, maybe more. In any case, I have reduced light intensity accordingly, and will continue doing that in future.
Impressions of the Photone app:
I loaded the app onto my IPhone 14pro. When the app opened, it confirmed that it was calibrated specifically for that phone. The app worked instantly without any programming issues that I noticed, it just worked as intended. The instructions were professionally prepared by someone fluent in English, and they are comprehensive, missing nothing as far as I could tell. Operation of the app is dead easy. The app even provides an outline on the phone screen that allows precise centering of the diffuser over the camera lens. I have rarely encountered an app as well designed, documented and behaved as this one.
As part of my homework, prior to loading the app, I reviewed the online information provided by the company and was impressed by the thoroughness of their their explanation of the technology involved. It certainly appears that the company has done a careful job of calibrating the app. As I have mentioned elsewhere in this forum, using a phone camera to measure PAR should be doable in theory, but doing so with any degree of accuracy would be impossible without calibration of the specific phone camera to light sources of interest. It is clear from the company's descriptions that this calibration has been done carefully, and the summary test data they present suggests that accuracy for calibrated phone models is somewhere in the vicinity of 2% which is far more precise than needed by us growers.
During the course of this mischief, I had contact with the company and found them willing to thoughtfully respond to enquiries. When I ordered the diffuser, I was surprised to notice that the price included international shipping by courier, and I did not have to pay extra for getting the courier package across the border. The package arrived with tracking, quickly, and without anything further from me. The free shipping needs to be kept in mind before assuming that the price is high. I do not think it is, at least not for international customers. International shipping would likely have cost me as much as the purchase price The diffuser is very well made (in Switzerland according to the label), fits perfectly on the phone, and readings using it seem consistent and repeatable.
All considered, had I known what I think I do now, I would have gone with Photone in the first place rather than spending a couple hundred bucks on a cheap par meter. It seems that Photone is more accurate, likely far more durable, and a tiny fraction of the price. For what it is worth, I highly recommend photone if a grower owns a phone for which the app is calibrated. I also recommend the diffuser, it will ensure the full effectiveness of the calibration done for specific phones.
This is the par meter that I have been using for a couple years:
Ignore the cord wrap around the wire, the unit has never been damaged in any way, I put that on simply to support the cord where it would otherwise be bent back and forth. There are various versions of this meter available online, I expect that they are all similar in quality, but can't confirm that.
As a result of the recent symptoms, I finally did more homework and tried the Photone app (available in the Apple app store, or Google play for Android users) Initial tests with a paper diffuser suggested that my par meter was underestimating light intensity roughly by 30% or so. However, paper diffusers vary, so to make sure that I was using the app to its full potential I ordered the proprietary diffuser. It arrived well packed as well as early early relative to expectations. Here are pictures of the diffuser and the stuff that came with it.
The small storage bag was included so that the diffuser is kept clean. Keeping it clean is needed to ensure the effectiveness of the calibration.
Comparative Results:
I tested both the par meter and the photone setup with four different light sources, three in my 'drobe in varying positions under my grow lights, and one under a ceiling fluorescent. I purchased the app add on which calibrates to full spectrum LED, and know that this would potentially make the fluorescent reading incorrect, but threw that test in just to see how the comparison varies between different light types. Each comparative reading was done with the two meters reading in exactly the same position. I made certain that the Photone app was set to diffuser accessory, and full spectrum LED calibration.
The four readings were 207,195, 339 and 96 (flourescent) for the Photone app, and 184,168, 303, and 88 respectively for the par meter. Averaged across all tests, the par meter was ~13% too high. Not as bad as the paper diffuser suggested, but still potentially a problem. Given the persistent symptoms that I have been dealing with, I suspect that at least for my lights, the overestimate by the par meter was at least this much, maybe more. In any case, I have reduced light intensity accordingly, and will continue doing that in future.
Impressions of the Photone app:
I loaded the app onto my IPhone 14pro. When the app opened, it confirmed that it was calibrated specifically for that phone. The app worked instantly without any programming issues that I noticed, it just worked as intended. The instructions were professionally prepared by someone fluent in English, and they are comprehensive, missing nothing as far as I could tell. Operation of the app is dead easy. The app even provides an outline on the phone screen that allows precise centering of the diffuser over the camera lens. I have rarely encountered an app as well designed, documented and behaved as this one.
As part of my homework, prior to loading the app, I reviewed the online information provided by the company and was impressed by the thoroughness of their their explanation of the technology involved. It certainly appears that the company has done a careful job of calibrating the app. As I have mentioned elsewhere in this forum, using a phone camera to measure PAR should be doable in theory, but doing so with any degree of accuracy would be impossible without calibration of the specific phone camera to light sources of interest. It is clear from the company's descriptions that this calibration has been done carefully, and the summary test data they present suggests that accuracy for calibrated phone models is somewhere in the vicinity of 2% which is far more precise than needed by us growers.
During the course of this mischief, I had contact with the company and found them willing to thoughtfully respond to enquiries. When I ordered the diffuser, I was surprised to notice that the price included international shipping by courier, and I did not have to pay extra for getting the courier package across the border. The package arrived with tracking, quickly, and without anything further from me. The free shipping needs to be kept in mind before assuming that the price is high. I do not think it is, at least not for international customers. International shipping would likely have cost me as much as the purchase price The diffuser is very well made (in Switzerland according to the label), fits perfectly on the phone, and readings using it seem consistent and repeatable.
All considered, had I known what I think I do now, I would have gone with Photone in the first place rather than spending a couple hundred bucks on a cheap par meter. It seems that Photone is more accurate, likely far more durable, and a tiny fraction of the price. For what it is worth, I highly recommend photone if a grower owns a phone for which the app is calibrated. I also recommend the diffuser, it will ensure the full effectiveness of the calibration done for specific phones.
