NikonGear'23
Gear Talk => Other => Topic started by: Andy on April 11, 2016, 22:23:03
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Got a Sekonic C-700R Spectrometer (http://www.sekonic.com/austria/products/c-700r/overview.aspx) a while ago as advanced light meter. It is not only able to measure light levels in ambient and flash light, but the C-700R can also measure SPD (spectral power distribution) over the visible light range (380-780nm) in 1 nm steps.
It is nice to see not only the average total luminosity, but where it is coming from - in case you are curious why for instance white balance didn't work out as expected, or why the noise level in one channel is particular high.
Here is an example of the spectral response of the Nikon D700 Color Filter Array (other models might deviate from this curve)
http://www.maxmax.com/nikon_d700_study.htm
Please find below some examples I took (a few spectral lines seems to be missing - need to check how to get rid of these missing lines, but they don't impact the overall picture of the distribution)
8am in the morning, blue sky. The sun hasn't raised yet over the mountains around us
(https://fsubjg-dm2305.files.1drv.com/y3mAMCBWtp9trsNLdhfG92eV_7W7BqtHvqvhb99t7uO_IgAtOZv6aMiRRzjJWLjfKI17wrrGLR44l7-PBZ1NM55lUY_1TT_Y_We5pJnwqHHTJGgj2EeOy-GcIw_ivRADFP2dFWiYDHyZntXKMWMbE9OOLTpc366AehlJYBRM6AjtKU?width=884&height=659&cropmode=none)
1pm, at 2000m above sea level, blue sky, the spectrometer directed to the sun
(https://fiubjg-dm2305.files.1drv.com/y3m9nbPEumV6wsdFfStLrQ07p3-FsXItH9eGFzP7gOpzn5jEOG1UXsmlMWhcLYbYBd4lxPnmX8HfKsG_NCB88WasU_lSoI0UanS3kGYqueFLaB2TV9Au9kyCmCX0puQc-X30lCtD4qc0UEdCPQ7tg00vhsnIpRO5bGbN6N9U_bQdPg?width=884&height=659&cropmode=none)
evening, light overcast, directed away from the direction the sun went down. The sun wasn't visible anymore
(https://fcubjg-dm2305.files.1drv.com/y3mVToTeOEeDiUL_ybQ5TAGzSFkQ5mIahWPE_XCxTW1XLiNJJE9paFqILZhKis6emgAkV-NHhe99fOFE9reIRWGLX2OiS9y7cjmu0oT8dBhvd-aa_CO1Ih9U6mSX5sFUPsSGH5Xbq6t5My-PFJ_mwNUI3mwSPpRXBjBQEUO5RDKxSM?width=884&height=659&cropmode=none)
rgds,
Andy
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In the street of the city - sodium high pressure light
There is just no blue or very low level of green the camera can properly recover from.
(https://ecubjg-dm2305.files.1drv.com/y3mJtRPcukrHJlbiEJSbBEX-EHegNGEzDJHENmHTLwv-BHW1NjC6BPirx7wgS1wJ1uFpSOXBR2saBpjncYquSpmFPkwMfBTh2wT5jfJuzG-ZS8pNnSVn_te-Qd2NzUCe9QvlQfeHIpNhLjmi85NIyds9dtwYY5907ZbE_mn_h9n2IU?width=884&height=659&cropmode=none)
in the street of the city - fluorescent tube
(https://hyubjg-dm2305.files.1drv.com/y3mK3UjTWQtlOS9VGV8rJqr6bG4_3_ywfPtQcRRpgif3697hVGrfhPHBtKJgG86X7jnoQI9yMdLtdr_Kb7woAeAbgvUY7aoI4OslTvh5JARNEiohyrbHi6l4hkJej2iw_VZVwEzrJiX3Uo5k8YP3DgVfokX03eRMTBRsIl0hiVMxUw?width=884&height=659&cropmode=none)
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at home
halogen bulb
Nice to see the very famous noise in the blue channel is coming from. There was no energy in the blue channel to start with ...
(https://hiubjg-dm2305.files.1drv.com/y3mDcl9BGYoYIXkoc8XEByRbqEujKF1h2tSmcdACFvNX4mduVxrmdM2JxM3YqAiMtAuLCisyP26-WzPhXAHCV1xpRODbCJZSLO5gI6PDBig5YiS0geI7TWPBrqmuR86RYuui8FPqavJakjOsntx1OoEVa4c5wuUPtR_JWn3hzMs5JA?width=884&height=659&cropmode=none)
Energy saving bulb - warm white
(https://fivmsq-dm2305.files.1drv.com/y3m066vEXe--DfPUbeHO4IjbYtpd-PbnrzDaZNFJJCzvGz4PLjStGa31cNzJ3N8mQ0bg7pJww6OCTANuueTuoeLX98fQyXNUJFHr5QZFrHQmj9-jPicPhl5Lw1r-_eezLb6GUL3JrXBDpQ2VSJIPPq0IE5Q1IsUwUSQHU6QLjQCJCU?width=884&height=659&cropmode=none)
LED bulb
(https://fsvmsq-dm2305.files.1drv.com/y3mKLv4JrdSgMk4nl2Z1z7fCt1Tb1vOl8yP7BFnv40w2d4hsAhCSIm_xB02unRvC82NmbSq6cMIMWrosbdEpYJmije8arD1czRIWIvY6QbCC-VSck-OcmFAoOav6j4U-ZZWn409T5v7iA-p5sBjkC8sK9A7lP-rSFKIvg4RiNQyOPw?width=884&height=659&cropmode=none)
"Daylight" bulb of photographic light system (CRI > 95)
(https://eyvmsq-dm2305.files.1drv.com/y3mEqkvaEjCaMkeXAE7eYqI_sE-KWYONRkkj6Qh8-quqY-XTuW8QnCpBxtCAxsgZLtmNlW1d66lJDws16xlTHu3rOOME6lNuTgA02DN7olKQDzBIbKkOf-VeYZdmZRuqF6eDA-BgzqjXzIQF5lTqMrK2603u9fxl5kWBIgZB4T6Rro?width=884&height=659&cropmode=none)
rgds,
Andy
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Thank you, Andreas. I really feel at home in you posts.
I do not hold any stock in any opinion. I just want to know how things are and how things work.
The Sekonic seems to be a perfect tool to determine why our sensors react so nicely/badly to certain light sources.
I have to get one of these!
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Very visual output ;)
Thanks !
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Very impressive output from this type of light meter. Thank you for showing us these charts.
I want one too, even though I cannot say that I need such an item. I so much wish the sensitivity extended down to 300 nm, because then I could make use of it in my UV photography.
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Andrea: the meter at the very least indicate the magnitude of the spectrum components you need to filter out :D
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halogen bulb
Nice to see the very famous noise in the blue channel is coming from. There was no energy in the blue channel to start with ...
Has anyone here tried an old time color conversion filter, modest ISO bump, and large aperture to obtain a better result than letting a camera's white balance try to do the job by itself?
What about under correcting to help the blue while having a more hand holdable exposure?
I've thought about doing some experiments for ages but never found the time.
Dave
I spend most of my time helping a semi quadriplegic friend.