Spot on the wall ? That's winging it? Show me any wall paint made of pure barium sulfate... it doesn't exist. At the very very best you have around 90% reflectance, with the remaining 10% being "off white". More likely, an alleged bright white will be around 80% at best. Using a good incident lux meter and then converting that, different story in principle; but it still leaves the other end, transmission-wise, potentially ambiguous unless proven otherwise. No thanks, I prefer a service tech and lab appropriately set up to do the job right in the first place.
Spot on the wall ? That's winging it? Show me any wall paint made of pure barium sulfate... it doesn't exist. At the very very best you have around 90% reflectance, with the remaining 10% being "off white". More likely, an alleged bright white will be around 80% at best. Using a good incident lux meter and then converting that, different story in principle; but it still leaves the other end, transmission-wise, potentially ambiguous unless proven otherwise. No thanks, I prefer a service tech and lab appropriately set up to do the job right in the first place.
I'm just suspicious of any application like that, Chan, at least in terms of doing things correctly in the manner a properly equipped technician makes his living doing. Even if one has only a single reference meter on hand, by which to check his other meters and potentially tweak their readings, that meter itself should at least be professionally checked or serviced if there is any doubt. With a kind of computer system and screen feedback, you've got all kinds of intermediate hurdles which have to be taken for granted, just like in TTL metering, but worse. Being half a stop off with some black and white films might not be earth-shattering; but it would be intolerable in the world of chrome film exposure, or even in critical lab applications of b&w films.
Not necessarily. Besides, manufacturers themselves might not respond to used equipment past a certain point. Many of the best meters are no longer being made, but potentially still have a longer useful lifetime. Some might have they own contracted repair facility, some might not. It all depends.
Of course this raises the issue is whether the NEC puck used for calibrating monitors is calibrated. NEC recommends calibrating your monitor every month or so. But I don;t know if they have a way of verifying and calibrating the puck
If one has two or more meters and they disagree in their measurements on scenes and on gray cards, which meter should be chosen to be the standard for all of them? Why?
Oh… I know the answer. Trust the meter you sent out for calibration.
I dunno, Sirius. My meters all read exactly the same when brand new, and still do, given just two instances of formal recalibration over the past 45 years. When the very first one needed to be held together with electrical tape due to all those years of hard use, I decided to retire it, even though it still read correctly, and find another one. And I did indeed stumble onto a pre-owned but apparently never used Pentax digital spot meter for only $200. Before purchase, I checked it against one of my other ones, and it read identically over the full range.
I do have an ancient Weston light meter which I inherited from my brother, and keep in my fun useless stuff drawer. If there were still an owner's manual around, I suspect it would state, "Look left, then right, go to the chicken shed and pluck a feather to see which direction the wind takes it, then count till you can't see it anymore, multiply that by four and divide by six, and use that as your shutter speed. "
I don't see they mention exposure meter.
If one has two or more meters and they disagree in their measurements on scenes and on gray cards, which meter should be chosen to be the standard for all of them? Why?
I think, I'm going to stick to the sun and'sunny-16', close enough for me.
best explained here:
Both of his meters are wrong. The Sekonic read 2/3 stops too high and the Minolta 1/3 stop too high. According to the sunny 16 rule the meter should read at ISO 400 the shutter speed is 400 and aperture is f/16. But if he uses 1/500 shutter speed the aperture should be f/11 and 7/10 or f/11 and 2/3.
For a scientific wild ass guess [SWAG] one could start with Sunny 16 as a standard source.
What I don't like about what he did is that he used 1/500 because he considered it's close enough to 1/400 but the meter read 16 and 4/10 and he said it's 4/10 too high.
I think, I'm going to stick to the sun and'sunny-16', close enough for me.
best explained here:
But, to counterpoint that method...if I believed Sunny 16 to be a good rule of thumb, if I 'calibrated' my incident meter to f/16 within the past 2 weeks, it would be -0.2EV compared to pre-'calibration', and if I calibrated my incident meter to f/16 a few months ago, it would currently be -0.7EV compared to the same pre-'calibration' measurement. IOW the calibration brightness had CHANGED by 2/3EV just depending upon when I did that procedure shown in the video?! Yes, it is a WAG, but not close enough to be scientific.Sirius Glass said:For a scientific wild ass guess [SWAG] one could start with Sunny 16 as a standard source.
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