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| Moderated by: chrisbet, | ||
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chrisbet
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Excuse my ignorance on this - I have been reading elsewhere about the use of incident light meters measuring the light falling ON the subject to set exposure - to my simple mind this seems innately wrong - surely you need to expose for the light REACHING the sensor, which for a dark subject will be considerably less than the light falling on it. Can one of our professionals cast some light on the subject? How do you get the subject best exposed - especially if back or side lit? |
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jk
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Using incident light metering you just point the invercone (white bobbly cover) back towards where you are taking the picture from and this gives you the notional equivalent of using a grey card with incident light metering. Does that make sense now? I can probably dig out a good tutorial on it or maybe Graham has one from his training notes. I will try to find a url. |
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chrisbet
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Yes I understand HOW to do it, my question is WHY do it that way ? Advantages / disadvantages? |
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jk
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Here you go. https://www.digital-photo-secrets.com/tip/3369/incident-vs-reflected-light-and-which-type-gives-you-better-photos/ https://blog.pond5.com/7066-perfecting-exposure-how-and-when-to-use-a-light-meter/ https://expertphotography.com/incident-light-reflected-light/ |
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jk
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The why is down to experience using any technique. Remember there isnt a correct exposure only an exposure! An image that is rendered as a high key image is exposed differently to one that is rendered as a low key image. In the high key image you will be shifting (increasing) your exposure of mid-grey towards white and the reverse if you are exposing to give a low key rendering. The light falling on the subject as measured by incident light metering will allow you render whatever is there as mid-grey, white or black at whatever is its true tone. With reflected light metering a dark subject will fool the meter and give you more exposure and conversely a light object will give you a suggested reading that is underexposing the subject. Try reading a tutorial on the Zone System. Sometimes it is easier to experiment and see than try to explain this stuff. https://photography.tutsplus.com/tutorials/understanding-using-ansel-adams-zone-system--photo-5607 |
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chrisbet
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That is where digital photography scores over film - you can see the results quickly and adjust as necessary, but that isn't always possible because you are capturing the moment. I tend to use spot metering with the horses as they are often backlit, that results in overexposed backgrounds - it was interesting to read in one of those articles that grass was close to 18% grey - I guess you could use the grass to measure exposure, lock that and compose - I wonder if the grey sand in the manege is close to 18% grey?  Click here to comment on this image. |
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jk
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OK so you want to shoot a white object and a grey object on a black background. If you use a reflected meter reading e.g. TTL then your camera will see a large black area with two small areas that are lighter. If you use Nikon matrix metering it does some clever metering so we will assume instead it is a dumb meter. So the meter sees the black ground mostly and thinks that correct exposure for this is for a mid-grey (Kodak Grey card or 18% grey card) so it gives say 1/15 at f8 for your ISO200 setting. However in reality it is a black background which is about 3-4 stops less exposure! So your exposure should be (3stops less) so 1/125 @f8 with ISO200. Now swap the black background for a white one. The meter sees it as a mid-grey again, not white (3-4stops more exposure is required), so gives you an reading of 1/1000 @f8 with ISO200. But the correct reading is 1/125@f8 with ISO200. Now swap the background for a mid-grey one. The meter sees a mid-grey again, so gives you a reading of 1/125@f8 with ISO200. If you had used incident metering then since the light falling on the subject is constant the correct exposure 1/125@f8 with ISO200 is always indicated, (for a mid-grey exposure) is shown whether or not the background is white, black or grey! That is the simple story. Then it is complicated by shiny or matt black, white grey. |
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jk
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Yes UK lush green grass is about 18% grey equivalent. Spanish green grass is paler (less green) so you need an adjustment, similar in Italy I would guess. The sand looks lighter than 18% grey to me but it could be that you need to EV+0.3 or even +0.7 to get it right. If you measure the difference between incident and reflective readings you should see the adjustment that you should or could apply. |
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chrisbet
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Ah - light bulb moment - so it is the meter in the camera being too damn clever for its own good! Yes, I use +0.7 in Italy - now I know why rather than fiddling till it looks right! But am I right in thinking that using spot metering on the part of the scene you want correctly exposed is the right thing to do? Or is HDR a better option? Or shooting in RAW and post processing? Just starting to get my head round the way the metering works - it was so much simpler in the old days of a box brownie with a fixed shutter speed and a lever for sunny & cloudy! |
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jk
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Click here to comment on this image. chrisbet wrote: Ah - light bulb moment - so it is the meter in the camera being too damn clever for its own good!Yes as long as it is mid-grey (Kodak 18% grey card). That is why some professionals carry a grey card. Like you have discovered grass in UK is mid-grey! But in sunny Italy and Spain it is lighter in the summer and darker in the winter. Or is HDR a better option? Or shooting in RAW and post processing? Just starting to get my head round the way the metering works - it was so much simpler in the old days of a box brownie with a fixed shutter speed and a lever for sunny & cloudy! HDR is a lot of fiddling and you actually need a lot of practice to get it right so it isnt garish or with bright bright highlights and dark grey shadows. RAW is my preference but if you are good at assessment the SOOC (Straight Out Of Camera) JPGs are Ok. It is about your end needs. No comment on the sunny/cloudy lever. Was it better that Nikon Matrix metering? I can remember a lot of duff over/under exposed images in the past! You can use Sunny16 rule.  |
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chrisbet
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Hmm - I think the brownie had f16 & f11, certainly they were the options on the 44B but then you got 1/30, 1/60 & bulb - loads of options! |
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Eric
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Incident light meters exclude any reflected or absorbed light variations that some surfaces may exhibit.... which can fool direct readings. The ideal exposure may not be the most obvious part of the subject when viewed by an averaging camera meter. Reversing the same incident meter and pointing its cone AT the subject invariably gave a less precise exposure. Of course the cone took a very wide angle of view. The very quality required for accurate incident reading! The advent of modern in-camera metering has gone a long way to making incident light meters redundant, using intelligent averaging of the surroundings being similarly lit to the subject. Spot metering restricts what the camera meter sees but it does require you to chose the right part of the image to base the exposure on. Even metering a coloured area can imprecisely position the exposure. As has been mentioned green grass is conveniently c.18% grey....not so for other colours. (Notice the darkness of the red seats in the mono image below) Using a grey card and spot metering will give you more consistent results but not everyone wants to go through that sort of precision. Using part of the image can be helpful, like the grey horse. But which part of the 18% grey horse is the right exposure?  Click here to comment on this image.  Click here to comment on this image. |
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jk
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As Eric says...."Reversing the same incident meter and pointing its cone AT the subject invariably gave a less precise exposure. Of course the cone took a very wide angle of view. The very quality required for accurate incident reading!" This why you need to point the invercone back from subject to the camera shooting position. This makes incident light metering more difficult, but provides a more effective measure of exposure. |
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Eric
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jk wrote:As Eric says...."Reversing the same incident meter and pointing its cone AT the subject invariably gave a less precise exposure.Of course they are totally useless when photographing the moon.  |
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Eric
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For anyone interested can I draw your attention to a programme called 'My Father and Me' now on BBC iPlayer https://www.bbc.co.uk/iplayer/episode/m000thyl Graham recently drew my attention to this programme. It's about the life and work of Maurice Broomfield the acclaimed industrial photographer. Some of his images give a good insight as why accurate incident light reading was so necessary for his work (with the equipment he used) back in the day. Yes, modern cameras with spot metering could achieve the same result...but establishing the right metering point and an understanding of tonal range are still needed in difficult lighting. |
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novicius
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I have several of those...Minolta...Weston EuroMaster ( the Latest model )..Vivitar 283 LX which is also a Flashmeter and has a 1/10 F-stop sensitivity ( the thing drives me nuts )...Lunasix 3 and a Lunasix F ( also with a FlashMeter )...the Luna`s are the Best ones, simply hold the meter straight-up and read off,and it`s Spot on....and there we touch the root of the problem, as in " How good are those meters" ..?..the Weston Master, which was probably the most famous of them all ( back in the day ),is a Daylight meter, even Twi-Light is to low a level,it`s Invercone does n`t help much to improve on matters, ...within a couple of years I was better in judging the Exposure with my very eyes vs. the Weston,..the Leica M-camera`s had a meter pushed on top of the camera, there are Two models called Leicameter and Leicameter MR, both were made by MetraWat, distinguished by the former having a glassfront having multiple lenses, and altho`being a reflected meter , it should be pointed downwards , about 60 degrees to avoid measuring the sky ,a kind of half Incident/ half Reflected meter...the MR has a Metal front door with a small hole in it . Closed it was for Daylight level and Open was for Low light level..neither of those are worth to write home about,....What I am saying is, the Quality of the Meter itself is More Important then the Method , as the Built-in meter of my Konica AutoReflex T was Way Better than the Weston Master,which when used with Color-Slide would give Disastrous results, whereas the Konica was Correct 9 times out of 10 ,..and yet , even Today , I have the Lunasix F in my bag,..that`s a Good one !!! |
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Eric
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novicius wrote:I have several of those...Minolta...Weston EuroMaster ( the Latest model )..Vivitar 283 LX which is also a Flashmeter and has a 1/10 F-stop sensitivity ( the thing drives me nuts )...Lunasix 3 and a Lunasix F ( also with a FlashMeter )...the Luna`s are the Best ones, simply hold the meter straight-up and read off,and it`s Spot on....and there we touch the root of the problem, as in " How good are those meters" ..?..the Weston Master, which was probably the most famous of them all ( back in the day ),is a Daylight meter, even Twi-Light is to low a level,it`s Invercone does n`t help much to improve on matters, ...within a couple of years I was better in judging the Exposure with my very eyes vs. the Weston,..the Leica M-camera`s had a meter pushed on top of the camera, there are Two models called Leicameter and Leicameter MR, both were made by MetraWat, distinguished by the former having a glassfront having multiple lenses, and altho`being a reflected meter , it should be pointed downwards , about 60 degrees to avoid measuring the sky ,a kind of half Incident/ half Reflected meter...the MR has a Metal front door with a small hole in it . Closed it was for Daylight level and Open was for Low light level..neither of those are worth to write home about,....What I am saying is, the Quality of the Meter itself is More Important then the Method , as the Built-in meter of my Konica AutoReflex T was Way Better than the Weston Master,which when used with Color-Slide would give Disastrous results, whereas the Konica was Correct 9 times out of 10 ,..and yet , even Today , I have the Lunasix F in my bag,..that`s a Good one !!!Yes that's a good point, not all meters are equal. |
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jk
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Yes indeed. I used to have a Weston Master V with invercone but whilst it was a good meter in ordinary light it was useless indoors. I bought a Gossen Luna Six Pro that did both flash and natural light. Unfortunately like most more sensitive meters it needs a battery! This has a built invercone that slides over the cell. I also have a Sekonic L-308B and a L-758D which is fantastic. Both do flash, incident or reflective light. The L-308B is a superb meter. It is small, light and ver accurate. It is very reasonably priced. The L-758D is brilliant as a studio flash meter and where you are working at a distance from the subject. This is an expensive meter but it can do anything. Bought in a moment of extravagance! |
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novicius
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J K : Bought in a moment of extravagance! I can relate to moments of Xtravagance...tho` I dare say a great deal of forethought goes on before that..at least a whole five minutes.. Sekonics were all the rage in the Eighties , even pushing the Minolta`s aside , which arguably were the most Sophisticated meters of all times, maybe cause them were prone to breakdowns,..mine is broken !.. ...as it is, a Good Incident meter can be a worthwhile investment, and in these days they`re also affordable, so yes, recommended ! |
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jk
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The Sekonic L758D is great if you want to spot meter a small area. The meter works well but is only used occasionally. |
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GeoffR
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May I put this another way? The light falling on a subject is not affected by the colour, reflectivity or any other property of the subject. The light reflected by the subject is affected by all these things. An example a black cat on a dark background. The light falling on the cat suggests an exposure of 1/250 at f8 the camera suggests 1/60 at f8. Now replace the cat with a white one, the incident reading remains 1/250 at f8 the camera suggests 1/1000 at f8. Use the camera readings and you get a grey cat on a grey background or a grey cat on a very dark background. Use the incident readings and the cats come out the correct shade, black or white. The thing is that none of these exposures is "correct" but one of them will achieve the desired result. |
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chrisbet
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Or - as I now think I understand it - the camera thinks everything it sees should be mid grey and adjusts accordingly which is fine if you want a mid grey image! I have given up with the meter and can't run around a moving horse with an incident light meter so I take best guess and adjust manually until I get the result I want - fixing ISO at a suitable value to minimise noise and juggling aperture and exposure time depending on DOF / blur - thank goodness for digital I can take several images to choose the best from. Maybe this is where an EVF scores because you can see the result of settings continuously - at least you can with my Canon XL1S, is that true for the mirrorless cameras? |
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jk
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chrisbet wrote:Or - as I now think I understand it - the camera thinks everything it sees should be mid grey and adjusts accordingly which is fine if you want a mid grey image!That is good. Correctly understood. But when you know which zones (Ansel Adams Zone System) each colour falls then it works great for everything. Yes but you just need to read once as long as the light doesn't change e.g. goes behind a cloud. Yes this is the huge advantage of a mirrorless camera with EVF that shows Exposure Preview (e.g. Nikon, Fuji, Sony, etc) and not just an electronic viewfinder as in many bridge cameras or the TFT back screen. I needs to show in WYSIWYG mode! |
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jk
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@Chrisbet Haha... This is why we need in line quotes in post! |
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chrisbet
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Ya - boo - sorted it |
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chrisbet
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Yes but you just need to read once as long as the light doesn't change e.g. goes behind a cloud.This is a constant problem in the manege for most of the day as one half is always in sun and the other in shade. |
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Iain
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Having done sports photography for so long I have got into the habit of using the grass to set my exposure if the light is consistent. |
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Robert
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Well my approach is boringly simple, while I am waiting for the 'main event' I bang off a few exposures at different exposure values, of the area I intend to photograph and assess the histogram to check it isn't climbing the wall at either side of the scale. Nicely in the middle. If I get it wrong I use levels in PS to put it right, although a correct exposure in the first place is better of course because correcting it in Ps means stretching the light values and loosing some range of shades. |
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novicius
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Robert wrote:Well my approach is boringly simple, while I am waiting for the 'main event' I bang off a few exposures at different exposure values, of the area I intend to photograph and assess the histogram to check it isn't climbing the wall at either side of the scale. Nicely in the middle.That`s the way I do it,..and yet , I still have the lunasix F with me...old habits persevere I guess.. |
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GeoffR
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"I have given up with the meter and can't run around a moving horse with an incident light meter" You don't actually need to get near the horse, as long as it isn't in shadow the same light intensity will be falling 6' away or further. Just hold the meter pointing over your shoulder when you are facing the subject, don't cast your own shadow over the meter. |
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chrisbet
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The challenge I have is that on a sunny day the arena is part in deep shade, part in dappled shade and part in full sun. On a cloudy day the light is very flat. |
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| A small amount of member data is captured and held in an attempt to reduce spammers and to manage users. This site also uses cookies to ensure ease of use. In order to comply with new DPR regulations you are required to agree/disagree with this process. If you do not agree then please email the Admins using info@nikondsl.uk Thank you. |