MikeSR Posted February 14, 2015 Share #1 Posted February 14, 2015 Advertisement (gone after registration) To begin with, this is not something that is causing me a problem, it's just that I don't quite understand what is going on. Where does my MM measure light for exposure? I thought that it was via the lens. If it is, why do I have to manually set things up when I add an ND filter (e.g. 6 stops for x64)? I don't seem to have any problems with my orange filter... but then I do tend to work on manual most of the time and tweak. Thanks, Mike Link to post Share on other sites More sharing options...
Advertisement Posted February 14, 2015 Posted February 14, 2015 Hi MikeSR, Take a look here Setting exposure with ND filters. I'm sure you'll find what you were looking for!
Jean-Michel Posted February 14, 2015 Share #2 Posted February 14, 2015 Hi, The camera's light meter measures light from about one-third of the sensor area, approximately the area within the 75 mm frame. It does not matter what lens is mounted, he area measured is always the same one-third area of the sensor. The meter is centre-weighted. Since the meter reads the light falling upon it, there is no need to make any adjustments for any filter, including ND filters. If you use a hand-held meter then you do need to take the filter density into consideration. But if you use an in-camera meter there is no need for any adjustments. Jean-Michel Link to post Share on other sites More sharing options...
MikeSR Posted February 14, 2015 Author Share #3 Posted February 14, 2015 Hi,The camera's light meter measures light from about one-third of the sensor area, approximately the area within the 75 mm frame. It does not matter what lens is mounted, he area measured is always the same one-third area of the sensor. The meter is centre-weighted. Since the meter reads the light falling upon it, there is no need to make any adjustments for any filter, including ND filters. If you use a hand-held meter then you do need to take the filter density into consideration. But if you use an in-camera meter there is no need for any adjustments. Jean-Michel That's what I thought but it simply does not match my experience... I'll do a couple of test shots tomorrow to demonstrate. Link to post Share on other sites More sharing options...
jaapv Posted February 15, 2015 Share #4 Posted February 15, 2015 To begin with, this is not something that is causing me a problem, it's just that I don't quite understand what is going on. Where does my MM measure light for exposure? I thought that it was via the lens. If it is, why do I have to manually set things up when I add an ND filter (e.g. 6 stops for x64)? I don't seem to have any problems with my orange filter... but then I do tend to work on manual most of the time and tweak. Thanks, Mike You don't. As it measures through the lens the camera will compensate automatically. And a sensor has no reciprocity failure... Link to post Share on other sites More sharing options...
sm23221 Posted February 15, 2015 Share #5 Posted February 15, 2015 I find that the exposure is quite inaccurate with moderate to dark ND filters mounted. I always have to increase the exposure 1-2 stops (depending on the density) to avoid underexposure. The "A" setting works great without a ND filter but once mounted, it somehow causes gross underexposure; I'm just not sure why. Link to post Share on other sites More sharing options...
pico Posted February 15, 2015 Share #6 Posted February 15, 2015 Can anyone could tell us what happens if we cover the little blue window? It should only inform Exif data. No? I use an ND 1.5 with a 35mm Summilux only rarely with no issues. . Link to post Share on other sites More sharing options...
Jeff S Posted February 15, 2015 Share #7 Posted February 15, 2015 Advertisement (gone after registration) http://www.l-camera-forum.com/leica-forum/leica-m9-forum/308321-underexposure-nd-filter.html Not many new questions around here. Jeff Link to post Share on other sites More sharing options...
MikeSR Posted February 15, 2015 Author Share #8 Posted February 15, 2015 http://www.l-camera-forum.com/leica-forum/leica-m9-forum/308321-underexposure-nd-filter.html Not many new questions around here. Jeff I had gone looking before but couldn't find an appropriate thread - so thanks for pointing it out for me. It appears that it may just be a matter of it being a bit too dark for the camera to work out. At least it shows that I am not going nuts! Anyway, I shall continue reducing the exposure by 6 stops and shall continue to get the results I am looking for (I hesitate to use the word "good"). Link to post Share on other sites More sharing options...
250swb Posted February 15, 2015 Share #9 Posted February 15, 2015 I find my MM can still meter with some accuracy with a ten stopper on the lens if you meter wide open then stop down and do the exposure calculation in your head. And the only thing that has momentarily had me baffled was in forgetting to switch off Auto ISO from the day before, and then the camera compensated for the filter, although the image at 8000 ISO still looked nice. So set everything to manual and for complete accuracy use a separate meter Steve Link to post Share on other sites More sharing options...
jaapv Posted February 15, 2015 Share #10 Posted February 15, 2015 Yep, but when it is too dark to measure a triangle will start flashing. Link to post Share on other sites More sharing options...
gravastar Posted February 15, 2015 Share #11 Posted February 15, 2015 Not all high density filters say 6 to 10 stops have the same amount of infra red transmission. Some leak quite a lot of infra red which the camera exposure meter has a residual sensitivity to. This can lead to underexposure and also a red/brown colour cast (in colour work) since the camera imager also has a residual IR response. There are ND filters claiming to have reduced IR transmission but I've never tried them. Bob. Link to post Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.