osroubek Posted November 19, 2015 Share #1 Posted November 19, 2015 Advertisement (gone after registration) I was hoping someone can help me on this one. I have tried several similar shots with similar results, but not with every shot. This was taken with a new MP 240 on a tripod and using the Lee Seven5 ND filter. Specifically I used the Big Stopper and their Polarizer. The Big Stopper was in the the Lee filter holder in the slot closest to the lens to create a good seal to prevent light leak. I used a cable release and stood over the camera so it was in shadow. The exposure was for 39 sec using the 50 1.4 Summilux at F16 iso 200 shot as DNG, auto WB. I tried F8 but could not get a long enough shutter to smooth out the water. In the lower left and right areas there is green blotching and the mid right area has blue streaking. Any thoughts would be appreciated. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/253320-long-daytime-exposure-whats-happening/?do=findComment&comment=2932388'>More sharing options...
Advertisement Posted November 19, 2015 Posted November 19, 2015 Hi osroubek, Take a look here Long Daytime Exposure: What's Happening?. I'm sure you'll find what you were looking for!
peterbob67 Posted November 19, 2015 Share #2 Posted November 19, 2015 Hi I've had this before and think it's light reflecting between the filters/lens, from the top... I tend to put a cloth over the top of the lens/filters, or shade with my hand... bit of a pain but I presume it happens with all similar set ups/cameras? Link to post Share on other sites More sharing options...
peterbob67 Posted November 19, 2015 Share #3 Posted November 19, 2015 Apologies, I hope that picture is accepted, it was taken in my Q (but this copy saved to my phone) with a big stopper, probably similar exposure to yours. Link to post Share on other sites More sharing options...
250swb Posted November 20, 2015 Share #4 Posted November 20, 2015 A specular reflection of polarised light ? Steve Link to post Share on other sites More sharing options...
osroubek Posted November 24, 2015 Author Share #5 Posted November 24, 2015 This topic has come to a halt. Here is another image that is more dramatic and I now wonder if there is a sensor issue. Has anyone shooting long exposures, up to 1 minute, stopped down, experience this? Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/253320-long-daytime-exposure-whats-happening/?do=findComment&comment=2935738'>More sharing options...
250swb Posted November 24, 2015 Share #6 Posted November 24, 2015 I think the second picture is perhaps showing a different problem that the first, and it is the light leak problem around the M mounting flange. It is well known and usually shows itself in exposures longer than 30 seconds. Essentially the light creeps in where the cut-out is on the lens flange, so it is variable depending on the lens design and the distance it is focused (sometimes the lens barrel itself acts as a baffle that fills the gap). The best way to solve the problem is an elastic band you can put around the base of the lens where it meets the body, women's hair scrunchies are ideal. Steve Link to post Share on other sites More sharing options...
MarkP Posted November 24, 2015 Share #7 Posted November 24, 2015 Advertisement (gone after registration) As Steve said above it has been addressed here before. The problem is indeed a light leak between lens mounting flange of the camera and lens typically (but not exclusively) in the upper right quadrant under the viewfinder window (but not through the viewfinder window). This happens with long exposures in daylight especially with bright sunlight falling on the above mentioned area. The black scrunchie fixes all! http://www.l-camera-forum.com/topic/212964-monochrom-long-exposure-issue/ (my post #22) http://www.l-camera-forum.com/topic/218866-risked-life-and-limb-to-get-this-shot-and-the-7000-piece-of-crap-let-me-down-again/ Link to post Share on other sites More sharing options...
osroubek Posted November 24, 2015 Author Share #8 Posted November 24, 2015 Thanks for your comments and the links to previous threads. I tried to re-create your experiment done previously and I have attached 4 images. Of note, with just the lens cap there are those circular reflections in the middle of the frame. Internal reflections in the lens? They go away when the end is completely covered. The best is with the hair tie. I have to find something thicker since the only one I could find was rather thin. What I don't get are the darker artifacts at the right, with a semi-circular shape. Is that still from the same problem? Thanks for your patience. This is totally new to me. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/253320-long-daytime-exposure-whats-happening/?do=findComment&comment=2936121'>More sharing options...
jaapv Posted November 24, 2015 Share #9 Posted November 24, 2015 It could be a piece of sensor dust. Link to post Share on other sites More sharing options...
pico Posted November 24, 2015 Share #10 Posted November 24, 2015 You got some good suggestions which I will not repeat. There might be more than one issue combined. First, regarding your test, a plastic lens cap will still allow infra-red to pass. In fact, I have an IR night vision outfit and I can 'see' right through the lens cap in daylight. Next, while it isn't profound on your daylight images, using a linear polarizing filter with digital can be problematic. A circular polarizing filter is best. Which are you using? And auto white balance with long exposures is a questionable practice. Link to post Share on other sites More sharing options...
osroubek Posted November 24, 2015 Author Share #11 Posted November 24, 2015 I am using a Lee circular polarizer and WB is using a graycard. I still have UV/IR filters from my M8. Maybe I should give that a try as well? Link to post Share on other sites More sharing options...
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