from darkness Posted July 23, 2007 Share Posted July 23, 2007 Hello guys. I want to buy a cockin filter wihich enables a step down of 10 stops. It is almost a black piece of glas. In order to use it I will have to set the camera on B mode and try manualy (remote)to use shutter lags bigger than 30". Do you have any experience with such situation. Is there a disturbing noise on such photos? Is the camera affected by the heating of sensor? Can I damage the camera?... Any info will be appreciated. Christian Link to comment Share on other sites More sharing options...
matthew_allen1 Posted July 23, 2007 Share Posted July 23, 2007 Pentax DSLRs have a custom setting for noise reduction on long exposures. It works by dark frame subtraction which involves the camera taking a second exposure after yours but with the shutter closed. The noise of the second exposure is 'subtracted' from the first and the result is a cleaner image. It does work too. If you take two 20 sec exposures one with and one with NR the difference is obvious. By default I think this setting is ON on all Pentax DSLRs. In principle, you will not damage the camera. One question though, why do you want to stop down 10 stops? Matthew Link to comment Share on other sites More sharing options...
andrewg_ny Posted July 23, 2007 Share Posted July 23, 2007 You didn't mention which camera you're using. With K10D you'll want updated firmware ( >= 1.1 ?) as v1.0 had an issue where Bulb exposure couldn't last more than 30-odd (?) seconds. While I haven't heard anything about sensor damage it is possible that for long exposures you may get uneven exposure--I think it is related to proximity of other components to the sensor. Some cameras are better at this than others. You might do some searches on astrophotography. Link to comment Share on other sites More sharing options...
from darkness Posted July 23, 2007 Author Share Posted July 23, 2007 Hello, Thanks for your answer. It is realy stupid from me. I have not given all the data. Camera - Pentax K10D - firmware 1.30 (the last one) Matthew - I want to use it on landscape photo, especially were water is in the frame. Link to comment Share on other sites More sharing options...
mountainvisions Posted July 23, 2007 Share Posted July 23, 2007 I assume this is for lakes/ocean. For moving rivers usually no more than 2 seconds is needed for a very ethereal effect. For lakes to get the smooth foamy water effect this filter might be needed. No damage will happen to the camera. I've been messing with star trails, 20-30 minutes at a time, but I'm looking to shoot 6-7 hours for a complete trail when I find a suitable location and a perfect cloudless night. Link to comment Share on other sites More sharing options...
from darkness Posted July 24, 2007 Author Share Posted July 24, 2007 Hello Justin - I want to experience a little with lake surface and star trails. Thanks. Link to comment Share on other sites More sharing options...
mountainvisions Posted July 24, 2007 Share Posted July 24, 2007 <p>for star trails don't use a filter...you will have enough trouble getting long trails at f/2.0-2.8 and ISO 200-400. Adding a filter will absolutely kill your chances. </p><p>use a longer lens for the trails to get complete trails faster. wide lenses add to the time exponentially. </p><p>lake surface might need several minute exposures to get very smooth. </p><br /><p>So far even 30 seconds has not yielded the results I want. I took about 20 bracketed shots this weekend at about 8-10 seconds and the lake still had detail. Enough so that I didn't like any of them, and the colors were not spectacular either. Here is my favorite shot from the weekend. So far although I am currently working on a 15 vertical shot 270* panorama as well. </p><p><a title="Early Morning Mist On The Bog River" href=" src="http://static.flickr.com/1186/882465219_c0b28672af_d.jpg" border="0" /></a></p><p></p> Link to comment Share on other sites More sharing options...
from darkness Posted July 25, 2007 Author Share Posted July 25, 2007 Thanks Justin. The Photo is ok, but you are right, the wave are still visible. It seems that I should try the Cockin filter... Link to comment Share on other sites More sharing options...
mountainvisions Posted July 25, 2007 Share Posted July 25, 2007 This wasn't a long exposure curec, actually, 1/1000th at f/11 from a moving/waterborne boat. It was about 45 minutes post sunrise. I wasn't pleasantly satisfied with any of the longer shots from Saturday nights sunset/twilight. And the Enloop batteries I was trying in my ist D kept showing low battery so I was hesitant to try any long exposures because the camera will shut down if it thinks the batteries are empty. I'm sticking with Lithium AA's for wilderness trips, just too much stress worrying about the batteries for this type of trip. My verdict on enloops is if you are maybe shooting in the city and can carry a few sets than it might be worth it.If your on a trip away from power where weight and space are an issue stick with lithiums. Link to comment Share on other sites More sharing options...
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