JS Posted May 12, 2016 Share Posted May 12, 2016 Hi, Is the exposure change while zooming using 16-50 2-2.8 lens in the above video normal behaviour for a variable aperture lens? Or do I have a faulty unit? I've tried every auto/dynamic/framing/metering etc. setting and nothing seems to get rid of it. Both camera and the lens are equipped with the latest firmware. Other people have wrote about it also in the b&h reviews(http://www.bhphotovideo.com/c/product/1022903-REG/samsung_16_50mm_f_2_2_8_s_ed.html). Quote Link to comment Share on other sites More sharing options...
NX1user Posted May 12, 2016 Share Posted May 12, 2016 When you are at 16mm what is your aperture set at? Quote Link to comment Share on other sites More sharing options...
Nikkor Posted May 12, 2016 Share Posted May 12, 2016 2-2.8 means it's f2 at 16mm and 2.8 at 50mm Quote Link to comment Share on other sites More sharing options...
Cinegain Posted May 12, 2016 Share Posted May 12, 2016 Looks normal to me. It goes from f/2 wide open to f/2.8 zoomed in and the other way around. It has to meter and adjust exposure with steps of shutterspeed/ISO accordingly if you run things automatically, that's not a fluid process. I think you're asking too much if you expect this to come out nicely... -- ok, with the later addition of the aputure set at f/3.5, that is interesting. I think we've seen exposure breathing like this before on the NX1, no? --- hum, check: http://www.eoshd.com/comments/topic/7770-nx1-exposure-drift-problem-fix/ perhaps. Quote Link to comment Share on other sites More sharing options...
kidzrevil Posted May 12, 2016 Share Posted May 12, 2016 try leaving it at 2.8 and zoom through the entire range. I noticed a slight change in exposure with my sigma zoom....but I think that's due to the nx1 image processing ? not sure Quote Link to comment Share on other sites More sharing options...
JS Posted May 13, 2016 Author Share Posted May 13, 2016 Thanks for the replies. Forgot to mention that it was shot f3.5, 1/50, iso was 800 or 1600. And I'm not sure if the aperture actually changes after it's settled. I think it stays the same. This doesn't happen while panning from bright to dark(the old exposure drift problem). Only while zooming. Quote Link to comment Share on other sites More sharing options...
Don Kotlos Posted May 13, 2016 Share Posted May 13, 2016 T stop can vary across zoom range even if F stop is constant. The camera probably has this information and it could be the case that it tries to compensate for the difference in brightness but with a small delay. JurijTurnsek and Marco Tecno 2 Quote Link to comment Share on other sites More sharing options...
JS Posted May 13, 2016 Author Share Posted May 13, 2016 Thanks Don, so maybe this a feature with this combo? Are there any nx1 users who could confirm this? And maybe someone with a different zoom could test if they are able to get a "clean" zoom? Quote Link to comment Share on other sites More sharing options...
Pavel Mašek Posted May 13, 2016 Share Posted May 13, 2016 5 hours ago, JS said: Thanks Don, so maybe this a feature with this combo? Are there any nx1 users who could confirm this? And maybe someone with a different zoom could test if they are able to get a "clean" zoom? I have same issue with 16-50 PZ. Even if I have full manual mode and aperture eg. f8 then I can see changes in exposure... it seems to be firmware bug to me. Quote Link to comment Share on other sites More sharing options...
sandro Posted May 13, 2016 Share Posted May 13, 2016 My 18-200 does the same, if I set the aperture to 6.3 while zooming out it sightly opens and then closes down to 6.3. Annoying and not acceptable for "video" lens. Quote Link to comment Share on other sites More sharing options...
JS Posted May 13, 2016 Author Share Posted May 13, 2016 Thanks guys. Looks like I've picked the wrong week to stop drinking. Anyone want to buy a nx1+16-50? Yes, it's a zoom lens but I like to think of it more as a series of primes for video. Geoff CB 1 Quote Link to comment Share on other sites More sharing options...
kidzrevil Posted May 13, 2016 Share Posted May 13, 2016 I get the same with the sigma 18-35 but i'll take your 16-50 off your hands lol @JS Quote Link to comment Share on other sites More sharing options...
JS Posted May 13, 2016 Author Share Posted May 13, 2016 So the feature works with third party lenses also? That's disappointing. Maybe the new gx80 would be better suited for my upcoming feature "Whip zoom to a coffee cup". Quote Link to comment Share on other sites More sharing options...
NX1user Posted May 13, 2016 Share Posted May 13, 2016 2 hours ago, kidzrevil said: I get the same with the sigma 18-35 but i'll take your 16-50 off your hands lol @JS So it's an NX1 issue no matter the lens? Any ideas of a workaround? Quote Link to comment Share on other sites More sharing options...
kidzrevil Posted May 13, 2016 Share Posted May 13, 2016 I have no clue whats going on. I am not accustomed to zoom lenses so idk if this is an nx1 issue or just something that happens cause of the design of zoom lenses vs primes @NX1user Quote Link to comment Share on other sites More sharing options...
Cinegain Posted May 13, 2016 Share Posted May 13, 2016 Anything to do with this? Quote Link to comment Share on other sites More sharing options...
kidzrevil Posted May 13, 2016 Share Posted May 13, 2016 Could be ! Could also be why we get the awful shifts in color when we use custom white balance @Cinegain Quote Link to comment Share on other sites More sharing options...
tugela Posted May 13, 2016 Share Posted May 13, 2016 I'm fairly sure that the reason is that your angle of view will change slightly as the lens focuses. This is not unique to the NX1 and is a lens design property. The change in apparent exposure is a consequence of this. If you watch the video you will notice that the exposure changes happen when the lens is refocussing. If you control the rate of autofocus adjustment you can probably minimize the exposure effect you are observing. If you have the camera in continuous focus mode and aim it at a scene where everything is in focus due to depth of field, but the autofocus system is making fine adjustments based on the elements within the image, you will sometimes see what looks like small changes in the angle of view constantly happening. One more thing, remember that as you zoom out from 50mm to 16mm, the lens will be collecting a lot more light. If you have aperture, shutter speed and gain all fixed, this will result in increased exposure. I am assuming that that you have aperture and shutter speed fixed, with gain floating. What happens when you quickly change your zoom ratio as in the video, changes to the gain will not happen until metering is done. Metering is probably happening at the same rate as refocusing, so until the lens starts to refocus it will still have the old gain (and hence inconsistent exposure). This would also apply to manual zoom lenses, since metering is not instantaneous. I guess what you need to do is just zoom more slowly, and the problem will go away. Essentially it is a property of the angle of view and the speed at which metering takes place. Quote Link to comment Share on other sites More sharing options...
JS Posted May 13, 2016 Author Share Posted May 13, 2016 Thanks Tugela. So this happens with other cameras and lenses also? Manual focus and slower zooming doesn't remove the problem. Quote Link to comment Share on other sites More sharing options...
sandro Posted May 13, 2016 Share Posted May 13, 2016 I believe it's a design of these electronically controlled lenses. It's disappointing it happens with a S lens... Quote Link to comment Share on other sites More sharing options...
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