GH2 - Timelapse Test

Uwe Lansing

Uwe Lansing

Veteran

http://www.vimeo.com/25186953

It´s the first time that I have a go at timelapses. In most of the shots some kind of weird dots are showing up - light and dark ones. Partly on the very spot - at 1:10 + 1:46 they are pretty obvious. At first I thought that it would be some kind of water dots or smudge. I cleaned the lens but the dots are still appearing. In normal film- or photo mode at shorter shutter speeds I can´t notice anything like that. Is it perhaps due to the longer exposure times? Kind of reflections? Any expert around here?

GH2, 14-140
Fader ND in around 70% of the shots
Music: Circ

Update 06-18-2011: I have tried out several things up to now

- I cleaned the lens intensively
- I tried to clean the sensor without success
- several test shots with different apertures and shutter speeds

results:

- the dots are still there at f16, f22 and long exposures like 2 seconds - with and without Fader ND. But it seems that the fader is causing the light dots at unconvenient light situations (as Alex said)

- as Sasha + Klaus mentioned here: the more you open the aperture the more the dots are gone. At f11 they are barely visible
- same goes for the shutter speed: at 2 seconds they are more pronounced than at 0,5 sec.

It isn´t really satisfying. I think that I need professional help for the sensor cleaning. But shooting sunrise/sunset timelapses at f8 or f11 with a shorter shutter like 0,5 sec seems to work quite acceptable with a Fader ND. Its definitely not the last word and I still don´t know what´s really going there but a prof. sensor cleaning seems to be essential...
 
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what did you use to clean the sensor with? CCD swabs? I know some people just used normal lens cleaning cloths which is a big no-no..
 
Nice shots. And yes, the dots are strange. My first reaction was that perhaps the coating of your lens was compromised assuming an older lens, but then I noticed the it was the modern kit lens and unless you have done something radical to it, that seems an unlikely candidate. So that would point to a defect in the fader ND, but then you say that at times you shot without it and got the same result. Is that correct?
 
Uwe, the more I think about it, the more I'm convinced it's a lens/filter issue. Those blobs are too big to be a sensor problem unless you have ant eggs on it. Light is very unpredictable which is why lens creation is a fine art. You have to deal with the glass itself, refraction from the tube, etc., so perhaps you can test with a completely different lens, preferably a prime. And without the variable fader. Perhaps a good quality fixed filter.
 
What brand Fader are you using?? Most of the cheap ones will produce what you're seeing. Also, at F/16 to F/22, you are well into Diffraction, which will make your images soft, and may aggravate the situation and make it look worse. For these m4/3'rds sensors, Diffraction sets in at as low as F/8, so I would never shot anything smaller than that.
Get some high quality ND filters, Name Brand, like Hoya, NOT Tiffen, and maybe a name brand linear polarizer, to control your light/exposure.

The cheap Faders have basically plastic window tint glued onto cheap glass or even plastic. There is nothing worse than using an $800+ lens, and a $40 Fader. You're defeating the whole situation right there, by degrading the image before it ever gets into the lens. Also look at Singh Ray. They are very expensive($300+ dollars), but, so is a lens. Don't use cheap filters!!!

Other than that, I liked your time-lapsed-very smooth and watchable.

EDIT: just thought of something else-that could very well be dust on your sensor. The way to check for dust on most sensors is to shoot the flat blue sky, or a gray wall, at F/22-you will see the spots, without any filters on the lens. Try that-and if you see the spots, it's dust on the sensor. Even though these sensors have a "cleaning" function, that may not do the job.
I can't stress this enough-do not attempt to clean the sensor yourself. Have a professional camera shop do it. It only cost maybe $50 or less, and they know what they are doing. If you have a lighted Loupe, you can inspect the sensor yourself-you will likely see some specs on it.
 
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Thanks guys for your kind response. I did a lot of testing today and now I´m pretty sure that it is dust on the sensor (the dark dots). I´ve shot with different lenses - Kit-Zoom 14-140, Nikon 28 + 50 - and the dust dots are always at the same position. But you only see them at f22 and f16. The shots at F11 are quite clean even with the FaderND. Take a look:

f22 at 0.5sec



f11 at 0.5sec



But the Fader ND is definitely causing the bright dots at some unconvenient light situations with longer shutter speeds such as 2sec. or more. At 0.5sec the bright dots are barely visible. Earlier this day I called a professional camera service. They want 60,- Euros for cleaning the sensor. On monday I´ll call the official Panasonic Service Station here in town. Maybe their price is a bit more reasonable. I´ll keep you updated...
 
I´ve read and watched quite a few tutorials about cleaning a sensor in the meantime. After that I dared to give it another simple go. But first of all I have to mention that this method is not advisable after all what I have read and seen in the tuts - but it worked fairly good in my case... => I simply hold the camera body up face down, blew carefully into the chamber with my mouth and used a Q-tip to press it gently on the sensor and then slid it from one side to the other. In addition I started several times the sensor cleaning function inside the camera. Now, there is only 1 dust dot visible at f22. At f16 I can´t notice a dot anymore. I think I can live with it now and leave it well enough alone. At the end of the day I suppose that a lot of dslr owner have that problem but they will never know it because nobody of them will ever shoot at f22...

F22


f16
 
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If you've never cleaned a sensor before, I highly recommend you have a professional do it. If you make one mistake, the sensor could be permanently damage.

Also, avoid shooting any higher than F/8. If you need less light/longer shutter speeds, you will have to use "good quality" neutral density filters. Hoya makes some decent ones that are only around $30 U.S. Anything higher than F/8 will make your images softer. Do some research on Diffraction. This sensor is far to small for anything smaller than F/8.
I sometimes stack an ND4, an ND8, and a polarizer on my lens, to avoiding stopping down any lower.
 
havasuphoto said:
If you've never cleaned a sensor before, I highly recommend you have a professional do it. If you make one mistake, the sensor could be permanently damage.
...
Click to expand...

I agree to a certain extent but everything can be learned. After digging deeper to get a better understanding of the sensor cleaning procedure I personally would now prefer to do it by myself. In some tutorials prof. photographers mentioned that they have to clean the sensor every 2-3 weeks, sometimes even weekly http://www.vimeo.com/14307408 It obviously depends on how often you change the lenses, in what surroundings and how often you´re shooting in general.

So, it possibly could be a pain in the ... neck and cost you a fortune if you always bring/send the cam to a service station. Not to mention the fact that it always takes a couple of days until you´ll get back your puppy. Sure, you need to buy a cleaning set and its necessary to aquire some new skills in cleaning a sensor. But that can be done. The question is: is it really important to get a very expensive set such as one from "VisibleDust" or is a cheaper one good enough to do the trick?
 
Uwe Lansing said:
I´ve read and watched quite a few tutorials about cleaning a sensor in the meantime. After that I dared to give it another simple go. But first of all I have to mention that this method is not advisable after all what I have read and seen in the tuts - but it worked fairly good in my case... => I simply hold the camera body up face down, blew carefully into the chamber with my mouth and used a Q-tip to press it gently on the sensor and then slid it from one side to the other. In addition I started several times the sensor cleaning function inside the camera. Now, there is only 1 dust dot visible at f22. At f16 I can´t notice a dot anymore. I think I can live with it now and leave it well enough alone. At the end of the day I suppose that a lot of dslr owner have that problem but they will never know it because nobody of them will ever shoot at f22...
Click to expand...

I've been using this technique to clean the sensor on my Canon 40D for several years without any problem. I do lots of high magnification macro photography in the field with a Canon MP-E 65mm. The effective aperture at 5x magnification and f16 on the camera is f96. You can see every little sensor mark. You see marks that just aren't there at f11 and normal lenses at normal distances. Even after cleaning and changing lenses as little as possible new spots start appearing in as little as a week. After a few weeks there's so many spots you waste hours spotting out the sensor marks on every image. It would cost me a fortune cleaning regularly with the sensor cleaning kits on sale. I came across the cotton bud method and tried it. I think as long as you don't press hard the chances of damage is slight. I have heard many cases of people scratching their sensor with the expensive swabs. Generally I get a new pack of cotton buds and use a new bud for every few strokes to cut down the chance of an abrasive particle scratching the low pass filter. The only slight problem I have ever had is the occasional fibre off the bud appearing at the edge of the frame, but I have always got rid of this easily. I know this technique probably sounds crude, but I think it comes down to being careful and not applying too much pressure. I wouldn't dare recommend it generally, as I think all these methods depend more on how you use them, rather than the kit used. However, I would say I have satisfied myself it works and if you are careful it is safe. At first I was very cautious but after cleaning my sensor numerous times like this I'm quite confident with it. I think most damage is caused by applying too much pressure and abrasive particles being trapped under the swab. It has also generally worked much better than the few proper sensor cleaning kits I tried. I also find it convient because I can just give a very light quick clean to a small area of the sensor if a few pollen grains have stuck to the sensor.
 
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