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Olympus OM-D E-M1 The first Micro Four Thirds camera that offers phase detect focusing so you can use Four Thirds DSLR lenses normally as well a Micro Four Thirds lenses.

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Old 2nd November 2013
birdboy birdboy is offline
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EM1 Fireworks

I just got the EM1 in time to try some fireworks pics tonight. Having not had livetime shooting before I thought I would give this a try.

The following pics were taken with 12-40 pro manual focus f7.1. Good use of this exposure mode as you can watch the picture develop. I did use low ISO.



All appeared well until you pixel peep. Urgh black spots They seem to only appear where there is little light. Could they be lazy photosites that need a good bashing with light to get to work. The following is a 100% crop showing the random black spots.



I know Carlos1 has experienced something similar but has anyone else seen this or better still explain it?
Thanks John
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OM-D E-M1, 12-40 f2.8 Pro, Tamron 14-150mm f5.8, E5, E3, Zuiko 50-200mm SWD, Zuiko 12-60mm SWD, Zuiko ED 70-300mm f5.6, 50mmf2, Zuiko ED 9-18mm f5.6, Sigma 50-500mm f6.3, EC14, EC20, RM-1, VA-1
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Old 3rd November 2013
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Re: EM1 Fireworks

John I think that's a lovely fireworks shot without the pixel peeping. Not sure what is going on in the crop though, isn't it just the way the noise shows up in the dark areas at that level of crop. Surely at some point the pixels will have to be black? Wouldn't any camera shot like this look similar at such a close inspection? I'm sure someone more knowledgeable will be able to explain.
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Old 3rd November 2013
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Re: EM1 Fireworks

Hi,could black spots be debris from the fireworks powder explosion?
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Old 3rd November 2013
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Re: EM1 Fireworks

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Originally Posted by pault View Post
Hi,could black spots be debris from the fireworks powder explosion?
I'd tend to agree with this as they appear the wrong shape for pixels, peeping at 2000% to see if they are pixel shaped would confirm if this is the case or not.
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Old 3rd November 2013
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Re: EM1 Fireworks

Overlay two frames from the same shoot and check if the spots stay in place. Sensor noise is stationary, but firework debris isn't.
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Old 3rd November 2013
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Re: EM1 Fireworks

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Originally Posted by pault View Post
Hi,could black spots be debris from the fireworks powder explosion?
Thanks for suggestion but its not firework debris as I can reproduce this away from a firework display

It happens with long exposures I shall take some raw pictures tonight to see if its in the jpg software.
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OM-D E-M1, 12-40 f2.8 Pro, Tamron 14-150mm f5.8, E5, E3, Zuiko 50-200mm SWD, Zuiko 12-60mm SWD, Zuiko ED 70-300mm f5.6, 50mmf2, Zuiko ED 9-18mm f5.6, Sigma 50-500mm f6.3, EC14, EC20, RM-1, VA-1
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Old 3rd November 2013
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Re: EM1 Fireworks

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Originally Posted by jmunkki View Post
Overlay two frames from the same shoot and check if the spots stay in place. Sensor noise is stationary, but firework debris isn't.
I took two frames at different ISO last night and the spots appear to be in the same place. It may be that this has something to do with the incamera noise reduction so I will try again tonight with that turned off.
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Old 3rd November 2013
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Re: EM1 Fireworks

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Originally Posted by OlyPaul View Post
I'd tend to agree with this as they appear the wrong shape for pixels, peeping at 2000% to see if they are pixel shaped would confirm if this is the case or not.
Zooming in to 11:1 they are clearly square and pixel shaped and appear to me to be something of an artefact you get associated with noise.

The good thing about this is that it is reproducible at the moment. So hope to get to the bottom of it.
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Old 3rd November 2013
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Re: EM1 Fireworks

Hi again,
It would interesting if Olympus could advise. Just a thought, wonder if these are pixels that are "mapped out" because they were "hot"
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Old 3rd November 2013
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Re: EM1 Fireworks

Simplifying a bit, there are two ways you can map out hot pixels: by interpolating from surrounding pixels or by subtracting the value you got when the shutter was closed. If I was responsible for writing the noise reduction software, I would try to do a combinatin of both. If you just subtract, you can sometimes end up with pixels that are darker than they should be. If you just interpolate, you lose detail that might otherwise be there.

If the black spots stay in place, then you are seeing hot pixels where the noise reduction has been hard at work. It's possible that a firmware update from Olympus could improve the processing to make these less noticeable.

Remember back in the days of film though... Film had grain and it was understood to be part of photography. Digital sensors have hot pixels and noise. It's not really that different.

If the E-M1 has a pixel mapping function, you could try running that. My E-520 has it and it's a good idea to run it every few months. They should have run it at the factory at Olympus, but maybe they forgot?
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Old 3rd November 2013
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Re: EM1 Fireworks

I've done a bit more testing (the darkness that lurks under my desk) using raw and noise reduction turned off. The black pixels are clearly visible but it seems only in darkish areas nearby pixels seem to have significantly higher luminance. The black squares are slightly less visible with the raw file and I can only assume that the NR in camera software makes things worst because it darkens adjacent pixels hence it appears as visible black dots at 100%. I have carried out 3 pixel mappings in total and this seems to make no difference.

The only thing I can think of is that I am seeing the PDAF pixels but there does not seem to be regular pattern and my understanding from the promo details is that these had been masked out.

Its time for an email now to Oly technical support.
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Old 3rd November 2013
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Re: EM1 Fireworks

It's just a limitation of sensor technology. If you want cleaner images, you probably have to consider a full frame sensor or wait a few years while technology improves. On even smaller sensor cameras, you can see artifacts like that even in normal lighting conditions. In general, it's not a good idea to expect 1:1 crops from consumer digital cameras to look perfect.
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Old 3rd November 2013
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Re: EM1 Fireworks

Quote:
Originally Posted by jmunkki View Post
It's just a limitation of sensor technology. If you want cleaner images, you probably have to consider a full frame sensor or wait a few years while technology improves. On even smaller sensor cameras, you can see artifacts like that even in normal lighting conditions. In general, it's not a good idea to expect 1:1 crops from consumer digital cameras to look perfect.
With respect I have the E3 and E5 cameras and have taken many long exposure pictures. I have gone back and inspected these and none of them show any signs of the black dots I see now or of limitation you think are present. And this is not a consumer digital camera but a pro spec, the top of range for Olympus.
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Old 3rd November 2013
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Re: EM1 Fireworks

Great firework pics again showing how nice the EM1 is.
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Old 3rd November 2013
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Re: EM1 Fireworks

They are not pdaf pixels.

http://www.43rumors.com/curious-e-m1...2-40mm-review/


Also, this may be useful

http://www.mu-43.com/showthread.php?...ght=hot+pixels
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