Iso grain at low iso

[hitman21988]

So a couple of months ago i noticed really hard grain at low iso, ex. is200-800, on clear bright days. The noise is very apparent in the out of focus area or " BOkeh." I have tried different ways to make sure it not user error in shaking and so forth. So first thing i did was go out side and take some samples at high shutter speeds. I did one shot on low then iso 200, 400, 800, and 1600. i noticed from when i got the camera to when i did these test pictures that what was going on that the amount of grain you would see at such iso ,example 800, was showing in iso400. So if I'm wording this right you see grain that is at a stop higher, if that makes sense. I even put it on a tried pod to make sure for certain that there could be no shaking.

So, is this a sign of a sensor going bad or something. Also i shot this all in raw but compared to my use of the camera through out the year what i have seen the last couple of months is making me go like !!

i hope this makes sense and if i anyone needs more info ill gladly try to explain as best to my ability. :thumb up:

Edit: link to the raw files. open in OV3.

https://www.dropbox.com/sh/866igiiped6xl0b/Pt1rWHmguN

 

[phl0wtography]

A little more inforamtion goes a long way
Maybe post a shot to see what you mean? Has this occured all of a sudden? Was it different when you got the camera?

m4/3 sensors are quite noisy at base ISO in uniformly lit/ coloured areas like a sky. It is especially apparent when shooting raw since the noise reduction doesn't kick in. I doubt though that you mean that.
Post a well exposed, stopped down raw taken at ISO 200, that would really help to see if the "really hard grain" you describe is anything out of the ordinary.

 

[tosvus]

So a couple of months ago i noticed really hard grain at low iso, ex. is200-800, on clear bright days. The noise is very apparent in the out of focus area or " BOkeh." I have tried different ways to make sure it not user error in shaking and so forth. So first thing i did was go out side and take some samples at high shutter speeds. I did one shot on low then iso 200, 400, 800, and 1600. i noticed from when i got the camera to when i did these test pictures that what was going on that the amount of grain you would see at such iso ,example 800, was showing in iso400. So if I'm wording this right you see grain that is at a stop higher, if that makes sense. I even put it on a tried pod to make sure for certain that there could be no shaking.

So, is this a sign of a sensor going bad or something. Also i shot this all in raw but compared to my use of the camera through out the year what i have seen the last couple of months is making me go like !!

i hope this makes sense and if i anyone needs more info ill gladly try to explain as best to my ability.

If you shot in Raw, I take it you use some kind of software (like Lightroom) to process your images. Have you checked if maybe the default settings for noise removal were changed lately? It's even possible between major versions of the software, that processing changes, so a setting that were ok on say "25" in the previous version, may need to be boosted to "50" in the later version.

 

[pdk42]

No, I'm not totally understanding your explanation.

In general though, it's a characteristic of the 16Mp sensors that you'll see some noise even at low ISOs. However, you'll only ever see it if you go pixel peeping. At web sizes and even on large prints you'll never see it.

 

[T N Args]

it's a characteristic of the 16Mp sensors that you'll see some noise even at low ISOs.

Surely that is not actually noise? Maybe I'm ignorant, but can we really perceive noise that is 35-40 dB below the signal strength in a well-exposed image?

 

[hitman21988]

i bought the camera new back in nov 2012. I use olympus viewer 3( it the newest one) and then export in tiff(with camera data exported) to lightroom 5. Yes, i will post my shots in raw. When i saw this it was in raw and noise reduction has always been turned off since i gotten the camera, also i do a custom batch to were the noise reduction is off. Also, before i even zoom in i saw noise that you wouldnt normally see on a well bright day shooting in a non shaded area, remeber this is in the bokeh area that i am seeing this at.

Ive had my 27" 1440p Samsung monitor for a while now and to one day notice grain in base iso was not something i would of missed easily.

P.s on the picture posting it will have to be a couple of hours from now because i have to go do taxes. fun stuff i know.

 

[hitman21988]

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[hitman21988]

bump

 

[phl0wtography]

Looked at all your images at 100%, it does look at bit weird seeing that it's so prominent in dark areas. However, the "amount" of noise so to speak is perfectly normal for the sensor used in the E-M5. Without knowing how those jpegs were processed it's hard to give an educated guess though. Maybe there's on of Oly's curves applied, maybe the shots were underexposed, and shadows lifted later, ... hard to tell without the raw.
Can you upload the ISO 200 raw (original .orf file, not exported jpeg) to db so we can d/l, and take a look at it with our interpreter of choice?

can we really perceive noise that is 35-40 dB below the signal strength in a well-exposed image?

Looking at DXO's SNR% curve, I'd say of course! The E-M5 hardly reaches your mentioned 35-40dB on screen. Does it make or break an image, though? Not at all!

 

[hitman21988]

Well I was originally going to do raw but drop box wouldn't let me. There nothing been done in editing. Contrast at normal, noise reduction off. Sat. Normal, sharpness is normal.

It could probably let me do tiffs but those files will be big. You have another site that allows raw uploads? I think flicker does but that user interface confusing me. Lol I'm a computer person but that sight needs to be redone lol

 

[hitman21988]

O, and it was all done ov3. But remember I'm looking at this on a 27" 1440p screen. Tonight when I'm off of work I'll try to get raw up and show some examples from last year around this time.

Also, could someone give me Info on when a sensor could be going bad? Like what signs to look out for?

 

[bobpur]

Olympus oversharpens, set it at -2. If it had -5 I would use it.

 

[hitman21988]

But I don't think sharpening would cause grain. Aka noise. Especially at low ISO. Example ISO 200.

 

[phl0wtography]

Dropbox lets you. Just don't upload as images but as a file and copy the public link.

Sharpening won't introduce noise but enhance what's already there, and there's no noise free digital image

 

[hitman21988]

Yes. I know but when regularly viewing the image and you see grain in the out of focus area that you wouldn't see to maybe 800. It raises concern.

 

[hitman21988]

link to raw files via drop box have been added to first post.

 

[HappyFish]

your one image is ISO 3200 ?

lower ones look normal maybe you are cooking them in post to much trying to bring out to much exposure over sharpen etc.. ?

 

[Luckypenguin]

But I don't think sharpening would cause grain. Aka noise. Especially at low ISO. Example ISO 200.

Sharpening doesn't create grain as such, but it will make existing grain (however slight) more obvious. I've copied and pasted a small part of a processing workflow I put together on another forum where I was demonstrating the use of the sharpening mask in Lightroom and how it can be used to remove noise from parts of the image that otherwise contain no detail. As described below, I have over-sharpened the example image to clearly show how obvious noise becomes when you sharpen an image taken at base ISO. The camera being used was an E-M5,

While I'm here I thought it might also be useful to have a quick look at the detail tab which handles sharpening and noise reduction. Both of these tend to be done "to taste", but a feature I feel that is worth having a look at is the Sharpening Masking. The contents of the panel as per my preset for this camera is as follows.

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To show the effect of masking I'm going to turn the sharpening up way high and set the masking value back to zero. A crop of the resulting image looks like this.

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The edges have been sharpened (over sharpened in this case) but also the areas of minimal or virtually no detail such as the sky which is not a desirable outcome. By adjusting the value of the Masking slider to 25 the image looks considerably different.

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What is happening here is that Lightroom is evaluating the original image and separating the parts of the image containing detail from those that don't. To see how it does this you can again use the Alt key while clicking and holding on the Masking slider. Lightroom will sharpen the highlighted sections but not the darkened sections. Adjusting the value of this slider adjusts the sensitivity for what is considered detail that is to be sharpened and what is not.

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[hitman21988]

ill post another image raw. i gave examples in the drop box from low to 3200iso. to illustrate more of what im saying. also let me clarify that this is before i even go in to editing that im getting this grain... i just rented the em-1 and im not even getting this type of grain at iso200.

New one is em-5 still. tom im doing a engagement photos and ill post one from there. i do have one from the em-1 at iso 200 but it done with flash and the background is completely white so it wont help illustrate what im saying.