Night photography....what am I doing wrong

[Robin Usagani]

I find a lot of discussions on different forums that says NR on camera will just add a tag but I cant find a link that talk about what you said twinky.

To my knowledge it does not just put a tag for use in post processing for whatever software to run noise reducs. It actually takes a second image that is black and then IN camera processes the two images to remove the noise in the RAW.

So when you upload your images to your computer, the noise reduction has already been done.

Do you have a link to what you are mentionning? I'd be interested in reading more

 

[bigtwinky]

Care to share one of those many discussion links?

First hit from google
Link= Long Exposure Noise Reduction | Albertdebruijn.com

How does it work? When you switch it on, you will most likely notice one particular thing, the exposures will take twice as long! Perhaps, marginal at 1 or 2 seconds, but try an exposure of 25 or 30 seconds and you’ll be waiting for quite a time before the camera is ready to shoot again.

What is going on?!

Well, the Noise Reduction funtion is using a technique called “Dark Frame Subtraction” which works pretty much as the name may suggest.
For short exposures the noise of a digital camera’s sensor is acceptable, but for longer exposures, the noise gets amplified along with the subject of the image. The longer the exposure, the more noise.

However, it’s generally true that sensors are noisy in predictable ways in the sense that some areas of the sensor are usually noisier than others. This means that if you were to know WHERE that noise is, you can compensate for it. And the way to do that is: Dark Frame Subtraction. What happens when this custom function is set, is as follows:

You take your normal picture, and the camera then takes another, a “dark frame” of equal length and exposure settings (which is why the time doubles when you use this feature). The idea of the dark frame is to gather the noise without any subject matter. The camera then does a “subtraction” between the two, and voila, the noise is reduced, if not eliminated. This happens in camera, BEFORE the image is written to the card, hence it also applies to RAW images, not just to JPEG as some people may think. The results can be stunning.
Give it a try. Happy shooting.

Google hit
Link= How does the "Noise Reduction" feature of my digital camera work?

Some Nikon cameras have a "Noise Reduction" (NR) feature which helps to reduce the noise in the final image. When active, this NR feature will take a "dark frame" (a photo with the shutter closed) after the main image and then electronically "subtract" the noise from the photograph. Because this second photo is taken, the time from pressing the shutter button until the image is recorded becomes doubled.

There are a bunch of other articles that all state pretty much the same thing. So again, I'd love to read articles on how long exposure noise reduction adds a tag to the RAW that post processing software reads and works on.

 

[FranDaMan]

I tried a bit, looking in the manual.

The Canon 550D works in this way....BUT......

when set to automatic, it depends on ISO value when the noise reduction kicks in. Shots taken with ISO lower than 1600 will only get Noise Reduction on shots longer than 30 secs. If ISO is 1600 or higher, it will kick in on exposures 1 second or longer.

Since my shot was done at ISO 100 / 8 sec......it didn't kick in

 

[Robin Usagani]

In Camera Noise Reduction question

now im confused

 

[bigtwinky]

That thread doesn't really mention much about tagging information. It actually mentions more how the Long Exposure Noise Reduction creates some "black holes"...they refer to it as Canon's in camera substraction.

But I think your confusion is that you are thinking of a different custom function.

Long Exposure Noise Reduction (what I am talking about and what I recommend for night shots) is NOT the same as High ISO Noise Reduction. Long Exposure NR has been around for a while with Canon. High ISO NR started around the XSI/40D time.

I dont use the High ISO NR.

The Long Exposure NR usually kicks in with shots that are 1 second or longer, regardless of the ISO your camera is at. If you are at ISO 1600 and your exposure is more than 1 sec, Long Exposure NR will kick in. If you are at ISO 100 and your exposure is more than 1 sec, Long Exposure NR will kick in. It will take a second black image and substract the noise from your original raw.

 

[FranDaMan]

The Long Exposure NR usually kicks in with shots that are 1 second or longer, regardless of the ISO your camera is at. If you are at ISO 1600 and your exposure is more than 1 sec, Long Exposure NR will kick in. If you are at ISO 100 and your exposure is more than 1 sec, Long Exposure NR will kick in. It will take a second black image and substract the noise from your original raw.

Not with my 550D. see my previous post

 

[bigtwinky]

The Long Exposure NR usually kicks in with shots that are 1 second or longer, regardless of the ISO your camera is at. If you are at ISO 1600 and your exposure is more than 1 sec, Long Exposure NR will kick in. If you are at ISO 100 and your exposure is more than 1 sec, Long Exposure NR will kick in. It will take a second black image and substract the noise from your original raw.

Not with my 550D. see my previous post

Then something is wrong with your camera. Check page 193 of your manual (i just did) and it says the same 1 sec thing.

Auto setting will set it off *if* the camera detects it needs it for 1 sec + images. On setting makes it always go off for 1sec+ images