40D "Long Exposure Noise Reduction"?

I was out chasing trains today and when I got home and down load the photos I hit the info, using DPP, and saw a line that states "Long Exposure Noise Reduction". Is there such and option on the 40D or is that a software thing?

Also what is the max exposure time that you can do on a 40D?

Thanks.

Kevin

In camera. It's a custom function. Page 156 of your manual. It's C.Fn II -1, btw. The max exposure time is 30 seconds. You can use "bulb", the Tv setting below 30", with a remote and have the exposure as long as you want.

Kevin

Long exposure noise reduction is selectable in C.Fn. II 1 (pg. 156, Instruction Manual).
Longest automatic exposure time is 30 seconds, but in Bulb mode you can make it as long as you like. (Pg. 96, IM)

Thanks. Has anyone tried and elapsed photo of the stars or something to that effect? If so how well did it come out?

LENR kicks in only for exposures 1 sec. or more. It functions by powering on the sensor for an amount of time equal to the shot but without opening the shutter, thus obtaining a 'black frame' image of the read noise which is then subtracted from the original shot data. This means that a 5 sec. exposure, for instance, will take 10 sec. to accomplish.

Use PS (is better)!

tzalman wrote in post #5591701
LENR kicks in only for exposures 1 sec. or more. It functions by powering on the sensor for an amount of time equal to the shot but without opening the shutter, thus obtaining a 'black frame' image of the read noise which is then subtracted from the original shot data. This means that a 5 sec. exposure, for instance, will take 10 sec. to accomplish.

This is an important point, and one that limits the practical usefulness of the function. If you're taking shots of 30 seconds, you have to wait another 30 (for every shot) before the camera is ready again.

If you do a maximum-length bulb exposure on a full battery, it will go for about 2hrs I believe. The grip will give you two batteries' worth, and further than that you'll need the AC adapter.

tzalman wrote in post #5591701
LENR kicks in only for exposures 1 sec. or more. It functions by powering on the sensor for an amount of time equal to the shot but without opening the shutter, thus obtaining a 'black frame' image of the read noise which is then subtracted from the original shot data. This means that a 5 sec. exposure, for instance, will take 10 sec. to accomplish.

I dont understand this at all - if its a shot with the shutter closed then this is not affected by the light in a particular shot. So these could be taken beforehand and stored in camera or used as a separate process in DPP. Dont understand why the same amount of time has to be used to remove the noise

riyazi wrote in post #5594075
I dont understand this at all - if its a shot with the shutter closed then this is not affected by the light in a particular shot. So these could be taken beforehand and stored in camera or used as a separate process in DPP. Dont understand why the same amount of time has to be used to remove the noise

It's because the noise is mostly down to thermal effects, so they're affected by things like how long the camera has been working and what the outside temperature is, and especially how long the exposure is. Taking an identical 'exposure' at the same time but without the shutter open will measure the exact same amount of thermal noise, which it can then remove from the original exposure.

Amazing as to how many people don't read the book that comes with the camera..

Madweasel wrote in post #5594437
It's because the noise is mostly down to thermal effects, so they're affected by things like how long the camera has been working and what the outside temperature is, and especially how long the exposure is. Taking an identical 'exposure' at the same time but without the shutter open will measure the exact same amount of thermal noise, which it can then remove from the original exposure.

Ahh that makes sense - thanks. My impression was that it was just trying to cancel out noise taking a pic with the shutter closed. Didnt realise that things like Thermal effects come in to play.

I read the book. The book does not talk about it in there that I was able to see so that is why I came on here and asked.

Hulka wrote in post #5602211
I read the book. The book does not talk about it in there that I was able to see so that is why I came on here and asked.

come on, both questions you asked are actually answered in the book. There's almost an entire page on LENR, and it does say max exposure is only limited by battery life.

There is a lot of information in the book, but sometimes it is nice to get a personal/experienced slant on a topic.

that's surely very true. But be honest, is there anything said in this topic that has not already been said before on POTN, and hence is found faster using search than through starting a topic?
I started with a 40D one week ago. After 3 days of shooting and reading the book twice I still had like twenty different questions, regarding both the camera and PP.
There wasn't a single one that was not answered on POTN..