Something I was not aware of

[freelanceshots]

I tried my first hour long exposure last night and I found out that after shooting this shot for 1 hour it takes the 5D2 another hour to process the in camera noise reduction before you can do anything else. For a moment I thought I broke my camera where I made a spur of the moment judgement call to shut it down after about 45 min and it kept going to my surprise. I was then going to pull the battery but decided to read the manual where it stated when using the camera in bulb mode with noise suppression activated that the processing can take as long as the initial photograph. Whew, OK then, I was glad to know that I did not break it but this is a major pain or draw back however you choose to look at it. Even with the long exposure noise control set to auto I can see noise issues so if I didn't use the noise reduction setting it would most likely be a pretty messy scene.

[William]

I remember reading something about this once before. I think it takes another photo without opening the shutter then subtracts one image from the other - or something like that. Not that you would want to but I think you can turn this option off, is that right?

[Daniel Browning]

The way I make an hour-long exposure is to set my remote timer to take 30 2-minute exposures with the dark frame subtraction ("long exposure noise reduction") disabled, then I combine them together in the computer. (I also usually build my own dark frames unless I have one from that exposure duration and temperature already in my dark frame library.)

[freelanceshots]

I'm trying to experiment and shoot a long enough exposure of the sky to get the stars blurred all the way across the image. I'm thinking I would need a 4 to 5 hour exposure to do it correctly at ISO 50. If i step the ISO up higher then I would assume noise would increase so thats why I thought I'd use ISO 50.


Daniel I don't understand what you mean by dark frame. Also when I shot my 1 hour exposure I only got a partial blurring of the sky but I did capture 3 falling stars that was kind of neat. I'm guessing that I'm probably going to need a 3 hr exposure to get what I need. That means I will need 6 hours of total time to let the camera sit and finish the image so that I can view the final product.


I don't have the extra money in the budget at the time to buy additional software like DXO, Noise Ninja or even Adobe Lightroom. Looks like I'm stuck with the in camera setting or to use DPP but I don't want to find out later after the fact that the in camera setting was the better option. Don't want to do the image twice which could mean 9 hours.

[Daniel Browning]

I'm trying to experiment and shoot a long enough exposure of the sky to get the stars blurred all the way across the image. I'm thinking I would need a 4 to 5 hour

I recommend stacking multiple shots for this due to less noise.

If i step the ISO up higher then I would assume noise would increase so thats why I thought I'd use ISO 50.

ISO 50 is a hoax. It's a practical joke played on photographers by Canon (one of many). It's the exact same as shooting ISO 100 with +1 EC on the exposure meter, then reducing brightness in post by 1 stop. I guess Canon is hoping that most of them wont notice that a full stop of highlights are clipped to oblivion.

[freelanceshots]

I will try the multiple exposures where I will shoot 6/30 min exposures. Do you suggest raw or jpeg images?

[Dr Croubie]

Daniel I don't understand what you mean by dark frame.


Don't want to do the image twice which could mean 9 hours.

Dark-frame subtraction basically means:


you take a photo (ie turn the sensor 'on', open the shutter), it has noise in certain places


you take a photo (same duration as the first, turn the sensor 'on', leave the shutter closed, it has the noise in the same places, but the rest of the shot is dark.


you take the 2nd 'dark frame' shot, and subtract the noise from the first photo. in-camera it's called 'long exposure noise reduction', but you can shoot RAW and do it yourself later (the noise may not be exactly the same if you do it in a warm-room vs cold outdoors though.


.


I always presumed noise was random, but i've just confimed it's in exactly the same spots on the sensor with 2 consecutive 10-minute exposures i took the other day i've just looked at...


.


ps, if you can trust the place you leave your camera, for it to not get stolen, rained on, eaten by a bear or whatever, the TC80N3 (or its $10 chinese ebay ripoffs) is your friend while you get a good night's sleep...

[freelanceshots]

I spent all night from 11:30pm to 5:30am pretty far out of the city to trying and get a magical long exposure shot with stars but it was just not happening. Noise is a major issue with long exposures over 20 where they can look scary without in camera noise reduction.Sky started out clear and then got cloudy but I tried to make the best of it. I feel robbed of my entire night because I don't have a lot to show for it. Back to the drawing board.


I used my 15mm fisheye lens because of its huge field of view plus I thought it looked good through the viewfinder at the time.


[View:http://community.the-digital-picture...neric/utility/ Lake Maumelle by freelanceshots, on Flickr:550:0]


The night was not a total waste as I take some pics of this spider where he was getting lucky off my light as he was catching majors bugs with my light near. It was running all over that net grabbing prey.


[View:http://community.the-digital-picture...neric/utility/ spider out in the woods by freelanceshots, on Flickr:550:0]

[Daniel Browning]

I will try the multiple exposures where I will shoot 6/30 min exposures. Do you suggest raw or jpeg images?

I suggest raw. The free DeepSkyStacker software can combine all your 2- or 5-minute photos into one6-hour-long photo. It's a very easy-to-use program.



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[clemmb]

Know where to find a tutorial for doing this in CS5?