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a77 elaboration speed

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ChimeraOscura

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Hi guys

For the first time i and a friend of mine went for some night shooting. I had my A77 and he used his canon 7d( if i remember well ). Shooting was satisfactory, being the first time for us, but i noticed that the elaboration speed of his camera was very very better than mine on longest shutter aperture. For example, after a 30 minutes exposure he just had to wait a minute or less, i had to wait 15-20 minutes...it was very frustating because this reduces greatly the number of pictures i could take.

There is some particular setting i have to modify?

My settings were 20MB sensor and recording raw, using a sandisk extreme 45MB/s class 10 ( pictures were about 24 MB )

Thanks in advance
 
ChimeraOscura said:
Hi guys

For the first time i and a friend of mine went for some night shooting. I had my A77 and he used his canon 7d( if i remember well ). Shooting was satisfactory, being the first time for us, but i noticed that the elaboration speed of his camera was very very better than mine on longest shutter aperture. For example, after a 30 minutes exposure he just had to wait a minute or less, i had to wait 15-20 minutes...it was very frustating because this reduces greatly the number of pictures i could take.

There is some particular setting i have to modify?

My settings were 20MB sensor and recording raw, using a sandisk extreme 45MB/s class 10 ( pictures were about 24 MB )

Thanks in advance
Click to expand...
Perhaps that's your "Long Exposure NR" taking a second exposure for dark-frame subtraction?

It can be turned off in a Menu if you wish, but you should search online and decide if that's what you want.
 
Yes you had long exposure NR on. In astrophotography its called a dark frame. The second frame is taken at the same time and temp to map all the long exposure hot pixels.

Turn it off and your camera will behave just like the 7D.
 
On Sony A77 it is called "Long Exposure NR". As others have said you can turn it off, I do this for fireworks or city lights. For astro take a shot with the lens cap on and combine that image with your long exposures in post processing to get the same effect as "Long Exposure NR"
 
yes, i had that feat on.

Thx for your replies guys, unfortunately i am not so clever in post-processing ( a medium-skilled monkey is probably better than me ), so i will think a lot before turning it off. I have to say that the pictures seemed to me quite clean, so it seems to work quite well, better than what i could obtain in post processing.

Just for my knowlegde... how do i use the second shot with lens cap tecnique? Say i use a 30 minutes exposure, after this shot i simply take a second one with which exposure?
 
If you take a long exposure, say 15min. Take another with the cap on for the same length of time. Of course take 20 long shots at 15min each you only need 1 with the cap on.

You then combine the two shots in software, I think with a 50% bleed though. It is important that the cap on shot be taken at the same outside air temp so don't wait until you go inside.

The concept is that the noise is random and combining the cap on shot with the actual shots the noise will cancel out.

Sarge
A99| A77| QX10
Bower 8mm & 14mm
Sony 28-75|70-200 G|70-300 G|70-400 G
Minolta 35-70|50mm|200 G|1.4 & 2X TC
Tamron 90|1.4 TC
Albums at www.sony-snapper.com
 
Edward Sargent said:
If you take a long exposure, say 15min. Take another with the cap on for the same length of time. Of course take 20 long shots at 15min each you only need 1 with the cap on.

You then combine the two shots in software, I think with a 50% bleed though.
Click to expand...
You have to subtract the dark frame data from the image data. In Photoshop, this is done by applying the dark frame as a layer over the image frame, using the Difference option. The degree of subtraction can then be controlled with the opacity setting of that layer. Or, there are programs that do the same thing automatically.
 
Thank's for the correction, I could not remember the proper steps.
 
The incamera function to reduce noise at long exposure affects raw files too.
--
· http://www.flickr.com/photos/blackhole_eater/
· (All photos are creative common licensed. Check them out.)
· English is not my native language.
 
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