A700 and long exposures

[kirk_keyes]

Has anyone here tried doing long exposure, night-time photos with their a700?

I've got the a100 and it gets a lot of bloom on the sensor with long (greater

than a few seconds). I'm hoping the a700 is more in line with the Canon 20D or

5D - both of which do pretty well at long expsoures due to their CMOS sensor.

 

Kirk

[mattbarber]

I got some strange results with my A100 at f/22 on an 8 sec. exposure. Is this the kind of 'bloom' you are talking about?<p>

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[kirk_keyes]

Perhaps "bloom" is not the right term.

 

On shots of around 30 and longer (I tried up to 400 seconds), in addition to an overall noisiness, I get a purple tint eminating from both of the upper corners of the frame fading in tint as you get away from the corners. The purple tint decreased the contrast of the original scene in the corners.

 

I'm not sure what you are seeing on your photo. Do you mean the flare coming off the lights?

[mattbarber]

Ah, I have heard of what you describe, though I haven't experienced it yet. This came up on www.dyxum.com (another forum) as well. <a href="http://www.dyxum.com/dforum/forum_posts.asp?TID=20629&KW=purple&PN=1">Link to relevant thread here</a>. Unfortunately, too few people are shooting w/the A700 as of yet, so no one over at dyxum has tried a long exposure w/the A700 either. Still, you might find the info in that link helpful.<p>

 

To deal with the purple corners on the A100 you'll have to turn on NR for exposures 30 sec. or over, according to the people on the dyxum board. No other way around it, apparently.<p>

 

As for my photo, it is a flare problem, but a weird one -- it only appeared with very small apertures (f/22 in this case). I was using the kit lens, though, so it may have lackluster coatings or something. There are also some odd reflections that might've come from my leaving the viewfinder uncovered (I was beneath a street light when I took this shot). Wish I could be of more help. I don't own an A700. Perhaps someone else will chime in.

[dagoimaging]

I shoot long exposures on my A100 (up to 30 seconds) but usually go no higher than iso400. I also use decent glass and cover the viewfinder. The camera is just a tool, we need to set it up right to get the desired results. :)

[andrew_ptak]

A bit off topic, but I have the same issue with my Sony R1. It has a night exposure setting as a seperate auto exposure feature and it does exactly the same thing.

[kirk_keyes]

Matthew - thanks for the link. That's the kind of info I'm looking for.

[mark_k3]

Kirk: try not to use aperture smaller than, say 16, with ISO set to 200 and shoot raw plus jpg.

[scott_lewis3]

I have done only one night shoot so far and found the A700 light years a head of the d7 and a100. The dynamic range controls are amazing

[kirk_keyes]

Thanks Scott. It looks like you used 30s, f/8, 400 ISO.

 

That is looking really nice.