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06-26-2008, 08:17 AM   #1
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Pentax and long exposures

There was a similar thread posted here a while ago, but it was more about cable releases.

My question: Has anyone tried a very long exposure with any 6 megapixel DSLR made by Pentax?

I'm talking about 5 minutes or more.

If you have, what were the results?

06-27-2008, 04:59 AM   #2
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I want to try this.....
At night on a busy road....

I love those light trail photos!
I bet my K100D will get a good shot...
06-27-2008, 05:30 AM   #3
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You don't need to make a 5 minute exposure for that. 30 seconds could be more than enough if the place is right.


I'd like to know if there's anybody who has already tried doing this.
06-27-2008, 05:54 AM   #4
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Sorry....

But may I ask why?
Why 5 min or more?

But I think you get intresting shots in a shopping mall or such like...

06-27-2008, 05:59 AM   #5
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Think astrophotography. That's what I need long exposures for.
06-27-2008, 07:27 AM   #6
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OOOOH

Never thought of that!
I wanna see pictures!
06-27-2008, 08:28 AM   #7
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I tried multiminute shots the other night and I had no luck at all.

ISO 200, bulb mode, with f8 and f22, after a couple minutes the shots were almost completely blown out overexposed.

I was trying to do startrails with a single long exposure, noise reduction turned off, and they just wouldn't not be overexposed. I was a bit surprised since I've done long exposure before with my Fuji s5200 and it worked great.

I haven't really looked into why it didn't work out yet.

If you are going to turn off NR, take a dark frame so that you can mask out the hot pixels that will show up.
06-27-2008, 08:48 AM   #8
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Was there anything creating light pollution where you were at? especially when compared to your previous experiences.

After that, the only other possibility is going to be the actual lens and camera (e.g. the iso of the Fuji vs. the 200 of your Pentax, the aperture, and focal length).

06-27-2008, 08:54 AM   #9
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QuoteOriginally posted by emalvick Quote
Was there anything creating light pollution where you were at? especially when compared to your previous experiences.

After that, the only other possibility is going to be the actual lens and camera (e.g. the iso of the Fuji vs. the 200 of your Pentax, the aperture, and focal length).
There is tons of light pollution, as I'm 10 miles from Boston. I thought maybe that the framing would be well exposed (trees) since there is light on them, but I didn't expect the sky to blow out too.

This was in the same area as my previous stuff, and the outside conditions are similar. I was using the 16-45 at 16mm. I think I'll need to do a comprehensive test to see what works and what doesn't. Part of the difference is that I was shooting 15 second shots with the Fuji and stacking them to get the long trails.
06-27-2008, 10:22 PM   #10
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long exposures

alohadave:
in a location like that f8 iso 200 probably wouldn't need more than the 15seconds you used on the fuji - minutes would be much too much, i think.

i spent a few years in providence, ri and did a star-trails shot there with the FA35. i stacked 61 exposures - i don't think there's anyway to do the length of time needed for significant trails with so much light pollution. they were 2sec, f4, iso400 i think, and i got a spike about 1/3rd over from the left on the histogram. (k10d, not 6mp).




i also recently tried a multi-min exposure on cape-cod with the K-55 f/1.8. it was of a beach, which was periodically (every 10sec or something) illuminated by the passing beam of a lighthouse. it was cloudy and still relatively bright. that came out nicely (a little underexposed, but hey, it was nighttime!) with iso 100, f8, 12min. (also k10d). i haven't done anything to it yet other than color-correct and straighten. unfortunately, there is quite a hotspot on the upper left of the frame.


Last edited by architorture; 06-27-2008 at 10:24 PM. Reason: fix image links
06-27-2008, 11:27 PM   #11
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I messed around with it a couple weeks back just to do informal tests. Way too much light polution and it was a little hazy to get anything good from the back yard but the K10D did okay. I used the cable release and shot 3 exposures. I *think* I used ISO 100 and f/22 for the shots. 1st exposure was a 20min one and the other 2 were 30min (one with NR turned on and one with it off). With NR turned off it was basically a snow storm of hot pixels but with it on the camera cleaned things up really good actually. The star trails were clear and pronounced considering the amount of light bleeding in from the city.

Keep in mind that the NR processing happens after the exposure is taken so and takes the same amount of time as the exposure; so a 30 min exposure burns thru 60 minutes of battery. I got all 3 shots on the body/grip batteries that had some use on them already but I went ahead and put them both in the charger afterwards to freshen them back up.
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