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Author Topic: Digital Long Exposure Tips?  (Read 11010 times)

Dave Gurtcheff

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Digital Long Exposure Tips?
« on: July 01, 2011, 03:22:32 pm »

Not sure where to post this, but here goes:
I have long admired here the seascapes made with long exposures to get the blurred moving water effect. I specialize in seascapes, but have never tried this. I bought a very "cheapy" 77mm multi coated ND Fader filter on ebay. It is cool, as it has marked increments from almost clear (probably one stop) to almost opaque. I assume shutter speeds around 5 to 10 seconds will be needed. I will be using a Pentax 645D, & mirror lock up. In my film days I did some long night exposures, and compensated for film reciprocity failue, but have never made digital exposures longer than around 1 second. Is there anything I need to know (noise, reciprocity, etc)? Any special processing from RAW? I will be using ISO 100 and f16 to 22 (I am willing to accept difraction lens issues).
Thanks in advance. If I get something worth keeping, I will post here.
Dave G
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Wayne Fox

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Re: Digital Long Exposure Tips?
« Reply #1 on: July 01, 2011, 05:06:17 pm »

Not sure where to post this, but here goes:
I have long admired here the seascapes made with long exposures to get the blurred moving water effect. I specialize in seascapes, but have never tried this. I bought a very "cheapy" 77mm multi coated ND Fader filter on ebay. It is cool, as it has marked increments from almost clear (probably one stop) to almost opaque. I assume shutter speeds around 5 to 10 seconds will be needed. I will be using a Pentax 645D, & mirror lock up. In my film days I did some long night exposures, and compensated for film reciprocity failue, but have never made digital exposures longer than around 1 second. Is there anything I need to know (noise, reciprocity, etc)? Any special processing from RAW? I will be using ISO 100 and f16 to 22 (I am willing to accept difraction lens issues).
Thanks in advance. If I get something worth keeping, I will post here.
Dave G
5 to 10 seconds is effective, but if you want the silky smooth stuff you might want to get to 30 seconds or even longer.  Not sure what the limit is on the pentax, but the dark frame subtraction will eliminate most of the noise issues for you.  Kind of a pain, you take a 1 minute exposure and then have to wait 1 minute to see the image and be ready to take another one.

One thing I've found is you sometimes have to shoot opposite of what you would do normally ... you wait till a wave crashes and then try to capture the flow running back into the ocean. 

When I want the really silky look I tend to do these long after sunset or even using full moonlight (8 to 10 min exposures).  I do have a singh-ray variableND filter which sounds similar to the one you describe... they are basically 2 polarizers.  Sometimes there is an effect from the polarizer but it works for the most part. A good 10 stop ND filter is handy for this kind of thing as well.  I also find splitND filters are very useful for this kind of stuff.  I know you can sort of do this in PS, but for this type of thing you keep the exposure times the same so the motion in the sky can match the water.

Fun stuff to do, success is kind of hit and miss.  Here's a few of mine if you care to look ...

You might also take a look at the work of Patrick Smith, who sort of specializes in very long exposures - seeing his work is why I started experimenting with it.
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Schewe

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Re: Digital Long Exposure Tips?
« Reply #2 on: July 01, 2011, 05:11:12 pm »

Here's a few of mine if you care to look ...

Wayne, nice...I like the two in the upper right...

As for the Pentax 645D, you'll need to check out the longest exposure time for the sensor. For example my P45+ can do an hour while my P65+ can only do a minute (and even 30 seconds starts showing pretty strong read noise)...huge difference.
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Doug Peterson

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Re: Digital Long Exposure Tips?
« Reply #3 on: July 01, 2011, 05:36:17 pm »

Generally speaking heat is a huge factor. If you can limit your shooting to cooler nights you'll be able to do longer exposures than on warmer nights. If you shoot several long-exposures one-after-another you'll be progressively warming the sensor up and increasing noise. So if you take several shots to get set up you might wait a few minutes before capturing your keeper. In some rare situations it might be worth it to use a cooling device (being careful of moisture and condensation of course).

Good luck.

Doug Peterson (e-mail Me)
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Dave Gurtcheff

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Re: Digital Long Exposure Tips?
« Reply #4 on: July 02, 2011, 10:59:04 am »

Thanks all. I will keep you informed of any success (or failure) I have. Fourth of July weekend here on a barrier island (read shore resort) is a zoo. When the visitors leave, I do most of my serious stuff.
Dave
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uaiomex

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Re: Digital Long Exposure Tips?
« Reply #5 on: July 02, 2011, 11:30:54 am »

In my experience for nice blurry clouds, smooth sea surface, steamy-like breaking waves you need at least 2 minute exposures. I found I needed around 4 minutes for the results I was looking for. Of course, the more time the blurriest. Some photographers go for the hours to achieve what they want but for this it's better to use film.
In my opinion you need an "old" PhaseOne P+ series back or a dslr.
Please check this work from me using this technique. http://forum.getdpi.com/forum/showthread.php?t=11310&highlight=zensorial
Eduardo

Not sure where to post this, but here goes:
I have long admired here the seascapes made with long exposures to get the blurred moving water effect. I specialize in seascapes, but have never tried this. I bought a very "cheapy" 77mm multi coated ND Fader filter on ebay. It is cool, as it has marked increments from almost clear (probably one stop) to almost opaque. I assume shutter speeds around 5 to 10 seconds will be needed. I will be using a Pentax 645D, & mirror lock up. In my film days I did some long night exposures, and compensated for film reciprocity failue, but have never made digital exposures longer than around 1 second. Is there anything I need to know (noise, reciprocity, etc)? Any special processing from RAW? I will be using ISO 100 and f16 to 22 (I am willing to accept difraction lens issues).
Thanks in advance. If I get something worth keeping, I will post here.
Dave G
« Last Edit: July 02, 2011, 11:38:19 am by uaiomex »
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Dave Gurtcheff

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Re: Digital Long Exposure Tips?
« Reply #6 on: July 02, 2011, 01:00:12 pm »

Eduardo: Thanks for the link and advise. I am anxious to try this out.
Dave in NJ
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uaiomex

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Re: Digital Long Exposure Tips?
« Reply #7 on: July 02, 2011, 03:03:43 pm »

My pleasure, Dave. I've found out that the full moon can provide you this effect at 4 minute @F4 iso 100, bare lens. ND's degrade IQ a little bit, even expensive ones. Try it out.
Eduardo
Eduardo: Thanks for the link and advise. I am anxious to try this out.
Dave in NJ
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Dave Gurtcheff

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Re: Digital Long Exposure Tips?
« Reply #8 on: July 02, 2011, 04:51:04 pm »

Bad news: I tested the filter on 2 cameras. It does not work. At max, or near max, you get 90% smoky black smudges over top of a light background image. It seems pretty good at minimum effect setting, but I need a heavy ND for long exposures. Ebay buyers beware!
Dave
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TH_Alpa

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Re: Digital Long Exposure Tips?
« Reply #9 on: July 03, 2011, 06:13:43 am »

Very nice shots, Eduardo!

Thierry


Please check this work from me using this technique. http://forum.getdpi.com/forum/showthread.php?t=11310&highlight=zensorial
Eduardo

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Wayne Fox

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Re: Digital Long Exposure Tips?
« Reply #10 on: July 04, 2011, 01:01:23 am »

Wayne, nice...I like the two in the upper right...

As for the Pentax 645D, you'll need to check out the longest exposure time for the sensor. For example my P45+ can do an hour while my P65+ can only do a minute (and even 30 seconds starts showing pretty strong read noise)...huge difference.
thanks Jeff.

There are times I miss my p45+ for that reason. Hoping my new IQ180 is a littler better than the p65+.

For the OP, I can't really find anywhere that states how long the pentax is capable of, everyone just mentions the 30 second limit of the camera itself.  Since it's a Kodak sensor, it may do quite well in long exposure times much like the Phase p45+ with it's Kodak sensor.
« Last Edit: July 04, 2011, 02:56:35 pm by Wayne Fox »
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Wayne Fox

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Re: Digital Long Exposure Tips?
« Reply #11 on: July 04, 2011, 01:16:36 am »

Bad news: I tested the filter on 2 cameras. It does not work. At max, or near max, you get 90% smoky black smudges over top of a light background image. It seems pretty good at minimum effect setting, but I need a heavy ND for long exposures. Ebay buyers beware!
Dave
This one by singh ray does work pretty nicely.  I've used it for 6 or 7 stops with good results.   You may also want to check in a LEE system and stack a couple straight ND filters.  As I mentioned for seascapes, split ND's can be very useful, and I normally stack a 2 stop and a 3 stop together.

Very nice shots, Eduardo!

Thierry

agreed ... love em.
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hjulenissen

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Re: Digital Long Exposure Tips?
« Reply #12 on: July 04, 2011, 01:58:47 am »

If you need 3 minutes, but the camera/temperature will only allow 1 minute before noise becomes an issue, perhaps you may take 3 separate 1-minute shots and average them in software? For the red/yellow car light images, this wont fly (as there will be discontinuities in the light path), but for this kind of images where you just want blurring of the water, it might work.

Taking many (sub) pictures is kind of pain, but you may get by using a single "blackframe" for subtraction later, reducing the total time spent.

-h
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TH_Alpa

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Re: Digital Long Exposure Tips?
« Reply #13 on: July 04, 2011, 10:20:55 am »

Some nice "smooth" shots on your site too, Wayne.
Love the smoothness.

Thierry

Here's a few of mine, if you care to look ...
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uaiomex

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Re: Digital Long Exposure Tips?
« Reply #14 on: July 04, 2011, 07:16:37 pm »

Well, always very nice to have some recognition but coming from you guys, it's really special. Thanks  a lot.
Wayne, you have great pictures all around in your website. Thierry, if you can get me an Alpa for a year long test drive (with a back of course)..........
Just kidding. :D
Best
Eduardo


This one by singh ray does work pretty nicely.  I've used it for 6 or 7 stops with good results.   You may also want to check in a LEE system and stack a couple straight ND filters.  As I mentioned for seascapes, split ND's can be very useful, and I normally stack a 2 stop and a 3 stop together.
agreed ... love em.
« Last Edit: July 04, 2011, 07:18:19 pm by uaiomex »
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SeanBK

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Re: Digital Long Exposure Tips?
« Reply #15 on: July 04, 2011, 11:13:36 pm »

I find this set of images excellent as refernce.
http://www.bwvision.com/
 Personally I use 77mm B+W 0.9 N.D filter from Adorama. That will give you 3 f-stops reduction in speed. Expensive but worth it.
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tsjanik

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Re: Digital Long Exposure Tips?
« Reply #16 on: July 07, 2011, 12:43:31 pm »

Dave:

I'm not sure what the exposure limit is for the 645D, doesn't seem to appear in the manual.  I've done a 2 minute exposure with the lens cap on to check for noise - very little , a few pixels with rgb values in the range of 6, 5, 5.  If you're not doing so already,  I would recommend using the remote, makes the process very easy. 

PS You can use two polarizers as a sort of variable neutral density.

Tom
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Doug Peterson

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Re: Digital Long Exposure Tips?
« Reply #17 on: July 07, 2011, 02:25:47 pm »

I'm not sure what the exposure limit is for the 645D, doesn't seem to appear in the manual.  I've done a 2 minute exposure with the lens cap on to check for noise - very little , a few pixels with rgb values in the range of 6, 5, 5. 

Just a quick note from my experience testing long exposures...

The lens-cap test is only so useful for a variety of reasons:
- doesn't show the effect of behind-the-scene noise reduction on texture/detail
- doesn't show drifts in color accuracy (especially shadow color) or per-channel
- if you don't cover the view finder light can make it's way in (only important when testing many-minute exposures in a normally lit room) and futz with the outcome

It's much better if you can shoot with and without a strong, high quality, ND filter and compare those two images. That's not a perfect test since you'll be adding optics which can soften detail but it's a better indication of real world performance in my opinion.

I've tested some cameras that do better in the real-world then their lens-cap test would indicate, and I've tested some cameras that do worse. I don't know and am not commenting on which is the case with the Pentax. I just though in a thread about Digital Long Exposures that a note about testing methodology might be relevant.

Doug Peterson (e-mail Me)
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uaiomex

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Re: Digital Long Exposure Tips?
« Reply #18 on: July 07, 2011, 08:04:08 pm »

You can always go out late afternoon before it get's "night" to do some long exposure tests. Even better than using the filter. Anything strange in the image would be the sensor's not the filter.
Eduardo


 
Just a quick note from my experience testing long exposures...

The lens-cap test is only so useful for a variety of reasons:
- doesn't show the effect of behind-the-scene noise reduction on texture/detail
- doesn't show drifts in color accuracy (especially shadow color) or per-channel
- if you don't cover the view finder light can make it's way in (only important when testing many-minute exposures in a normally lit room) and futz with the outcome

It's much better if you can shoot with and without a strong, high quality, ND filter and compare those two images. That's not a perfect test since you'll be adding optics which can soften detail but it's a better indication of real world performance in my opinion.

I've tested some cameras that do better in the real-world then their lens-cap test would indicate, and I've tested some cameras that do worse. I don't know and am not commenting on which is the case with the Pentax. I just though in a thread about Digital Long Exposures that a note about testing methodology might be relevant.

Doug Peterson (e-mail Me)
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Murray Fredericks

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Re: Digital Long Exposure Tips?
« Reply #19 on: July 10, 2011, 05:11:16 am »

Dave,

I shoot a lot of long exposures on MFDB and DSLR in both day and night time situations.

The best bit of kit I can recommend is a good quality 10stop ND. The 77mm can be found here:

http://www.bhphotovideo.com/c/product/752928-REG/B_W_1066186_77mm_110_Solid_Neutral.html

I use these filters on time-lapse sequences during the day to get the aperture open and to drag the shutter at around 2-5sec. Here's an example over water:



I also use this filter to smooth out the water a bit when it was distracting. These still images were shot on the Phase One Achromatic Back with a 10stop ND to smooth the water a bit. The exposures were around 5-7sec...

http://www.murrayfredericks.com.au/projects/hector/index.html#1

Your biggest issue is going to be noise as mentioned in earlier posts. That's down to the ind of sensor. If the noise is too great then removing the noise will take a lot of detail with it...

Hope that all helps!

Murray

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