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Newbie: advantages of really long exposure times (>30s)?

carstenw

carstenw

Active member
I am trying to decide which digital back I want to save for, and at the moment I am considering the Kodak DCS Pro, the Phase One P21, and similar backs, and finally, after the recent price drops, the Sinar 54LV.

One difference which I have repeatedly heard about is the Phase One backs' ability to do long exposures. When is this relevant? The Sinar backs are able to do about 30s, which to me seems quite long already. What is a use case for really long times?

Thanks in advance!
 
Jack

Jack

Sr. Administrator
Staff member
Hi Carsten -- it can be relevant if shooting in the early pre-dawn or post sunset light, or in dark environs like slot canyons or unlit building interiors. In these situations it is not uncommon for me to have exposures run several minutes. OTOH, if you don't find yourself doing that type of shooting with your present equipment, then it's probably not a concern for you.
 
C

carbonmetrictree

Guest
Hey Carsten, Jack is right on the ball about sunset shots or dark environments. The longest exposure I've ever ran was around 10mins at f/16 ISO50 in a really dark and unlit street at night with a plus series Phase back. Most of my personal work heavily relies on Phase's long exposure capabilities, it would be tough to walk away from an amazing location if I couldn't capture it at the exact ISO and f stop I would like to photograph it at. Though, I've noticed that most of my paid work does not require more than 30 seconds at ISO100 for interior and exterior architecture shots. If it does require more time, then I'm not lighting enough!

Either way, you'll be happy. A quick way to figure out if you need a Phase back would be to look at your entire portfolio and see how many images are committed to long exposures.

Good luck!

Andrew
 
carstenw

carstenw

Active member
I see. Well... I don't have any. On the other hand, I am not getting into this to do the same thing I always did, so I will have to consider it a bit. On the one hand, I am sure my use of the camera in really dark places will be minimal. On the other hand, it would be nice to be able to, and to try. Hmm. Is there some other solution, if, say, I had a Sinar E54LV, capable of going to around 30s?
 
G

Graham Mitchell

New member
Only very specialized situations will require more than 30 seconds. That dusk shot which I posted for you was shot at 2.5 seconds at ISO 50 and f8, to give you an idea.
 
T

thsinar

Guest
hi Carsten

I second Graham's experience with some other images taken during night. Go here and look at Rainer's work, especially "Suvarnabhumi Bangkok Airport": all the night shots were taken with eMotion 22 (the previous model of the 54), at maximum 20" and f8 or f11 and ISO 25.

Here:

http://www.tangential.de/tangential-de/_html-seiten/pages-01_suvarnabhumi/index.htm

Best regards,
Thierry

foto-z said:
Only very specialized situations will require more than 30 seconds. That dusk shot which I posted for you was shot at 2.5 seconds at ISO 50 and f8, to give you an idea.
Click to expand...
 
T

thsinar

Guest
hi Doug,

Nice!

Do you mind to share a bit more, technically speaking, about your thesis? Such as camera/capture medium used, technical aspects and issues to take care of, etc ...?

Would be interested to know, found it always an amazingly interesting subject, shooting stars.

Thanks and best regards,
Thierry

dougpetersonci said:
Definitely specialized and rare to need over 30".

P.S. My senior thesis back in college was involved star trails and exposures in this field can last hours.
Click to expand...
 
D

dougpeterson

Workshop Member
thsinar said:
hi Doug,
Do you mind to share a bit more, technically speaking, about your thesis? Such as camera/capture medium used, technical aspects and issues to take care of, etc ...?
Thanks and best regards,
Thierry
Click to expand...
It was a year+ long project, and I am a sadomasochist so there were many many technical issues. I'll say a bit about the star trails just to avoid completely hijacking the thread.

First I shot a single long frame (5min+) for each frame of the output video. But this meant the star trail moved too fast relative to its length for my taste (I wanted to establish a relaxed and aloof sense of time, not a rushed feel). Also, background light became a technical problem at anything past a minute. The ambient light would build up a noise floor that overwhelmed all but the brightest stars.

So second I reduced the shutter speed for each input frame to 30 seconds and then I combined them into an output frame in the following manner. Each output frame consisted of 30 frames. Each sequential output frame added one input frame and dropped the oldest input frame (i.e. a First-In-First-Out stack). All the frames were set to "brighten" meaning that if any input frame contained a star then the output frame contained a star. This was awesome because it allowed me to adjust the length of the star trail (the number of frames in the stack) as well as the apparent movement speed across the sky (the number of frames added per cycle). However it required an enormous amount of processing time and the process introduced strange artifacts and noise which clashed with the clean white snow shot i wanted to pair it with.

So finally I used the above technique to create a single frame of a simulated 20 minute exposure and then used a series of photoshop actions to rotate the star field a fraction of a degree around the north star and save as a new image. Repeat this several hundred times and then mask the stars over a standard time lapse of the below horizon content.

Of course the frame that I used was heavily enhanced. I started off by clipping the histogram at the noise floor and then stretching the histogram to brighten dim stars. Then I switched to LAB and stretched the alpha and beta channels so that the range of colors in the stars was expanded to cover the whole color circle.

Doug Peterson, Head of Technical Services
Capture Integration, Phase One Dealer
Personal Portfolio

*by the way I made up the exact numbers because I couldn't remember if it was 30 or 35 frames, 5 minutes or 6 minutes etc
 
D

dougpeterson

Workshop Member
Man viewing it now I wish I had another year and a quarter million to do it again and do it right. It's okay, but the original vision was more powerful then what we were able to produce.
 
carstenw

carstenw

Active member
foto-z said:
Only very specialized situations will require more than 30 seconds. That dusk shot which I posted for you was shot at 2.5 seconds at ISO 50 and f8, to give you an idea.
Click to expand...
Nice shot, btw, Graham. Do you have a perspective control lens for the 6008, or is it software?
 
T

thsinar

Guest
Thanks Doug, much appreciated!

Thierry

dougpetersonci said:
It was a year+ long project, and I am a sadomasochist so there were many many technical issues. I'll say a bit about the star trails just to avoid completely hijacking the thread.

Doug Peterson[/SIZE]
Click to expand...
 
Guy Mancuso

Guy Mancuso

Administrator, Instructor
One nice thing I have noticed shooting the Phase backs which I find really a great feature but the back actually counts time elapsed so you can read it as you are shooting on the back, no need to count when on bulb. Nice thing is you can repeat a shot accurately which is really handy when doing Pano's and such. Not sure the other backs on the market do this but avery useful tool. Sounds trivial but when in the field and in the dark very very handy because you can see the back count.
 
D

Dale Allyn

New member
Funny you mention this, Guy. I felt pretty silly when I finally noticed it after taking a couple of frames and carefully counting because I couldn't see the second hand on my watch. On about the third or so frame I noticed the feature and kind of felt like discretely looking around to see if anyone was laughing at me. (I was in a river canyon and no one was around, but I still sort of had the feeling.) Made me laugh. :)

Great feature.
 
Guy Mancuso

Guy Mancuso

Administrator, Instructor
Truth be told , i did not notice it either for awhile . i was doing the one one thousand, two one thousand and I looked at the back and felt pretty stupid but happy it was there. LOL
 
C

carbonmetrictree

Guest
Hey Guy, have you ever noticed if your back counts faster than an actual second? I have to use a stop watch because my back seems to count faster than it should. If I do a 10 second exposure, the back will be around 18-20 seconds.

Any ideas?
 
yaya

yaya

Active member
Maybe it is counting One, Two, Three instead of One One Thousand, Two One Thousand...
 
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