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Author Topic: Longest Daytime exposure  (Read 7660 times)

roskav

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Longest Daytime exposure
« on: November 20, 2007, 12:15:48 pm »

Hi there another one.. what's the longest daytime exposure you've managed to do with current digital equipment and lenses.  Has anyone got more than 30 seconds? ... Has anyone tried using multiple ND filters?  Image quality is not paramount!... Would I be better off with film for 5 minutes and more?


Ros
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CatOne

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Longest Daytime exposure
« Reply #1 on: November 20, 2007, 12:49:29 pm »

Quote
Hi there another one.. what's the longest daytime exposure you've managed to do with current digital equipment and lenses.  Has anyone got more than 30 seconds? ... Has anyone tried using multiple ND filters?  Image quality is not paramount!... Would I be better off with film for 5 minutes and more?
Ros
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What's the point?  You might be able to stack a couple 10-stoppers but this is a bit of an odd question?  Image quality not important?

I've done maybe 10 seconds with a 10-stop at f/22 to play with water effects, but it's better in the shade ;-)
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roskav

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Longest Daytime exposure
« Reply #2 on: November 20, 2007, 01:38:15 pm »

Well..... I want to use a long exposure on a shot along a path while moving the camera along the track on a roller, pointing forwards.  The image will essentially be a blur of soil, hedge and sky.  

I was just wondering how much ground I could cover in one shot.... I might vary the aperture during the exposure as well ...

Ros
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Tom Maher

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Longest Daytime exposure
« Reply #3 on: November 20, 2007, 03:39:03 pm »

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Well..... I want to use a long exposure on a shot along a path while moving the camera along the track on a roller, pointing forwards.  The image will essentially be a blur of soil, hedge and sky. 

I was just wondering how much ground I could cover in one shot.... I might vary the aperture during the exposure as well ...

Ros
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Using the K10D - ND filter and Multi-Exposure mode, 18 seconds in full sunlight. Essentially, they were 9 shots at 2 sec each merged into one in the camera. One image resulted with an effective 18 second exposure time. The ability to EV balance when using the multi-exposure feature is godsend..
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mahleu

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Longest Daytime exposure
« Reply #4 on: November 20, 2007, 04:20:35 pm »

You can use something like the startrails action (google startrails.atn) to stack a whole lot of images. Then just set your camera to burst fire and use a cable release to make it shoot continuously.
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sposch

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« Reply #5 on: November 22, 2007, 12:08:02 am »

You could try stacking two polarizers. This will provide a variable ND filter. As you rotate one filter with respect to the other light transmission can be changed to the point of no light when they are 90 deg out of phase.(I assume this works with circular polarizers as it does with the linear ones).

Steve.
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francois

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« Reply #6 on: November 22, 2007, 06:38:30 am »

Stacking polarizers or using neutral filters is fine but for heavy users of long exposure, Singh-Ray offers Vary-ND and Mor-Slow filters. They add 2-8 stops (Vari-ND) and 5 stops (Mor-Slow). I haven't used them as they are very expensive and I rarely take very long exposures.
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Francois

Gregory

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Longest Daytime exposure
« Reply #7 on: November 22, 2007, 10:08:33 am »

I have wondered the same thing, the purpose being to allow the people to blur while the buildings remain sharp.

but would 2-8 stops (at f16 or smaller, ISO 100) be enough to shoot a street scene in daylight for 1 min? probably not...
« Last Edit: November 22, 2007, 10:09:42 am by Gregory »
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francois

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Longest Daytime exposure
« Reply #8 on: November 22, 2007, 10:33:35 am »

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I have wondered the same thing, the purpose being to allow the people to blur while the buildings remain sharp.

but would 2-8 stops (at f16 or smaller, ISO 100) be enough to shoot a street scene in daylight for 1 min? probably not...
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You can always add a Mor-Slow filter to get another 5 stops... It's becoming expensive, though.
« Last Edit: November 22, 2007, 10:34:19 am by francois »
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Francois

Hank

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Longest Daytime exposure
« Reply #9 on: November 22, 2007, 10:33:54 am »

I'm always prepared to do so, carrying both an array of neutral density filters and a pair of polarizers to use when circumstances dictate long exposures in spite of the light.  The ND filters are easier to manage in general and more useful when reflections are not an issue, or in fact may be desirable.  Be aware that many polarizers can cause color shifts to green or olive when paired, especially if you mix brands.  I've found paired BW polas to be the least offensive.

What's my most useful circumstance?  Any time people are likely to pass through a scene I'd rather show without crowds.  Same process as long shooting indoors or at night.  Think about the possibilities, and you too might incorporate long exposure tools into your daylight shooting routine.
« Last Edit: November 22, 2007, 10:37:09 am by Hank »
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wolfnowl

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Longest Daytime exposure
« Reply #10 on: November 22, 2007, 12:39:25 pm »

FWIW, Singh Ray has a blog site that talks about their filters, including the variable ND filter.  The page is basically advertising for their filters, but it does include some useful information and examples of images taken using those filters.  The site is here: http://singhray.blogspot.com/

Mike.
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Jonathan Wienke

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Longest Daytime exposure
« Reply #11 on: November 25, 2007, 02:17:17 pm »

Quote
You could try stacking two polarizers. This will provide a variable ND filter. As you rotate one filter with respect to the other light transmission can be changed to the point of no light when they are 90 deg out of phase.(I assume this works with circular polarizers as it does with the linear ones).

Nope. A circular polarizer emits circularly polarized light, which in the context of this discussion is indistinguishable from unpolarized light. Linearly polarized light going into an SLR camera can confuse the metering and autofocus under some circumstances, so a circular polarizer is needed to prevent this. Stacking two circular polarizers will give you a sort of combination fixed ND and variable warming/cooling filter effect (at least with B&W and Canon circular polarizers), but the ND part of the filter remains essentially constant.

You can stack a linear polarizer on top of a circular polarizer, though, and get the variable-density ND filter effect. The linear polarizer just has to be the front filter.
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roskav

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Longest Daytime exposure
« Reply #12 on: February 26, 2008, 01:26:35 pm »

Hi guys back again .... I've decided to do this at the last minute as usual and the darkest ND filter I can get at short notice is 10 stops worth.  However I'm going to put a d2x on a sucker pad in my car window and try to take a 15 minute exposure at dusk as I travel along the motorway ....

A quick question ... I'm using a pocket wizard trigger, and when the camera is on bulb, you have to switch it off to close the shutter... any pointers to a better method while driving? .. and anyone know what damage I could do to the camera with such a long exposure? ... Hope you can help.. cheers!

Ros
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mahleu

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Longest Daytime exposure
« Reply #13 on: February 26, 2008, 01:55:22 pm »

Quote
Hi guys back again .... I've decided to do this at the last minute as usual and the darkest ND filter I can get at short notice is 10 stops worth.  However I'm going to put a d2x on a sucker pad in my car window and try to take a 15 minute exposure at dusk as I travel along the motorway ....

[a href=\"index.php?act=findpost&pid=177531\"][{POST_SNAPBACK}][/a]

I can't imagine any sensor damage unless the camera is pointed at the sun for 15 mins.

I've been meaning to try something similar but with much shorter exposures (a few seconds). What kind of effect are you aiming to get? I've seen some pretty impressive car shots of just a few seconds.
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Colorado David

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Longest Daytime exposure
« Reply #14 on: February 26, 2008, 02:10:31 pm »

Has anyone thought of using the filter from an arc-welder's helmet?  I used the darkest filter available for arc-welding once many years ago to view a solar eclipse. They are available in different densities and different sizes.  There may be one close enough to fit a Lee filter holder.

AndyF2

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Longest Daytime exposure
« Reply #15 on: February 26, 2008, 10:22:41 pm »

Quote
Hi guys back again .... I've decided to do this at the last minute as usual and the darkest ND filter I can get at short notice is 10 stops worth.  However I'm going to put a d2x on a sucker pad in my car window and try to take a 15 minute exposure at dusk as I travel along the motorway ....

Ros
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If image sharpness is not the prime criteria, you could make a projection box and take a long exposure of the dim projected image instead of taking a direct exposure.  At one end of a box that will be light-tight when closed, open a hole to match one of your lenses, a fully manual one preferably.  Mount it securely in place with whatever materials work from a hardware store.  

Inside the box at the other end, mount a white, non-glossy screen similar to projection screen material.  Some type of inkjet photo paper will probably work.  Focus the box lens manually and tape the aperture and focus rings down.  

Mount the camera inside the box, aimed and focused on the screen.   In the extreme case, you can now set both the box lens and the camera lens to f22, and the projected image itself is dim.

A better in-line method that wouldn't have trapezoidal distortion, would be to use a translucent material for the projection screen and mount the camera on-axis behind the screen.  There will be some sharpness lost by scattering within the screen.

You'll probably have to mount the whole thing on a roofrack since it'll end up being about 2 ft x 2 ft x 3 or 4 ft long.  

Andy
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AJSJones

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Longest Daytime exposure
« Reply #16 on: February 26, 2008, 11:52:13 pm »

You might check with Tom K here - he has some nice images and might have specific technical help for you
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roskav

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Longest Daytime exposure
« Reply #17 on: February 28, 2008, 06:27:00 am »

Andy you're a man after my heart ... lovely solution!..   I tried yesterday eve but it was too dark .. and was caught in the middle of rush hour!... Tried again this morn under overcast sky and am pretty happy with results!... f22 @100iso with 10 stop ND filter.  Travelled about 15k in 10 minutes.  Exposure time 602 seconds.  I used a cable release for the d2x on bulb and long exposure noise reduction.

Thanks everybody!

ps image also of set up in window
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mahleu

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Longest Daytime exposure
« Reply #18 on: February 29, 2008, 01:59:25 pm »

I had a go but with a shorter exposure. Will try some more tomorrow.
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