I believe this picture needs a little explanation :)
I guess most of the viewers curious about two things: How it is done and what equipment I used?
First about the equipment. It was made with a Pentax K10D with a Tamron Adaptall-2 01BB 24mm f2.5 lens. Personally I love this lens, one of my favourite photos -a HDR called Dreamland - was made with this lens. The lens feels well built and luckily I have a very good copy of it. To achieve this long-long shutter-speed (381 seconds or 6 minutes 21 seconds) I had to greatly reduce the amount of light. To achieve this I used a welding safety glass, reducing the incoming light with 12 EV and on top of that a Cokin ND8 filter (-3EV) to achieve an effective 15 stops longer shutter speed, all packed in a Cokin filter holder with 55mm filter thread adapter. It was put on the top of a Giotto's tripod and used a home made wired remote controller to keep the shutter open for the desired amount of time. I also used a MS-Excel sheet made by me to calculate the shutter speed on my Nokia N97 and used the built in timer function on my other phone, an INQ Mini 3G. I also used my friend, BP, to entertain me while I was waiting for the shot to be made :D
Things you have to be careful about when doing long exposure shots is you have to block the light's way trough the viewfinder as it can effectively ruin your picture. Another issue is the lens casting reflecion on the welding glass, so you can't have the sun at the front of the camera. Luckily in the afternoon the sunlight came from behind. Another issue comes with the Cokin filter system, the light goes in at the sides of the filter holder, so you have to create a kind of shade to eliminate this as it will light the dust particles on the glass creating flares on the picture. This was when the case for my tripod came in, as I used the casing for covering the camera from behind, including the viewfinder and I used it's belt around the filter holder as a sunshade. Looked silly enough but it was effective :) Yet you can still see a little dust-flare on the lower left corner of the picture.
To calculate the correct shutter speed I used a little excel sheet I created earlier. The whole thing is based on the formula for calculating the EV, which is
EV=LOG2(AP^2/SS)-EC
Where is
EV = Exposure Value
AP = Aperture
SS = Shutter Speed
EC = Exposure Compensation (for ISO I used ISO100 as 0, ISO200 as +1, ISO400 as +2, ISO800 as +3... etc. and ND2 as -1, ND4 as -2, ND8 as -3... etc.)
From this you can get the Shutter speed with the formula
SS=(AP^2)/2^(EV+EC)
First I made a test shot without any filters on ISO100, f4 and got a shutter speed of 1/640. This gives an EV of 13,32. So I added the modifiers, such as -15EV and f16 and got a shutter speed of 13 minutes and 39 seconds. As it was cold and the sun was about to go down I've decided to choose half stop faster on aperture so f11 for a bit faster aperture speed. This is how I got the shutter speed of 387 seconds which is 6 minutes 27 seconds. I set the egg-timer on my INQ Mini 3G (which is a great and very cheap phone) for 6'20" and begun the capturing.
The result... well it was green.
The original picture with Auto WB and Auto Tone.
I guess most of the viewers curious about two things: How it is done and what equipment I used?
First about the equipment. It was made with a Pentax K10D with a Tamron Adaptall-2 01BB 24mm f2.5 lens. Personally I love this lens, one of my favourite photos -a HDR called Dreamland - was made with this lens. The lens feels well built and luckily I have a very good copy of it. To achieve this long-long shutter-speed (381 seconds or 6 minutes 21 seconds) I had to greatly reduce the amount of light. To achieve this I used a welding safety glass, reducing the incoming light with 12 EV and on top of that a Cokin ND8 filter (-3EV) to achieve an effective 15 stops longer shutter speed, all packed in a Cokin filter holder with 55mm filter thread adapter. It was put on the top of a Giotto's tripod and used a home made wired remote controller to keep the shutter open for the desired amount of time. I also used a MS-Excel sheet made by me to calculate the shutter speed on my Nokia N97 and used the built in timer function on my other phone, an INQ Mini 3G. I also used my friend, BP, to entertain me while I was waiting for the shot to be made :D
Things you have to be careful about when doing long exposure shots is you have to block the light's way trough the viewfinder as it can effectively ruin your picture. Another issue is the lens casting reflecion on the welding glass, so you can't have the sun at the front of the camera. Luckily in the afternoon the sunlight came from behind. Another issue comes with the Cokin filter system, the light goes in at the sides of the filter holder, so you have to create a kind of shade to eliminate this as it will light the dust particles on the glass creating flares on the picture. This was when the case for my tripod came in, as I used the casing for covering the camera from behind, including the viewfinder and I used it's belt around the filter holder as a sunshade. Looked silly enough but it was effective :) Yet you can still see a little dust-flare on the lower left corner of the picture.
To calculate the correct shutter speed I used a little excel sheet I created earlier. The whole thing is based on the formula for calculating the EV, which is
EV=LOG2(AP^2/SS)-EC
Where is
EV = Exposure Value
AP = Aperture
SS = Shutter Speed
EC = Exposure Compensation (for ISO I used ISO100 as 0, ISO200 as +1, ISO400 as +2, ISO800 as +3... etc. and ND2 as -1, ND4 as -2, ND8 as -3... etc.)
From this you can get the Shutter speed with the formula
SS=(AP^2)/2^(EV+EC)
First I made a test shot without any filters on ISO100, f4 and got a shutter speed of 1/640. This gives an EV of 13,32. So I added the modifiers, such as -15EV and f16 and got a shutter speed of 13 minutes and 39 seconds. As it was cold and the sun was about to go down I've decided to choose half stop faster on aperture so f11 for a bit faster aperture speed. This is how I got the shutter speed of 387 seconds which is 6 minutes 27 seconds. I set the egg-timer on my INQ Mini 3G (which is a great and very cheap phone) for 6'20" and begun the capturing.
The result... well it was green.
The original picture with Auto WB and Auto Tone.
So in Lightroom I was setting the White Balance manually for 5452K / +150. Yes, Tint to +150. A little play with the other values and voila, up there you can see the result :)
Just a side note: The above formula only works with digital cameras as with film you need to add a multiplier because the different nature/system behind film photography.
Just a side note: The above formula only works with digital cameras as with film you need to add a multiplier because the different nature/system behind film photography.
