Camera shake - Long exposure

Unregistered User · 01-01-2015, 01:14 PM

Hi all! Happy new year!

I was doing some long exposures the other night and as always I use MUP or the 2s delay to take my images. One thing I started to wonder about is why does the initial shake, ever so small, have a so huge impact on the image if I take a 30s exposure? Should´nt it just fade the longer the shutter speed I use? A mirror slap in the beginning ruins the shot...

What am I missing?

**baro-nite** · 01-01-2015, 01:21 PM

Originally posted by Tjompen1968

why does the initial shake, ever so small, have a so huge impact on the image if I take a 30s exposure? Should´nt it just fade the longer the shutter speed I use? A mirror slap in the beginning ruins the shot...

For an exposure over 1" or so, mirror slap isn't much of a factor, if the camera is on a stable platform. I did some testing with high-magnification macro, where camera shake is a big problem, and confirmed this. For a 30" exposure it shouldn't matter at all. If you're finding camera shake at such long exposures you must have ongoing vibration from wind, or your own movements shifting the tripod if you are on something unstable, or just a plain unstable tripod and/or camera attachment.

Unregistered User · 01-01-2015, 01:37 PM

As you are saying, it should not have a huge impact. But it does... Or?

I am doing night sky images and if I do not use the 2s or MUP I will have stars that has a nice curve to them, like a comma sign. Or may it be that the SR, that turns of when using MUP or 2s, does a number... Have not thought about turning it of. Will check this out next time...

My tripod is sturdy and no wind or other vibrations. I am countious about the problem making sure it is stable...

**jbinpg** · 01-01-2015, 02:26 PM

Best way to determine your lag time for zero vibration is to put the camera into "2-press" mode in MUP + remote release mode and point it at a bright star. Then first shutter press of remote release locks mirror up and second press opens shutter. Vary the time between presses until you find one that has no visible vibration signature. You can use whatever actual shutter time you want for the exposure but using manual and a repeatable exposure will remove a varying exposure time as a variable. Every tripod/camera load will vary in its inherent stability and vibration dampening properties and this will also depend on environmental variables such as wind, earthquake activity, etc.

Jack

**savoche** · 01-01-2015, 02:34 PM

Originally posted by Tjompen1968

As you are saying, it should not have a huge impact. But it does... Or?

I am doing night sky images and if I do not use the 2s or MUP I will have stars that has a nice curve to them, like a comma sign. Or may it be that the SR, that turns of when using MUP or 2s, does a number... Have not thought about turning it of. Will check this out next time...

I would think SR to be the culprit here. Would definitely recommend turning it off when using a tripod.

**baro-nite** · 01-01-2015, 03:39 PM

Originally posted by savoche

I would think SR to be the culprit here. Would definitely recommend turning it off when using a tripod.

Ah, right, I was thinking MLU therefore no SR, but of course OP is asking about the results without MLU. I've ruined some video (on the Q) by forgetting to disable SR -- it makes random jumps.

Gimbal · 01-02-2015, 12:06 PM

Originally posted by Tjompen1968

As you are saying, it should not have a huge impact. But it does... Or?

I am doing night sky images and if I do not use the 2s or MUP I will have stars that has a nice curve to them, like a comma sign. Or may it be that the SR, that turns of when using MUP or 2s, does a number... Have not thought about turning it of. Will check this out next time...

My tripod is sturdy and no wind or other vibrations. I am countious about the problem making sure it is stable...

Are you using a cable or infrared remote? The remote turns off the SR as well, if I recall correctly.
Anyhow, some stars are pretty bright so I guess they will make a "mark" on the sensor even if the shake is short. Perhaps you could try to give the camera a bump with your hand during a long exposure with MUP and I guess you will see similar marks as well.

Unregistered User · 01-02-2015, 01:42 PM

I use both. With IR the SR turns off automatically. I am waiting for the skies to clear and the moon to turn off and I will go out there again doing some test shots with these ideas in mind.

jawsy · 01-02-2015, 10:55 PM

It does and doesn't depending on the subject. If you are shooting something that is bright enough to have light trails, such as stars, headlights or street lamps, the mirror slap will be noticable. If you are shooting something that is static like landscape or a bullding, it will make no difference at all. It all comes down to the strength of the brightest point of light hitting the sensor. I've taken a lot of both and don't use the 2S delay unless I have to. The basic formula for either circumstance is to use a sturdy tripod, turn SR off, use a cable release or remote shutter device, cover the viewfinder and block bright sources of light outside the shot frame but visible to the lens to prevent ghost flares.

**baro-nite** · 01-03-2015, 06:48 AM

Originally posted by jawsy

If you are shooting something that is bright enough to have light trails, such as stars, headlights or street lamps, the mirror slap will be noticable.

Ah, of course that must be it. I forget that stars are point sources and behave very differently than most other light sources in photographs.

01-01-2015, 01:14 PM	#1
Unregistered User Guest	Camera shake - Long exposure Hi all! Happy new year! I was doing some long exposures the other night and as always I use MUP or the 2s delay to take my images. One thing I started to wonder about is why does the initial shake, ever so small, have a so huge impact on the image if I take a 30s exposure? Should´nt it just fade the longer the shutter speed I use? A mirror slap in the beginning ruins the shot... What am I missing?

01-02-2015, 10:55 PM	#9
jawsy Veteran Member Join Date: Mar 2009 Location: Australia Photos: Gallery \| Albums Posts: 422	It does and doesn't depending on the subject. If you are shooting something that is bright enough to have light trails, such as stars, headlights or street lamps, the mirror slap will be noticable. If you are shooting something that is static like landscape or a bullding, it will make no difference at all. It all comes down to the strength of the brightest point of light hitting the sensor. I've taken a lot of both and don't use the 2S delay unless I have to. The basic formula for either circumstance is to use a sturdy tripod, turn SR off, use a cable release or remote shutter device, cover the viewfinder and block bright sources of light outside the shot frame but visible to the lens to prevent ghost flares. Last edited by jawsy; 01-03-2015 at 04:04 AM.

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01-01-2015, 01:21 PM	#2
baro-nite Loyal Site Supporter Join Date: Aug 2011 Location: North Carolina, USA Photos: Gallery \| Albums Posts: 5,294	Originally posted by Tjompen1968 why does the initial shake, ever so small, have a so huge impact on the image if I take a 30s exposure? Should´nt it just fade the longer the shutter speed I use? A mirror slap in the beginning ruins the shot... For an exposure over 1" or so, mirror slap isn't much of a factor, if the camera is on a stable platform. I did some testing with high-magnification macro, where camera shake is a big problem, and confirmed this. For a 30" exposure it shouldn't matter at all. If you're finding camera shake at such long exposures you must have ongoing vibration from wind, or your own movements shifting the tripod if you are on something unstable, or just a plain unstable tripod and/or camera attachment.

01-01-2015, 01:37 PM	#3
Unregistered User Guest	As you are saying, it should not have a huge impact. But it does... Or? I am doing night sky images and if I do not use the 2s or MUP I will have stars that has a nice curve to them, like a comma sign. Or may it be that the SR, that turns of when using MUP or 2s, does a number... Have not thought about turning it of. Will check this out next time... My tripod is sturdy and no wind or other vibrations. I am countious about the problem making sure it is stable...

01-01-2015, 02:26 PM	#4
jbinpg Site Supporter Join Date: Mar 2008 Location: Prince George, BC Photos: Gallery \| Albums Posts: 3,546	Best way to determine your lag time for zero vibration is to put the camera into "2-press" mode in MUP + remote release mode and point it at a bright star. Then first shutter press of remote release locks mirror up and second press opens shutter. Vary the time between presses until you find one that has no visible vibration signature. You can use whatever actual shutter time you want for the exposure but using manual and a repeatable exposure will remove a varying exposure time as a variable. Every tripod/camera load will vary in its inherent stability and vibration dampening properties and this will also depend on environmental variables such as wind, earthquake activity, etc. Jack

01-01-2015, 02:34 PM	#5
savoche Master of the obvious Join Date: Jun 2011 Location: Lowlands of Norway Posts: 18,311	Originally posted by Tjompen1968 As you are saying, it should not have a huge impact. But it does... Or? I am doing night sky images and if I do not use the 2s or MUP I will have stars that has a nice curve to them, like a comma sign. Or may it be that the SR, that turns of when using MUP or 2s, does a number... Have not thought about turning it of. Will check this out next time... I would think SR to be the culprit here. Would definitely recommend turning it off when using a tripod.

01-01-2015, 03:39 PM	#6
baro-nite Loyal Site Supporter Join Date: Aug 2011 Location: North Carolina, USA Photos: Gallery \| Albums Posts: 5,294	Originally posted by savoche I would think SR to be the culprit here. Would definitely recommend turning it off when using a tripod. Ah, right, I was thinking MLU therefore no SR, but of course OP is asking about the results without MLU. I've ruined some video (on the Q) by forgetting to disable SR -- it makes random jumps.

01-02-2015, 12:06 PM	#7
Gimbal Pentaxian Join Date: Apr 2007 Location: Sweden Posts: 2,106	Originally posted by Tjompen1968 As you are saying, it should not have a huge impact. But it does... Or? I am doing night sky images and if I do not use the 2s or MUP I will have stars that has a nice curve to them, like a comma sign. Or may it be that the SR, that turns of when using MUP or 2s, does a number... Have not thought about turning it of. Will check this out next time... My tripod is sturdy and no wind or other vibrations. I am countious about the problem making sure it is stable... Are you using a cable or infrared remote? The remote turns off the SR as well, if I recall correctly. Anyhow, some stars are pretty bright so I guess they will make a "mark" on the sensor even if the shake is short. Perhaps you could try to give the camera a bump with your hand during a long exposure with MUP and I guess you will see similar marks as well.

01-02-2015, 01:42 PM	#8
Unregistered User Guest	I use both. With IR the SR turns off automatically. I am waiting for the skies to clear and the moon to turn off and I will go out there again doing some test shots with these ideas in mind.

01-03-2015, 06:48 AM	#10
baro-nite Loyal Site Supporter Join Date: Aug 2011 Location: North Carolina, USA Photos: Gallery \| Albums Posts: 5,294	Originally posted by jawsy If you are shooting something that is bright enough to have light trails, such as stars, headlights or street lamps, the mirror slap will be noticable. Ah, of course that must be it. I forget that stars are point sources and behave very differently than most other light sources in photographs.

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