Problems with long shutter speed when it gets dark?

Paul Baker Jones said:

Dear Nikonites,

Hello everybody I've joined Nikonites today the 16th of June.

I bought a brand new D7000 in March of this year 2013.

I live near the coast of Pembrokeshire, in Wales, UK and often go out to the local beaches around 1 hour before sunset to get some shots of the sun illuminating the clouds and sea. Colours and atmosphere become very interesting around sunset as I'm sure you all know.

I've just read "Understanding Exposure" the 3rd Edition by Bryan Peterson and last night I decided that I would like to experiment with some longer shutter speed exposures to get that motion blur effect of the waves rolling up the beach. I found that as the ambient light got darker and I wanted to extend the shutter speed up to 30 seconds a message - Job (Nr) - was displayed. What does - Job (Nr) - mean? With the camera in Manual Mode with ISO 200 and f/22 the camera was refusing to take shots.

Does anybody have an explanation for this?

Regards,

Paul.

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RockyNH said:

I am only guessing, but if it was getting darker out an/or low contrast, your camera may have had trouble focusing... If set to auto, and unable to obtain the focus, it locks out the shutter.

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RockyNH said:

Hello Paul,

What you are seeing is an indicator the Long Exposure Noise reduction is now Active. After taking the shot, it will take a 2nd with mirror up to use as a template and try to reduce the noise in your shot. This is explained in more detail in your manual. (You can turn it off if you choose)
Pat in NH

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nickt said:

Pat, I'm not so sure about the 2nd photo for a template. Sounds like you are mixing up with dust reference? I think the NR is strictly a process applied to the single shot and it roughly doubles the time. You can move the camera around after the initial shot during the process time. But if you happen to switch it off, the picture will be saved but not the noise reduction. The mirror might stay up, I forget, but its not taking a second shot.

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nickt said:

Pat, I'm not so sure about the 2nd photo for a template. Sounds like you are mixing up with dust reference? I think the NR is strictly a process applied to the single shot and it roughly doubles the time. You can move the camera around after the initial shot during the process time. But if you happen to switch it off, the picture will be saved but not the noise reduction. The mirror might stay up, I forget, but its not taking a second shot.

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• On – When you select On and an exposure is longer than 8 seconds, the camera will take two exposures with approximately same time for each. Nikon says that the D7000 can sometimes take the second exposure in as little as half the time as the first one. The first exposure is the normal picture-taking exposure. The second one is a black-frame subtraction exposure, which is a second image that is exposed for the about the same duration as the first image, but the shutter is closed. The noise in the black-frame exposure is examined and then subtracted from the original image. It’s really quite effective and beats having to blur the image to get rid of noise. I’ve taken exposures of around 30 seconds and had perfectly usable results. The only drawback is that the total exposure time can be as much as doubled because two exposures are made. The black-frame exposure is not written to the memory card, so you’ll have only one image, with much less noise, in the end. While the black-frame exposure is being processed, a message of Job nr will blink in any active displays. When Job nr is flashing, you cannot use the camera. If you turn it off while Job nr is flashing, the camera will keep the first image, but it won’t do any noise reduction on it.

Horoscope Fish said:

Nikon has this to say about Long Exposure Noise reduction: "[the] Noise Reduction feature will take a “dark frame” (a photo with the shutter closed) after the main image, and then electronically “subtract” the noise from the photograph. Because this second photo is taken, the time from pressing the shutter button until the image is recorded is doubled."

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RockyNH said:

Nick,I

was incorrect on the mirror staying up but many sources on the net explain there is a 2nd shot, black (not saved). This states the shot is taken with the shutter closed...

This had come up as a question on teh forum a few weeks back which is

Here is one such example....

Nikon knows that their sensors might exhibit more noise than is acceptable in exposures longer than 8 seconds. The sensor can start to warm up a little when longer exposures are used. This causes a condition called amp noise, in which warmer sections of the sensor start to create more noise than cooler sections. There are two settings for Long exp. NR (figure 2):

• On – When you select On and an exposure is longer than 8 seconds, the camera will take two exposures with approximately same time for each. Nikon says that the D7000 can sometimes take the second exposure in as little as half the time as the first one. The first exposure is the normal picture-taking exposure. The second one is a black-frame subtraction exposure, which is a second image that is exposed for the about the same duration as the first image, but the shutter is closed. The noise in the black-frame exposure is examined and then subtracted from the original image. It’s really quite effective and beats having to blur the image to get rid of noise. I’ve taken exposures of around 30 seconds and had perfectly usable results. The only drawback is that the total exposure time can be as much as doubled because two exposures are made. The black-frame exposure is not written to the memory card, so you’ll have only one image, with much less noise, in the end. While the black-frame exposure is being processed, a message of Job nr will blink in any active displays. When Job nr is flashing, you cannot use the camera. If you turn it off while Job nr is flashing, the camera will keep the first image, but it won’t do any noise reduction on it.

Anyway, have fun shooting...

Pat in NH

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nickt said:

Interesting. So, it is a second photo, but not of the scene, just a closed shutter sample. Because I'm pretty sure I have dismounted the camera and come back inside while its still processing to avoid the bugs. This is a good excuse to get off the couch tonight and get re-familiar with night shots. Thanks for the info. And my apologies to Pat.

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nickt said:

Yes, the mirror up with remote is in the shooting menu. First press of remote is m-up, 2nd press takes the picture. Top dial stays on remote, not m-up position.

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Paul Baker Jones said:

Do you agree that it is best to switch off auto focus in low light conditions in order to extend shutter speed?

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Horoscope Fish said:

Auto Focus has no bearing on shutter speed.

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Paul Baker Jones said:

A earlier reply from RockyNH states that in low light conditions the auto focus is unable to focus and so locks out the shutter.

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Ima Hack said:

If I'm taking a long exposure shot, say 20 or 30 seconds, I always see "Job (nr) after the shot has been made, if I wait ten seconds or so the completed image shows up in the display. I believe it takes the camera a few seconds to process the image.
Is this what your're seeing or does an image never appear?

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Paul Baker Jones said:

Thanks Ima. This is the first time i have experienced "Job (nr)" on the LCD display. It prevented me from taking further shots and seemed to jam the camera. I think that switching off the auto focus is propably the answer to resolving this.

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Horoscope Fish said:

You need to sit down and spend some time with your manual... This is not an "issue" with anything, you're simply not understanding how your camera works.

You have Long Exposure Noise Reduction enabled on your camera. With this feature enabled your camera automatically takes a second "reference photo" with the shutter closed (pure black). Your camera then uses this reference photo to remove noise from the exposure you took. The "job NR" message is your camera telling you what's it's doing and until it's done processing one picture, it can not take another. This has nothing to do with Auto Focus.

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