How to shoot in Bulb mode


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Bulb mode
What is bulb mode. If you have a bulb in the room and you take picture in that room, is it bulb mode? Well no. Bulb mode is a special mode present in almost all DSLRs and Mirrorless interchangeable lens cameras. This mode allows the photographer to have a shutter speed as long as the photographer desires. It can be as short as 2-3 seconds, to as long as hours, depending upon your battery and camera.
The term came from old style cameras where you had pneumatic "bulb" shutters. Press bulb to open shutter, release bulb to release shutter.

The Need for bulb mode
The most common modes on a DSLR are P-A-S-M
P - Programmed Auto
A- Aperture priority (you select aperture)
S- Shutter priority (you select shutter)
M - Manual, you select both aperture and shutter.

Then there are scene modes, full auto modes, and lots of gimmics

In all these modes, you have preset combinations of shutter and aperture available.
For example you may have the following shutter speeds available in seconds
1,2,4,8,10,12,16,20,25,30 etc.,

In manual mode you can take a 30 second exposure max with your preset aperture.

Some cameras go upto 60 seconds(Panasonic).

However, if you want to have an exposure for an arbitrary amount of time, longer than 30 seconds, you have to fall back on bulb mode.

This is available only in M. The reason for this is simple.
In shutter priority, you set shutter speed, and camera calculates aperture. In bulb mode, how will the camera know how long you are going to press the shutter, unless it can see the future.

Using Bulb mode

Using bulb mode is very simple. You set camera to "B" or "Bulb" in M mode. Different cameras have different dials for achieving that, and you can check out your user manual on how to do that.

Once in bulb mode the difficult part starts.
So lets say you want to take a 320 seconds exposure. You set a stop watch, press shutter, and keep it pressed for 320 seconds.
5 minutes and 20 seconds later, you have a sore finger, and a blurry photo.

It is humanly impossible to keep holding the shutter for so long manually.

So that brings us to the actual way this is done

1. Cable release
2. Remote shutter

Cable release
This is the simplest method. You need to purchase a wired shutter release for your camera(search ebay for cheap ones).
Then you simply press the shutter button on wired release, and then lock the button, and forget it.
When you want to end exposure you simple release shutter button.

All you touch is a cable connected to your camera, so camera is not disturbed. You don't even need to keep shutter button pressed, it can be 'locked' into position

Why I say its simple, well here's why

1. Connect cable release to camera, and it automatically behaves like shutter button.
2. Press button and lock
3. Release button and unlock

Simple? Well not so simple, some other things are needed, but we will talk about that later. For taking a bulb exposure, this is all you need.

Wireless remote
This is the slightly difficult method. Why? Because you have to change the camera mode to "remote". Different cameras have different settings, so check your user manual.

After that you simply put camera in bulb mode.
Point remote at it and press once to press shutter

When you want to end exposure, you press again to release shutter.

In Nikon cameras, this method means you are limited to 30 minutes. If you do not press remote button within 30 minutes again, camera will stop after taking a 30 minute exposure.

But thats hardly a limitation, with a digital sensor, you don't want to take exposures longer than 30 minutes. Noise is a real issue.

So that brings us to the end of the tutorial? Well no. there are other things you need to take care off.

Points to note
1. FOCUS - You will normally take bulb exposures to expose stars or night landscapes, when 30 seconds is too less. this means it will be dark, which in turn means, if your camera is set to AF, it may simple keep hunting for focus.
So best practice. Find a bright object, such as moon, if you are exposing objects far away.
For nearby objects, walk to object, turn on a torch keep it there.

After you focus on torch or the moon, simple flick the lens AF switch to "MF". there your focus is done.
DO NOT TOUCH focus ring after that. Slight changes also can ruin your shot, esp when using long lenses.

2. TRIPOD - A stable tripod is a must, and more so for bulb. If its windy, your flimsy tripod will move little bit, and this will give you blurry shots. Most tripods have a center hook. Weigh it down.
If its sandy or soft surface, DIG your tripod on. And then tighten it. Most cheap tripods "creep" due to gravity. So make sure your does not.

3. Bright scenes - If you have a city in front of you, long exposures will ruin the shot and it will be blown out. No getting around that, its useful for very dark landscapes

4. Exposure - Always try to get more than the anticipated exposure. Lets say you think you need 10 minutes. Take 15 minutes. Even if you take 20 minutes, you are overexposing by 1 stop. From such a long exposure, if you have to recover from a dark shot in RAW, you will get lots of noise. Its better to overexpose and then fix it in RAW. And remember always shoot RAW. When you invest so much time on a shot, better to devote some time in PP too.

5. Mirror lockup - Its not really necessary for very long exposures. For example, if your mirror slap causes 3 seconds of vibrations, in a 300 second exposure it will not be noticeable, However, if your scene has objects like a bright light far away, it may have some effect. With a wide angle, such problems are minimized.

6. Temperature - If its cold, you will get a better exposure. Sensors are less noisy when cold, but batteries last less when cold which brings us to
7. Batteries - Make sure you use a fully charged battery, esp when cold.
8. LIVE View - Sometimes when its very dark, with no moon, you will have to use manual focus, and see through viewfinder. But many cameras have poor viewfinders, and you cannot really make you if the scene is in focus. In that case you can switch to live view, zoom in 10X, and then slowly move the focus ring on lens till you get the desired result. However, this heats up sensor. So if you do this, after completing focus, swich lens to MF, and then switch off camera for 3-4 minutes. Then take a 30 second ISO 3200 shot to check focus, and then again switch off for 2-3 minutes. then start your long exposure.
9. Viewfinder cover : When there is some light behind the camera, it can go through the viewfinder of the camera to sensor, and botch up exposure. So cover the VF in such cases

Limitations of brands etc.,
Not all cameras are same when it comes to very long exposures
1. Full frame DSLRs give the cleanest exposures. For example 5D MK-II
2. In APS-C Sony, Nikon and Canon are your best bets. Nikon and Sony use almost same sensor. Canon 350D-450D are the cleanest when it comes to very long exposures. 550D-600D have more noise, but due to higher rez, you can downsize image in PP, and this will take care of noise problem to a large extent. This means practically, 350D-450D-550D all will give similar results.
That said, From what I have seen on web, 350D is indeed among the best when it comes to very long exposures, and none of the current offerings from canon or nikon match it, but with clever PP, you can get around the drawbacks without an issue

3. 4/3 sensors are smaller, and most of those cameras limit bulb to 4 minutes or 8 minutes max. Even a 8 minutes exposure on such a camera can be very noisy, even at base ISO

Further reading
If you are into astrophotography(not just aesthetic, but actual astrophotography), you have to invest in telescopes, adapters and "Equatorial mounts". you can read up on the internet
Cable releases also enable you to take continous exposures of 30 seconds consecutively. So if you want a city scape with star trails, this is the best method.

Thats all folks
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Reclaimed and Recycled
Classic guide!
One thing, why full frame exposure shots are 'clean' w.r.t crop DSLRs? Bigger sensor size?
Rather than the size its pixel density.
So if you have a 20 MP APS-C sensor, and a 20MP full frame, the pixel density of the full frame will be lower. The lower the pixel density, the better the high iso and long exposure output.
A 20MP 35x26mm Full frame would have lower pixel density than a 20MP 23x15mm crop DSLR? :confused:
Sorry didn't get this, can you elighten a bit more?


Tanveer, could you also throw light on:
1. Minimizing the hot pixels during long exposures.
2. Focusing manually, to say a subject like moon or a bright object, where you'd see at least 2 shadows/glares of the subject when seeing through a viewfinder.


Reclaimed and Recycled
Tanveer, could you also throw light on:
1. Minimizing the hot pixels during long exposures.
2. Focusing manually, to say a subject like moon or a bright object, where you'd see at least 2 shadows/glares of the subject when seeing through a viewfinder.
Hot pixels will depend on ambient temperature. Some cameras have "Long exposure NR". This option takes a "dark frame" after finishing your exposure.
So camera will take a 300 second exposure after your 300 second bulb exposure and subtract the 300 second dark exposure. This will give cleaner image, but can double your actual exposure time

2. Point your focus point to the object, half press shutter when in AF mode. After camera locks focus, simple release shutter button without taking picture, and then flick switch to MF