How Often Should You Clean Your Lens Or Camera Sensor?

Cleaning your camera and the lens is a very important part to take care of your equipment and it helps to produce a good quality picture consistently. Even small fingerprint on the front glass of the lens can impact on the quality of the photos. How often should you clean your lens and the camera? It all depends on how often you shoot and where do you shoot. For example, if you shoot a lot in a beach area where sands and dusts are present, you may have to clean your lens for every next shot and your camera sensor more often than people who shoot inside the studio. It’s very strange to accept the fact that lots of photographers who own an expensive lenses and camera body never pay an attention on cleaning their tools which help them capturing stunning photographs. If we take good care of equipment, our equipment takes care of us. Personally, I clean up my equipment every time I come back from the shooting and before storing it to dry cabinet. It is also very common for photographers to use an UV filter in front of their lens so that the actual lens won’t get accidental scratch and they don’t have to clean their lens every time and just cleaning an UV filter will do the job.

Lens cleaning kit

You can use a microfiber towel to clean the lens body and the front glass which doesn’t leave a residue on the surface. Don’t try to clean your lens or camera sensor with a rough surface material like normal towel or napkin paper; you may permanently scratch the front glass of the lens if you use hard surface material. I don’t recommend cleaning your sensor unless it is covered with the dusts and you are experiencing a problem with the image quality. Cleaning image sensor by yourself without having proper knowledge may destroy your camera permanently. Some DSLRs (Nikon D90 for example) come with an option that will lock the camera mirror up and allows you to clean the sensor using a blower or other cleaning tool provided by the camera manufacturer or the other individual company who produces quality accessories for DSLR.

If you go to the SETUP MENU by using the MENU button on the back of your D90 or other model DSLR, you will see an option called “Lock mirror up for cleaning” which is specifically designed for the photographers to clean up the sensor if in case there is a dust. You can use this option to raise the mirror up and open the shutter so that you will have access to the sensor for cleaning with a blower, brush, or swab as shown in the picture above. You can find those lens cleaning kit online for $20 or less. Nikon D90 allows you to use this feature only when your camera has a fully charged battery or sufficient battery for the cleanup because you don’t want the camera power to fail while you are still cleaning your sensor.

What Is Depth Of Field (DoF)?

This post is a part of our Q&A section. If you want to submit your question, please use the form in the Contact page.

Manjit Singh (Delhi, India) asked : Can you please explain me about Depth of Field and it’s relation to the camera settings?

This is what Wikipedia says about DoF - In photography, depth of field (DoF) is the distance between the nearest and the farthest objects in a scene that appear acceptably sharp in an image. Although a lens can precisely focus at only one distance at a time, the decrease in sharpness is gradual on each side of the focused distance, so that within the DoF, the unsharpness is imperceptible under normal viewing conditions.

Sometimes you want to focus everything inside the frame (for example you are doing landscape photography), and a large DoF is appropriate. And in other cases where you are doing macro photography or portrait photography and want to blur the background, a small DoF may be more effective, emphasizing the subject while de-emphasizing the foreground and the background. Usually, a large DoF is often called deep focus or deep depth of field, and a small DoF is often called shallow focus or shallow depth of field. Now let’s discuss briefly about these terms.

Shallow depth of field: When you selectively focus one part of the image and let rest of the image go out of focus, you will get shallow depth of field. This is pretty famous when you are shooting macro or portrait and want to blur the background or produce nice bokeh in the background.

Shallow depth of field

Focal length : 28mm     Aperture : F/4.5     Shutter speed : 1/40 sec     ISO : 200

Deep depth of field: When you want to keep everything inside the frame from the foreground to background in focus using correct combination of camera settings, it is called deep depth of field or larger depth of field.

Deep depth of field

Focal length : 32mm     Aperture : F/8     Shutter speed : 8 sec     ISO : 200

Now let’s take a look at the camera settings that affect depth of field. The DoF is determined by an Aperture, lens Focal length and the physical distance from the subject.

1. DOF and its relation to an Aperture

To get shallow depth of field, you need large opening of the Aperture. And please keep in mind that large opening of Aperture means small f-stop value. Smaller the f-stop value, larger the lens aperture opening will be (allows more light and faster shutter speed) and larger the f-stop value, smaller the lens aperture will be (allows less light and slower shutter speed).

In another word, we can say: for a given subject magnification, increasing the f-number (decreasing the aperture diameter) increases the DoF; decreasing the f-number decreases DoF.

If we keep the focal length and the distance from the subject fixed: larger the opening of Aperture (small f-stop value), shallower the depth of field you will get and smaller the opening of Aperture (large f-stop value), deeper the depth of field you will get.

2. DoF and its relation to the Focal length

Focal length is something that depends on type of the lens you are using. If you are using zoom lens, you can zoom in and zoom out to increase and decrease lens focal length.

If we keep an Aperture and the Distance from the subject fixed: larger focal length will give you shallower depth of field and smaller focal length will give you deeper depth of field.

3. DoF and its relation to the Distance

Physical distance from the subject to the camera also affects depth of field.

If we keep an Aperture and the focal length fixed: closer you are to the subject, shallower your depth of field will be and farther you are from subject, deeper your depth of field will be.

Conclusion: Larger aperture opening (small f-stop value), closer to the subject and larger focal length will give you the shallowest depth of field possible.

Dealing With The Digital Noise

Visual image noise is the random grainy effect on the photograph which is disturbing most of the time rather than pleasing. If these grainy dots, also known as a digital noise, are noticeable or objectionable in the photograph, it can ruin the beauty of the photograph by distracting the viewers mind from the subject. Digital noise is mainly caused by either high ISO settings or a long exposure shooting. Let's discuss these two main factors which contributes to the production of the digital noise.

1. High ISO Setting

High ISO noise commonly appears when you raise your camera’s sensitivity setting above ISO 400. Different camera’s sensitivity level with light differs from one another and sometimes it determines how good your camera is with the lights. With the Nikon D90, noise may become visible at ISO 800, and is often fairly noticeable at ISO 1600. And at ISO 3200, noise is usually quite bothersome. Nikon advises that using ISO 6400 in special situations like very low light condition may help you but you should consider labeling it H1.0. You can expect noise in any pictures taken with that ISO level which is obvious. High ISO noise appears as a result of the amplification needed to increase the sensitivity of the sensor. While using higher ISO settings do pull the details out of the dark areas, they also amplify non-signal information randomly, creating the noise. You’ll find a High ISO NR option in the Shooting menu, where you can specify High, Norm, or Low noise reduction, or turn the feature off entirely. Enabling the noise reduction tends to soften the grainy look, you may want to disable the feature if you‘re willing to accept a little noise to get more details in your picture.

2. Long Exposure Shooting

A similar noisy phenomenon occurs during the long time exposures, which allow more photons to reach the sensor, increasing your ability to capture a picture under low-light conditions. However, the longer exposures also increase the likelihood that some pixels will register random phantom photons, often because the longer an imager is, the warmer it gets, and that heat can be mistaken for photons. There’s also a special kind of noise that CMOS sensors (like the one used in the D90) are potentially susceptible to. With a CCD sensor, the entire signal is conveyed off the chip and funneled through a single amplifier and analog-to-digital conversion circuit. Any noise introduced there is, at least, consistent. CMOS imagers, on the other hand, contain millions of individual amplifiers and A/D converters, all working in unison. Because all these circuits don’t necessarily call process in precisely the same way all the time, they can introduce something called fixed-pattern noise in the image data.

Fortunately, Nikon has done an exceptional job minimizing those noises from all causes in the D90 and other Nikon DSLRs. Even so, you might still want to apply the optional Long Exposure Noise Reduction that can be activated using “Long exp. NR” in the Shooting menu, where the feature can be turned On or Off. When the Long exp NR feature is turned on, D90 takes a second blank exposure and compares the random pixels in that image with the photograph you just took (first image). Pixels that coincide in the two pictures represent the noise and can safely be suppressed. This noise reduction system, also called dark frame subtraction, effectively doubles the amount of time required to take a picture, and is used only for exposures longer than one second. Noise reduction can reduce the amount of details in your picture, as some image information may be removed along with the noise. So, you might want to use this feature with moderation.

If you shoot in a RAW mode, you can also apply the noise reduction to a lesser extent by using post processing software like Photoshop, Lightroom, CaptureNX2 or Aperture later on the computer.

Source: David Busch's Nikon D90 Guide to Digital SLR Photography