Monday, November 24, 2008

Exposure Conpensation

Exposure compensation is a technique for adjusting the exposure indicated by a photographic exposure meter, in consideration of factors that may cause the indicated exposure to result in a less-than-optimal image. Factors considered may include unusual lighting distribution, variations within a camera system, filters, non-standard processing, or intended underexposure or overexposure. Cinematographers may also apply exposure compensation for changes in shutter angle or film speed, among other factors.

Generally used in Aperture and Shutter Priority Modes...

In photography, some cameras include exposure compensation as a feature to allow the user to adjust the automatically calculated exposure. Compensation can be either positive (additional exposure) or negative (reduced exposure), and is commonly available in third- or half-step[1] increments, usually up to two or three steps in either direction; some digital cameras allow a greater range. Camera exposure compensation is commonly stated in terms of exposure value (EV); 1 EV is equal to one exposure step.

LOOK for +/- sign on your Camera Body.. If not able to locate, try to check Menu or Function Controls available in some cameras.

Monday, November 17, 2008

Light Meter in SLR Cameras

Knowing how your digital camera meters light is critical for achieving consistent and accurate exposures. Metering is the brain behind how your camera determines the shutter speed and aperture, based on lighting conditions and ISO speed.

Understanding these can improve one's photographic intuition for how a camera measures light.

Light Meters:

- Reflected Light Meters
- Incident Light Meters

Normally you can see an Exposure Scale in your cameras. Most of the times when we start using new SLR cameras, it takes time to estimate the right exposure (Aperture + Shutter Speed) in different light conditions. Light Meter Scale is dem=noted by a line having zero value in middle & -ve values on right side. +ve values are on left side and denotes over-exposed. This does not mean that zero is the ideal Exposure. This needs to be estimted by photographer becuase every Ligt Meter has different algorithm to judge light coming to the lens. So it might be the case and -2 is ideal exposure in sunlight (It's just an example).

How to try:

- Go to manual mode of your camera
- Set some value of Aperture (Whtever you want)
- Check the value in Camera Light Meter
- Now click photograph at some Shutterspeed
- Check how it can be improved.
- Now try this again n again with different Shutter sppeds and also check Light Meter regularly.

You can also try the same thing with fixed Shutterspeed. Remember, always check Light meter when you change Aperture or Shutter-speed. Over the time it will give you an idea about Exposure values for different light conditions.

Thursday, November 6, 2008

My First Photography class

Today I had my first photography class where we discussed some basics on Photography and basic information about type of Cameras.

Diaphragm: A stop in the light path of a lens, having an aperture that regulates the amount of light that passes. These are actually blades which are moved to achieve a particular Aperture Value.

Shutter : Overlapping Curtains behind Lens to control the passage of light towards Sensor.

Types of Cameras:

1. Simple Viewfinder Cameras:

- Viewfinder: A viewfinder is what the photographer looks through to compose, and in many cases to focus, the picture.
- These Cameras have Parallax Error (Parallax is an apparent displacement or difference of orientation of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. KNOW MORE... )

2. Rangefinder Cameras: A rangefinder camera is a camera fitted with a rangefinder: a range-finding focusing mechanism allowing the photographer to measure the subject distance and take photographs that are in sharp focus. Most varieties of rangefinder show two images of the same subject, one of which moves when a calibrated wheel is turned; when the two images coincide and fuse into one, the distance can be read off the wheel. Older, non-coupled rangefinder cameras display the focusing distance and require the photographer to transfer the value to the lens focus ring; cameras without built-in rangefinders could have an external rangefinder fitted into the accessory shoe. Earlier cameras of this type had separate viewfinder and rangefinder windows; later the rangefinder was incorporated into the viewfinder. More modern designs have rangefinders coupled to the focusing mechanism, so that the lens is focused correctly when the rangefinder images fuse.

- Used these days : Leica ...
- Compact Cemaras
- Coupled range finder (Prizm) is used to reflect the view from lens for user eyes during capture process.
- Photographer needs to adjust the lens to get sharp image through these cameras.
- No noise, thats why used by Street Photographers
- Manual Adjustment Lenses are used in these kind of cameras

3. Twin-Lens Cameras: A twin-lens reflex camera (TLR) is a type of camera with two objective lenses of the same focal length. One of the lenses is the photographic objective (the lens that takes the picture), while the other is used for the waist-level viewfinder system. In addition to the objective, the viewfinder consists of a 45-degree mirror (the reason for the word reflex in the name), a matte focusing screen at the top of the camera, and a pop-up hood surrounding it. The two objectives are connected, so that the focus shown on the focusing screen will be exactly the same as on the film. However, many inexpensive TLRs are fixed-focus models. KNOW MORE...

- Paramender is used to overcome Parallax

4. Single Reflex Cameras (SLR): The single-lens reflex (SLR) camera uses an automatic moving mirror system which permits the photographer to see exactly what will be captured by the film or digital imaging system, as opposed to non-SLR cameras where the view through the viewfinder could be significantly different from what was captured on film. KNOW MORE...

- Mirror goes up when shoot button clicked.
- Mirror is used before shoot to show the view in viewfinder. So in this case light comes through lens and same view is also passed to Viewfinder.

5. View Cameras: It comprises a flexible bellows which forms a light-tight seal between two adjustable standards, one of which holds a lens, and the other a viewfinder or a photographic film holder.

The bellows is a flexible, accordion-pleated box, which encloses the space between the lens and film, and has the ability to flex to accommodate the movements of the standards. KNOW MORE...

- Huge Cameras
- Big film/Digital back sheet
- Always mounted on stand
- Lenses can be tilted
- Shutter is part of lens
- Companies like Sinar produces this kind of cameras. Check Google for other brands.



- 35mm Format film cameras <36mm*24mm> 24+11mm = 35mm (Including perforation of 11 mm)
- 24mm*16mm sensors in small format digital cameras: Small format Digital SLRs : APS-C Format (Advanced Photo System) : D200,
- We should not compare Digtal Camera quality with Film cameras because of different reasons???


- Nikon D3, D700
- Digital cameras with sensor 24mm*36mm


- 6'*9' inches & 8'*12' inches
- Sinar Brand cameras


- 120 format, 220 format, 645 format (greater than 24mm*36mm frames)
- Mamiya (Japanese), Hasselblad
- 645 = 6*4.5 cm by Mamiya

Checkout Nikon D3 & Nikon D700

*** Today I saw a lens with Aperture Controls... Need to know about the details ***

Sunday, November 2, 2008

Digital Camera Comparison - MegaPixels

What are those megapixels anyway? Digital cameras capture photographs on image sensors, rather than on film.

The megapixel count is how many individual ‘dots’ are there on that image sensor, making up the photograph. 3 Megapixel cameras have 3 million dots on their sensors. 4 Megapixel cameras have 4 million dots . . . and so on.

You might assume then, that those extra million pixels will improve your digital photography. Not by much it won’t!

You would have to jump from a 3 megapixel to a 6 megapixel to really make a difference to your digital photography. (As compared to moving from 3MP to 4 MP... )

The reason I’m explaining this? When you are making your digital camera comparison, standing in the shop, ready to hand over your money – don’t concern yourself with whether camera ‘A’, has 1 million more pixels than camera ‘B’. It won't make a huge difference.

Other things to consider about the number of megapixels:

There are two things you should consider when making your digital camera comparison:

- How important is picture quality to you?
- How will you view your photographs, computer screen or print?

Picture quality:

This is determined by more than just the number of pixels. In fact, some cameras with a lot of megapixels produce worse pictures than cameras with fewer. The reason is twofold:

First, the more pixels crammed onto an image sensor, the smaller each individual pixel must be. The pixels are so small it’s difficult to accurately record the light hitting them. The results are what we call in digital photography ‘noise’ and ‘purple fringing’.

Second, the quality of lenses. The best sensor in the world will be useless without a good lens to focus light onto it. At the same time, a lesser sensor, but with a good lens in front of it is capable of taking very good photographs. Read about the importance of brand when making your digital camera comparison.

How will you view your photographs?:

If you plan to use digital photography to take photographs that you will only ever view on screen, then you won’t need many pixels. A standard 15” monitor will be 1024 pixels wide, and 768 pixels high. The total is only 0.8 Megapixels. No point buying a 6 megapixel camera if you only need 0.8 of them!

Maybe someday you'll want to print them out:

One day you may well decide to print the results of your digital photography. Most people do at some point, and therefore you’ll need to think carefully about the number of pixels when making your digital camera comparison.

The holy grail for printing is a resolution of 300 dots per inch. Click if you want to read more about image resolution. You will still get a good print from around 240 dots per inch though.

What does this mean for you in terms of megapixels? Have a look at the relationship below which shows how big a print you can realistically make:


2MP >>> 6"*4"
3MP >>> 7"*5"
6MP >>> 10"*8"
8MP >>> 12"*10"

How SLR Cameras are better than Compact Cameras

SLRs are big, heavy and expensive when compared to compact digital cameras.

So wouldn’t you be better off with a compact? Well, not necessarily.

This page outlines the key differences between the two, and will hopefully show you that there are good reasons why keen photographers carry bulky SLRs around with them!

It’s difficult to pin down just one advantage of digital SLR cameras, because there are so many of them. Here are some them:


Many compact cameras these days have a huge number of megapixels. More in fact than a lot of digital SLRs. You could be forgiven for thinking that this must mean better photos?

Unfortunately you’d be wrong. More megapixels doesn’t equal better quality. The problem is the image sensors on compact digital cameras are just too small. When 10 million pixels are crammed onto them the individual photosites on the sensor are too small, and too close together.

This closeness and their size means they suffer from interference. When you look at photos closely they have speckles on them. This is called digital noise. The effect is worse in low light.

The lack of noise in photos is one advantage of digital SLR cameras when it comes to picture quality, but not the only one. Another advantage is SLRs’ ability to shoot in RAW mode.

By shooting in RAW mode the camera captures more detail, and allows for far more flexibility when it comes to editing photos later on.

Overall photo quality is one advantage of digital SLR cameras over compact digital cameras.


When I talk of “speed”, I am referring to the speed of camera operation.

There are a number of factors that contribute to the overall speed of a digital camera.

First, there is the speed of focusing. When composing a shot, cameras clearly need to focus first.

In any given situation a digital SLR camera will focus on the subject faster than a compact digital camera.

This speed advantage of digital SLR cameras is even more obvious in low light conditions.

Second, there is the frame rate. Frame rate is the number of frames per second a camera can take.

Digital SLR cameras are usually good at taking a sequence of photos of a moving subject; and will be able to keep re-focussing as the subject moves too. Have a look at the photo below to see the effect.

Another element of speed is how long the camera takes to switch on. With a digital SLR, especially the more recent Nikons and Canons, as soon as you turn the switch, it’s on. That’s it. No lens to extend. No motor whirring. It’s just on, in an instant.

If you are interested in capturing a moment, this “on” speed might be the difference between getting your shot, and missing out. This is a definite advantage of digital SLR cameras.

A final note on the speed of operation is the speed of zooming. When a compact camera zooms the motor whirrs and the lens slowly extends. Digital SLRs don’t work in this motorised way. You zoom the lens by turning the lens barrel. This gives you an instant zoom.

With this type of manual zooming it is also easier to nudge the zoom in or out a little if you need to – just a little flick of the wrist is all that’s needed, and you’re there.

Speed of operation is therefore a clear advantage of digital SLR cameras over compact digital cameras.


With a digital SLR you have the choice of hundreds of different lenses and a huge range of flash options.

Why should you care about the lenses, after all, compact digital cameras come with good zoom lenses, don’t they? Well, yes, they do. But the quality of the lens is poor in relation to the lenses available to digital SLRs, and there is no comparison when it comes to aperture.

Lenses on digital SLRs have wide apertures, much wider than the zoom lenses on compacts. This provides two advantages of digital SLR cameras over compacts.

First, this means that shutter speeds can be faster because more light can enter the camera.

Second, it means you are able to control the depth of field in your photos. A shallow depth of field is particularly flattering in portrait photography, and is impossible to achieve with a compact camera because the lenses just aren’t up to the job.

And then there’s the flexibility of the flash on offer. The small flash on top of compact cameras is no match for the powerful flashguns that are available for digital SLRs.

Not only are flashguns more powerful, but they also able to “bounce” the flash off of ceilings and walls. This diffuses the flash, and eliminates red eye.

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