Podcast Episode 8 – NEX Lenses 55-210mm, Zeiss 24mm, Metering Modes and RAW vs JPEG

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The Sony Alpha A77 gets DXO Mark treatment, we go hands on with two new Sony NEX lenses (55-210mm and Zeiss 24mm f/1.8), Metering Modes and RAW versus JPEG, thats what we are talking about in Episode 8


Lets first talk news. Sony’s Alpha A77 sensor got put through it’s paces over at DXO Mark. These guys do tests to see just how well a camera’s sensor does in areas of noise, dynamic range etc and allows you to compare the results with other cameras they have reviewed. The A77 has done very well, even bettering some cameras we did not expect it to beat. You can check out the results for yourself here.

Hands On

We have been testing two of the recently announced Sony NEX lenses lately, namely the 55-210mm and Zeiss 24mm f/1.8

The 55-210mm is a great lens and makes far more sense from a size and weight perspective than the 18-200mm which is a real monster. Image quality and autofocus is great, a good companion for the standard 18-55mm.

The real beauty here is the Zeiss 24mm f/1.8. This lens – if it was available yet – would in an instant be my standard lens for an NEX camera. The f/1.8 aperture comes in super handy and image quality is great. Focus is fast and quiet as we expect from NEX but even nicer is the soft Bokeh you get. What is Bokeh you ask? It is a word that talks about the out of focus area in a photograph with shallow depth of field. Cheap lenses which can give very harsh out of focus areas, the Zeiss 24mm blurs things nicely.


Last time we spoke about how the camera measure 18% light reflectancy as correct exposure. Today we want to look at what the three metering modes are on your Alpha camera.

Centre Weighted

This metering mode is the original method used in many of the earliest cameras. Simply put, the camera would base (depending on the manufacturer) between 60-80% of its exposure calculation on the light reading coming from the centre of the viewfinder. This form of lightmeter was easily fooled at times and – as you will find when we talk about composition – was not great if you composed your images more creatively, meaning, the subject is not in the middle of every picture you take.

Partial or Spot Metering

This method of metering uses the centre of the viewfinder or frame (you will usually see a thin circular line showing the exact area of the meter) to measure the light ignoring the rest of the frame. This was very useful when measuring the light off a grey card for example or the neutral brown wing feathers on say a bird, like a fish eagle, thus ignoring any white or other areas that would adversely effect the exposure.

Matrix or Multi Segment Metering

This metering method is the most commonly used one today. Essentially the camera divides the scene up into different segments (depending on the camera they could be from as few as 2 to in the thousands) and each segment is measured and an average is determined that should provide good exposure over the whole image… while its better by far than Centre Weighted in the vast majority of situations, it is not fool proof, so learn to see the light and know its impact on your image. With digital that is easily previewed on the LCD screen on the back.

Viewers Question

Mat Rogers sent us in a question recently asking if on the Alpha A55 does it really matter whether you shoot RAW or JPEG and why in RAW mode special effects like partial colour don’t seem to have any effect.

Mat here is the simplest way to answer your questions. RAW files are files where the camera captures as much information or DATA about the scene you have photographers as possible. Because it is the RAW information the file is free of any effects, white balance setting etc as you are required to adjust the image in software like Adobe Lightroom etc later on to get the final product you want before you save the image as a JPEG or TIFF file.

JPEG is a standard for compressing image data. By compressing the image data there is a lot of information that gets discarded in the camera to make the file significantly smaller on your memory card. For this reason it will save any effect you make to the image as well. It is a hotly debated subject as to which is better. I shoot RAW when I want to give myself the room to fix an image later if need be. For general snaps where I dont want to sit behind a computer processing files I shoot JPEG. If you would like to see a great article on this check out the post at Pixiq.


That about brings us to the end of another show. Be sure to check out our website http://alphatutorials.co.za for more articles and information. For example there are three articles following our first show each on one of the areas of exposure, ISO, Aperture and Shutter Speeds. You can also send your questions in to us on the the site.

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