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 The 'Depth of Field' - Scale!

 

 

                                                                                                                                                           
15th February 2014


The 'Depth of Field Scale' on the barrel of lenses is starting to disappear. I can understand that lenses have to become cheaper and this 'lack of scale' may prove to be okay for those photographers who simply want to autofocus on a subject and just take the picture.

However, there are photographers who like to move around their chosen 'depth of field' in relation to the aperture they are using on the lens by manual adjustment. Either pulling it back from the subject or by pushing it away. This is achieved by noting the depth of field distances using the aperture to distance scale indicators on the lens, and then using the focus ring to move the known distances nearer or further back.

One benefit, is that you can use apertures like f8 - f22 which have a fairly large 'depth of field' on a wider lens, like the Zeiss 35mm f2 ZM T* Biogon prime lens shown, which under normal circumstances would be difficult to blur the background or foreground to any great degree at those aperture settings. Once you have used a reliable lens like the Zeiss pictured, you get to know the tolerances of the aperture to distance scales and you can almost visualise the effect as you move the 'depth of field' about on the scale. Its fast, accurate and once you have mastered this method, you can even use the scales with wider apertures.

Many photographers also use the lens aperture/distance scales for 'hyperfocal' photography. Manual focus lenses are a real pleasure to use in this way as they have aperture/distance scales selected manually on the lens barrel and you can do the same thing with autofocus lenses which also have lens barrel scales by using them in (switched) manual mode.

Lets say that you want to use an aperture of f8, so you select it (on the lens barrel) and set the distance scale infinity mark on the lens barrel to just inside the aperture scale f8 mark on the right - now everything from infinity back into the image (read the distance on the left side of the distance scale against f8 - 1st table below) is in focus to that distance reading on the left f8.

Please Note:
These tables are for example only - they are not to scale.

 

Metres   2 3 5   oo    
f22 f16 f8 f4 f2 f4 f8 f16 f22


If you want you can move/reduce the 'depth of field' whilst still maintaining the f8 aperture by pulling the DOF back whereby the infinity mark is now placed on the f2 mark on the centre line (as shown in the table below) and you read off the new 'shorter' distance back from infinity on the f8 mark on the left.

 

Metres   5   oo        
f22 f16 f8 f4 f2 f4 f8 f16 f22


You can also push the DOF by moving the 'subject distance' to just below the f8 mark on the right whereby everything is in focus between the two f8 marks but everything beyond the right f8 is out of focus. In this way you can create a pleasing 'gradual' blurred background from the subject whilst using a 'stopped down' f8 aperture instead of a 'wide open' f2 aperture.

 

Metres   1.2 1.5 2 3 5 (SD)    
f22 f16 f8 f4 f2 f4 f8 f16 f22


Using these methods you can use the distance scale against both f8 and other aperture marks to adjust other distance settings to create as well as move a 'depth of field' to suit the scene.

A street photographer can use a manually adjusted lens in this way, pre-set the aperture and agreed distances on the scales for a controlled and 'fixed' depth of field, set the aperture priority mode in the camera, lock the exposure, then when required, raise the camera from your side and take the picture, very quickly and without any concern, all you have to do is frame it and press the shutter!

Even although I use autofocus a lot, I still prefer lenses which have manual capability and aperture/distance scale combinations!

 

 

 

 

 

If you have enjoyed this article - please donate to my Charity of Choice   -   The Sick Kids

 

Richard Lawrence
Scotland
United Kingdom

 

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