Great article on Depth of Field
Discussion
The rather excellent Luminous Landscape web site has this rather good article on understanding the Depth Of Field concepts for different size lenses.
Better still the additions to the article at the end of it have interesting relevance to any sports photography enthusiasts we may have in the forum.
I guess those that already have autofocus lenses will know all about this but people like me, with a manual focus preference from past experience, may find the information useful when considering future purchases.
Better still the additions to the article at the end of it have interesting relevance to any sports photography enthusiasts we may have in the forum.
I guess those that already have autofocus lenses will know all about this but people like me, with a manual focus preference from past experience, may find the information useful when considering future purchases.
Oops - did you miss the link?
Is it this one:
http://luminous-landscape.com/tutorials/dof2.shtml
There's another one that includes this (logical when you think about it, but at first it may appear counter intuitive), the sort of article which I love about LL....
At the beginning of this tutorial I wrote, "Most people also believe that wide angle lenses have more depth of field than telephoto lenses (false)." Why is this such a common misconception?
It seems logical. Wide angle lenses appear to have more depth of field than long lenses, don't they? Yes, they appear to but only when you don't take subject size into account.
Imagine a person in a photograph holding a flower in front of them, and with a mountain range in the background. Now set up the shot so that the person's head fills about half the frame. Take a series of shots with every lens in your arsenal, from a 14mm ultra wide to a 600mm ultra telephoto. As long as the head is the same size in each frame the Depth of Field will be the same. The flower and the mountains will be equally in focus or out of focus as you change lenses.
>> Edited by beano500 on Monday 11th July 11:12
Is it this one:
http://luminous-landscape.com/tutorials/dof2.shtml
There's another one that includes this (logical when you think about it, but at first it may appear counter intuitive), the sort of article which I love about LL....
At the beginning of this tutorial I wrote, "Most people also believe that wide angle lenses have more depth of field than telephoto lenses (false)." Why is this such a common misconception?
It seems logical. Wide angle lenses appear to have more depth of field than long lenses, don't they? Yes, they appear to but only when you don't take subject size into account.
Imagine a person in a photograph holding a flower in front of them, and with a mountain range in the background. Now set up the shot so that the person's head fills about half the frame. Take a series of shots with every lens in your arsenal, from a 14mm ultra wide to a 600mm ultra telephoto. As long as the head is the same size in each frame the Depth of Field will be the same. The flower and the mountains will be equally in focus or out of focus as you change lenses.
>> Edited by beano500 on Monday 11th July 11:12
beano500 said:
Oops - did you miss the link?
Is it this one:
<a href="http://luminous-landscape.com/tutorials/dof2.shtml">http://luminous-landscape.com/tutorials/dof2.shtml</a>
Err, yes, oops indeed, forgot the link and it is that one - thanks beano!
I blame the heat ...
... and the sudden urge to mess around with V6GTO's "Why?" image to see what is going on with it.
beano500 said:
Yeah - there's not something on LL about that is there? I know I've read something somewhere on this topic.....
I have not found anything directly relevant yet but a there are a number of articles referring to the relatively narrow (6 stop) range of contrast values available. And also the one about filter flair and the strange effects one can get from street lights, which in many way cannot be so different from shooting into the sun!
I find you get better graduation and intensity of sunset by stopping down and losing the shadow detail. Now if you look at the histogram of Martin's shot there are several 'mounds' of data volume and a large mass around the mid to lower shadow area (the bush in the bottom left where there is quite a lot of detail though all dark) plus the extremes at the darkest and lightest values.
It occurs to me that thet sky area represents getting on for half of the image total and is all pretty much in the same colour and exposure area but has little detail. Whereas the sand and the bush have a lot of detail to record and the sensor and software are probably biased towards processing for dark areas and avoiding noise. So the allocation of colour seperation data is apportioned according to the colour complexity info available. In the sky there are large areas averaged out from a relatively small section of the data collected and so, to save data storage capacity for the detail in the darker areas, the software will interpret the larger sky areas into fewer graduations of what are essentially the same colours as it seems them.
If you stop down - or even play around with the histogram settings - to make the shadows darker, the sky can be given a more even colour graduation.
Of course we may also need to consider the screen (and printer?) capabilities for this.
LL indicated that 35mm images on the right film can offer an 8 stop range (iirc) and maybe a little more grey scale capability from B&W films.
All of which is very well and just my guesswork - AND of course in completely the wrong thread now!
The other thought I had was that the effect is not dissimilar the to a 'rainbow' but in a very limited susceptible colour range. So this is going back to the filter or lens flair possibility. The chances are the tha optics or filter could 'colour', either additively or subtractively (? i.e. take out some blue for example) in a rainbow effect according to the refractive index of light in the glass used.
If you were to see this effect overlaid onto the evenly diffused but graduated light of the subject the effect would be intensified within a very narrow colour spectrum. This could provide the CCD and software with yet more data to suggest there are really only relatively few red/orange (or perhaps virtually no blue) colours when the area is averaged and 'compressed' (even at RAW settings)
If you were to see this effect overlaid onto the evenly diffused but graduated light of the subject the effect would be intensified within a very narrow colour spectrum. This could provide the CCD and software with yet more data to suggest there are really only relatively few red/orange (or perhaps virtually no blue) colours when the area is averaged and 'compressed' (even at RAW settings)
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