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Showing posts with label how it works. Show all posts
Showing posts with label how it works. Show all posts

Wednesday 20 September 2023

Increasing depth of field (DOF)

Hyperfocal distance is not something that trips off the tongue in this modern age of auto focus. In fact digital camera lenses do not have the facility to take advantage of this compositional tool. You just have to compare today’s lens with yesterdays they don't have aperture settings and therefore you can not play with hyperfocal distance settings.


So what is Hyperfocal distance?

When a lens is set to infinity, the depth of field (D.O.F) closest to the camera is known as the Hyperfocal distance for that aperture. If you have an older lens its barrel will be marked with these distances.





How to change the Hyperfocal distance.


Set the lens focus to infinity, and then read the lower mark for whatever aperture you have set. If you then refocus the lens to the lower mark known as the optimum distance you will increase your depth of field by fifty per cent of the optimum.


For example:


This was made using a
 telephoto lens at close distance.
 The use of hyperfocal distance has
 pulled the area of sharp focus
to the front of the ball.
I have used an old 50mm Nikon lens (pictured) to show how it works. I have set the focus to infinity and the aperture to F16. The good thing about this lens is that it shows the upper and lower limits of each aperture with lines on the lens barrel. Looking to the right (marked A) you can see that the last line on the lens barrel is opposite the five meter mark (about fifteen feet). By resetting the focus to optimum in this case five (A). Then look at the lower limit (marked B) for F16, it is about two and a half meters (eight and half feet). The resetting will extend the overall sharpness of the picture by an extra two and a half meters which is 50 percent of the optimum.

The longer the lens the greater the increase is. For argument, an 80 mm lens with an aperture of F22 set, would have a depth of field from 2.8 meters all the way to infinity when optimum focus is used. Instead of 5.6 meters to infinity.


If  hyperfocal distance had been
used with this picture the
 front post would be sharp.
 
In some cases where you do not have aperture lines on the barrel of the lens some cameras and lenses have a shut down button. This allows you to see before you press the shutter where the hyperfocal distance ends. So you can adjust it if needs be.

Being able to increase the depth of field (D.O.F) can be very useful when using medium and long telephoto lenses for subjects close to the lens, allowing narrow fields of sharpness to be moved. This makes sure the front of the item is in focus.


Friday 10 November 2017

Many formats in one camera Zero 6 x 9 pinhole.

Zero 120 multi format pinhole camera
I've had my Zero 6 x 9 second edition multi format camera for years  I don't use it as much as I should this is because it comes into conflict with my Bronica SQAi which I really love using. I enjoy using the Zero but have found that it is spending a lot of time in my camera bag. This shouldn't be the case as they both have completely different characters. Since the beginning of the year I determined that I would use my pinhole camera more. I have been true to my word in that I have set time aside, it maybe the simplest way of making images, it also happens to take time to set up and expose the film. Not always conducive for the way I go about making images. The strange thing is I need a certain frame of mind when I want to use it. 

How the different negative
sizes look.
Being multi format I thought it was time to see how the other formats come out. I know after all these years it will be the first time I explore the formats ether side of my favored 6x6 negative size. So what are the other sizes, down stream is 6 x 4.5 I had not realised until I had moved the partitions to this position that with the camera horizontal it produced the frames in portrait format and that if you wanted landscape I had to stand the camera on it's side. I chose to keep it the way it is.


Upstream from 6x6 is 6 x 7 and 6 x 9 this will be the first time I have made images at these negative sizes so I'm excited to see what they will look like. Something else I did not realize was the large margin between the frames for 6 x 7. The margin is that big I think you could get another frame if the numbers were spaced differently on the backing paper. I'm used to the frames on some occasions with 6x6 bleeding into each other. When it came to the 6 x 9 negs there is no margin making it look like one image over the whole length of the film. Requiring precise cutting when putting them into the storage sheets.

How the different negative sizes are achieved.

It is simple to change the negative size with the Zero you just move the little divides into the preset slots once done you load the film and away you go. 

It has taken quite a time to realize that Fomapan 100 in my case developed in RO9 gives me a stile of image that I really like, making it my default film, dev combination when using this camera. Although that my change since I started using delta 100.

There is a picture post to follow showing some of the images made using the different formats. They have been posted click here.