Foucsing and DOF

[ahmad sabry]

i started to take pictures with different focus but the kids didn't let me continue. so i hope i have time today to start again

[William W]

. . . Using CANON 5D MARK III, 70-200 mm F 2.8 II lens . . . Is this could be fixed via adjusting the technique or I need a macro lens (specially I want the background to be totally blurred)

You have adequate discussion about other techniques and also comments that a Macro Lens will not assist much more than the lens you already have: but I cannot see any comment about what lens will assist.

The answer is:

A TS-E 90mm F/2.8 in conjunction with a 12mm Extension Tube and a x1.4MkII Tele-extender: but the TS-E 90mm lens by itself, will do a good job.


WW

[Inkanyezi]

You have adequate discussion about other techniques and also comments that a Macro Lens will not assist much more than the lens you already have: but I cannot see any comment about what lens will assist.

The answer is:

A TS-E 90mm F/2.8 in conjunction with a 12mm Extension Tube and a x1.4MkII Tele-extender: but the TS-E 90mm lens by itself, will do a good job.


WW

At only about twelve hundred dollars that lens is a bargain, but I'm afraid it won't fit the purpose.

The problem is that there are two contradictory requirements, first optimal sharpness over a large depth of field, then substantial blurring of a not very distant background. There is no lens, absolutely no lens, that can solve this problem, but combining various techniques can. I used tilt to see whether it would be sufficient for shooting the sharp part of the image in one single shot, and I also posted it to show how far one would get with that. From my point of view, it is insufficient, hence stacking is a better solution, and once decided to stack, a tilt lens won't do a better job than any lens.

Bokeh is really not a problem, once advanced image manipulating techniques are applied. Gaussian blur is one of the simplest filters that can be applied to create just as much bokeh one would like to any area in an image. So in essence, bokeh is not an issue, it can always be added. Sharpness however, cannot be acquired by editing, sharpness must be there in the image, and the stacking technique is superb for great depth of field in a small object at close distance. It is however a bit cumbersome and time consuming without the help of software, and can only be used for immobile objects, as for example this model car.

If the shortest close-up distance of the zoom, 1.5 metres, is too far, the simplest and cheapest solution for a shorter distance is to use a close-up lens that is screwed into the filter thread. A +1 lens will take the far distance to one metre from the edge of the close-up lens, and the close distance to about 75 cm, which probably is sufficient, and the reproduction scale is adjusted by zooming. Such a moderate lens will not compromise sharpness much, particularly not in the centre of the image, and for the rest of the image, sharpness is not desired. The 70-200 zoom can do the job by stacking, whether at normal focusing distance or with a close-up lens. If a longer focal length close-up lens is needed, it is not available in the photo business, but an optician can adapt a lens of less than one diopter.

PP blurring can do a better job than a tilt lens for the out of focus areas.

[William W]

ORIGINAL STATEMENT:

You have adequate discussion about other techniques and also comments that a Macro Lens will not assist much more than the lens you already have: but I cannot see any comment about what lens will assist.
The answer is:
A TS-E 90mm F/2.8 in conjunction with a 12mm Extension Tube and a x1.4MkII Tele-extender: but the TS-E 90mm lens by itself, will do a good job.
WW

REBUFF to the ORIGINAL STATEMENT :

At only about twelve hundred dollars that lens is a bargain, but I'm afraid it won't fit the purpose.

The problem is that there are two contradictory requirements, first optimal sharpness over a large depth of field, then substantial blurring of a not very distant background. There is no lens, absolutely no lens, that can solve this problem, but combining various techniques can. I used tilt to see whether it would be sufficient for shooting the sharp part of the image in one single shot, and I also posted it to show how far one would get with that. [I tried to take a toy car with horizontal tilt, to see whether it would be possible to achieve sufficient DOF, but it does not cover the width of the front of the toy car at f/16 with the 50 mm lens.] From my point of view, it is insufficient, hence stacking is a better solution, and once decided to stack, a tilt lens won't do a better job than any lens. . . .

***

Below is an image made of a model ‘bus, which is 130mm long and about 90mm high (many times bigger than the car in the original sample).

Note the ‘bus is about TWICE the length of the car in the original sample.

Choosing a longer Subject goes to making it MORE difficult to attain a reasonably sharp focus along the length of the Subject.

Note this image approximates the image the OP placed as a sample.

Apart from downsizing to facilitate web inclusion this is the JPEG SOOC.

Note the edge of the table, behind the ‘bus and on which the bus is situated - are reasonably OoF – the bus is about 1mtr from that edge.

Note that the chairs in the room behind are quite OoF and those chairs are about 2.5mtrs away from the ‘bus.

I have loaded this image quite large, so it might be interrogated.



***

Here is a very quickly sharpened version – nothing more than ‘typical’ sharpening:



***

This very quick sample provided, was predicted on the mathematics for the shot, which also was why I made the original statement:

“The answer is: A TS-E 90mm F/2.8 in conjunction with a 12mm Extension Tube and a x1.4MkII Tele-extender: but the TS-E 90mm lens by itself, will do a good job.”

***

The Image I’ve provided might not make muster to be “perfect” to all who might critique it – but, especially as my sample is TWICE as long as the sample in the Original Post -

I don’t believe there is much argument that the sample image of the ‘bus does indeed satisfy the two main criteria of the Original Post:

I am trying to
 . . . get the whole car in focus
 . . . I want the background to be totally blurred)

.

***

This very quick Demonstration Image of the ‘bus, was made with a Canon EOS 5D and a Canon TS-E 90:



***

The fact that one might make a test image using a 50mm lens, applying tilt and then conclude that that specific image does not sufficiently suit the criteria:

- does NOT disprove the claim that the properly applied use of a TS-E 90 lens – “will do a good job”.


WW


Addenda:
1. The lateness of this sample and reply was due to my lens having been loaned to Student, to complete her assignment.

2. The fundamental Mathematics, which were the predicate of my original statement can be found by researching:

• Generally - (the physics of) Camera Movements
• the LIMITS of the MOVEMENTS of the Canon TS-E 90;
• the ARRANGEMENTS of the MOVEMENTS of the Canon TS-E 90
• the Field of View of that particular lens
• the Mathematics of Depth of Field as it applies to the Tilt and Shift movements of that Lens