About making pictures   - DOF and sensor size  by  Waeshael

 

DMC-LC5 with 6mm f2.0 WA Adapter(35mm equiv 28mm) compared with Leica M6 with 28mm Elmarit f2.8

They weigh the same, about 1 lb 13 ozs, and are about the same body size. The M6 uses film, of course, and the DMC-LC5 (which is the same as the Leica Digilux 1, but prettier,) has a 1/1.7” CMYG sensor with 4MP resolution. The DMC-LC5 with its small sensor has a much bigger Depth of Field, so that at f5.6 there is hardly any need to focus the lens for objects more than four feet away, as everything will look sharp between 2 ft and infinity.

In daylight the DMC-LC5 will usually set to f8 and 1/1000 sec for ordinary scenes at ISO 100. All Pictures with the 6mm lens will be sharp from 1.3 feet to infinity. In this case, the focus could be set to manual mode and a hyperfocal setting of 2.2 feet. You could then shoot all day using the 28mm optical finder without having to refocus. If you set manual exposure f8 and 1/1000 there would be no shutter delay at all. Even at f2.0, the DOF of this camera/6mm would be better than  the M6/28mm at f8.

The M6 with the 28mm Elmarit at f8 would have to be set to 10 feet Hyperfocal distance to have everything between 5.5 feet and infinity in focus.

THis applies to any full frame sensor, like the SONY A7 mk II, A7R, and A7, M9. For subjects closer than 10 feet it would be necessary to refocus the lens.

To have a similar DOF to the DMC/6mm the M6 would need a 15mm CSV lens set at f8.


And for SONY NEX-5 cameras with APS-C sensors, the Hyperfocal distance at f8 is 6 feet, and everything from 3.2 feet to infinity would be in focus with the focus set manually to the hyperfocal distance of 6 feet.


So, what do we learn from this? Small sensor cameras are much easier to focus sharply, because they are not fussy about getting the subject exactly on the focal plane. Full frame cameras require special focussing techniques to make pictures sharp. Now with phase detectors on the sensors (phase detection has been standard for DSLRs, and only recently on mirrorless cameras such as the SONY NEX 5-T, A6000, and A7 series.) 


My good friend Wilson took a D300 (APS DX) camera and a Lumix ZS15 (1/2.3”) to Africa recently. The ZS was damaged due to the sand, but he brought home a whole bunch of great pictures made with that camera. They were sharp, in focus, and had great color. When set to WA (4.3mm = 24mm equivalence) at f8, the DOF was 0.8 feet to Infinity at a HF distance of 1.3 feet.

The Pentax Q7 makes the most of the increased DOF with small sensors. The sensor is 1/1.7 on the Q7 and the QS-1.The kit lens goes from 5mm - 15mm f2.8 -4.5. Today the Q7 and basic kit zoom can be purchased for $400. The newer QS-1 for $500. I could use my Leitz glass and Pentax Glass and CSV, and get 70mm to 630mm equivalent FOV covered. And a 70mm FOV is great for portaits.


There are lens adapters for many makes of lenses. Remember that the actual FL of the lenses will have to multiplied by 4.6 in order to see what the 35mm equivalent FOV would be. So, for a Leica 28mm Elmarit the effective FOV on this body would be the same as a 28 x 4.6 mm lens, or 128mm lens on a full frame camera. Even my 15mm CSV would have the equivalent FOV of a 70mm lens on a FF camera.

Hektor 135mm is equal to 630mm FOV - wow what a package. The Leica SM 135mm Hektor is small, the lens is inexpensive, and the screw mount adapter is cheap. DOF at 50 feet is 3 feet at f5.6. Compared with NEX APS-C sensor and 400 mm Telyt, which has a DOF of only 1.16 ft at f5.6.

This 135mm Hektor on my NEX-5 would have the FOV of  630mm on Q7/ QS-1

18mm Auto 110 Pentax = 84mm FOV on Q7