The Ricoh GRD snap focus explained and a depth of field primer
If you never really understood the snap focus, fear not! Here’s a complete explanation of it all.
Understanding Depth of Field
The first things first: What is depth of field? Without fancy words, it’s the area that is is focus in a photo. More specifically it’s the amount of acceptable sharpness before and after the focused area. Shallow DOF means a really small area that is in focus, the rest is out of focus, like this:
Note: Taken with Ricoh GXR 50mm, you cannot produce a photo like this with a Ricoh GRD, I’ll explain why later.
A large depth of field means that there is a large area in focus, like so:
Notice how everything is pretty much sharp. Now the thing you have to understand (and engrave in stone in your mind) are a few factors that influence depth of field: – Aperture – Focal length – Camera to subject distance
The larger aperture, the lower f-number, the faster the lens, and the shallower the depth of field. The smaller the aperture, the higher f-number, the slower the lens, and the increase in depth of field. So f/1.8 will give you shallow DOF And f/22 will give you a great DOF.
The longer the focal length, the higher the mm, the shallower the depth of field. The shorter the focal length, the lower the mm, the increase in depth of field. So a 50mm will have more stuff in focus at f/8 than a 200mm will have at f/8.
Note: The longer the focal length, the more compressed the background (it will appear close), the shorter the focal length, the more decompressed the background (it will appear far).
See the compression effect with a zoom lens here to understand (called Dolly Zoom).
The longer the focus distance, the larger depth of field. The shorter the focus distance, the shallower the depth of field. So focusing on something at 0.5 meters will have less stuff in focus than focusing at something at 5 meters.
Small sensors All of the above is pretty straightfoward, but here’s the catch: sensor sizes. Without going too much into the details, the smaller the sensor size, the longer the same focal lenght will appear to be. A 50mm on a 35mm camera gives you a FOV of 50mm A 50mm on an APS camera like the Ricoh GXR, Leica M8, Epson RD1, etc gives you a FOV of 75mm A 50mm on a m43 camera like the Olympus Pens, OMD or panasonics gives you a FOV of 100mm A 50mm on a Pentax Q (small sensor) will give you a FOV of 250mm
You can calculate those by seeking the crop factors. So what do we see? A normal 50mm on a 35mm camera actually ACTS as a telephoto on a pentax Q wich has a sensor slightly bigger than the Ricoh GRD. For the sake of comprehension, let’s say that the Ricoh GRD actually had a crop factor of 5 and could mount lenses. A 50mm on a Ricoh GRD would act as a 250mm, so if we wanted for the Ricoh to have a 28mm, it would have to be a 5.6mm lens. At this very short focal length, what happens? The depth of field is immensely greater.
Before getting into snap, you have to understand zone focusing. Before auto focus, even rangefinders, people had to find a way to focus quickly, so what they did is use zone focusing. Basically they looked at the lens markings to know what areas were in focused by looking at their depth of field scale. At the smaller apertures the scale could be divided into zones to have large areas in focus. Look at the lens below:
I simplified it so that you could understand, I put my lens at f/16, and put the first marking of f/16 on 0.7, automatically I can see that from 0.7 to 1.2m will be in focus at f/16. That would be my first zone, if I twit the lens than another zone will be in focus, etc, etc.
Few, ready for it? Ricoh GRD (And GXR and GX100-GX200) have a feature called snap focus. the idea is simple: On snap focus the camera focuses on a specified distance: 1m,1.5m, etc. That’s it. What is the fuss about? Well the simple fact that the GRD is a small sensor camera with a fast lens. What does that mean? it means that if you are un the streets, you can simply shoot without even thinking about focusing. Let’s say you are a relatively fast shooter, you simply set you shutter speed at something like 250 (if you are slow you can do 80-100), lock your aperture at f/8, leave your ISO on auto, and you will be pretty much guaranteed a good exposure and depth of field from 1m (depending on your snap setting) to infinity. Pretty useful, no?
In essence, to bring everything down, snap focusing is zone focusing at a specific distance, but because of the small sensor you can get mostly everything in focus at a generous apertures like 5.6. But the REAL treat is the fact that you don’t even need to go into the menus for snap focus, you can set it up to full press snap. So you can focus regularly with a half press than shoot, or you can full press (with no half press) to do snap.
The double operation, and semi automatic controls of the GRD IV makes you more like a ninja than a photographer. You are limited by your gear, I learned that the hard way once I sold my GRD III, I bitterly regretted it and never felt so constrained by other cameras in my life! Many of my shots I would never get if it weren’t for the blazing speed of operation of the Ricohs. Here are some examples:
I did not even look when taking the first 2 images, I framed mentally, the last one was taken from a moving car, all thanks to the snap focus. I hated the 28mm on the GRD at first but i’m now wondering how I managed without it. Hope I helped
First image shot with GXR 50mm, the others Ricoh GRD III. All processed with Street Presets LR or SE