Tilting and shifting either lens and/or film plane was commonly used in the old days with large format cameras (Ansel Adams camera for example). In today's market, the film or sensor plane can not be moved any longer in the DSLR or medium format cameras. Photographers need to rely on so-called manual focusing tilt/shift prime lenses which allow up and down or sideways movement of the lens plane as well as tilting it. Common focal lengths for tilt/shift (T/S) lenses are 17, 24, 45, and 90 mm for cropped and full frame DSLR cameras. But who can make use of T/S lenses, what are they good for?

Wide angle T/S lenses are commonly used in architecture and landscape photography, but also with longer lens focal lengths for closeup photography of jewelry, even sometimes for portrait work. Architectural photography commonly makes use of the shift function in the T/S lenses: Falling lines of tall buildings can be reduced or fully avoided. The image plane and therefore the focus are kept parallel to the subject. There are post processing programs out there which correct falling lines in photos taken with regular lenses, too. This gives a more natural look very similar to a photo taken with a T/S lens, but it will crop the photo without keeping the regular film or senor proportions of the negative or RAW file.  

Shifted vertically, lines can be kept parallel to the subject which leads to a more natural look as seen in the central University building at Princeton University below. This was taken with Canon's 24/3.5 T/S lens where the lens was shifted 10 mm up. 

Instead of shifting the lens vertically, sometimes it is useful to have it shifted horizontally to create a distortion-free panorama photo. The crosswalk photo is a stich of three single photos - one shifted horizontally fully to the left, one center one (not shifted), and one shifted to the right. Have a look at the pillars - they are all straight, only the one far left is bent a bit due to the lens angle towards the subject. By stiching three 24 mm T/S photos together, the field of view is similar to a 14 mm lens! Landscape photographers apply this technique to create a natural looking super-wide angle view.

Lens tilting can create the "miniature effect" - focusing on one specific subject in the frame, and making the surrounding area blurry. The photo below taken at the Red Mill in Clinton, NJ shows this effect - I used the few mm tilted 24/3.5 T/S lens in combination with a 2x teleconverter making it a 48 mm f/8 lens. The shallow depth of field surrounding the fisherman in the middle of the photo was only created by tilting the lens out of its focal plane following the Scheimpflug rules. 

The lens was also shifted a bit up to have the sensor plane parallel to the corner wall side of the Red Mill behind. Combination of shift and tilt can work nicely, but it takes a bit trial and error to get used to. A camera equipped with LiveView is very helpful here since it allows you to see instantly the final composition of the photo. 

Instead of creating more shallow depth of field, tilting the other way allows much deeper depth of field at a fairly low aperture number (more wide open aperture). The photo with the old barn in Valley Forge Park, PA is an example for this: To have both the brick wall in the front and the building in the back in focus, normally you would need a small aperture like f/22. This shot again was taken with my 24/3.5 T/S lens, but at an aperture of f/4.5. Tilting and shifting the lens in the right directions allows to focus both background and foreground reasonably sharp and keeping the sensor plane parallel to the structures. If you look closely, you will see that the plant branches in the middle are unsharp - the result of the Scheimpflug rules since the depth of field is no longer horizontally aligned when the lens is tilted! 

T/S lenses take some patience and experience to get used to. You always need a tripod to work with a T/S lens. Also they do not come with AF. In case the lens is shifted and tilted, I recommend checking the focus confirmation with the enlarged area finder in LiveView. Exposure also changes with the shifted direction of the lens. But main disadvantage is the price - they still cost about $1K as used and older lens versions. Latest new T/S models are at least double this price. They have less vignetting and a better rotation system of tilt and shift being parallel or perpendicular. I am still using the older (first) version of Canon's 24 mm T/S lens, and so far I am fine with it, too. If you once get used to T/S lenses, you will always carry one with you if composition allows to use it for.

There is this weird thing in photography called "Bokeh" - often misunderstood as synonym for shallow depth of field. Yes, it is related to depth of field, but it is by far not the same. Bokeh is a Japanese word which means blur or haze, and is here in photography related to some artistic quality of the blur. The appearance of the bokeh effect mostly depends on the lens construction itself and the form of the lens aperture shapes. The more wide open the aperture, the better the bokeh normally - it is visible as circular patterns in the highlighted  blurred background of a photo. The Christmas Light photo below demonstrates this effect with the circular pattern in the background. The photo was taken wide open at f/2.0 with a 135/2.0 lens.

It is mostly a matter of taste to like this effect or not - I personally love a beautiful and especially colorful bokeh effect in photos taken with a wider open aperture. Bokehs can look fairly unattractive at smaller apertures due to less circular shaped patterns (which means there are more edges visible leading to polygonal shapes and hard-edged bokeh). The more aperture blends a lens contains - preferably even with rounded edges - the better looking is normally the bokeh effect. The photo on the right was taken purposely to create this out-of-focus effect (135/2.0 at f/2.0).

How can we explain this effect from a technical point of view? In out-of-focus areas each point of light displays an image of the aperture of the lens, normally a round disc. Depending on the lens construction and the aperture used for the photo, you might see big full circular shapes, oval ones, or donut-like discs. The brightness of this disc largely depends on the lens correction, too (it means how they are corrected for spherical aberration). Some modern lenses use so called apodization filters to even enhance a smoother looking bokeh effect. 

Often bokeh effects appear in the photo unexpectedly. When I took the shot shown below of a mockingbird (which was fairly aggressive against me when I disturbed it), I later found the nice looking bokeh discs on the left which fitted perfectly to the overall composition. This photo was taken at 400 mm focal length at a smaller aperture of f/7.1.

In my experience, the best bokeh effects can be often achieved by highlighted backgrounds, sun reflections from the side hitting foliage/leaves, light reflections on water or other shiny surfaces. You might see that some of your lenses are better than others in your collection to reveal a beautiful looking bokeh. 

An old but often repeated question in photography - which kind of lenses are better, zoom or prime lenses? In my blog I share my experience by using both kind of lenses and where one is better than the other type. 

When I first started many years ago in film photography, I herited two simple M42 thread based simple prime lenses with 28 and 50 mm focal lengths. I am still convinced today that starting out with a simple 50 mm prime lens (no need for a super fast lens copy at this point!) is the best way to learn about composition and photography. It still amazes me today what you can do with this focal length on full frame (this is the 35 mm film format). Just go a few steps forward or backward and voilà, you get the perfect composition even mostly distortion-free. It is a decent portrait lens to do either head shots at closer distance or family portraits from bit further away. And with a simple close-up lens or extension tube between lens and camera, the 50 mm lens can be converted into a decent macro lens, too - only to name a few examples. Recently I took this infrared photo below with my 50/1.2 prime lens - I had to walk to the right spot to frame it the way it is seen here, but no further processing was necessary in the composition!

Later in life I switched mostly to zoom lenses for several reasons: (a) Price: Decent zoom lenses are still quite a bit cheaper than faster prime lenses in a similar focal length. 

(b) Convenience: the zoom lens covers a broader range of focal lengths which avoids changing lenses too often and having the risk of dust getting inside the camera and on the sensor. This can speed up the "snapshot" effort to capture something quickly - in case a prime lens needs to be changed first, the critical moment will have vanished for sure. 

(c) Weight: Instead of carrying a bunch of prime lenses, one single zoom lens is easier portable which is a big advantage for travel or on hikes for example.

Seeing this, why would anybody bother with much more expensive prime lenses? Well, there are a couple of good reasons: (a) People often claim quality of primes having the edge over zoom lenses. This was definitely true in the past, but needs to be a bit more elaborated for more recent times. When comparing excellent prime lenses with newer zoom lenses at the same applied aperture, you will not see a difference easily. All big photo gear brands have now new top quality level zoom lenses which compete easily in photo quality with prime lenses in the same focal length. There is a different story for cheaper and slower zoom lenses, especially so called super-zooms which extend over a broad range of focal lengths (e. g. 28-300 mm) plus having some macro capabilities. I recommend to avoid super zoom lenses - their performance is very weak towards the long end (loss of sharpness and especially in contrast), and they tend to show more distortions at the wide end. A super zoom lens is an optical compromise to make the best of covering a broad focal length range. By knowing its limitations it can be still used sometimes in a decent fashion under good light conditions - I also own one of those fairly cheap super zoom lenses, and I used it a few times for short travels where I couldn't take a lot of gear with me. I was lucky enough to get this close up photo of a sea lily done with my 28-300 macro zoom lens from a distance!

(b) Speed: In my opinion the biggest unbeatable advantage for a prime lens - the main reason why I went back using mostly fast primes. Prime lenses in general have the same speed or are faster than zoom lenses. My prime lens setup consists of the 35/1.4, the 50/1.2 (and 50/1.4 which is also very good), the 85/1.8, and the 135/2.0. Together with a 1.4x teleconverter I can convert the 135/2 lens into a 189/2.8 lens which covers the medium tele range. Speed is important for taking photos under low light conditions, for night photography, for portrait shots, and for better auto focus (AF) accuracy. More light can get into a fast lens at its widest open aperture still providing a focused image with a shallow depth of field (DoF). A good example is the night shot in Holmdel Park below which was taken without tripod support under very dim light conditions with my 35/1.4 lens at f/1.4.

(c) Weight: This claim really depends. The faster the lens, the more and also bigger glass is built into the lens body which increases the weight. My 24-70/2.8 lens is heavy, but adding the weight of my 35/1.4, 50/1.2, and 85/1.8 lenses, I am nearly at the double of the weight of the zoom lens (950 g for the zoom, 1600 g for the set of primes). So the weight argument is a bit vague here in case somebody wants to cover the range of a zoom lens with several very fast prime lenses. It makes sense on the other hand when comparing two sort of prime lenses with each other - the 50/1.2 weighs 590 g, while the 50/1.4 (one third stop slower) weighs only 290 g. That's why I am keeping the 50/1.4 - ideal to reduce weight if needed and still having a fast lens!

Personally I often mix up both of the worlds - depending on the situation, I sometimes choose my 50/1.2 in combination with my 70-200/4 IS lens. For landscape shots I always take my 17-40/4 and my 24/3.5 T/S lenses accompanied again by my 70-200/4 IS. For far tele ranges I only have a slower zoom lens, the 100-400/4.5-5.6 which was so far always sufficient to me. For close-up and macro studies, I often only take primes like my 100/2.8, 105/2.8, or 65/2.8 macro lenses. I also managed to take fantastic close-ups with my 24-70/2.8 and with my other tele zoom lenses by using extension tubes or a reversed lens setup (this setup will be described in my future macro photography blog). The dragonfly photo below was taken with my 70-200/4 IS lens, 1.4x teleconverter, and 12 mm extension tube.

Overall, there is nothing wrong using a good zoom lens! It provides more flexibility and often reduces weight. For more creative photography, I recommend using prime lenses. Just because the depth of field effects are so much better with fast primes. My photos are taken with a broad mix of different kind of lenses - in the end the final photo and the composition counts, it is the photographer's job to ensure the most is made out of the wanted effect no matter how this task is accomplished. Tools (related to lenses) are not just tools, some can be applied better for one kind of job than others. This makes photography exciting!