eXtensions

eXtensions - Sunday 12 August 2018

Rethinking Photo Workflows (7): Prime Lenses, Telephoto Use and Extension Tubes

By Graham K. Rogers

Lenses

When high street shops sell DSLR cameras as kits, they usually include an adjustable lens. As users learn more about their cameras, some may prefer to move to other types of lenses for better photographs and add to the toolbox with specialised equipment.

I bought a Nikon D850 about 4 months ago, and apart from a couple of confirmation shots, hardly used my D7000 in the weeks that followed. I did toy with the idea of selling it, but the market for used DSLR cameras is not particularly good right now. In the end I thought it might best be passed on to a young friend and when he came down to Bangkok during the university break, I handed it over. I knew he wanted a small camera, but this served better.

A question arose about a lens. I wanted to keep my prime lenses (24mm, 50mm and 85mm), so looked around for a lower cost alternative, deciding on Nikkor 35mm or 50mm, but gave him the choice. He had borrowed the D7000 in the past so was familiar with different lenses, but I outlined some basics before he tried in the camera shop and made a decision.

I explain differences between lenses in a class I teach to engineering students, most of whom do not take good photographs, particularly of the equipment they use in their Senior Year projects. To demonstrate, I use tethering, so photographs are displayed onscreen almost as soon as they are taken. The computer is linked to an overhead projector so all in the class can see. It always produces moments when the penny clearly drops.

The lens is usually designated by its focal length and this produces different effects in a photograph. A lens for a camera is not one piece of glass: better lenses have more internal lenses or elements. The more elements, the heavier the lens, so students are often surprised that the 24mm lens I have is much heavier than a telephoto lens I picked up cheap in Bangkok.

24mm Nikkor Lens

The 24mm lens

That 24mm lens is sometimes referred to as a wide-angle lens. There are wider lenses, but while these are useful for landscape photography, the lens can cause problems in some situations. One problem can be in a cityscape: buildings in the center of the shot will be vertical, but those to the far left or far right begin to lean inwards.

This is sometimes more noticeable in smartphone lenses that have a focal length of around 4mm. The lens construction and software do much to correct the images produced, but that perspective - worse the closer to the edges the objects are - is still evident.

Another problem of the 24mmm feature set is that the lens is less suitable for portrait photography. To take a decent portrait, the camera (and lens) needs to be closer to the subject. This was explained to me as the air between lens and subject. If, for example, the nose is properly in focus, the ears may not be. Better for the purpose are 50mm or even 85mm lenses. You can get round this with the use of a telephoto lens in some cases, particularly in street photography with candid images, but a proper portrait should be taken close up.

The 50mm lens

I bought my 50mm lens as a stop-gap several years ago and use it often. I had seen a photographer using one and not long after I broke the adjustable kit lens that came with the D90 I had then. That 50mm Nikkor has stood me in good stead for several years and is a bridge between the 24mm and 85mm lenses I use. It can be used to take landscape photographs, but I found on a couple of occasions when my field of view (in a narrow street for example) was limited, that I had to resort to stitching software (like Hugin) for a better image. This is not the best solution but in some cases the 50mm will work for landscapes.

50mm Nikkor Lens

The narrower field of view and the depth capabilities are to a photographer's advantage in some cases, and particularly for taking portrait photographs, either close up or full length body shots. If I had to leave home with just one lens, it would be the 50mm lens, so I was pleased when my young friend decided on that rather than the 35mm option.

I also have a heavy 50mm Distagon lens for my Hasselblad medium format camera. It requires me to approach a shot differently as there is no autofocus and the input - the lens settings - will depend on the ISO of the film I am using. I use an iPhone app (Pocket Light Meter) for readings on conditions, and I adjust the lens according to the data on that. The Distagon lens is not easy to adjust, slowing me down even more, but it does produce sharp pictures.

The use of such lenses may add to the frustration when taking photographs with film on such a camera, but it has also increased my abilities as I learn about settings values. A recent comment by Dominik Vanyi on DIYPhotography explains this ability to learn through mistakes as it forced to compose his photographs differently.

Hasselblad lenses: 50mm Distagon (left) and 85mm lens

When I bought the Hasselblad it came with an 85mm lens and although this is easier to use, I find the results less satisfying. The 85mm Nikkor lens that I use with my DLSR cameras is a different matter.

Output from Nikkor 50mm lens (left) and Nikkor 85mm lens

The 85mm lens

I was at a dinner a couple of years ago with a number of media people who worked in Bangkok, including a freelance photographer. When talking about taking photographs, I mentioned the use of a telephoto lens to take candid portraits. It was he who made the "air" comment and gave me some clues to taking better pictures of faces. He specifically mentioned the 50mm and 85mm lenses.

85mm Nikkor lens

A few days later I had a look at a Nikkor 85mm lens and was impressed both with the images it could produce and its faster auto-focusing abilities. Unlike the older 24mm and 50mm lenses, there are no markings round the outside of the body: the lens is adjusted by camera software. I have since found a couple of idiosyncracies here, but nothing I cannot work round. I was also helped considerably recently with the use of autofocus on the D850 with the knowledgeable article on focus points (Ryan, Capetown Photography Tours).

Output from 85mm Nikkor lens

Telephoto Lens

When I lived in the outer suburbs of Bangkok, the garden was visited by many monitor lizards, snakes and different bird types. I found the snakes quite defensive and it is not wise to approach closely: they have a limit. To try and deal with this and the fear of humans in birds, I bought a cheap telephoto lens, but the camera shake it induced did not always give me the results I was hoping for. I would love to take better photographs of birds and wild animals so when I saw mention of a 18-400mm lens in an online discussion, I started to look. I decided that the lower end would overlap with lenses I already had, so widened my search to lenses in the 100-400mm range, settling on the Sigma telephoto lens.

Sigma 100-400mm lens

With image stabilisation, camera shake is almost removed, but there are limits with a minimum aperture of F5 at 100mm up to F6.3 (400mm). While the camera will adjust fairly well in lower light conditions (I have it set to Aperture Priority) this is best used in the day. Bryan Carnathan (The Digital Picture) has some helpful comments online about this lens. I am still learning to use this lens, although it has produced some quite good results for me so far. It does of course move away from the argument (above) of minimising the air between lens and subject, but in some situations (timid animals) this is a good compromise solution.

Macro Photography

In a contrast from the use of a telephoto lens, macro photography seeks to move in closer to a small subject and requires a different approach. I do have some extension tubes which are used in macro photography. The idea being that the tube is placed between the camera and the lens (they are engineered for this), which increases the focal length and thus magnifies the subject.

Extension tubes

Not all lenses will work effectively. The Vivitar extension tubes (12mm, 20mm and 36mm) were the only ones that Amazon would ship here when I bought them a few years back. These can be used with Autofocus as there are electrical connections. With all three, that adds 68mm to the distance between camera and lens. It is not at all easy to focus even with Autofocus, and depth of field is limited.

Images taken using the extension tubes

I saw an article on a bellows-type macro mount on the Digital Photography School site and while Ivo Guimaraes had an older device, there was a link to Fotodiox which has these for several brands of cameras, including Nikon. The bellows will extend up to 150mm which could give me some unusual shots. The D850 was not listed, so I sent a query to the company on Monday morning which had been answered by the evening. Yes, it will work, but I was reminded that it would be best with lenses that display the aperture number on the lens (modern lenses do not) and I was reminded that it would be operated manually. I have saved the link to the site as they have a lot more that I could be interested in.

This type of macro photography does not reach the extremes that some photographers can produce with specialist equipment, like extreme closeups of plant biology or the eyes of insects. That is perhaps best explained by Marek Miś where examples of his equipment and the excellent output are shown.

Comment

Over the years I have learned to take photographs that are better (I think), but I have to be my own worst critic. There is always room for improvement and understanding how the equipment works and its shortcomings is a long road. When I was younger I was put off of photography by family experts who used to lecture me on what settings were best in the situation. I have found that instinct is a better teacher, but this comes from that equipment familiarity and an understanding of ambient light conditions: experience.

Using prime lenses is limiting: the lenses need to be suitable for the task. The results, however, are improved when the right lens is used for a situation. While editing and cropping may help, the initial photograph itself should not be a compromise.

This is perhaps what I wanted my young friend to learn when I gave him the camera and 50mm lens. That will restrict his field when taking a photograph, but he will learn much in adjusting his approach to a subject.