What makes a good lens?
There’s actually a very simple answer to that question. A good lens is the one that does what you want or need it to do. So really, the type of lens you need is actually the second thing to consider. Your first question should always be: what type of photo do you want to take? Once you’ve figured that out, finding the right lens is the easy part.
In the kind of architectural photography we do at rbmp, we need very specific equipment. The lenses we choose aren’t just there to make a pretty or interesting picture, they all serve a specific technical function.
A lot of our work involves visualising building proposals to very precise measurements. We need to provide our clients with an accurate representation of what a proposed build will look like.
To make these photomontages, which we often call verified views, we will take a photo of the site from a predetermined angle and record all of the data about the photo conditions. This includes the exact position of the camera, weather conditions, date, time of day, and crucially the lens used.
For this kind of photography, we need to portray the proposal in its natural environment in the way that it would look in reality. Surprisingly however, the kinds of lenses you need to get that look can vary a lot. Like we said earlier, the kind of lens you need depends entirely on the kind of photograph you need and no two photos are alike.
So below we will quickly run you through a selection of different types of lenses, along with how they work and why spending a lot of money on them is worth it for us.
Our go-to lens is often a 50mm prime lens. For middle to long distance photography, this is the lens to use.
One of the most common points of confusion with this lens is why it is necessary at all. Whenever you buy a DSLR camera, it usually comes with a kit zoom lens that will cover 18-55mm. The 50mm lens falls right into that range so what is the point of buying a new lens for a focal length that you already have?
Well, as you might expect, a basic kit lens has a lot of limitations. Firstly, they can usually only let in so much light. Most kit zooms will have a maximum aperture somewhere between f4 and f5.6 which means to get a good low light shot you need either to crank up the ISO, turn on the flash or get out a tripod.
A 50mm prime lens will be significantly better in low light conditions with a maximum aperture between f1.2 and f2. This means it will let a lot more light in without needing you to keep the shutter open for longer and blur the image.
Opening the aperture up like this is perfect for the kind of photography that we do as well because it almost eliminates the depth of field effect. This means that everything in the photo will be in focus. The last thing we want when we visualise a building is to realise that half of the image is blurry.
The other big difference is the optical quality. A kit lens will have a lot of issues because they tend to be quite cheap and basic. There will be unwanted lens flare, aberrations and on the whole the image will just be less crisp. The nice thing about a 50mm lens though is that they are very simple internally and so it doesn’t break the bank to buy a decent one.
Wide Angle (28mm or 35mm)
There are some locations where you need to assess the visual impact from quite close up, such as the view of a proposal at the end of someone’s garden. For shots like these you need to show as much of the scene as you can from fairly nearby.
In times like these, wide angle lenses are ideal. While a zoom lens will flatten the image, a wide angle will curve it, adding more and more of a fisheye effect the wider you go with it. We aren’t in the business of taking photos like this most of the time because they can really warp your perspective, making certain objects seem bigger or smaller than they are in reality. That’s the last thing we want to do.
Now these lenses are the fun ones.
We have written a more in depth article about tilt-shift lenses here, but here’s a quick overview.
They are called tilt-shift lenses because they do two things: tilt and shift. The tilt function allows you to tilt the lens in relation to the sensor on the camera. This can give you really interesting effects like being able to ‘miniaturise’ landscapes, giving them depth of field effects that make town look like model villages.
The function that we prefer however is the shifting effect. This is particularly useful for our line of work as it allows you to photograph tall buildings from a distance without the lines converging.
Image you are looking up at a tall building. The lines converge towards the top making the building look smaller as it goes up. When you look straight at the building at your level, that doesn’t happen anymore. The shift function of a tilt-shift lens allows you take that second photo then shift the lens upwards, without moving the camera itself, and take that photo again but from higher up.
If you cover the whole height of the building doing this then you can stitch the images together and you’ll end up with a photo of a tall building without converging lines.
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