Andrew Macpherson

Using a Tilt Shift Lens, let’s re-design for photographers not the convenience of lens makers

by on Oct.22, 2013, under Equipment, Off the wall

In the beginning cameras with lenses (vs pinholes) were built round a laboratory optical bench, where the various elements could be relatively easily adjusted. This led to the “Stand” and “Field” plate cameras where he lens and the plate (sensor) could be moved relative to each other.

This arrangement had lots of freedom, but the basic arrangements were relatively easily split into what we now call Shift or Perspective Control, and Tilt where we take control of the “plane” of focus. I put “plane” in quotation marks because in the general case, where very clever lens designers have not been at work, that plane is actually the round inside of a ball, and we rely on depth of field and the effective radius of that ball to compensate.

Perspective adjustment (shift) works by setting the back of the camera flat on to whatever we want to look straight, and then moving the lens up, down and sideways relative to the back of the camera until the image appears in then right place on the sensor. Shift lets you take photos of mirrors apparently in the centre of your frame without showing the reflection of the camera, of a tall building with its sides vertical without having to hire a helicopter to get to that position half way up and so on. The usual issue with these shots is the vignetting of the further parts of the image — in effect only half the image will suffer, and in digital post production one stage will be to add temporary blank pixels (or a layer with the 180°opposite shift for symmetry) to the “near” side of the image so that the vignetting circle is around the midpoint, allowing standard lens correction tools to be used to cancel it out in post. With a Canon TS lens on a tripod one can simply rotate the lens to get the perfect 180° reverse shift to make sure the generated composite is the correct size.

Tilt is much harder to use. What tilt lets you do is play with your plane of focus, either reducing it to a narrow line across your frame, or bringing a large receding plane into focus, from foreground right to the furthest distance. This is where the mechanical design of he lens can make all the difference to how easy the lens is to use for the photographer.

The ideal Tilt lens will have a tripod mount ring, and the tilt’s axis or point of rotation will be across the sensor of the camera. This lets the photographer compose their shot, and use the most sensitive central focal sensor on their camera to get a sharp focus, then switch to using a peripheral focal sensor and rotate the camera body (remember we’ve clamped the lens to the tripod, leaving the camera body mobile) until that point too is in focus. The central point will have remained in focus because that’s at the centre of rotation. The composition too will remain almost unaltered.

My Canon TS lenses completely fail on the usability front. They rotate about the front of the camera body rather than the sensor, with no regard to the photographer who will have to try to use it, each movement of the tilt mechanism changes the composition and the focus. This fault is also there in Lensbabys, Samyang and all sorts of other lenses with tilt capability. The “Why?” Is fairly obvious: by having a short radius the lens designer gives themselves twice the angle for a given movement, and reduces the consequential vignetting but at a massive cost in ease of use.

I’m still searching for a lens manufacturer with the guts to trade “spec” figures for usability

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Photographing Charity Cycle Rides – lessons learned

by on Jul.28, 2013, under Equipment, Learning

Well it’s the 4th time I’ve had a go at photographing the participants in the London to Cambridge sponsored charity cycle ride. Each time I get a little closer to getting it right, a little more confident of getting a reasonable set of results.

So where have I got to?

  1. This may be a daytime event but I definitely want flash to get separation from a darker background
  2. If the aim is to get each participant there is not time to capture each and get AI servo lock, and definitely not time to focus so a big depth of field and manual pre-focus is crucial, especially as the riders are all over the road, which means
    • Strobe in high speed sync
    • or high power low ISO (recharging time is an issue)
    • This year I had a speed light with an external battery pack which both gave good recycle time and over 2000 discharges at 1/8 from the 12 AA cells, but in hindsight I could have done with being at 1/2 power (or 2 strobes at 1/4) but I’m not sure about charging being fast enough
  3. It may be worthwhile using a crop frame sensor and shorter (absolute) focal length lens to improve the effective depth of field for a given composition
  4. Get the other stuff right then shoot medium JPEG, there are several thousand riders, one really does not want 100G of raw to process
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Liberty Business in Stortford

by on Jun.26, 2013, under Off the wall

The Mayor’s Business Networking event around the Market Square in Stortford variously in Baroosh, Zizzi and Host, and with a few brave souls in the square itself

The Camera Club, had been asked to take a few shots… Seems I was the only one available

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Opportunistic lighting

by on Jun.20, 2013, under Equipment, Learning

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A neighbour’s daughter was being particularly cute, telling her aunt to pick up a book and read, then gazing into one herself.

Outside we had bright sunlight, with a slightly north facing window. The window light reflects ideally from the book into her face, so I sneaked a grab shot, holding the camera low (and failing to get the focus perfect- it’s on her arm rather than her eye) I thought I would share the shot for the lighting anyway

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Photo challenge cards, topic suggestions needed

by on May.14, 2013, under Camera Club, Learning

In preparation for the season when the club goes out and about I”m making up some sets of photo challenge cards, 5 topics per card, which I’ll make available here in due course ready to print and run through the card cutter (standard10 cards per sheet cutter when the image is centred & printed)

In the meantime I’ld very much appreciate suggestions to add as topics in the different contexts — the cards will be based on topics such as town, country, seaside, day, night, seasonal, different weather conditions etc. I’ll make up a grid where the topics apply

The final aim being to have cards prepared and to hand, as a fallback whenever we sally forth.

Please leave suggestions below, or tweet them to me. many thanks!

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What files have I worked on?

by on May.10, 2013, under Learning, Retouching, Workflow

Ever find you have to do some work in Lightroom without adding Picks, selections, stars or other obvious Metadata?

Select Develop Preset

Select Develop Preset

I recently found myself tweaking a friend’s images so she could use them immediately rather than wait to get home and work on them at her desktop…  She had literally hundreds of photos on the card, but wanted to see them full screen, then wanted a few adjusted, and the issue was, at the end of the exercise, to identify quickly which had been touched to re-export them.

All your modifications will be under "custom"

All the modifications will be under “custom”

With the folder open in the Lightroom Library Module I went to the Filter bar press ‘\‘ if it’s not showing at the top and select ‘Metadata’ then set my selection to ‘Develop Preset’ at this point you may have a few choices particularly if you have used any presets, but everything I had touched was under custom enabling me to quickly pick them out for re-export.

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