Focus Stacking for Macro

A great article with some excellent examples of focus-stacking in macro photography on dpreview.

The 'new' focal lengths are the old focal lengths...

I spent an evening in York the other day (see previous post), and knowing that I'd be on foot, shooting hand-held in low-light, I took my current 'walk-round' outfit. Now I'm generally no fan of zooms, preferring instead fixed focal length  (prime) lenses with a decent fast maximum aperture.

On this occasion I went equipped with a Nikon D7000, an old Nikon 20mm f/2.8 Ai-S manual focus lens, a Nikon 35mm AF-S f/1.8 DX lens and a Nikon 85mm f/1.8 AF-D. You'll notice that these are all fast, but not the fastest available, and there's 2 good reasons for this: cost and weight.

As an example, the 35mm f/1.8 weighs some 400g less than it's f/1.4 cousin, and costs over a thousand pounds less. OK, the f/1.4 is the better lens under some circumstances, but it also serves to demonstrate what great value it's slower cousin is - but only if you are shooting DX of course!

I was really pleased with the results from this little outfit, and it made me reflect on how this harks back to the sort of gear you might have had, or hankered after, 30 or 40 years ago when 35mm SLRs came to the attention of mainstream consumers. Chances are if you had a Zenit, Praktica, or if you were really fortunate like me, a Pentax ME Super, then you would have started with a 50mm, added a 28mm wide angle, and perhaps a 135mm telephoto. Fast forward 40 years, and that's pretty much how my 'compact' outfit stacks up: the equivalents are 30mm, 52mm and 127mm.

In terms of portability, quality and value (if you purchase the 20 & 85 used), I think this trio will take a lot to beat. Provided that is, it suits the style of photography you want to practice with it.

Two other essential pieces of equipment needed for a rainy shoot - lens hoods and a clear shower cap. The shower cap goes over the camera (it's best to remove the strap), protecting it from rain but allowing you to see and access controls and LCD, but I found it best to pull it off the viewfinder to compose.

If you keep the lens pointed slightly down, lens hoods protect the front element from rain spots. The hood for the 85mm is a bit bulky, so I used a Hoya rubber one, which also happily fits the 20mm and can be extended or retracted to suit either lens. The smaller plastic hood supplied with the 35mm did the job perfectly.

Turning rain to your advantage

The current UK 'summer' weather has been extremely frustrating, the only thing to do is to try and turn it to your advantage, like some moody shots of wet cobbles perhaps?

 Nikon D7000, 85mm f/1.8 AF-D 1/100 @ f/2.2, ISO 1800

As above except ISO 1250

Nikon D7000, 35 f/1.8 AF-S DX, 1/40 @ f/2.2, ISO 1000

All the above taken in The Shambles, York

Digital Panoramas - part two

Following on from my last post, let's have a look at two more techniques for digital panoramas, both involving using software to stitch together multiple images, for which I use ptgui.

4. Stitching - using a panoramic head

There are a few of these on the market, all of them allow for proper alignment of the shot images, by rotating the lens around it's nodal point. You have to calibrate for each lens you intend to use, but it only takes a few minutes to do.

I use the Nodal Ninja 5, which offers solid support but is correspondingly big and bulky, and you really need a levelling base on the tripod for ease of use. I generally put the camera into portrait (vertical) mode, and shoot 6 or 7 overlapping frames, depending on the lens.

This setup gives me around a 108 megapixel 3:1 image when using the 24 megapixel Nikon D3x, but I often have to crop this a little, as it's quite difficult to visualise the finished result. Still, plenty of resolution to play with.

There's a couple of options on the market for automated, motorised panoramic heads, onto which you mount the camera, programme in what you want in terms of angle-of-view, and let the electronics do the 'hard' work. Trouble is, I don't feel that the actual picture-taking is the hard work bit. Great idea I suppose if you need to repeatedly shoot the same angle of view, or need a 360 degree view for VR purposes. Gigapan sell a model suitable for use with SLRs. the Epic Pro, which is available in the UK from Red Door VR (they also sell Nodal Ninja products).

Eardisland

5. Stitching - using a shift lens

By mounting your camera rigidly on a tripod and taking a sequence of 3 images with a shift lens, 1 with no shift, 1 with maximum left shift and 1 with maximum right shift, you'll get either a 2:1 image when using full frame, of 3:1 if using DX format.

For my purposes, DX works best, and offers 32 megapixels when used with the Nikon D7000, enough for a print up to 30" wide at 300ppi. A 24 megapixel DX SLR would take this to nearer 40".

The advantages of this solution are that it is relatively portable, and also it's possible to use a tilt movement with Nikon's PC-E lenses, to give great front-to-back sharpness. Also, the images are nicely aligned with big overlaps so your stitching software has an easy job.

Unfortunately, tilt/shift lenses are quite expensive (although you could try the older Nikon AI shift lenses, but you need to watch compatibility as you can damage your camera depending on the model) and metering can be tricky. Also as with any stitching technique, it's difficult to pre-visualise the final result (although I find it a bit better in this regard than using a panoramic head).

(The above applies to the Nikon PC-E lenses, which offer +/-11mm of shift, but I believe Canon's equivalents are very similar)

Digital Panoramas - part one

I love the panoramic format, and when I say panoramic, I mean 3:1 aspect ratio, printed big (and by big I mean a minimum of 2 to 3 feet wide). In my opinion, anything wider than 3:1 looks contrived, and anything narrower isn't really a pano. Nope, 3:1 it has to be, and nothing works better in conveying a sweeping vista.

Let's look at the options in the digital world:

1. Film(!)

Yeah I know I said 'in the digital world', but you can't ignore the 6x17cm film format, as made popular by the likes of Colin Prior. There are a few camera options available, both new and secondhand, but the obvious choice are the Fujifilm G/GX 617's. Now out of production, but readily available second hand.

Obvious advantages are the fact it is a 'native' 3:1 format, so what-you-see-is-what-you-get, and quality is very high due to excellent lenses and that massive slab of film (it really is 5.6cm x 17cm, so does fulfil my 3:1 requirement!). Scanning at just 1200dpi would be good enough for a 27" wide print at 300ppi.

Downsides are that these cameras are expensive to buy and run: c£2000 body only and c£2 per shot for film and processing (not including scanning!). Depreciation should be pretty low though.

2. Dedicated digital panoramic camera

There's only one of these that I know of - the Seitz 6x17 Digital. First, the good news is we have native 3:1, plus a resolution of 160 megapixels! Yep, that's enough for a 70" wide print at 300ppi.

Bad news is this camera, with a couple of lenses, spare batteries and a very powerful computer is going to set you back close to £40,000! There's a 18 megapixel version which is cheaper but doesn't quite  make a 2-foot wide print at 300ppi, and as we'll see this resolution can be met by a digital SLR these days.

If you're still reading after that price tag, see what can be done with the 160 megapixel version by David Osborn of British Panoramics.

3. Cropping

Most digital SLRs have a sensor in the 3:2 aspect ratio, so by simply cropping away half the frame, we get 3:1. Good news is many SLR's have gridlines in the viewfinder, or we can use black tape on the LCD to mask the image, allowing us to visualise the final panoramic composition.

We have to be careful about exposure, as the camera is metering from the whole scene, but with care and bracketing this could work quite well. Given that a 24 or 36 megapixel DSLR will make a 20" or 24" print at 300ppi, this is quite an easy way to get into the format, but it doesn't really allow me to make the sort of print sizes I would like.

(A while ago I even asked Nikon if they could introduce a 3:1 viewfinder mask on the D3x, just as they have for DX and 5x4 formats, but I got the standard 'this is not something we're planning' email back. If they were to do this for the D800, I'd probably buy one, but they probably won't)

In part two, I'll be looking at stitching techniques.

Creating Panoramas

A couple of people have asked me about creating panoramas, which I've been doing a lot just recently, so I thought I would post about the three methods that I use.

1. Cropping - dead easy this one, simply take a single exposure as normal, and then crop it down to your desired format. Positives are that you can visualise how the final image will look, and your camera may even have guidelines in the viewfinder or on the LCD to help compose the picture. Also, this method works for moving subjects, can be used handheld and requires no additional equipment. Downside: you are throwing away perhaps half the resolution of your camera. Tip: to help with composition, stick a bit of semi-transparent gift tape across your LCD to show your preferred aspect ratio, but still allows you to compose using the full frame when you want to.
2. Stitching - the basic principle is to create a row or rows of overlapping images that can then be 'stitched' together on a computer. Quite tricky to do without a specialist panoramic tripod head, which helps to eliminate parallax error so that the images captured will stitch accurately in your software (I use PTGui). Positives are you can achieve very high resolution images: typically when I create a 3:1 panorama using this method, the final image will be 40 to 80 megapixels, and that makes a high quality panoramic tripod head very economic compared to the cost of a higher-resolution camera. Of course, this method doesn't work with moving subjects, and can be quite slow and cumbersome to set up. It's also more tricky to visualise what the final image will look like. Oh, and that super-duper wide angle lens you just bought? Sorry, but you are more likely to be using a short telephoto with this method :-)
3. Shift lens - both Canon and Nikon produce shift lenses that allow you to create 2:1 panos on full 35mm frame digital SLRs, and 3:1 on cropped-sensor cameras. You simply take 3 images, one shifted left, one with no shift, and one shifted right. These are then stitched in software as method 2. There is no problem with parallax as you are shifting the lens and not the camera, and it's slightly easier to visualise the results, especially using Liveview. However, shift lenses tend to be expensive and quite heavy.

For me, option 1 is really a stop-gap when an unexpected opportunity presents itself and there isn't time for the one of the other methods (or you don't have the right equipment with you!). My preference is for method 2, with 3 as an option when travelling light.

My Top 10 Sunrise, Sunset Tips

1. Never, ever, look directly at the sun, especially through your camera.
2. Know where the sun rises/sets and keep an eye out during the day for locations that will have some foreground interest, like a tree or boat, or reflections on water etc.
3. Plan ahead so you are in place in plenty of time before the sun comes up or sets.
4. A little underexposure is generally good as it will help to give warm, saturated colours. Switch to manual and bracket exposures (take several shots with different exposures, not just what the camera recommends). For sunrise I find 1.5 to 2 stops below the meter reading works well. Sunsets are a bit more unpredictable, as the sun is already in the sky, so try metering from a patch of sky without the sun in it. Use the histogram to judge exposure after every shot, as the light levels will usually be constantly changing.
5. Set your cameras' white balance to cloudy and/or use a subtle warm-up filter (Lee Filter's red enhancer is expensive but works brilliantly) to keep colours warm. Yes, you can fix this in Photoshop, but much better to get it right in the camera in my opinion.
6. Dress well for the climate and season, as you could be standing around for a while. It can be unexpectedly chilly at sunrise, and the temperature can drop swiftly after sunset, so keep yourself comfortable, safe and free from distractions.
7. Consider how easy/difficult/safe getting to or from your location will be in the dark, and adjust your plans accordingly.
8. A head torch fitted with a green or red lens is a good idea, so you can see where you are going and operate your camera without messing up your night-vision.
9. When photographing a sunset, have a good look round with your torch before you leave to avoid leaving anything behind.
10. When you think you've got the best shot, don't look back, as you can guarantee that the moment you pack up your gear and head back to the car the light will get even better :-)