Friday, June 29, 2012

D800 - love it and hate it

Thoughts on the D800 from a D3x owner:

Love it
  • Resolution
  • Dynamic Range
  • Same battery as D7000 (no forking out on more batteries or chargers)
  • Sensible remote options (10 pin on D3x is major PIA to attach, especially with cold hands!)
  • Size, weight
Hate it
  • Dramatic drop in D3x used values!
Will I get one? Possibly, as the cost-to-change from the D3x is still quite low. Would like to see some authorative reviews, for example from Thom Hogan, before making a final decision, and would also like to be sure that initial production issues are cleared up.

Thursday, June 28, 2012

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).


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)

Monday, June 25, 2012

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.