Time for BIG prints

More testing of our GigaPan Epic Pro

I’ve been out with the GigaPan head again, looking for ways to use it for large prints.

The black and white shot is one of the squares on New Walk in Leicester, dating from the 1860′s

De Montfort Square, Leicester – Statue of Sir Robert Hall. Click for bigger image in new window

The GigaPan is an interesting device for taking high resolution shots and in many ways matches some of the considerations you’d consider for Large Format photography (see some of my previous GigaPan notes – First look and Out at night)

I should point out that we’ve got it for making printable images, although we can supply Web Panoramic type shots if needed.

The small image is a 100% crop from the original colour image.

Detail from the full size colour original stitched image

The stitched colour image was converted to B&W using both the normal PS B&W conversion adjustment (for the sky) and Nik Silver Efex 2 for the rest of the image.

Both conversions were created as layers over the colour original, with the sky ‘painted in’ via a mask. Nik Silver Efex 2 may be great for many images, but I do find that even with control points, some of the the local contrast enhancement adjustments can spill into broad halos with a blue sky and the fine detail of the winter trees.  By all means make use of features such as you find in Silver Efex, but always beware of overdoing things.

Many of my recent high resolution shots have been taken with the Canon 1Ds3 and TS-E90mm lens (no shift or tilt used), where I’ve had to move to smaller apertures than I’d normally like (f13 instead of f/8) so as to increase depth of field.

At full resolution, you can see that the statue is slightly less sharp than the background, but you’d really need a huge print to notice.

Detail of statue, showing focus softness (100% crop)

Indeed, a masked application of a bit of smart sharpening to parts of the statue (~2 pixel radius) would bring back local contrast and show the statue almost as sharp  - in a print - as the background.

That lack of sharpness if you have items at different distances is always there – you just don’t see it in a 20MP image as opposed to a 500MP (equiv) image. Of course I could reshoot the image and do some focus stacking, but I suspect I’d need to do it manually, since most focus stacking software might balk at multiple 1.5GB layers…

I’m looking at other software for stitching too, since geometry restrictions, and in particular the limit of 8 bit working make the GigaPan software less than ideal for print work.

The 8 bit limitation was one reason for the multiple conversions when producing a B&W image. 8 bit colour source images are much more likely to show banding in monochrome, particularly when darkening the blue sky, as I did for this example.

I’ve not worked on this image to alter or ‘fix’ much, but for big prints I do take quite a while getting rid of cigarette ends, litter and other items that draw your attention far more than they would in real life.

More testing to come…

  • Lynn Allan

    Good article. I have a question about your statement:
    “smaller apertures than I’d normally like (f13 instead of f/8) so as to increase depth of field”

    I’d be interested in your feedback to a comment I read “somewhere on the web” … don’t recall the link, sorry

    It was roughly equivalent to saying:
    “Don’t go to an f-stop more closed-down than f11 on a crop or full-frame camera. The gains in DOF are counter-balanced or worse by overall loss of sharpness due to defraction.”

    • http://www.northlight-images.co.uk Keith

      Sometimes the loss of sharpness (from diffraction) makes a difference to the image, sometimes not. It does depend on what you’re using the images for.

      It’s well worth setting up your camera looking at a very detailed subject at say 5 metres, with a distant background, and taking a series of shots at different apertures.

      The ‘problem’ of diffraction is wildly overestimated by many, and unless you are printing big, may not really be obvious even at f/22. I do indeed prefer to use my (best) lenses, such as the TS-E24, at f/7.1 or f/8 for critical detail, but I know that at longer focal lengths (such as the stitching example) I may need to go higher