Liverpool workshop

[Pearl]

<a href="http://www.flickr.com/photos/realimage/4297501233/" title="Liverpool waterfront zoomed by Pearl Bucknall, on Flickr"><img src="http://farm5.static.flickr.com/4005/4297501233_59861e1c41.jpg" width="500" height="333" alt="Liverpool waterfront zoomed" /></a>

Tried this technique for the first time. I zoomed the lens during the long exposure, taking care not to shake the camera. Pearl

[Chris Noble]

Excellent results Pearl from a very tricky technique. Can never seem to manage to avoid camera shake when I've tried this. Any tips. Very well done.

[TonyHoward]

<a href="http://www.flickr.com/photos/43458114@N04/4310637657/" title="liverpool-cathedral1 by Tony Howard1, on Flickr"><img src="http://farm5.static.flickr.com/4015/4310637657_d9beb5a4de.jpg" width="333" height="500" alt="liverpool-cathedral1" /></a>

To follow up on the HDR discussion last night at the Academy, I have attached an HDR image taken on the Liverpool workshop similar to one shown by Adrian. There was some debate about the optimal number of images to use in HDR merges and I would be interested in others experience here. My impression is that using more than 3 images can produce finer detail and more subtle tonal gradations. This particular picture merged 9 images using the image enhancement mode of Photomatix through a tonal range spanning about 5 stops. The selection of exposures was biased towards ensuring that there reasonable representation of the stained glass window. Interestingly, using Photoshop HDR generation, whilst requiring a lot of manual manipulation and taking quite a lot of time, defined the window much better than Photomatix with nice tonal gradations around it. So to produce the final image I merged the Photoshop window into the Photomatix picture. The unnatural blue cast produced when reducing the colour temperature to compensate for the tungsten light that was discussed last night was reduced using the selective colour tool in Photoshop as described by John Bubb at the November Academy workshop. The orange is a lot more saturated on the jpeg in the Flickr web site than the TIFF on my monitor in Photoshop and on the print. Curiously, I think that the final result looks a lot more like Gilbert Scott's Gothic idyll than the reality of his Liverpool work.

[Adrian Wilson]

The question of how many shots to take is always an interesting on.

the true answer is probably "as many as you can", but a few factors come in to play then

1 - time, it takes a while to dial in and take 5-7-9-11-13 shots...
2 - camera wear, we have limited shutter lives, so taking more than you need adds to that
3 - storage - you'll use your cards up and fill your hard drives if you start taking too many

I've found that in most situations, taking 3 shots at -2 0 and +2 is ample, but for the Liverpool cathedral shoot I could have probably done with 4 or 5 - taking a couple lower exposure shots to cope with the very bright windows and lights.

If you are taking shots outside at night and want street lamps ir shop windows to be full of detail, you need to shoot lower exposures for those too. It's an artistic choice though, when I look at a street lamp, it naturally dazzles, glistens and looks very burned out, so for me, I'm happy to have that in my photograph. For others, they may choose to get that surreal look of every tone exposed correctly. It can work really well, or look like a computer game - it depends on the processing.

Have a go at Exposure Fusion with Photomatix - I've found that to give the most realistic results of any sortware I've used of late.

The blue cast is from having 2 light sources - tungsten (orange) from the indoor lighting and daylight from the light coming in through the windows. It's not easy to manage this with normal photography - you'd need to convert your RAW twice, one for each white balanc, then blend them together with layers and masks.

With HDR, you do the same thing, but if you had 3 source files, you'd need to create 3 TIFFs for tungsten, generate an HDR from them and tone map - then do the same again with the daylight white balance.