Large Format Diaries
#14. Filters for Slide Film
I’ve just been re-reading – again! – Joe Cornish’s First Light, alongside David Ward’s books Landscape Within and Landscape Beyond. For relative newcomers to large-format photography, these are really important books to get hold of, I think. Jack Dykinga’s introduction to large format landscape photography is also very very good, and describes in great detail all the things you need to think and know about technique and lenses. Where the work of Joe and David comes into its own, though, is the amount of technical detail the books provide about shooting conditions and decisions made about about filtration. In the UK, the light is so changeable that shooting large format with slide film’s narrow exposure window and exposure characteristics necessitates the varied use of filters to balance exposures or achieve the right colour balance. While I’m finally getting my head around using grads properly on 5×4 – I’ve just added a 0.45 hard grad, and should really have a 0.75 as well – I’m still yet to get to grips with filtration for colour effects, probably having relied too much on the ability of my digitization and photoshop work to adjust colours to suit. The problem with this is that having to change too much is a risk when the original slide’s dynamic range is hard-wired.
Having looked over my best work, and compared exposure times to those provided in the above books, I’ve made a few observations: I have tended to stretch Velvia 50 exposures to well beyond what David or Joe had, even with colour correction filters which I don’t yet own. It’s also apparent that Velvia 50’s sweet spot for 5×4 seems to be times below about 4 to 8 seconds, after which warm-up filters or colour correction filters are the order of the day – and where, inevitably, a good deal of guesswork, or bracketing, is probably necessary. I’ve been thinking about why colour correction or warm-up filters would be necessary rather than photoshop, and I sense that it becomes even more about getting the satisfaction of a perfect exposure, along with the sharpened incentive to concentrate on what you do or do not want to do with the scene before you press the shutter rather than rescuing something afterwards – I haven’t used colour correction or warm-up filters yet, but I reckon that looking through them would give a great idea of when and when not to use them. The most important point here is not to use them when you want to preserve a colour contrast that the raw Velvia slide produces – especially between cool blues and warm yellows, or between greens and reds. This is why David Ward uses them less often than Joe Cornish, I think, since he looks for scenes where Velvia will naturally enhance the colour differences.
The new filters I’ll probably want to invest in are as follows:
81B warm-up: something to use for exposures of longer than ½”, especially in overcast or shaded conditions, if the result is likely to be too strongly blue: worth bracketing.
85C warm-up: a stronger warm-up, to enhance a really flat and overly blue scene, especially from about 8 seconds exposure time upwards: worth bracketing.
#10 Magenta: recommended for Velvia 50 after 15 seconds, after which Velvia has a green shift: again, worth bracketing. Given reciprocity failure, the Velvia data sheet does not recommend exposures at 64 seconds; I think with judicious bracketing with colour filters, perhaps with additional Photoshop work, things can turn out well at times of a minute or longer.
also possibly a warming polarizer: I already have the original Lee 105 CP-L, which has a very cool colour cast; for waterfalls and seascapes under muted lighting a warming polarizer is likely to be very useful (Lee’s landscape polarizer essentially has an 81A built-in)
Here are some illustrations below of some of my previous work, where use of filters listed above would and would not have had a worthwhile effect.
Bernwood Forest Bluebells:
Original exposure time 1 min 13 seconds. Velvia has added quite a lot of green to the scene. Using Photo Filters in photoshop, a magenta filter (25% density) at 70% creates an overall colour that more naturally reflects warm evening light (image also darkened a little).
Lathkill Dale Waterfall
Original exposure time 8 seconds, including Lee 105 CP-L. Velvia and the polarizer have rendered a very cool scene. Addition of an 81B – or perhaps better warming polarizer -would have made this pop even more nicely. Effect attempted with 81 filter in Photoshop, second image.
Porth Meudwy Rocks
Original exposure time 50 seconds, including use of polarizer. Again, Velvia has a lot of green to the scene. Addition of the photoshop magenta filter makes the original shot suddenly seem far too green. What I should probably have done was dispense with the polarizer (and its 1 2/3 stops of extra time) and used an 81B to warm the scene a little.
5 Pebbles, Porth Meudwy
Original exposure time 1/2″. Demonstrates the effect that deep shade under blue sky has on Velvia. Addition of 81B would have shifted this blue a bit.
Gardom’s Edge Oak Detail
Original exposure time 6 seconds. Velvia has enhanced the separation and between the reds and greens here. Adding an 81B filter – here mimicked with the 81 filter in photoshop – has warmed the scene but at the expense of that crucial colour juxtaposition – here’s where it would have been detrimental.