filters – Dave's Place

Long exposures at the weir

My first attempt at a long exposure wasn’t a resounding success but it provided some very useful food for thought and experience. It also provided a surreal moment as I woke on Sunday morning to find it featured in Flickr’s “Explore” section despite its obvious flaws.

My second attempt therefore was made on a slightly more open stretch of the River Calder although for the initial close-in shot, the trees on the left hand side and part of the front of the scene were still fairly close to the drone. Once again I am using the Freewell 10-stop ND filter.

I have visited this part of Cromwell Bottom a few times recently, shooting the weir from above as an incidental part of a wider scene as well as deploying the infra-red Fuji.

My aim was to keep the shutter speed to around 1 – 2 seconds increasing the ISO if needed in order to do so. In the event it was a bright sunny morning so I was able to keep the ISO at 100 and still shoot with the desired shutter speeds.

© Dave Whenham — weir at Cromwell Bottom, River Calder 10-stop Freewell ND filter

I was using the iPad with the drone for the first time and the larger screen was a boon in quickly identifying that movement was still an issue when the drone was just 14 feet up but as the height increased the stability improved. As I mentioned earlier there are a lot of dense trees to the left of this shot and immediately behind the little monitoring station. I had wondered if these would help shelter the drone perhaps from the slight breeze but on reflection wonder if they were once again swirling the drones own backdraft around? Whatever, once we clear the trees matters improved although that begs the question what would happen in a stronger breeze?

The four images above are straight from the drone and even at this size the motion blur in the first is very evident. I needed to reduce the exposure time for shot three but looking at others I took around 90 feet the thoughts on height affecting motion blur in this situation hold.

All of the images shot at between 1 and 2 seconds above tree height were very usable, and if the scene had been more photogenic would no doubt have been properly processed too for my Flickr feed and blog. However, this trip was about learning the possibilities and so I wasn’t precious about the actual view. The question remained though, could I salvage the first image, shot from just fourteen feet up? I took the unprocessed image into Photoshop and applied the Shake Reduction filter. I manually selected five areas to provide multiple traces for the software and as you can see above the end result was definitely usable.

I played with a few exposures between 3 and 6 seconds but wasn’t happy with the results of these on the day. It could be that such lengthy exposures are possible on very still days but that will need some further tests. For now an exposure time of between 1 and 2 seconds seems to give me a nice creative look to the image without too many problems vis-a-vis image quality. As with the first attempt I am very pleased with the neutrality of this ND filter too.

So, a successful morning, a few more lessons learnt and some more food for thought. I’m looking forward to shooting some 1 and 2 second shots above the Northumberland shoreline in the Autumn!

Long-exposure

Not my best photography ever but I learnt a lot from this mornings mini test on the footbridge over Woodside Locks.

Part of the reason for venturing out this morning was to scratch an itch and also to test a new filter. It had to be done very early (I was out well before 7am) to ensure I didn’t get in anyones way as this towpath is popular with cyclists, joggers and dog walkers at almost all times of day.

I fully understand the concept of ND filters for the drone, especially in controlling shutter speeds for smooth video, but have been surprised to see advertisements for ten-stop ND filters which can extend exposure times into the seconds even in bright sunshine. As drone photographers we tend to keep our ISO at the lowest possible setting but even at 100 ISO and on an overcast morning in the shade of some trees I was getting eight seconds this morning. I could have pushed the ISO up and reduced the shutter speed but the purpose of today was to learn rather than create an image for the wall.

As you can see from the image above, the drone was no more than seven feet above the bridge over the lock with trees encroaching to within the same distance from above, behind and the right. The morning breeze combined with the downdraft from the drone in such a confined space meant it was struggling to remain perfectly still; indeed I was surprised at how buffeted I was stood below and slightly to the drones right.

An eight second exposure was probably a lot to ask in these conditions! I knew it would be tight under the trees, I’d even put the drone into Tripod mode to ease it gently in to the space, but had not really appreciated quite how much wind turbulence there would be.

A healthy dose of the shake reduction filter in Photoshop has produced an image that confirms the filter is neutral, and that given the right circumstances it should be more than practical to use slow shutter speeds in daylight to achieve a perfectly acceptable long-exposure from the air. To be fair I could have increased the ISO and thereby increased the shutter speed to 2 or 4 seconds for example, but this was after all just a quick experiment to see whether the new filter lived up to the good reviews I’d read online and to prove that the drone could hold still enough for a longer exposure.

I’m convinced that in a better environment I will be able to capture some interesting and creative images with the drone. I probably need to avoid hovering in what was effectively a wind tunnel next time! Mind you, that won’t stop me trying this again with a shutter speed of 2-4 seconds to see if that helps.

FREEWELL ND1000

The filter I was using this morning is a Freewell FW-MAV-ND1000 Filter. It fits snugly and easily and is also straightforward to remove afterwards yet still feels very secure on the lens. Drone start-up and gimbal calibration was not affected and the files have no appreciable colour cast in the test shots I took this morning returning an image with the same colours compared to shots from the same basic area and height but with no filter attached.

Mavic Pro – polariser vs none

In You Get What You Pay For I wrote of my experiences with some budget graduated filters for the Mavic Pro and concluded that whilst the set I had were not up to the job I needed to do some more research before buying a more expensive set of filters.

I also have a set of ND filters and a polariser for the Mavic Pro made by the same budget-priced company. Whilst the ND filters will be of more use once I start to seriously explore aerial video or what to start experimenting with slower shutter speeds for aerial stills but the polariser is already proving useful for stills photography.

The polariser I have is a simple push-on affair and once airborne, as with all these filters, cannot be adjusted. It is a matter of looking through the filter and turning it until the desired effect is reached and then pushing it firmly onto the lens. Of course, the effectiveness of the filter varies according to the drones position relative to the sun too so as you fly and manoeuvre its quite possible that the optimal amount of polarisation is not being applied. However, with all that said the filter does help particularly when photographing trees and foliage as it helps cut through the glare and intensifies the colours. The two images above illustrate this nicely – top left and bottom right are from the polarised frame whilst top right and bottom left are from an unpolarised frame. To make the comparison fair I applied the same basic RAW adjustments to both images.

It is possible, especially with the new Dehaze slider, to add punch back into non-polarised images (see below) but given that the files are only 12mp to start with I prefer to keep post processing to a minimum wherever possible.

The polariser is one filter I won’t leave home without and indeed based on my experiences to date I will probably upgrade to a premium brand at some point.