Adventures in videography

Anyone that’s been following my recent posts about my Brevis 35mm adapter will know that I’ve been having problems with dark edges on a lot of my lower light shots. Previous attempts I’ve made at working around this problem have included tweaking the alignment of the brevis, shooting with different exposure settings and zooming in past the frame.

First of all, here’s a few stills of how the light fall off looks at different zoom levels.
   

This evening I’ve been experimenting with another technique which although not ideal does seem to produce more usable footage. I’ve even tried shooting with image stabilisation turned on which is normally a big mistake when using a 35mm adapter. 

Shooting
Rather than zooming to Z70 or higher to frame the image produced by the brevis, I’ve switched on the the 80% safety marker on the EX1’s LCD and framed the brevis image to fill that area instead of the whole LCD. Doing this only requires the EX1 to zoom to around z60 which results in the outer edges of the frame not being used to capture imagery.

Doing this obviously means losing some resolution, but for my usage which is mostly Internet delivered video this 20% drop in resolution is not a problem. In the clip below you’ll see the images I’ve shot this evening of my kids. This low light situation would normally make the Brevis impossible to use without getting major vignetting, but because the usable image is well within the frame it’s not being effected by any dark edges that remain at z60 – z65.

In this example I’ve also switched on the image stabiliser so you can see how that’s moving the lens element around to adjust the position of the image and counteract my deliberately shaky camera work. At times I zoomed in further to test the effect of extreme stabilisation. Interestingly the image stabiliser also causes some rolling shutter artifacts (wobble) as it adjust quickly 50 seconds into the video. Something else to be careful with!

Editing
Although quite an interesting effect we obviously don’t want our final video to look like this so what I’m doing in final cut is to enable the title safe overlays during my edit which gives me a guide as to the area of the frame which is going to be part of my final edit. Doing this allows me to make cuts and play with edits without having to render out video every time.

Once happy with the basic edit I then cropped the sequence in FCP to 1024×435 which is a 2.35:1 aspect ratio. This video was originally shot as 1280×720 (720p) but you could shoot at 1080p and retain a lot more resolution of required. You could also just as easily use a 16:9 aspect crop.

Once re-rendered the video then starts to look a lot more normal and the best part is that it’s still free from the dredded vignetting. The images also appear to retain better edge to edge sharpness which I can only assume is a result of the EX1 performing better optically at the wider zoom angle and not having to obtain focus on the outer edges of the frame.

I won’t make a final decision as to whether I want to continue using this method until I’ve tried using it in daylight, but it’s nice to know that there is a way to get around the Brevis’ issues, even if it does mean a slight loss in resolution.

music: “F-Stop Blues” by Jack Johnson – Buy on iTunes