ISO 6400 anyone?

© Dave Whenham

During a short trip to London recently I used the Fuji X100T for some “street” photography. The camera handled brilliantly but some of the resultant images were a little hit and miss. With the benefit of looking through the files in Lightroom I realise that I could and should have used a far wider aperture. Probably as a result of using full frame cameras for so long I instinctively went for f8 or f11 and occasionally wandered to f5.6. But as the shot above shows even  f5.6 on a 23mm lens with a cropped-sensor camera gives far more depth of field than is needed especially when you consider I was not zone focusing but focusing each image separately.

More importantly it meant that the camera was regularly selecting ISO 6400 which is the maximum I have set in Auto-ISO mode.  Now that isn’t necessarily a problem as this camera handles ISO 6400 respectably well but I have found that it is vital to nail the exposure on your subject. The image above was underexposed by almost two stops, probably as a result of light bouncing back off the floor fooling the camera’s meter. I had turned the LCD screen off to avoid chimping and also to be more discrete on the streets. The JPEG was unusable to my taste but fortunately I was able to rescue the shot by careful processing of the RAW file.  A tick for my RAW+JPEG strategy.

The second image however, below, also shot at 6400 ISO, was properly exposed and as a result apart from a crop this is the JPEG as-shot. No noise issues and almost no post-processing time required.

© Dave Whenham

The third image here is not my finest hour by a long chalk but it illustrates the major knock-on problem of setting too small an aperture. I was stood by the top of the escalator in St Pancras and looking to capture an image which showed the hustle and bustle of such a busy location. This composition pulled together everything in one frame I thought; the traveller with his luggage, businessmen talking but clearly in a hurry to move along and the ubiquitous traveller on the phone as he rushes to his destination. It looked great on the back of the camera. If only I’d been watching all of the  information in the the Fuji’s viewfinder though.

© Dave Whenham
Hustle’n’ Bustle – St Pancras

The EXIF data for the image above tells everything that is needed. It was a stop underexposed so needed brightening (which at ISO 6400 increased noise). It was also shot at f11 which necessitated a shutter speed of 1/17th second!! Hand held!!!  So we have camera shake and a degraded image through under-exposing at such a high ISO.  As I say, not my finest hour but some good learning points.

And wider apertures are perfectly adequate for this type of candid imagery. Take the image below, ISO 6400 again but with an almost perfect histogram, 1/45th second which is on the border of what I would typically opt for in terms of shutter speed when handholding and an aperture of f4. The image is sharp front to back, from the edge of the table to the wall socket (which I will probably clone out for the finished image).

© Dave Whenham

So, all in all some useful learning points here and I have added to my personal experience of using the camera. My choice of setting a maximum ISO of 6400 is vindicated but with the important caveat that I need to ensure the shot is correctly exposed as pushing exposure in post production exacerbates the noise present in the file.

The next time I get the opportunity for street photography with the Fuji X100T I am going to try using f2.8 as my go-to aperture, leaving the Auto ISO at a maximum of 6400 and keeping an eye on both shutter speed and histogram.

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