
Toronto, CA
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>I have been reading this with great interest as I am >entertaining the purchase of a D800 to supplement my D2X. All >this info on shutter speeds is concerning. My question is >this. If D800 users are having these issues, what are the MF >guys shooting 40-80 MP backs doing with lenses that have a top >speed of 1/500 second? Are all these folks using a tripod and >Mirror Lockup for each and every shot?
I'm not sure what you mean about medium format lenses with a top speed of 1/500s. Lenses don't have shutter speed settings, but I could be missing your meaning. A typical Phase One medium format camera offers shutter speeds up to 1/4000s. Typical medium format digital cameras used in professional studios are shot either handheld at very fast shutter speeds (1/1000s or faster) under at least enough light to also accommodate base ISO, or from a tripod using an equally fast shutter speed under the same lighting. Typical medium format digital cameras used in the field for professional landscape work are almost always shot from a tripod at whatever shutter speed accommodates something close to base ISO given the available light. The more light, the better.
>Not trying to stir the pot, I dearly love my D2X and my D2H as >well, but if I have to use a quite fast shutter speed, tripod, >and/or possibly Mirror Lockup, would I not be better off with >a Pentax 645D?
Not necessarily. There are few practical reasons besides ultra low natural light (in a shooting situation in which a flash setup or a fixed artificial lighting setup is inappropriate or unavailable) that forces ISO into unacceptable territory, to use slow shutter speeds. Another exception might be a high contrast scene (e.g., which includes bright, moving water that you want to smooth out) which can't be knocked back far enough with whatever neutral density filter you've got on hand. In that situation you might have to drop your shutter speed below handheld threshold and make use of a tripod with any camera. One way or another - especially for photographers who plan on viewing and displaying their photos at something larger than laptop, web site or desktop monitor sizes and resolutions - printing at 16x20/A2/B3/C2 sizes or larger, and projecting at those sizes or larger will reveal every single bit of softness, blur and hazy detail in a photo shot a slower-than-optimal shutter speed and higher-than-optimal ISO.
There are always exceptions, but photographers who regularly print or who produce photos that are going to be printed in full page mag spreads or double-leaf spreads or posters or as fine art prints, sometimes have to almost turn themselves inside out to get the kind of sharpness and resolution of detail that holds up for high linescreen/high resolution/high ppi output when viewed at typical distances when reading a large format fashion mag, appreciating a photo hung in a gallery, or when taking in a photo exhibition at the sizes typically displayed in the best shows. The money to fund the acquisition of $30,000 medium format cameras (never mind the additional thousands of dollars/pounds/yen/euros needed to fund the acquisition of the best lenses) is found in the art, fashion, landscape and portrait photography dodges most often. There are certainly other uses for medium format shooting, but you won't find any of those photographers getting remunerative results out of handheld medium format shooting at the slow shutter speeds and the silly-high ISO settings that many of us get away with for photos that end up being used for tablet, laptop, desktop and web display.
>I know im missing something here so please inform me where I >am going wrong. While I am not nearly as heavily invested in >the Nikon system as lots of you, it is a somewhat sizeable >investment that I would like to utilize. Perhaps I am somewhat >skewed in my view as I try to shoot at the lowest ISO since I >was a Panatomic-X shooter in my film days.
The more pixel density on a given sensor surface, the higher the resolution. The reason is basically that the smaller and more discretely that a light-gathering sensel can be created as part of the sensor surface, the smaller the detail that can be detected and recorded. The smaller the recordable detail, the higher the resolution. The problem raised by your question is answered by basic physics. Above a certain threshold - say, 1/125s on average - blur caused by slight, almost imperceptible movement of the photographer or the camera when the shutter is fired (e.g., caused by the downward push of the shutter, heartbeat pump tremor, slight hand movement, wind gust, etc., etc., etc.) is less likely to be visibly recorded in a 6-12 megapixel system. The reason is simply that the slight movement (below a certain amplitude) is insufficient to be recorded at shutter speeds of 1/125s which overcome the effect of such slight movement in that range of pixel density. The movement I'm referring to is natural enough in most photographers, and has formed part of the design basis on which recommended shutter speed/focal length ratios have evolved over the years in respect of detail resolution at typical print sizes and print viewing distances. Photographers who now have the option of only ever displaying their work at small tablet, laptop, desktop and web site sizes can push the shutter speed/focal length ratio a bit smaller (while still being cognizant of the softening effect of digital noise creeping in at high ISO settings), but as desktop monitor sizes and resolutions increase and as tablet resolutions increase, the older rules have reasserted themselves.
Now take the same shooting situation, but increase the camera sensor's ability to record finer detail using sensors ranging in resolution from 16-36 megapixels. What happens is that the slight movement that was insufficient to create recordable blur at 1/125s is now occuring while using a camera that has a lot more pixels per square mm of sensor area. The slight movement which was inconsequential at 1/125s in the 6-12 megapixel cameras is recorded as slight but visible blur in the much higher resolution cameras because 1/125s is not fast enough to overcome the ability of the higher resolution sensors to record the movement. The way to help eliminate the problem is to increase shutter speed. It's not a penalty - it's just what happens to be needed to accommodate a given sensor resolution and focal length being used in the lighting available.
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Howard Carson, Managing Editor Kickstartnews Inc. - http://www.kickstartnews.com
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