I just had a talk with a someone about long exposure times in architectural photography. He said that the p45+ is still a de facto standard among architectural photographers because of its ability to make exposures of up to one hour. He went on to say that for example during the blue hour this can come in handy.
In this regard I have two questions:
1. How can you expose for one hour at night without getting a completely white image anyways?? I mean, even at an aperture of 16 and at ISO 50 ... after 3600 seconds, there must be enough light to completely blow out the sensor? Down my street at night for example, at an aperture of f8 and with iso 50 I get an exposure time of a few seconds ... but a lot less than a minute even! Can somebody explain to me how such long exposures are even possible?
2. If one has a P65 back for example, can one do all tasks in architectural photography with it or are there scenarios where the long exposure capability of the P45+ enables a special kind of photography otherwise not possible?
An HOUR is indeed a very rare exposure requirement - those looking for star trails when there isn't much moon light and in an area without much light pollution would be an example. Technically speaking the back can go for much longer if it is colder than 64F/18C (chart of
temp vs max exposure). However, 4-15 minute exposures are not uncommon at all.
The following factors lead up to longer exposures:
- f/16 is not uncommon, f/22 is less common but used
- everything that can be shot at ISO50 is shot at ISO50
- graduated ND filters, polarizes, light source filters (yes there is still good technical reasons to use these even when shooting raw) are more common in architecture than in most styles of photography
- moderate to extreme camera movement (significant rise) comes with either vignetting or center filters (either way less light)
- bracketing to get detail in areas of deep covered shadow can require several more stops than the general exposure
- when adding your own light into the scene the ability to do a longer exposure means you can carry less powerful lights in your kit, which usually means more lights on a particular circuit or generator and less expensive rental/purchase/replacement. one of our favorite architectural shooters, Jeffrey Jacobs, (bias alert: we do
architectural lighting workshops with him) works mostly with (hundreds of) household tungsten lights when lighting interiors
So yes, most of our architectural customers are opting to stay with the P45+ which is the best camera system on the market for very long exposures. The P65+ is a fantastic back and I know a lot of architectural shooters who would love the additional resolution (heresy amongst those who assume no one needs more than 20ish megapixels, but it's true), but it's not the right back if long exposures are a requirement or mainstay of your work.
Also keep in mind that with a Phase One, or any other back, there is usually a stated maximum exposure which represents the longest exposure which is still "pretty good" but if you're looking for the absolute maximum quality (especially regarding shadow noise and color accuracy) then you'll probably want to stay a good margin away from that absolute longest exposure.
Doug Peterson
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