Old coloured filters on DSLRs?

[invisible]

Brian, thank you once again!

 

[Garbz]

The only time you can't replicate a filter is if the response of the colour you're filtering falls outside the bounds of two of the sensor colours. I.e. if you're trying to filter out a deep red or even infrared compared to simply a normal red, and none of those reds have a spectral response that excites any of the green or blue pixels on the sensor, then you're only left with filtering before the colour gets to the sensor.

This really only applies to infrared. Cameras are typically pisspoor at UV recording so the other end of the spectrum doesn't matter.

 

[jbarrettash]

While it may be true of these filters (that are, as previously noted, B&W filters for affecting contrast and B&W colour shifting (i.e. darkening blue skies)) that they can be recreated in "post", one must be wary of this advice in general. Filtering is a powerful photographic tool and the idea that everything should be pushed to post/editing goes against all my instincts and all my photographic knowledge. A quick example is, of course, a polarizing filter that changes values within the photographic image by manipulating the amount of light reflected from certain angles of objects that make it to the film plane/sensor. This effect is a function of the light traveling through optics, and cannot be recreated in post through editing.

The same can be said for filters like the enhancer, ND grads, infrared and a handful of others - they are filters that alter the quantity or quality of light reaching the camera, and if they cannot be recreated can only be very roughly approximated, at best, in post/editing.

One further step down the rung is the idea that filters themselves can replace naturally occurring meteorological events - i.e. a "fog" filter, whether on camera or in post/editing, compared to natural (or man-made on location) fog. Filters, whether on camera or in post, may seem to simulate fog, but what occurs with regular fog is physically very different optically: the closer to the camera the subject appears, the less accumulated atmospheric haze is seen; the farther away, the more "foggy" the subject appears. So the idea of creating fog in camera or in post is at best a bad workaround. The same can be said with post effect filters like "diffusion" and "grain" - while useful tools in post, IMHO it is always more gratifying and effective to capitalize on the abilities (or idiosyncrasies) of your camera and the available light (and, of course, the filters on hand). These, to me, are your primary creative tools. Post/editing are secondary tools - to compensate for errors or to push an image to limits not attainable optically on location.

So for me an ideal workflow (in order of occurrence but also of importance) is:

-choose a subject
-visualize what you want to do with it (thanks to monsieur Adams )
-choose your filters, iso/filmstock,and exposure
-click the damn shutter!
-and finally adjust in post to complete that part of your vision unattainable optically or with the available light in post editing


...And that's my rant. Sorry, felt like waxing pedantic. I really am a fun guy, i swear! (but a noobie here, so forgive the enthusiasm!)

Cheers,

jbarrettash