considering digital... questions about color temperature

[anish]

I primarily shoot landscapes with an Elan 7, and use Valvia + an 81B when

appropriate. I am going to go digital and am looking at the 30D plus the 10-

22 zoom. Having read about the post processing options available with RAW

formats, in particular what can be done with color temperature, is there still

a need or benefit in having a warming filter? 77mm filters are costly and

when using multiple lenses, time consuming to constantly remove and re-attach

in the field. if the same results can be achieved by adjusting color

temperature in post processing, i would rather not buy the filter. Any

thoughts? Thanks in advance,

 

Anish

[barry_h]

If you shoot in RAW you do not need a warm up filter as this is done in Raw conversion, just use Photoshop. Only filter you may need are Gray Grad to stop light skies etc burning out. You will also need another lens like 24-105. I shoot slide and digital, still prefer slide when the light is right, digital is better in overcast conditions.

[pavel_olavich]

I agree with Barry,...but want to add the need for a polarizing filter. Shoot raw and learn post processing.

[mark u]

Color filters have almost no use in digital photography. Exceptions are such things as IR filters, or possible a filter that reduces a particular colour channel that overexposes too easily typically when photographing certain kinds of plant. Filter effects can be created in post processing, or even by using a "warm card" and setting a custom white balance. The card is actually a slightly cooler colour than a neutral white, so the custom white balance corrects for that, producing a slight warming of the image:

 

http://www.studio1productions.com/warmcards.htm

 

You may find that if you shoot at high altitude a sharp cut UV filter could still be useful. Otherwise, there is no substitute for a polarising filter where you would normally use one.

 

Even normal neutral density filters can be mimicked in software: the problem is that with a slowest ISO of 100 and probably the best compromise of sharpness, diffraction and depth of field being at no more than f/11 with the 1.6 crop sensor, you will get rather shorter exposures than shooting Velvia rated at ISO 40 and f/22, so "bridal veil" waterfalls and the like have to be achieved through averaging several consecutive exposures using something like Imagestacker software.

[pavel_olavich]

I disagree Mark U....neutral density filters are still very relative in digital photography, and the best way to get their effect is to actually slap one on the end of your lens. Using digital means in post processing to similate this filter is not often good, or more trouble and work the simply slapping the filter on.

 

To not use a Neutral density filter is to risk lens diffraction which often starts after F11 or F13. Or what about the prevention of a blown out sky? No better way then to slap on a graduatuated ND filter....I assure you once the sky gets blown out, no amount of post processing time or skill is going to save the image.

 

I agree that most filters are no longer relavent in the digital realm, but as of today, there is no digital way around a good polarizing filter, nor ND filters.

[mark u]

I don't think that Pavel fully understood my post. The point about long exposure times with a slow film is that they blur the motion of water. The lack of availability of a low ISO (unless you use something like the Kodak SLR/C) and the need to use a wider aperture with a smaller sensor to avoid diffraction inevitably means that correctly exposed shots will need a shutter speed that is several stops faster than with shooting slow film, which will not blur the water adequately. There are two ways around this problem: one is to use a strong ND filter (you might need to stack more than one filter, potentially degrading the image optically) that will account for the 3 stop+ difference in optimal exposures to give the required slow shutter speed; the other is to use post processing.

 

By taking several shots in succession, you are effectively simply dividing up what would be captured by a single shot. By using the averaging technique, you are merging the exposures together to achieve the blurred result you seek without blowing out highlights (you aren't adding the exposures, but averaging them, which is almost exactly what you do by using a slow film and narrower aperture and longer exposure).

 

You could even choose to vary the exposure of the sequence of shots, allowing capture of both highlight and shadow detail that would be far beyond the dynamic range capture capability of a transparency film such as Velvia. Selective layering of the images and careful adjustment of each layer using levels and curves can then be used to produce an image that displays a much fuller dynamic range, albeit carefully compressed for output. You can also do this by different "development" of the same RAW image. Such a high dynamic range technique far exceeds the capabilities of using a graduated neutral density filter.

 

Last autumn, I tried shooting Velvia at Burnham Beeches - a location for great autumnal colours. There was no exposure that would satisfactorily capture shadow detail and the glow of the sunlight through the golden and coppery leaves still on the trees - and no way that a grad ND could possibly begin to cope with the complex patterns of light and dark areas of the image. The only satisfactory images were simpler compositions that captured either the soft, shaded tones on the woodland floor or when the sun wasn't shining, or ones that concentrated exclusively on the backlit leaves. Of course, the Velvia colours are gorgeous (and digital still can't entirely convincingly mimic the pleasing effects of that film or several others), and the images are sharp and detailed with the fine grain - but digital capture would have given me another option - to recreate the light and the shade as a landscape painter might have done.

[mark u]

Answering a question in the Lighting forum, I was reminded of one circumstance when an ND filter is the only way to make the shot with a DSLR and a flash that doesn't handle high speed sync: using flash as fill for portrait photography in bright light with a limited max X sync speed. In those circumstances you are likely to want to shoot at a wider aperture than the ambient exposure at the lowest ISO and X sync speed dictates, and the only way to do so is to use the filter. The flash will still need to be pretty powerful as you could be effectively shooting at the equivalent of f/11 or f/16 at ISO 100 by the time you allow for the filter.

[anish]

Thank you all for the informative responses. I had definitely planned to continue using a polarizer and my GNDs. My main concern was the warming filter.

 

Anish

[asr]

Anish,

 

Your question is perplexing to say the least.

 

Here I am wondering about making the switch from digital to film; and the only issue that seems to be still holding me back is the high cost of media (and processing, storing, archiving and scanning it, and storing it again).

 

One issue that I want to highlight is that with film, there is almost no post-processing to worry about - whatever hit the film is what it is and that was what it was able to capture.

 

With digital however, whatever hits the sensor is just plain unuseable, and is the beginning of a long drawn and ardous process - which people claim is versatile and flexible, but in reality it isn't.

 

You can't even change contrast and saturation and temperature without blowing out details and color, and once you start manipulating things in digital to bring the image to look like the way you think it should have been - we're already beginning with a shot that the hardware sensor found itself capable of shooting but worthless.

 

Take the example of color temperature - I doubt the color temperature slider in digital RAW software can achieve anything close to what a warming filter can do on a film camera. Here is a great example from Darwin Wiggett I would like to use:

 

Here's a shot without all the filters stacked: http://www.singh-ray.com/gallery/mpwiggettfbefore.jpg

 

And here it is with all the filters: http://www.singh-ray.com/gallery/mpwiggettf.jpg

 

That warm glow you see in those photographs - I doubt that can be achieved with the color temperature slider in digital.

 

I do agree that film is expensive and clumsy; but it's lightweight, doesn't need extra batteries in the field nor extra storage in the field, and works at almost all altitudes; and gives a first hand proof of what you really composed in the field.