Reverse Neutral Density Graduated Filters

[Lataxe]

Land and seascapes feature most prominently in my photography.  I've tried a number of methods for capturing the sometimes wider-than-camera dynamic range of such subject-matter.  Multiple exposures give the best result but usually need a tripod, which I'm reluctant to cart about on the often strenuous walks to various scenic vistas.

I should mention that the photography is secondary and incidental to the walking.

So I often use an ND grad as the best compromise.  As all you experienced landscapers will know, such filters have disadvatages.  They like a straight horizon co-incident with the big change in the view's brightness, for a start.

One particular drawback is that most ND grads seem to be the wrong way around in the grad portion.  This is particularly noticeable when using a 24mm or wider lens - the filter causes heavy vignetting of the top corners as well as the over-rapid descent into darkness of the higher part of the sky.  The light coming it at top (at an angle) must travel through a lot more filter thickness than the light coming in at the centre of the image.

I looked at "Daryl Benson Reverse Neutral Density Graduated Filters", the only ones I could discover that at least have the grad part of the filter darkest near the transition from the transparent half.  They still seem to have only a linear grad though; a more semi-circle shaped graduation would surely be better, to match the nature of circular fields of view through a lens......?

Has anyone experience with such filters?  Is there a better brand or even a better design for reducing the heavy-vignetting at wide angles?

All advice and pointers gratefully recieved.

[David Sutton]

Not a direct answer to your question, but if your camera shoots at 3 frames a second or more, and there is enough light to keep up the shutter speed, you can AEB hand held. I set the self timer to 2 seconds, frame the shot and hold my breath. Another option is the combined walking stick/monopod. Makes it easy.

[feppe]

Not a direct answer to your question, but if your camera shoots at 3 frames a second or more, and there is enough light to keep up the shutter speed, you can AEB hand held. I set the self timer to 2 seconds, frame the shot and hold my breath. Another option is the combined walking stick/monopod. Makes it easy.

Doesn't have to be super accurate in aligning each shot if you're using PS: just align the photos using the photo stitching feature, which takes care of small camera movements between shots. There's a checkbox "align pictures" or something along those lines so PS doesn't actually stitch anything, just aligns each layer.

[Lataxe]

Thanks both for the advice concerning multiple shots.

I do have a fine walking pole with a camera tripod bush under the smart wooden knob that screws on its top.  It does serve as a poor man's tripod for single shots, certainly.  Unless I can find a handy drystone wall or similar, the monopod isn't quite sufficient for multiple shots, because unfortunately my cameras are both lacking in sufficient technical support for muti-shots. 

A Sony R1 takes wonderful images but has a pathetically slow frame rate for RAW files so takes too long with its bracketed shots when perched on a monopod, especially in the wind.  Mind, its jpegs are not bad at lower ISOs - no smear or mush from the camera jpeg engine.  Still, one gets addicted to 16bit RAW files, as you will know.  :-)

A Samsung EX1 is my ideal fellwalking camera as it is so small yet also produces unbelievably good RAW images for such a small sensor.  It too has slow RAW write times.  Worse, the multi-shot bracketing facility works only with jpegs, which are not free from the unpleasant artefacts often introduced by camera jpeg engines (not to mention a tendency to blow the highlights - highlights that are recoverable in the RAW files).

Since I have long taken agin the DSLR (because they are moneypits and also rather cumbersome to deal with) I don't want to get a more suitable camera for bracketing shots.  So you will understand why the ND Grad filter is of interest.

Interesting, though, that CS5 (which I have and am well pleased with) can auto-align similar shots that are relatively "out" by a pixel or n.  But what is the value of "n" before the facility gives up I wonder?

[Peter McLennan]

Interesting, though, that CS5 (which I have and am well pleased with) can auto-align similar shots that are relatively "out" by a pixel or n.  But what is the value of "n" before the facility gives up I wonder?

It functions very well. N is a large, real integer. : )

Load your source images as separate layers into a single document, select all the layers in the Layers Palette and choose "Edit|Auto Align Layers"