Posted by David Schoen on February 10, 2009 at 10:08 PM
What is the difference between .9 GND and 3 stop GND? Can one determine what GND is soft vs. hard without statement as to such? What is so special (other than price) about Singh Ray GND filters? Is there any advantage to 2 vs. 3 stop filters?
Posted by David Bostedo on February 10, 2009 at 10:27 PM
0.9, 8x, and 3-stop all mean the same thing David. Just different nomenclature from different companies.
I've always seen hard or soft included in the description of the grad. If all you see is a description like "3 stop GND", there's no way to tell.
I would think that more expensive filters would be more expensive possibly for a few reasons - neutrality, accuracy, and coatings. Cheap filters may be more likely to add color casts, not be an exact amount of stops, and have lesser (softer, or just not as good) coatings. Singh-ray is well regarded in these veins, but I've never used the brand.
2 stop vs. 3 stop totally depends on the exposure you want to control. I don't use them, so I can't comment on what's more common, but it depends on what you're shooting.
Posted by Robert Fisher on February 10, 2009 at 10:35 PM
.9 is 3 stops as far as I know. Other than a description of whether it's hard or soft or looking at it, I don't know that there's a way, generally, to tell. Is there an advantage to 2 vs. 3 stops? Is there an advantage to 1 vs. 2 stops? If you need it, there's an advantage to having it. The obvious is it gives you an extra stop of filtration. Depending on what's being photographed a 2 stop might work and then you could play with the shadows and highlights after the fact to get them where you want; or you can put 3 stops of filtration in front of the lens and get it right (or closer to right) at the time of shooting. Singh Ray are supposed to be very good filters. Very high optical quality. Completely neutral. There's a price to be paid for quality.
Posted by David Bostedo on February 10, 2009 at 11:56 PM
...Very high optical quality...
And the fourth and best reason to get well regarded, high quality filters. I really should have mentioned that one!
Posted by Larry Puckett on February 11, 2009 at 11:19 AM
If you go to the online website or catalog it will tell you whether it is soft or hard GND most are available in both configs. As for the 2 vs 3 stop factor if you ncan only afford one to start with go with the 3 stop. If you use a 2 stop and still have too much light then you're done but with a 3 stop you can always just increase the exposure time to get more light. You should also factor in the 1-2 stops you'll get if you stack the filter with a Polarizer--Larry
Posted by David Bostedo on February 11, 2009 at 11:58 AM
...with a 3 stop you can always just increase the exposure time to get more light...
Not necessarily, Larry. If the extra time would blow-out detail in the clear part of the grad, increasing exposure time isn't an option.
Posted by Robert Fisher on February 11, 2009 at 12:03 PM
While it's not considered proper from a technical standpoint due to fears of loss of quality, I carry a 1 stop and a 2 stop. If I need 3 stops, I combine the 1 and 2. The other thing that lets me do is vary the grad even more if I need to.
As I said, it's not considered good practice but it works.
Posted by Larry Puckett on February 11, 2009 at 12:42 PM
David--you're correct of course--I had a minor brain fart on that one and was thinking about NDs not GNDs. With the ND you can always just shoot multiples at various exposure settings and then do a merge to mimic a GND--Larry
Posted by David Bostedo on February 11, 2009 at 2:28 PM
With the ND you can always just shoot multiples at various exposure settings and then do a merge to mimic a GND
Well if you're going to do that, you might not even need the ND depending on what effect you want. GNDs are often used for "normal" exposures to squeeze the scene's dynamic range into the cameras recordable range. ND's more typical use is to obtain long exposures, which has nothing to do with dynamic range.
So if you're are willing to take multiple exposures and combine them, you don't need GND filters at all. Which is why I don't own any.
Posted by Larry Puckett on February 11, 2009 at 2:54 PM
Well, I was out to SNP last week to shoot some icy waterfall scenes and didn't have the ND and could have really used it. There was no way I could have slowed the exposure enough to get the streaming water effect in the open water sections. And with the 10-22 mm lens on the way I decided to go with the 4" Z filters instead of screw ons in order to prevent vignetting at those wide angles. This is starting to become an expensive hobby!
Larry
Posted by Joe O'Hara on February 12, 2009 at 12:38 AM
David, regarding your questions, I would say, respectively, none, only by comparing them, and they are well-regarded for quality and have the authentication (not to be discounted) of having been used by Galen Rowell. Regarding your last question, my approach is as follows: Meter the scene with a spotmeter (most convenient, but I suppose you could use a digital camera meter in spot mode also). Determine the luminance of the bright parts. If your medium (film or digital) cannot hold the detail you want in the bright parts when the dark parts are exposed where they need to be, use the grad that keeps the bright parts in range. Only experience (i.e., many failures) will teach you what your medium can do. (This process is faster with digital.) In practice I find I use .6 (2 stop) and .9 (3 stop) grads the most. I can imagine needing to concatenate filters for more extreme situations, but that will exaggerate the "grad line" effect unless you are careful.
Discussion
10 repliesI've always seen hard or soft included in the description of the grad. If all you see is a description like "3 stop GND", there's no way to tell.
I would think that more expensive filters would be more expensive possibly for a few reasons - neutrality, accuracy, and coatings. Cheap filters may be more likely to add color casts, not be an exact amount of stops, and have lesser (softer, or just not as good) coatings. Singh-ray is well regarded in these veins, but I've never used the brand.
2 stop vs. 3 stop totally depends on the exposure you want to control. I don't use them, so I can't comment on what's more common, but it depends on what you're shooting.
And the fourth and best reason to get well regarded, high quality filters. I really should have mentioned that one!
Not necessarily, Larry. If the extra time would blow-out detail in the clear part of the grad, increasing exposure time isn't an option.
As I said, it's not considered good practice but it works.
Well if you're going to do that, you might not even need the ND depending on what effect you want. GNDs are often used for "normal" exposures to squeeze the scene's dynamic range into the cameras recordable range. ND's more typical use is to obtain long exposures, which has nothing to do with dynamic range.
So if you're are willing to take multiple exposures and combine them, you don't need GND filters at all. Which is why I don't own any.
Larry