Nuetral Density Filters and stepping rings

[paul_jones7]

Hi,

 

I'm looking at buying some Lee neutral density graduated filters. My

questions is that the holder mounts onto a 67mm filter thread on the

lense and this is perfect for my 24mm lense, but if i use the filters

with a stepping ring on my 35 or 50mm lense which both have 49mm

filter thread, wont i then be just shooting through where the the

neutral density and clear part of the filter join. So i'll be missing

out on the area above and belowe the join in the filter.

 

I hope this makes sense.

 

Thanks,

Paul Jones

[william_baguhn1]

Welcome to the problem with all graduated filters. You need a collection of different filters with different rates of gradation to use them fully with each lens/scene combination (or just suffer with moderately improved results instead of fantastically improved results).

 

Lee filters are rectangular, right? and they're in a sliding mount? wouldn't that allow you to slide it to the "right" place, so that your ND starts just above the horizon, no matter your composition or focal length?

 

Your question almost makes sense, but there is a built-in workaround with the sliding mount. If you're really worried, go into your friendly local camera shop that you're going to buy it from, ask to put it on your camera and look out the window. Play with it. Does it work?

[kevinoneil]

The Lee split ND filters are rectangular, and can be moved up and down, as well as the holder itself can be rotated. As such, you will not have a problem placing the edge line where it is needed for each image.

 

The Lee filter holder also has adapters of various sizes to attach the holder to your lens (up to 82mm). I'd suggest that if you can, purchase the adapters needed for each lens rather than using stepdown rings. This is especially true for wideangle lenses where adding length may cause vignetting.

 

If you are going to use the filter holder on wide angle lenses, such as a 20mm, you may need to modify the holder slightly. The holder allows you to stack three filters. You need to remove the two outside clips (very easy) to avoid vignetting.

 

For an article on using split ND filters, go here:

 

http://members.aol.com/kevinoneil/nd.html

[mark_lagrange3]

Let me try to better interpret the question, and then give you my thoughts. Hopefully, a better technically proficient photographer will confirm my suggestion ... or set me straight.

 

Paul, if I understand you right, when you look throught the lens you are able to see and adjust the dark part of the GNDF to reduce the light in a certain area of the frame ... lets say the sky. You can also see in your viewer how this does not affect the light part of the filter which will be covering the darker area of the ground. The problem arises when you use a lens with a physically smaller front element. The problem appears in the form of a viewer image where the filter can only be on the dark, light or graduated part of the filter. This does not allow you to use the lighting control that the filter was designed to do. Have I understood the problem correctly? If so, here's two thoughts

 

First, your answer: Explore a the option of a "hard edged" GNDF. This filter will more quickly change from light to dark.

 

Your question brings to mind a second, very common, and often missed issue that even professional photographers overlook.

 

In landscape or scenic photography it is common to use smaller apertures to obtain depth of field throught an image. When we stop down to smaller apertures, it has a similar effect/problem regarding filter control as you described here with a smaller front lens element. Cameras are designed to allow us to view the image at the maximum aperture in order to permit the brightest image in the viewer. The problem comes when we don't account for the stopping down that occurs when the actual image is taken. When we release the shutter, the lens closes down the aperture and potentially radically alters the relative alignment of the filter. Furthermore, the smaller aperture opening may not be able to utilize the graduation of the filter.

 

Two solutions: 1. Try using hard edged filters 2. Use DOF preview. While the image will appear dark in the viewer, it will allow you to see how adjustments in your filter will affect your final image. It will allow you to line it up more appropriately.

 

Someone please check my thinking here.

[paul_jones7]

Hi,

 

Thanks for all your replied.

 

Just to clarify my question, which i probaly could have worded better.

 

If i had say two Graduated ND filters, one designed for a 49mm filter thread and one designed for a 67mm filter thread, would the graduated area of the filters be the same width? or would say the graduated area be 10mm on the 49mm filter thread and 15mm on the 67mm filter thread (these numbers are hyperthetical).

 

Sort of hard to explain myself clearly :)

 

Thanks,

Paul Jones

[erick_lamontagne]

Paul, you should read Kevin's article on Grad ND. I only have experience with Cokin holder but I assume the Lee system works in the same way.

 

There are three parts to the Grad ND filter system: the ring, the holder and the filter.

 

1-The ring attaches to your lens and should match the filter thread size of your lens. In your case, 49mm and 67mm.

 

2-The holder is then attached to the ring. The holder will fit on all rings, regardless of filter thread size (as long as its a Lee ring with a Lee holder).

 

3-The filter will then fit in a slot in the holder. Grad filters are square and are half clear, half dark . You can adjust where you want the dark part by sliding the filter up and down in the holder's slot.

 

Basically, you need a 49mm ring, a 67 mm ring, a filter holder and one or many filters of different densities.

[frank_kimble]

Lens are round, the filter holder is round where it attaches to the lens. A stepup/down ring is round. When all are attached together,the center of each lens will be looking thru the center of each filter holder hence thru the center of each filter.

[mark_lagrange3]

Frank .... not so with Grad Neutrals ... see above discussion.

[bill_proud]

Let me take a stab at this. Your concern is how steep is the graduate curve from 0 to 2 or 3 stops. I'm assuming the Lee filters are soft edges, (I use Tiffen so I'm not sure), which gives a smoother, but longer gradation from 0 up to 3 stops. These are pro filters designed for larger diameter lenses. The Cokins are hard edged and give a more pronounced effect in a shorter distance, which makes them more suitable for smaller diameter lenses. The technique is somewhat tricky. The soft edged gradation doesn't give you that black line in the middle, but the hard edge gradation goes from 0 to sixty in less time(a metaphor). You are correct that the narrower focal length lens diameters allow for less gradation effect since they cover a smaller area. Anyway the basic technique simplified is push the filter down, shoot some frames and see the effect. Hope I helped.

bill Proud