You have reversed the definition of Less and More DOF. Higher F Stops have more DOF Lower F Stops have Less DOF.

Hi.
A little clarification and explanation:
Without any ND filter you need to set the iris smaller and you will get a large DOF (depth of field). (However, don't go past about 8 or so with these small chip HD camcorders. Too small iris makes you losing sharpness.)

With ND engaged (or additional ND filters in a matte box) you can open the iris more for more shallow DOF (if you have light enough with the selected shutter time and gain.)

Unfortunately the aperture is a reciprocal number (like 1:2 or 1:8) and photographers usually omit the "1:" part of the number. This leads us to the strange fact that a larger number (like 8) has a smaller iris but "8" means technically that the diameter of the iris is 1:8 or 0.125 of the focal length of the lens.

The amount of light which can pass through an iris is proportional to the diameter squared which makes the exposure calculations harder to do.

Thats why you can double the exposure time from 1/60 to 1/30 and compensate by only change one f-stop from 1:1.4 to 1:2. (Where 1.4 is almost the square root of 2 etc.)

Good luck with your filming. But I'm quite sure you will need the ND filters if you have normal light in the mountains.

More about filter
 

Make sure you clean your filters if they become dirty.

When using wide angle focal lengths; any dirt on the filter together with small iris will make the dirt clearly visible on the video!

Maybe you don't see it first but if you zoom it will look very annoying. Once you see it you will find it on all shots. This has ruined some nice shots for me in the beloved Kenya ...

Thanks Daniel...typo on my end....

OFR Mist and Kimwipes are the preffered method for cleaning lenses and filters here at Schneider.

Ryan Avery
Schneider Optics

Allright thanks again. Hopefully I'll be able to figure out whatever you guys just said!

-Anthony

I am surprised by this. From what I have read, while Kimwipes can be used to clean delicate surfaces, they are not recommened for cleaning optical surfaces, such as lenses, as they can scratch the optical surface. From personal experience, I always thought that Kimwipes were rough to the touch, not soft like lens cleaning tissue or cloth.

Ryan, I assume that you and Schneider know what they are doing, it just surprises me that something as rough as a Kimwipe would be recommened for cleaning an optical surface.

The following Wikipedia article discusses Kimwipes. Please refer to the section on Kimwipes near the bottom of the article.

http://en.wikipedia.org/wiki/Kimwipes

Ahem, Kevin,

You've got it the wrong way round. Shallow depth of field is due to a large aperture. Deep depth of field caused by a smaller aperture.

Using the ND filters causes one to have to open up the stop, thereby LESSENING the depth of field.

Harry

Kimwipes are seemingly rougher to the touch but they grab heavy dirt and are disposable. The use of them alone is not recommended. In combo with OFR Mist, Kimwipes work well.

The best way to clean an optical surface is our PhotoClear cloths. They are made of the finest quality microfiber and clean well. The problem with this, and any other microfiber cloth, is that they trap dirt and get reused with out proper washing. This causes them to act like sandpaper. A Kimwipe on the other hand is disposable and doesn't cause this effect because it can't be reused.

If you are willing to wash your microfiber every 5 to 10 uses, then the PhotoClear is the finest available and significantly larger than those lesser very small cloths that you see for $5 on the counter at the camera store.

http://www.schneideroptics.com/ecomm...=1111&IID=2059

You should be able to get these at most dealers but not any sponsored by this site.

Ryan Avery
Schneider Optics

Dear Ryan,

Thanks for the additional information.

Thanks Harry...I think I had posted it was a TYPO on my end...

but non the less...hopefully Anthony is getting the info he needs.

Cool.

Best,

H.