Re: slit width experiments

[Alan Zinn <azinn@xxxxxxxxxx>]

At 11:16 PM 9/3/2000 -0700, you wrote:
>Ron
>
>     Why would reducing the slit size cause banding?  Less light =  slower
>rotation = less of a problem with banding?   Is this being used at auto
>exposure or manual?
>
>      With the 220 VR banding is more common at very high speeds, 1/250 th,
>or when using auto exposure...the drastic slowing and speeding of the motor
>can cause this......Is this a mechanical problem unique to cirkuits?   Have
>you found an optimal slit size for sharpness, or is it simply the smaller
>the sharper?
>
>Bill G
>
>
>
>----- Original Message -----
>From: "Ron Klein" <panorama@xxxxxxx>
>To: <panorama-l@xxxxxxxxxxxxxxxxx>
>Sent: Sunday, September 03, 2000 9:10 PM
>Subject: slit width experiments
>
>
>> > The film in my camera isn't getting enough light..... so this wouldn't
>> work!  Anyone played with Cirkut slit widths?
>>
>> Clayton:
>>
>> I have done modest experimentation with changing the slit width.  I took a
>> #10 that had a 1/4 inch slit and changed it to 3/8 inch with only a very
>> slight loss of sharpness.  In the other direction, I have reduced the slit
>> width to 1/8 inch and had much sharper images, but indeed banding became a
>> noticeable problem.
>>
>> If you are trying to shoot photos in low light conditions, it would be
>much
>> better to have a longer exposure time rather than a wider slit.  The
>> electric motor combo that I am playing with currently has four speeds that
>> are 1/6, 1/3, 3/4, and 1 and 3/4 seconds.  Odd combinations, but they seem
>> to give me everything I need for low light shooting.  If I need faster
>> speeds for groups, I can reduce the slit to 1/8 inch wide and get 1/15
>> second.  If you need more details about the new cirkut motor I have
>> designed, feel free to write me a separate email note.
>>
>> Ron Klein
>> panorama@xxxxxxx
>>
>>


Guys,

Moving the slit closer to the film and/or making it narrower (and leaving
the speed the same) causes sharpness due in part to the lessening of the
blur of camera movements other than rotation. Doing this increases the
chances that the legions of gremlins that cause the film and rotational
movement to vary will show up as bands. The film itself is in my experience
the worst cause of trouble and the least fixable. 
If the camera can be optimized for smooth action the increase in sharpness
aforded by a narrower slit is very great. It is worth the occasional band.
Gonna give a dance ya gotta pay the .... . 

Speaking of bands - it is delightful to be able to rescue images with a band
or two using PhotoShop. Has anyone found a sure-fire method? Somehow I don't
think there is a Debando plug-in.

AZ


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