Nifty Accessory for AI Lens Focusing

[AVCONSULTING 0]

Just ran across this very handy little item from CBC (Computar) that lets you focus auto iris lenses during daytime hours. One of the biggest problems in focusing an auto iris lens is that if you focus it during the day you almost never get a good picture at night. This is caused by the depth of field effect of a tightly closed iris. This little accessory from CBC helps to overcome that problem. Below is a link to the item.

 

http://www.cbcamerica.com/cctvprod/ganz/access/man_cfb1.pdf

[rory 0]

any idea on cost?

 

thanks

Rory

[kdberg 0]

Neutral Density (ND) filters are a standard photographic item that you should be able to pick up at any camera store. Tiffin ND filters run $10 to $20 depending on the filter diameter. There are a few different densities, depending on the percentage of light that you want to block out. The filters can also be ganged together to achieve higher density.

[jimbo 0]

We paid $80 (Cdn) for a ND filter and then one of the guys dropped it.

 

Go to your local welding supply shop and pick up some welding filters (we pay about $5.00 (cdn)each. I try and wrap the edge with duct tape and attach a lanyard so you can hang it around your neck.

 

Again I quote from Charlie Pierce's site (http://www.ltctrainingcntr.com/)

 

If you contact a manufacturer, they will tell you to use an "ND" (neutral density) filter. These filters are very expensive however. To combat cost and potential loss (dropping of very expensive filters) I recommend welding glass filters (about $5.50 each). I also recommend that you purchase four different densities to combat the various lighting conditions that you may be working under (#1, #3, #5, #. A #1 filter is very light and is like a pair of sunglasses. A #8 filter is extremely dark and is good for very bright conditions (full sunlight).

[Cooperman 0]

I completely agree with kdberg about the ND filters (and they are not very expensive!) .... although their is another way of creating a variable ND filter arrangement.

 

If you overlay two polarising filters, and rotate one over the other, the effect is from virtually clear (perhaps equivalent to NDx2), through to virtually opaque.

 

Many decent photographic dealers (particularly long established ones) have clearance bins where they get rid of old filters and bits for next to nothing, so you can often pick up some bargains.

[Randy 0]

I use the replacement lens from a welders helmet. Not the really dark arc welding type but the lighter lens used for brazing or cutting steel.