Re: [APML] Adapting Nikon F3/T for gas purge

[KGKIRKLEY@aol.com]

In a message dated 6/10/00 3:35:49 PM, ireland@gate.net writes:

>Hi all,
>
>
>
>I could use some advice on adapting my two Nikon F3/T bodies for a gas
>purge
>
>system.  Living in South Florida (e.g. high humidity just about all of
>the
>
>time), this is probably a necessary evil for the hypered PJ400 I like to
>
>use.
>
>
>
>Drilling through the tripod socket permanently alters the cameras, which
>I'm
>
>not inclined to do.  So, it occurred to me that I could order two additional
>
>camera backs, and drill through those instead.  I could use any advice
>
>anyone would have regarding how/where to drill; type of valves to use;
>other
>
>equipment, etc.  By the way, I've ordered two additional standard F3 backs,
>
>not titanium ones.
>
>
>
>Ideally, it would be nice to rig up a system whereby one or both cameras
>
>could be used at the same time (with a splitter valve of some sort).  Also,
>
>sometimes only one camera would be used.  I plan to use Nitrogen, but may
>
>also consider the dry air purge.  It seems to me, however, if going to
>this
>
>much trouble, I might as well use Nitrogen.
>
>
>
>Would appreciate any advice.
>
>
>
>R. Scott Ireland

Scott:
Using the interchangeable backs on the F3's is an interesting solution, but 
N2 is usually introduced in front of the film, either in the mirror box, 
coupling adapter, or off-axis guider body. If introduced through the camera 
back it's difficult for the N2 to get to the mirror box to keep the emulsion 
dry. It will keep the film dry in the cassette and take-up area and may 
eventually get into the mirror box, forward of the shutter.

Using nitrogen you will need serveral things:
1. Nitrogen tank of appropriate capacity
    They usually come in 20, 40, 80, 200 cu. ft. sizes. In the smaller sizes 
you 
     usually have to buy them. The 200 can be rented. For ease of 
transportation, 
     the 40 or 80 are best. The 200 is fine for permanent observatories.
2. Pressure regulator with Flow meter
    The regulator controls and lowers the pressure.
     The flow meter allows you to regulate the flow of N2 down to very small 
levels.
      The N2, tanks, regulator with flow meter are available from welding 
supply co.
3. I use drip-irrigation tubing and valves, available at Home Depost, etc.
      All kinds of on-off, splitter valves are available and they are cheap.
      Once the N2 leaves the flow meter, there is very little pressure.

If you proceed with the F3 Back N2 Introduction idea, please post your 
results.
thanks,
Kent Kirkley


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