You suck film holder. (Vac.810 holder)

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After perusing the archives I came accross some concerns regarding film sag. The posts struck home as I am shooting 810 straight down. I have been satisfied w/ results so far, However I am considering buildig some sort of vacuum holder that will insure that these images really are as sharp as they possibly can be. If I have a # of small holes around the middle area with hose & tupperware attached to a sacrificed film holder, could that cause a reverse problem? Ideas? Comments? Ajectives? Other than a dust problem, is there any reason not to try laying my film on a sheetof glass, of course, adjusting focus to the different film plane.

-- John Forrest Grunke (johngrunke@msn.com), March 21, 2002

Answers

Why not try a piece of double sided tape in the middle of the holder? Once the film is inserted just tape it in the middle to secure it to the tape.

-- Stephen Willard (willard@peakpeak.com), March 21, 2002.

You might have flatter film, but then you have to be concerned about vibration. I'm not sure how you would use such a back in the field unless you develop some type of battery powered holder. In any case it seems to me like you might be fixing a problem that isn't a problem; but yet the solution might be.

-- David Grandy (dgrandy@grandyphoto.com), March 21, 2002.

David, Thanks for the response. Per my humorous title, I would be the power supply for this apparatus. As I am having great results doing super macro I am beginning to see a plane of focus that is not the area that I focused on. "The titty may be tough but the milks still good said the kitty"

-- John Forrest Grunke (johngrunke@msn.com), March 21, 2002.

Sinar makes super flat film holders. They are expensive!!!

However, you may be able to duplicate them to some extent:

The 5X7 and 8X10 holder have a very weak adheasive inside the holder. The film stays absolutely flat, and the glue does not transfer to the film. They do sell repositionable adhesive tissue separately for these holders...You may try that or try to find a weak spray glue that will work the same way...

-- Per Volquartz (volquartz@volquartz.com), March 21, 2002.


The glue you could use might be the 'low tack' spray used for doing DIY stencilling. It is available in UK from hardware stores like B&Q and Homebase.

-- Colin Carron (CICarron@aol.com), March 21, 2002.


Do these adhesive type holders tend to accumulate dust? Or is that not a problem.

-- Steve Clark (agno3@eesc.com), March 21, 2002.

John, the vacuum holder [using your own suction] is not THAT far fetched. In fact, Linhof used to make such holders with that very feature [a little plastic tube came out one end]. But that was many, many moons ago!

-- Alec (alecj@bellsouth.net), March 22, 2002.

In a macro configuration, film sag is really not a problem.

Next time you are set up, try focusing with the back standard and notice how far you have to move to affect even a slight change in focus....and translate that into film sag.

-- Bruce Wehman (bruce.wehman@hs.utc.com), March 22, 2002.


I apologize for a very confusing statement. What I tried to say was that the ammount of sag is small when compared to what is necessary to cause an error in focus at or about 1:1.

-- Bruce Wehman (bruce.wehman@hs.utc.com), March 22, 2002.

Didn't Hoffman make vacuum backs that were evacuated by mouth or a small bulb?

-- Wayne DeWitt (wdewitt@snip.net), March 25, 2002.


Thanks for the responses.. I went ahead& made a vac. holder using a 35 film canister cut to 1/4" jb welded to center of 810 holder, film side lined w/black-out tape to prevent reverse buckle, vac. hose attaches via canister cap. only very slight vac. is needed to adjust film to exact shooting position. It works perfectly!!!!! Thanks for not calling in the white jackets.

-- John Forrest Grunke (johngrunke@msn.com), March 27, 2002.

Add. Drill several small holes inside the area where the film canister is attached. Make sure all is light proof. Use black automotive hose. Ah! The joys of BIY! Cheers!

-- John Forrest Grunke (johngrunke@msn.com), May 29, 2002.

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