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AlexGard
3-Jul-2017, 00:48
Looking to buy a 12x20" Korona in the next couple of weeks.


Camera comes with 2 film holders. Obviously its all pretty old gear.


Realistically speaking, is *converting these film holders for glass much the same process as with modern smaller fidelity holders or should i start hunting around for someone who can convert or make Korona-friendly plate holders?*

Tried contacting AWB but the email bounced.


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Jeff Graves
4-Jul-2017, 05:34
Alex,

I converted a old 8 x 20 Korona wooden holder for wet plate and got a year of service out of it before the residual silver nitrate ate thru the modified steel sheet septum. My long term solution was to have a plastic holder manufactured. If you modify an old holder I would suggest coating the remaining edges of the steel septum with asphaltum.

Jeff

Len Middleton
4-Jul-2017, 14:40
Jeff,

As another 8x20 owner, wondering about your thoughts on the economics of that solution i.e. what did it cost to have the plastic holder made, versus the market value of the 8x20 film holder...

And to Alex's decision, would you go that way again knowing what you know now?

Just curious,

Len

Mark Sawyer
4-Jul-2017, 14:51
The problem with ULF film holders being converted for wet plate is that the dark slide is very close to the plate surface, and contact between the two will ruin many plates. With dry plate or film, such contact is not an issue. Best to build a custom back for wet plate, and leave a half-inch or inch of space in-between.

AlexGard
4-Jul-2017, 15:28
Thanks for the replies all. It appears one of these film holders the septum comes out alltogether. In regards to your concerns Mark one solution might be to use thinner glass (I generally use 3mm thick glass. 2mm is possible with more care)

Jeff, may I ask who you went to to have a plastic holder made? I have anticipated that sooner or later I will need a replacement given the nature of silver and wood.

Asphaltum is not available to me where I live. Thanks.

Here are some photos this fellow has sent me. https://uploads.tapatalk-cdn.com/20170704/6463f8c6205b395112360d0838bb1c68.jpghttps://uploads.tapatalk-cdn.com/20170704/bd29b9978a449df2e7b923cc30332403.jpghttps://uploads.tapatalk-cdn.com/20170704/26ca552ad2f32614b2c95d10d1cda156.jpg

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Jeff Graves
5-Jul-2017, 05:59
I asked Jody Ake at InCamera Industries to build it. I can't remember exactly what it cost. $500-600. I think he no longer builds them but he did make two of them with the hope of selling the other.

AlexGard
6-Jul-2017, 01:49
Thanks heaps Jeff. I got in touch with him. He's going to see if he's got enough materials leftover.

In any case I'm looking forward to tackling these wooden holders. I'm optimistic they will work.

Jeff Graves
6-Jul-2017, 05:47
Len,
Looking back, I would do the same thing. Mark does have a good point with a custom made back and holder for wet plate. That solution would save the standard back of the camera from silver nitrate staining.

Mark Sawyer
6-Jul-2017, 12:41
Thanks for the replies all. It appears one of these film holders the septum comes out alltogether. In regards to your concerns Mark one solution might be to use thinner glass (I generally use 3mm thick glass. 2mm is possible with more care.

Keep in mind that thinner glass won't save any space between the dark slide and the plate. The sensitive surface must stay the same distance away to stay in registration.

You might consider radically modifying the plate holder by adding an inch or two to the overall thickness, moving the plate back and using material that won't be so much affected by silver nitrate. Mind you, that would mean also adjusting the ground glass position to stay in registration with the plate surface.

AlexGard
9-Jul-2017, 07:26
You are absolutely right Mark.
Perhaps I shall wait until i receive the camera and see what needs to or what can be done. Maybe modifying or replacing the dark slide is another option..

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Mark Sawyer
9-Jul-2017, 10:17
Maybe modifying or replacing the dark slide is another option.


Perhaps an addition to the front of the holder to move the dark slide forward a bit. That would thicken the holder and necessitate relocating the ground glass again. A big advantage to a custom back is you wouldn't have to modify the camera or a holder, so you preserve the option to shoot 12x20 film/dry plates/paper negatives in the future. Also, most custom backs will accomodate a variety of plate sizes, so you could have it built to take 12x20, 8x20, 12x16...

And yeah, it's tough waiting for a new camera, especially something as epic as a 12x20.

AlexGard
10-Jul-2017, 02:12
Thanks again mark. Will have to wait and see what needs to be done. All valid thinking points. Cheers.
Yes very excited to get this camera up and running. I hate the wait!

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AlexGard
19-Jul-2017, 15:50
Seems I may be in luck. Conversing with another member here who got in touch and told me about his Korona plate holders.

Seems that one of the 'film holders' I have may actually be a plate holder that had a film holder adapter made for it, in the form of a removable metal septum with the sides folded over that is inserted into where the glass plate normally would be.

If this is the case, I might be in luck... I'm just hopeful that the 'plate holder' can accept 3mm thick glass...