KT 6x12

**FpJohn** · 4-Apr-2006, 16:34

I have a question on the Guohua (KT) 6x12 back. What is the film aperture size? The Shen Hao is 55x110mm, a tad short of 6x12.

yours
Frank Johnston

**Patrik Roseen** · 4-Apr-2006, 17:27

Hi Frank,

the issue of frame size was discussed in another thread recently related to the ShenHao 6x12 back, see

http://largeformatphotography.info/lfforum/topic/504763.html#586889

John Mackay, has a brilliant description of different numbers and actual framesize in that thread. You will see that 6x12 is actually about 55x110.

**Bob Salomon** · 4-Apr-2006, 18:11

"You will see that 6x12 is actually about 55x110."

Except for the company that started the format. Linhof Techno Rollex and Technorama 612 is 56x120mm.

Some others are 56 x 112mm or 56 x 111mm.

**FpJohn** · 4-Apr-2006, 19:15

Hello:

Thank you both. The dimensions of the KT 6x12?

yours
Frank

**Patrik Roseen** · 5-Apr-2006, 07:02

Hi Frank,

I do not know if the (KT) is different from the Guohua GH6x12 back being offered on ebay currently. Anyway, I asked the guy selling this and his respons was:

The actual size measure 56 x 111.5mm.

Hope this is what you are lo0king for.

**FpJohn** · 5-Apr-2006, 08:50

Hello::

Thanks. The KT and GuoHua appear to be the same.

yours
Frank

**Richard Littlewood** · 6-Apr-2006, 06:51

I've got one of these plastic Chinese backs and on the whole I'm OK with it but.. I would recommend that you be brave, and unscrew the metal plate (with care, it's gummed on also), and file the squared film aperture edges (facing away from the film) to a nice bevel, and then do the same to the plastic aperture that is behind the metal part. Then paint them matt black. I found I was getting edge density build up on my negs that often ruined some shots - especially ones with good skies. Angling these 2 edges has removed the problem. As far as re-assembly goes, the gummy glue is there to make a 'spacer' so the dark slide will still be free even though the 8 screws are tight - without the glue the darkslide wont budge!, it's held in tight. My way round this was to strip away this gunky glue, then re-assemble making a spacer out of double sided carpet tape - 2 layers of thickness did it. The whole job may take an afternoon to do, but it is worth it.
Hope this helps.