how to sizing
Due to the many requests, this post will be useful to those interested in having a Bomm screen.
The necessary measures are few but it is very important that they are carefully taken. One of the most important aspects is the parallelism: be careful to measure the lengths parallel to the sides, because a measurement taken with a different angle even of a few degrees can cause measurements larger than many millimeters. Another fundamental aspect is the parallax error: You must be exactly on the vertical of the index of your measuring instrument, otherwise half a millimeter more could make it impossible to mount your new screen. However, I make every screen kit about 1 millimeter less than the measurements you will provide me.
Make sure you use only quality measuring instruments, such as digital gauge or Class 1 tape measure, they are the tools we use and with which we make cameras and accessories. We cannot be held responsible for measurements obtained by you with too large tolerances.
Let’s start!
The dimensions to be taken are four and must be in millimeters:
AxB: glass side frame Hole – the frame seen from the observation side
CxD: lens side frame hole – the frame size under the glass, this is generally a little smaller than AxB and is exactly the frame size of your camera, for example in an 8X10″ camera it will be 203×254 mm.
D.I. : Depth of inlay for glass (inner wooden frame)
D.B. : Depth of the frame Below the glass
please note, in cameras with a spring-loaded glass frame this measurement refers only to the glass frame and not to the sum of this frame and the removable back
REMOVE THE SPRING LOADED FRAME FROM THE CAMERA BACK 
MEASURE ONLY THE SCREEN FRAME
That’s all. Please accompany your requests with some photographs of your glass frame, above and below, the more accurate you are in providing this data, the easier it will be to work for you.
Send your requests to: max@bommcameras.com and please be patient, I do these jobs by myself and it is not easy to please everyone within a few hours. I will try to gather as many requests as possible to work together with several screen kits.
I have to specify that the Fresnel lens I use on my screens works very well on film and wet plate photography, but keep in mind that since the Fresnel lens is a lens like any other, it has its own specific focal length which makes it unsuitable for wide-angle lenses, due to a marked directionality projected onto the screen. Please keep this in mind before placing orders.
I actually can make screen kits up to 14″
Thank You very much!
Max.