By Pim Rietbroek (pimr@euronet.nl)
The very useful Pentax FAQ contains a short list of available Pentax LX accessories, including interchangeable focusing screens. The descriptions found there give you a rough idea in which circumstances you might use them, but you might like to have more specifics. In order to get those, you would need to consult the "LX Interchangeable Focusing Screen Operating Manual" supplied with each focusing screen. But if you are not sure which focusing screen fits your needs, how would you know which one to order in the first place? This document aims to provide you with all the information you need. It is derived from the "LX Interchangeable Focusing Screen Operating Manual" that I got with my SA-23, which I have just now installed -- with some difficulty and trepidation, I might add; probably because of my inexperience in these matters.
I welcome suggestions and comments. Please send them by email.
The Operating Manuals, both an older version and a later one, fail to mention that the tweezers that are supplied with each focusing screen are held one way when pulling down the screen retainer and grasping the screen, and the other way round (i.e., holding them by the end where the little lip for grasping the focusing screen is) when pushing back the screen retainer. I only found this out when I studied the tiny explanatory photographs more closely. Otherwise the instructions are clear enough.
Legal note:
I have no affiliation with Pentax whatsoever (other than liking their LX camera). This information is supplied "as is". Use it at your own risk. On no account will I be held responsible for any errors contained in this document and/or linked documents, or for any damages resulting from the use of this information.
You get the drift...
If you want to consult the Table of Pentax LX Focusing Screens and (K, KA and KAF mount) lenses, click here.
(If you are using a browser that does not support tables, click here.)
For a Description of Pentax LX Focusing Screens including diagrams, click here.
If your browser does not support tables, click here.
Sometimes when you use a rear converter on your lens, a focusing screen becomes unusable, because either the split-image or the microprisms (or both) are darkened. Much depends on the maximum aperture of the lens used. In this table the constraints are set out. (Click here if you are using a browser that does not support tables.)
Additional note: the "Operating Manual" dissuades the use of the SA-23, SA-26, SC-26 and SE screens with Rear Converter K T6-2x.
I don't know anything about their application, so I'll just quote from the Operating Manual. "When focusing with these screens, while looking through the viewfinder, place the subject you want to focus on in the central cross hairs, and focus the lens. When the subject does not come off the central cross hairs even if you have moved your eyes slightly to the right or left, your subject is then in focus. The SD-11 is suited for astrophotography and photomicrography, and if used for other purposes, or depending on the telescope or microscope to be used with, the corners of the frame may be darkened."
The Operating Manual states: "These all-microprism screens make the viewfinder image look brighter, and help you get focus accuracy all the time even in long-time shooting. These, however, make it difficult to preview the depth of field.
The following use of these screens is not recommended as they cause vignetting.
As stated above, apart from one omission the instructions included with each focusing screen are clear enough. This link will take you to a step-by-step tutorial.
Page created 19 August 1998.
Last modified 29 August 1998.