Nancy and list, Maybe you need to adjust the brightness setting on the CRT display itself; turn down brightness. Sometimes low brightness and high contrast work; sometimes low contrast and high brightness work. Also, there are various ways to adjust the CRT lens itself; try unscrewing the top of the lens to make it longer, instead of screwing it all the way down into the lens barrel. Remember, TSI developed at least two types of CRT lenses, one for CRT screens with larger print, and another for CRTs with smaller print. Below, I'm adding the instructions that were included with the CRT lens for larger print CRTs. If you have an R1D or R1C optacon, the CRT lens was supposed to work in inverse mode. If you have an optacon 2, adjust the mode slide switch either in the lowest or highest position; the middle position is normal, if I recall correctly, and not often used with a CRT lens. If inverse won't work, use normal mode; Windows often has dark colors on a light screen. Here, starting in the next paragraph, are the instructions. Maybe this information will help somebody else on the list, too. TELESENSORY SYSTEMS, INC. 3408 Hillview Avenue P.O. Box 10099 Palo Alto, California 94304 Telephone 415/493-2626 Telex 348352 OPERATING INSTRUCTIONS FOR CRT LENS’* MODULE F1A INTRODUCTION The CRT Lens Module F1A is an Optacon accessory that may be attached to the retina of a Model R1C/D Optacon to read some Cathode ray Tube terminals. There are numerous variations in CRT’s including those which are supposedly identical, which mean that one’s own Optacon, the F1A CRT Lens Module, and the specific CRT in question must be evaluated together to determine if an effective reading system can be achieved. Although the CRT Lens Module is designed to read characters 1/8 to 1/4 inch (3 to 6 mm) tall, there are significant variables which prevent TSI from consistently predicting which CRT’s are readable. These include the brightness and contrast of the CRT display, the focus adjustment of the CRT, and presence of a dust cover with its underlying CRT tube curvature, extraneous light from the surrounding room, the refresh rate of the CRT, and the ratio of character height to width. FEATURES OF F1A ..’-. - ..--. The bayonet sleeve which accepts the Optacon retina is on the back side of the F1A at the end closest to the user and furthest from the CRT screen during use. The front end of the F1A contains three small nylon ball bearings which are positioned directly against the CRT ^ screen during use. The features below are described in a sequence from back to front. Bayonet sleeve - accepts the Optacon retina which is inserted with a push/twist action. Zoom lens magnification adjustment - The zoom lens adjustment ring is at the back of the F1A barrel, just before the barrel makes a right angle turn to the bayonet sleeve. The ring has a larger diameter than the barrel. It slides forward and backward approximately 1/4 inch (6 mm) with the forward position providing the greatest magnification. The ring can be locked into position from its ”free-sliding” position by twisting it” either clockwise or counter-clockwise relative to to the barrel. Focus adjustment - Focus is adjusted by varying the length of the barrel. About 3/4 inch (19 mm) forward from the zoom ring are two smaller knurled rings having the same diameter as the barrel. The forward ring is attached to the front half of the barrel. Turning it adjusts barrel length. The second ring (toward the back) is a lock ring. A flat side on the circumference of the barrel just forward of the two focus adjustment rings provides a tactile monitor of the number of turns made while adjusting barrel length. .^Eleven complete turns will adjust the barrel from minimum to maximum length. ^ ’ Light shield - The two inch (51 mm) diameter disk near the front of the F1A is designed to shield the CRT from extraneous light. In some situations, this shield may be unnecessary. It can be unscrewed from the barrel and removed after separating the barrel in two by completely unscrewing the front ^ section beyond its maximum extension. Nylon ball bearings - Provide smooth, low-friction movement of the F1A across both glass screens and protective dust covers. SET-UP PROCEDURES Preliminaries: The sighted CRT user will generally prefer a very strong contrast between the characters and the background. This is usually not ideal for the Optacon. The Optacon generally works best when the CRT is very bright, in which case the contrast may be low. In other words, both the characters and the background are usually bright when CRT adjustments are optimum for Optacon reading. Frequently the best CRT brightness and/or contrast settings will result in the appearance of retrace lines on the screen. Preliminary to evaluating the F1A, one could ask a sighted assistant to adjust the CRT brightness and/or contrast controls (if present) to yield characters and background as bright as possible without significantly distorting character focus. Next, use the chart below to make an initial focus (barrel-length) adjustment. This adjustment will be based upon two factors: (1) F1A’s are factory-adjusted at TSI to various internal lens settings, and (2) CRT’s come with or without cover screens. NOTE: For best results with a CRT with cover screen, the screen should be removed. If the screen is not removed, you may not be able to read some parameter information. CRT Without Cover CRT With Cover ’., Screen ’ Screen’ F1A Lens Setting No. 4 9 complete turns 9 complete turns (reads larger print) from minimum. - from ’minimum F1A Lens Setting No. 7 4 complete turns 1 complete turn^’ (reads smaller print) from minimum from minimum Remove the standard lens module from the Op’tacon retina module and set it aside in a safe place. , Adjust the zoom ring to minimum magnification by unlocking it, sliding it back toward the bayonet sleeve as far as possible, and relocking it. Now, hold the F1A against the CRT screen. If your Optacon is designed for left index finger reading, turn the F1A until the bayonet sleeve (which accepts the retina) points left. (If your Optacon is designed for right index finger reading, the bayonet sleeve should point right.) Holding the F1A this way, insert the retina module into the F1A bayonet sleeve so that the camera cord emerges from the 12 o’clock position. CRT Light Adjustments: The following procedures are designed to determine whether the CRT emits enough light for the Optacon to operate properly. ’” 1. Both the CRT and the Optacon should be on, with the Optacon’s normal/invert switch in the invert position. 2. Aim the F1A at a blank screen or blank portion of the dis- play previously adjusted by a sighted assistant. 3. Turn the Optacon’s threshold counterclockwise until the array ”blooms”. (Namely, all of the pins are vibrating.) Then back off by turning the threshold clockwise until the bloom just disappears. 4. Display a line of ”L’s”across the screen. 5. Leaving the Optacon threshold at the setting in Step 3, scan the ”L’s”. If the Optacon responds, proceed with F1A focus adjustments in the next section . If the Optacon does not respond, increase CRT contrast and repeat steps 2-5.” If the Optacon still does not react to print with any of the CRT contrast adjustments you have made, the F1A you are using is probably not receiving enough light from your CRT’s screen and probably will not work with your equipment. Try evaluating an F1A with a different factory-adjusted lens setting (if you have one available), starting again with ”Preliminaries”. Note: If the ”L’s” appear upside down, remove the retina module from the F1A, rotate it 180° and replace it. F1A Focus Adjustments: ’ Ignore image size and leave magnification at a minimum with the zoom ring all the way back (toward you) . Try to improve focus by using various barrel lengths, adjusting Optacon threshold after each barrel length adjustment to determine if the image is becoming clearer. Try to find the barrel length adjustment which will provide the best average focus for characters appearing in both the corners and the center of the portion of the CRT screen that you will want to read. Magnification Adjustment: . Using the zoom ring and Optacon’s threshold adjustment, adjust magnification. When the magnification is adjusted to provide the correct image size, the focus may require readjustment, especially if your F1A has lens setting Number 4. ” Improving CRT Light Adjustments: Assuming that previous adjustments were properly made, the F1A should require no further focus or magnification adjustments. Next, you want to determine whether any additional adjustments to the CRT’s intensity and/or contrast controls result in clearer images for the Optacon. . -..- , -,. Before attempting to improve the CRT’s light adjustments, note the ; Optacon’s threshold setting and ask a sighted assistant to note the starting point CRT intensity and/or contrast settings. Now, without adjusting the F1A, determine whether variations in the Optacon threshold adjustments and the CRT intensity and contrast adjustments provide improved images. If not, return to the settings in use at the beginning of this section. Make note of these settings so that next time you use this CRT, you will have some way of quickly making the proper settings. The above instructions assume that the CRT has brightness and contrast controls. Not all CRT’s do. Some have a single brightness control which simultaneously adjusts intensity and ’contrast. Others have no ” external controls. If you cannot make the exact adjustment suggested, do the best you can within the limitations of your system. You may notice a beat frequency or periodic pulsation in your Optacon’s array when reading the CRT screen. This is due to the fact that some CRT screens renew their images at a different rate than the Optacon views them. The Optacon camera’s scan rate has been adjusted to the average refresh rate of the most popular CRT’s. This may not be an | exact synchronization with your CRT. This electronic incompatibility ’ does not damage your Optacon in any way. Some CRT cover screens are quite flexible. As a result, you may discover that a character is in focus when you are applying very little pressure against the screen and out of focus when you apply enough pressure to bend the screen inward. Performance may be improved by removing the cover screen, if it is possible and safe to do so. 3a0 to view the list archives, go to: www.freelists.org/archives/optacon-l To unsubscribe at any time, just send a message to: optacon-l-request@xxxxxxxxxxxxx with the word "unsubscribe" (without the quotes) in the message subject. Tell your friends about the list. They can subscribe by sending a message to: optacon-l-request@xxxxxxxxxxxxx with the word "subscribe" (without the quotes) in the message subject.