Variables that will effect results are as follows:
1. Temperature, altitude, & the effects these have on different powders.
2. Temperature of the barrel and the ammunition itself. a cold barrel will produce different results from a very hot one. The same with the ammunition.
3. Lighting - MUST be balanced on both sensors evenly. If the sun changes position, you must maintain a balanced condition on both sensors. Whether in bright sunlight (using the top screens) or on shady days (in which the top screens are optional), it is critical to maintain a balanced situation on both sensors. DO NOT position a chronograph with the sunlight directly behind or in front of your shooting position. In this situation, the light will always be stronger on the sensor closest to the position of the sun. Relocate to another position where the light is to the left, right, or overhead positions. It is possible to tilt a tripod panhead allowing the screens to angle themselves toward a late afternoon light in order to maintain a BALANCED diffused light on both sensors. Remember to also angle your shooting position to prevent damaging the equipment with a stray shot.
4. Muzzle blast - If the muzzle blast reaches the first sensor before the projectile, your results may be in error or not recorded at all. If the muzzle blast causes your screens to shake, the readings could also be affected. Suggestion - when using high powered rifles move back away from the chronograph sensors (12 - 18 feet), until proper velocities are recorded, and then move forward one foot at a time, to determine the closest distance at which each weapon will perform at. Then record that information for future use. Different calibers, brands, barrels, and ammunition will affect the distance, so it may be necessary to test each accordingly.
5. The CED Infrared screens are designed for use when mother nature is not cooperating or for times and locations where insufficient light exists. If they are used under bright sunlight condition, it is possible that the sunlight may over-power them or create an in-balanced condition. It is critically important on ALL chronographs to maintain a BALANCED light condition on both sensors. Therefore, in such conditions re-position the chronograph to an area of shade away from the sunlight, or remove the infrared screens and use natural sunlight in a balanced position, or cover the infrared screens with a large cardboard to prevent natural sunlight from reaching the sensors.
6. Spacing. Make sure that your sensors are properly positioned and tightened. If they are off by even 1/16" it will cause incorrect readings. Each sensor has an internal pressure plate. Slide the sensor completely on the mounting bracket until it fits snugly and then tighten the custom pressure plate from the bottom of each sensor until it stays firmly in place. DO NOT over-tighten as it may become difficult to remove later.
7. Glints - If there is water, sand, snow, or bright concrete on the ground below your tripod / chronograph set-up, the sunlight may bounce (reflect) light off the ground surface shining it back up onto the projectile, which in turn may prevent the sensors from detecting a light drop (shadow)of the projectile, resulting in a poor or no reading situation.
8. Indoor - Fluorescent lighting is the kiss of death to any chronograph system. Their light does not allow the sensors to "see" the projectile properly. Additionally, as all fluorescent lights "flutter", it is possible for the chronograph sensors to detect this fluttering which in turn will create false velocity readings. The chronograph may fill itself with velocities in a short period of time, all caused by the overhead lighting itself. Cover the top of the IR screens if this type of lighting is near your chronograph set-up to prevent it interfering. Also make sure that no additional light is penetrating onto either sensor which could then create an in-balance of light on them.
9. Some ranges are designed with small narrow bays or short backdrops, which may cause excessive sound wave and / or muzzle blast problems. These have been known to cause interference with chronograph results.
10. When using the CED Infrared in an indoor shooting range with AC electricity to power the infrared screen set, make sure the AC supply itself is a full 110V output. If the range is located a great distance from the power transformer, it is possible that the output is less than 110V and this may prevent proper performance. Customers in a few cases have found that although they got green lights on both IR screens, no recordings occurred. In such cases, it is better to use the NiMH Battery Pack instead. When the switch to the NiMH Battery pack was made, the problem ceased.
11. Other variables - Depending on the quality of the chronograph & sensors, other variables such as mobile phone transmissions and high electrical tension poles or electrified fencing can all have effects on chronograph performance. Even high amounts of static electricity from summer thunder storms in the area of use can result in problems. In such cases, change the location of use or wait for better weather conditions to occur.
