Udc 2800 Manual

[Yufei Labbe]

Ive searched here, and on the internet, but haven't found any explanation. Below are the controls. There is also a slide on the front that may be set at a blue dot, a red dot, or "M" I'm assuming (manual).

I usually just slide it to the right when I want the flash to act as if I had the camera at a low ISO, and to the left when I want the flash to assume I'm at a high ISO - but I'm not sure I can tell the difference in the flash output anyway.

Can anyone explain how these controls actually work?

(p.s. strobist info: one flash with westott microsoftox at 1/8 handheld. The subject is sitting in a white baking dish).

4:49PM, 18 July 2009 PDT(permalink)

Yeah, I've got the slidey thing on my Vivitar whatever-the-heck. It's useless. I've got full power "M" and 1/8 power which is a triangle. But that's in a separate switch. If that's your only control I think you're stuck with full.

Not that's it's not useful, it's just annoying.

ages ago(permalink)

If you look at the front there's also a sensor hole. Moving the from slider closes an aperture over the sensor. Your flash is fully automatic, but you do have some form of control. Im M mode the flash will send a full power flash. In "Red" it sends a high power "automatically adjusted" flash, and a less powerful flash when set to "blue." Here's a (temporary) link to something similar:

I have a couple of flashes that operate like this. They're very limited, but useful for some shooting. I had great success with one as an "On camera" flash before I got an ETTL model. Having the flash decide the power level was great when shooting fast in a run-n-gun environment. The flash was adjusting the power each shot, saving me time and effort had I only a manually settable flash.

Originally posted ages ago. (permalink)

Robertv! (Edinburgh, UK) edited this topic ages ago.

You just need to know how to use an auto thyristor flash. Set the ISO slider to match the ISO on your camera, and match the aperture on the lens with the flash (blue dot red dot?) & you usually get decent exposure. The flash shuts off when the sensor gets enough reflected light for your aperture setting.

The manual www.mattdentonphoto.com/cameras/vivitar_2800.pdf

Originally posted ages ago. (permalink)

Murray McMaster edited this topic ages ago.

Thi is a bad flash to use on manual. The problem is the auto off circuit. The capacitor is charged up to the charged voltage then the charge circuitry turns off. And the voltage on the capacitor then starts to drop since the ready light is loading the capacitor. The longer you wait the lower the voltage until the flash will not fire.

The charge circuit will only start again if you fire the flash or if you turn off, then on, the flash again.

So used on manual, the power level will not be consistant. It depends on when you fire the flash. This is one of the more useless flashes for strobist use.

Used in the auto mode will give a power level dependent on the reflectivity of the scene. This is ok if you are just using one flash. But if you are using multiple flash then the light from other flashes can mess up the control of the auto set ones.

Originally posted ages ago. (permalink)

rudy__ edited this topic ages ago.

you can open the flash, measure the photo sensor with a multimeter (ohms) when fully dark. then get a similar range potentiometer and replace the sensor with that. Fully manual and adjustable flash. (but with the problems rudy said.)

ages ago(permalink)

The Bureau of Land Management manuals contain policy and procedures to manage programs. BLM manuals define the basic authority for performing tasks and identify who bears the ultimate responsibility for seeing that these tasks are accomplished. Each BLM handbook is controlled by a manual section.

The RX -2800 TBR/W is a top-quality 7x27mm monocular that incorporates the additional benefit of a state-of-the-art laser rangefinder capable of measuring the distance of a deer-sized animal from 7 yards to 1100 yards, trees from 7 yards to 1300 yards, and a reflective target from 7 yards to 2800 yards. It emits a series of invisible, infrared energy pulses that are reflected off the selected target back to the optical unit. State-of-the-art circuitry and precision computing circuits are used to calculate the distance by measuring the time it takes for each pulse to travel from the RX-2800 TBR/W to the object and back.

The Organic Light Emitting Diode (OLED) display reflected into the optical path can be manually switched between ranging modes, as measured in meters (M) or yards (YD), or used to obtain distance while simultaneously viewing the target. (The RX -2800 can also simply be used as a 7x monocular without activating the OLED.) INTERNAL DEFAULT DISPLAY AS SEEN THROUGH THE RX-2800 TBR/W WHEN THE RANGEFINDER IS TURNED ON Upper display indicates TBR output setting, lower display indicates your load group. If Last Target is on, it will be shown at the top of the display.

The ranging accuracy of all Leupold RX -2800 Series rangefinders is 0.5 yards/ meters at distances less than 125 yards/meters, while the accuracy at maximum distance is 2 yards/meters. The maximum range of the unit depends on the reflectivity of the target and atmospheric conditions.

Surface texture, color, size, and shape of the target all affect reflectivity, which in turn affects the maximum range of the instrument. As a rule of thumb, brightly colored targets are much more reflective than darker targets. Tan game coats are more reflective (and thus provide a more solid reading) than a black roof. A shiny surface is more reflective than a dull surface. Smaller targets are more difficult to range than larger targets. Light conditions, haze, fog, rain, and other environmental conditions can all affect ranging performance. Any factor which degrades air clarity will reduce the maximum effective range. The sun generates infrared energy that can degrade ranging performance in bright conditions or when ranging towards the sun.

To manipulate a function, press and release the MODE button until that function is flashing, then use the POWER button to change the setting. If this is the last function to be changed, you can allow the rangefinder to sit idle for 20 seconds which will cause an automatic power-off, saving all selections. If additional functions require manipulation, simply press MODE to continue through the Quick Set Menu.

To reset your RX-2800 to factory settings, Press POWER to activate the rangefinder, press and hold MODE, then press and hold POWER. A 10-second countdown timer will appear; factory reset will occur after 0 has been reached.

TBR calculates the equivalent horizontal range (level fire range) from which you can determine the correct aim for the conditions. For example, if you are shooting a .270 caliber, 130 grain bullet at 3,050 feet per second up a 30 incline at 400 yards, direct line of sight, the TBR output will be 367 yards. The first step in correctly using TBR is to Practice, Practice, Practice. Anytime you handle a firearm, you are ultimately responsible for your projectile.

BAS displays the equivalent horizontal range, which is based upon the ballistics group and sight-in distance you will choose in a later mode. This is the range you will want to use when shooting, rather than the line of sight distance, which may contain gross errors depending upon the shot angle. Readings will be displayed with equivalent horizontal range in the lower portion of the display.

MIL will display the appropriate amount of holdover in milliradians to use, which is based upon the ballistics group and sight-in distance you will choose in a later mode. The lower display shows the line of sight (LOS) distance to the target. The upper display will show the appropriate number of mils to holdover. Hold values shorter than your sight-in distance represent hold-under. In the example to the right, the line of sight distance is 484 yards, and the upper display indicates that you should hold 2.9 MILS above your intended point of impact. Holdover values will be displayed in MILS for both yards and meters modes. The E to the left of the holdover value represents Elevation. The angle display in the lower right represents the inclination angle to target.

MOA Mode will show the minute-of-angle adjustment for your target which is based upon the ballistics group and sight-in distance you will choose in a later mode. The lower display shows the line of sight distance to the target. The upper display will show the appropriate number of MOA to adjust or holdover the target (assuming you are beyond zero range). In the example to the right, the line of sight distance is 484 yards, and the upper display indicates that you should dial the scope up 10.25 MOA to account for bullet drop. Scope corrections will be displayed in MOA for both yards and meters modes.

TRIG, a function that is included to support anyone interested in distances to objects, and displays the true horizontal range and true vertical range, which is based upon trigonometry using angle and line of sight distance. Line of sight distance (300.0 yards) readings will be displayed in the lower portion of the display. The upper display will briefly show the true horizontal distance (254.4) then the absolute value of the true vertical distance (146.9). Have you ever wondered if that leaning tree would hit your home or tent if it fell? Measure the height by obtaining the true vertical distance and then measure the distance from your house or tent to the tree and you will know. This horizontal distance is the method competitors use when describing their ballistic solution. It is a good approximation for distances out to 400 yards and angles less than 30 degrees.

Wind hold values will be displayed in the same output format as elevation; either MOA, MIL, or inches/cm hold values. TBR/W provides .5 MOA accuracy on elevation and 1.5 MOA accuracy on wind values at 600 yards for cartridges expected to reach that distance. As with TBR, the maximum distance is 800 yards.

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