Opticstar PL-130M Autoguider
Serial Number T1002709
How does this economically priced auto guider actually perform? I purchased one of these cameras in 2008 but got some very strange results!
This camera features a 1280 x 1024 CMOS chip with 5.2 micron pixels. It is a combined video and long exposure camera. The manufacturers claim long exposures of up to 10 seconds. This, on paper, seemed ideal for me as I would need long exposures to find guide stars with my off-axis guider. The reality was somewhat different!
I began to have my suspicions something was very odd with this camera when exposures longer than about 2 seconds did not seem to produce any fainter stars. However, I needed to produce a 10 second long star trail image (mount drive switched off) for periodic error calibration. This exposure revealed some very strange goings on with this camera!
The star trail picture explained fully why I was not getting any fainter stars with exposures longer than about 2 seconds. To cut a long story short this camera has periods when it records and periods when it doesn't. Between 2 and 5 seconds the camera was simply not recording - it was busy doing something else. Measuring the trail image, it turned out that it recorded for 1.5 seconds then rested for 3.75 seconds before starting the cycle again. This meant a 5 second exposure only had 1.5 seconds worth of real exposure and a 10 second one only 3 seconds worth! In other words 70% of the time it was not recording!
The above is a single trailed exposure of over 12 seconds. It is not 3 stars but the same one. The gaps where is has recorded absolutely nothing are about 2.5 times as long as the periods when it does record an image. I also took images of 6 seconds and 10 seconds and they produced the same pattern - 1.5 seconds record, 3.75 seconds off.
I have tested cameras from most manufacturers but I have never seen anything like this. To be fair to Opticstar, when I returned the camera they refunded my money. However, advertising this camera as having 10 second exposures is perhaps being somewhat economical with the truth. Yes you can put 10 seconds in a box but in reality anything over 1.5 seconds is literally a waste of time. Statements such as "longer exposures greatly increase the camera's sensitivity" are simply not borne out by real test results. Opticstar were made aware of how their camera actually behaves but continue to market it as having up to 10 second exposures - buyer beware!
Solar Image - collected in video mode. No problems with 1/25th second exposures!
|Return to imaging menu|