IO:O is equipped with a large diameter Uniblitz iris shutter. This results in a different exposure time between the centre and edges of the field of 80ms. For reasonable photometric accuracy exposure times should therefore be greater than 20 seconds. Please feel free to discuss this issue with the LT Support Astronomer should you require short exposure times. It is of course possible to defocus the telescope so that bright targets can be observed.
IO:O's other specifications are listed below.
Detector: 4096x4112 pixel e2v CCD 231, deep depletion, Astro ER1 coated
Pixel size: 15.0 x 15.0 microns
Pixel scale: approx. 0.15 arcsec/pixel (unbinned) 
Field of view : 10 x 10 arcmin 
Read noise: < 8 electrons 
Dark current: < 0.002 e / pix / sec (unbinned, 263K)
        ~ 0.01 e / pix / sec (unbinned, 273K)
Binning: 1x1 and 2x2 
Readout time1: ~37 sec (1x1 binned), ~13.5 sec (2x2 binned) 
Windowed modes: Not currently available 
Bad pixels: 6 dark point defects; 2 hot pixels; 1 column defect. (pixel mask)
Gain (1x1): 1.6 electron / ADU 
Gain (2x2): 1.6 electron / ADU 

Quantum Efficiency (figures supplied by manufacturer)
Wavelength(nm)    Quantum Efficiency(%)
350                              43
400                              59 
500                              83 
650                              97 
900                              56