I have been able to use very viewable red lights without negative impact as long as I left them on all night. On one tank I have a dome style set of LED's (don't know the wattage), on another I used an outdoor light with red velum and then red painted housing and on a third a red screw-in fluorescent 13 watt bulb (60 watt equivalent). They will never be good for photography but are great for viewing and interacting. I keep a red lit side on all my octo tanks and up until senescence, the animals have preferred this side of the tank for denning as well as awake time.
I avoid flash photography with all my cephs BUT have accidentally forgotten to use my no flash settings (not possible on my newest camera but my Canon did not require me to activate the flash manually). The occasional flash did not produce a reaction and others have had similar results with intentional flash photography. I would not recommend using it often or for more than one shot during an interaction. If you want to try, I suggest using a tripod to get your best image and not trying again if you get a reaction.
New arm growth starts out looking like a thin string. With my first experience, I thought it was dead material from the original injury and wondered if it should be removed . I left it alone and just observed it to be sure there was no infection. The string developed tiny suckers (or may have had suckers that I could not see) and eventually thickened to recognizable regrowth. On a young animal, it will be hard to detect the repair after several months.
I avoid flash photography with all my cephs BUT have accidentally forgotten to use my no flash settings (not possible on my newest camera but my Canon did not require me to activate the flash manually). The occasional flash did not produce a reaction and others have had similar results with intentional flash photography. I would not recommend using it often or for more than one shot during an interaction. If you want to try, I suggest using a tripod to get your best image and not trying again if you get a reaction.
New arm growth starts out looking like a thin string. With my first experience, I thought it was dead material from the original injury and wondered if it should be removed . I left it alone and just observed it to be sure there was no infection. The string developed tiny suckers (or may have had suckers that I could not see) and eventually thickened to recognizable regrowth. On a young animal, it will be hard to detect the repair after several months.