I have an IPC-T3241T-ZAS (from Andy). Following the advice I've seen from several on this forum, I went with a vari-focal that I can use to tune my needed focal length and then use that as a basis for purchasing fixed focal length cameras. I am guessing at how to do that and would like confirmation and suggestions on how to do this.
For instance, this camera has a range of 2.7mm to 13.5mm. When I set it to the correct zoom level, I don't see any way, either in Blue Iris or the camera settings, to derive the focal length. So, assuming it's linear (which may or may not be correct) I do the following calculation: the setting in the Dahua camera zoom slider shows a range of 0 to 2343 and my desired zoom is 540. 540 is 23% of the zoom range. Applying this to the spec'd camera focal range of 13.5mm minus 2.7mm = 10.8mm, 23% of 10.8 is 2.5 which added to 2.7 is an estimated focal length of 5.2mm. So, I would probably buy a 6mm if I was willing to go a little tighter.
Does that analysis hold water? Maybe I'm over-thinking it?
For instance, this camera has a range of 2.7mm to 13.5mm. When I set it to the correct zoom level, I don't see any way, either in Blue Iris or the camera settings, to derive the focal length. So, assuming it's linear (which may or may not be correct) I do the following calculation: the setting in the Dahua camera zoom slider shows a range of 0 to 2343 and my desired zoom is 540. 540 is 23% of the zoom range. Applying this to the spec'd camera focal range of 13.5mm minus 2.7mm = 10.8mm, 23% of 10.8 is 2.5 which added to 2.7 is an estimated focal length of 5.2mm. So, I would probably buy a 6mm if I was willing to go a little tighter.
Does that analysis hold water? Maybe I'm over-thinking it?
