This lens (Canon 85mm f/1.8) isn't working out for infra-red photography - I can't seem to get rid of the hotspot in the center of each image.
Sunday, January 17, 2010
Cactus Garden - Infra Red
This lens (Canon 85mm f/1.8) isn't working out for infra-red photography - I can't seem to get rid of the hotspot in the center of each image.
Subscribe to:
Post Comments (Atom)
IR hotspots are an issue with some lenses. If you have a lens that is prone to hot spots there really isn't anything you can do about it. Normal techniques used to reduce lens flares can help but you will never completely get rid of them on such a lens.
ReplyDeleteYou just need to keep trying lenses until you find one you are happy with. (I'm sure you can find a good list to start with on Google.) The old glass (Topcon) that I'm trying to find adapters for is supposedly good for UV photography. I don't know if that translates into the IR spectrum. They are good for UV because the glass isn't coated like modern lenses.
Still waiting until I can afford an IR setup. :^)
What f-stop are you using? If it is wide open try stopping it down a bit.
ReplyDeleteMy first pass at IR was wide open at f/5.6. These were taken at f/11 and f/16, and the hotspots are still there - I need to use a different lens. I ordered a cheap off brand IR filter for my Canon 17-40mm ($60, instead of several hundred for the Hoya). Hopefully it will work - thought about having my old Rebel converted, but haven't committed to that just yet.
ReplyDeleteThe filter shouldn't be creating the hot spot. What filter are you using? I see two Hoya's at Adorama, one for $88 and one for $392! I was thinking about getting the $88 one until I have another camera to spare on a conversion. It is the R-72 that passes anything above 720nm which is the range I was looking at. The more expensive one is 900nm and above.
ReplyDeleteTry borrowing a couple of lenses if you don't have any other to try. It would be interesting to see the differences. You can also try step up/down rings if you have a lens with a different filter size.
I have a 58mm Hoya R-72 which only fits on my 85mm and 100m lenses (I originally bought it for the stock lens that came with my old Canon Rebel, but that lens went bad). I've ordered a step down ring so I'll be able to use it on a 50mm standard lens. I really want to try IR on my 17-40mm zoom, which takes a 77mm filter. That's what the Opteka IR will be for - hopefully it works!
ReplyDeleteWow! $18.50 for an IR filter. I figured for that price I may as well give it a shot. It may not be the best quality but it might hold me over until I can afford to convert a camera body.
ReplyDeletehttp://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370316729476
They have several sizes available - but only 720nm.