iR Filter problem

311

Just recieved my iR filter ,stuck it on my 30mm lens and I have a problemo....
A whitish circle in the centre of the image ,regardless of direction of sun.

Has anyone had problems ?

Fenster

That's flare from your lens - literally overexposure from light bouncing around your lens - and there's not much you can do short of buying a lens that has good flare coating (Sigma gets my vote here).

fatbudgie

The properties of infra red are different to visible light. Lenses are designed to work with visible light and may or may not work well with infra red. You tend to get some lenses which are good for infra red and some bad. I use an infra red filter with a canon slr and the kit canon 18-55mm lens and also found the dreaded hot spot. The hot spot is caused by internal reflections within the lens produced by the lens' coatings. Some types of coating are not transparent to near-infrared wavelengths. I had some success working out the spot in photoshop and some shots the spot is more obvious than others. I had a trawl through the web and found the following list:

Fixed focal length Lens

Recommended for IR:
Asahi Super-Takumar 55 mm f/1.8 MF (*)
Canon EF 28 mm f/2.8
Canon EF 35 mm f/2.0 (*)
Canon EF 50 mm f/1.8 MKI
Canon EF 50 mm f/1.8 MKII
Canon EF 100 mm f/2.8 macro
Canon EF 135 mm f/2.0 L
Lensbaby 50 mm f/2.8
Nikon 20 mm f/2.8 D
Nikon 20 mm f/3.5 AI-S
Nikon 28 mm f/3.5 PC AI-S
Nikon 85 mm f/1.8 Pre-AI MF (*)
Peleng 8 mm fisheye
Phoenix 100 mm f/3.5 macro
Sigma 105 mm f/2.8 EX DG macro (*)
Vivitar 24 mm f/2.8 MF (*)

May produce a hot spot:
Canon 85 mm f/1.8

Gives hot spot:
Canon EF 20 mm f/2.8
Canon EF 24 mm f/2.8
Canon EF 50 mm f/1.4
Canon EF 50 mm f/2.5 macro
Canon EF 85 mm f/1.8
Carl Zeiss Planar T* 50 mm f/1.4 (for Contax)
Nikon AF 50 mm f/1.8 D
Sigma 30 mm f/1.4



Zoom Lens

Recommended for IR:
Canon EF-S 10-22 mm f/3.5-4.5 USM
Canon EF 17-40 mm f/4 L
Canon EF 24-70 mm f/2.8 L
Canon EF 28-135 mm f/3.5-5.6 IS
Canon EF 70-200 mm f/4.0 L
Canon EF 75-300 mm f/4.0-5.6 IS
Canon EF 100-400 mm f/4.0-5.6 IS L
Nikon 18-55 mm f/3.5-5.6 AF-S G ED DX
Nikon 18-70 mm f/3.5-4.5 AF-S G ED DX
Nikon 24-70 mm f/3.5-5.6 UC
Nikon 35-70 mm f/2.8 AF D
Nikon 35-70 mm f/3.3-4.5 AF (1986) (*)
Nikon 35-135 mm f/3.5-4.5 AF
Nikon 70-210 mm f/4.0-5.6 D
Sigma 12-24 mm f/4.5-5.6 EX
Sigma 18-50 mm f/3.5-5.6 DC (*)
Sigma 55-200 mm f/4.0.5.6 DC (*)

May produce a hot spot:
Sigma 10-20 mm f/4.0-5.6 EX DC HSM (*)
Sigma 70-200 mm f/2.8

Gives hot spot:
Canon EF 16-35 mm f/2.8 L
Canon EF-S 18-55 mm f/3.5-5.6
Canon EF 24-85 mm f/3.5-4.5 USM
Canon EF 28-70 mm f/2.8 L
Canon EF 35-80 f/4.0-5.6
Canon EF 70-200 mm f/2.8 L IS
Nikon 12-24 mm f/4.0 G IF-ED AF-S DX
Sigma 18-50 mm f/2.8 EX
Tamron 17-35 mm f/2.8-4.0 SP AF Di
Tamron 18-200 mm f/3.5-6.3 AF XR (IF) Di-II
Tamron 70-300 mm f/4.0-5.6 AF LD macro
Tokina 12-24 mm f/4.0

311

Fenster wrote:

That's flare from your lens - literally overexposure from light bouncing around your lens - and there's not much you can do short of buying a lens that has good flare coating (Sigma gets my vote here).

Thanks fenster ,I gave it another go with a lens hood and pointed the completely opposite way to the sun ,so I coud catch reflections only.
It looks like I lost the spot ,Nice one.:)

Roen

Nice post Fatbudgie, very informative!

311

Whats all this about ? http://personales.ya.com/javier_laina/ARTICULOS/FILTRO/filtro350deng.html

Fenster

_Brian_ wrote:

Thanks fenster ,I gave it another go with a lens hood and pointed the completely opposite way to the sun ,so I coud catch reflections only.
It looks like I lost the spot ,Nice one.:)

That spot is most assuredly still there, depending on what you're shooting, you can either use the hotspot to enhance the subject, or you can burn it out or even just replace the sky

mathias

Whats all this about ? http://personales.ya.com/javier_lain...ro350deng.html

Wow but that looks like a very easy way to wreck an expensive camera , I think these guys are modifying for astrophoto work in particular and the final shots show that the camera is pretty much useless for anything else afterwards.

Also , in the photos that work is very sloppy and unsafe to the camera , that soldering iron is far to big for the job , there are SMT irons and air solders especially made for that type of PCB and being the "ESD man " at work , I would in no way recommend working on a sheet of paper , a known charge generator !! :eek:
There are ESD wrist straps and sheets for this type of work at home and they cost just a few euros. If you must modify the camera , use the correct gear. Like this ...

http://www.maplin.co.uk/module.aspx?ModuleNo=-173&doy=14m2

311

mathias wrote:

Wow but that looks like a very easy way to wreck an expensive camera , I think these guys are modifying for astrophoto work in particular and the final shots show that the camera is pretty much useless for anything else afterwards.

Also , in the photos , that soldering iron is far to big for the job , there are SMT irons and air solders especially made for that type of PCB and being the "ESD man " at work , I would in no way recommend working on a sheet of paper , a known charge generator !! :eek:
There are ESD wrist straps and sheets for this type of work at home and they cost just a few euros. If you must modify the camera , use the correct gear. Like this ...

http://www.maplin.co.uk/module.aspx?ModuleNo=-173&doy=14m2

Don't worry ,not a hope in hell of me trying that.
I have a sneaky feeling that the iR filter has shown up a flaw ,in something I done a couple of months back.
Theres a tartan line effect in the few shots I managed to take ,multiple lines both vertically and horizontally. Is this because of the filter ,or because of the copperhill cleaning kit ?