Reply to thread

Message

<blockquote data-quote="BackdoorArts" data-source="post: 489563" data-attributes="member: 9240">The four main things to evaluate with various lenses and IR are...1. Hot Spots - do they appear, and if so when (focal length &amp; aperture)2. Vignetting - how well does the IR light transmit to the complete frame (the anti-hot spot)3. Sharpness - duh, but this also could mean how well/if you can achieve an AF with your camera since IR light focuses at a slightly different point4. Light Transmission - how much IR light is filtered by the elementsMost IR ratings only concern themselves with the first two, and then they'll pay some attention to #3.&nbsp; Very few speak to the last, and that's what I'm looking for.&nbsp; I need to get out midday one of these days into a place that has a nice, balanced range of IR lighting and just shoot with all the lenses I have - same scene, same spot.&nbsp; That's the only way to truly see the difference.As for my current lenses, I find the 24-120mm f4, 16-35mm f4 and Sigma 15mm fisheye to be stellar performers in terms of 1-3 above.&nbsp; The 24-70mm Sigma and Nikon 24-85mm f3.5-4.5G are some of the worst I've seen for hotspots.&nbsp; Primes tend to be better, but I tend not to carry them when I'm carrying two cameras.&nbsp; I need to test them, but my old 50mm f2.0 Nikkor that I got with my FM is a stellar IR lens.</blockquote>

[QUOTE="BackdoorArts, post: 489563, member: 9240"] The four main things to evaluate with various lenses and IR are... 1. Hot Spots - do they appear, and if so when (focal length & aperture) 2. Vignetting - how well does the IR light transmit to the complete frame (the anti-hot spot) 3. Sharpness - duh, but this also could mean how well/if you can achieve an AF with your camera since IR light focuses at a slightly different point 4. Light Transmission - how much IR light is filtered by the elements Most IR ratings only concern themselves with the first two, and then they'll pay some attention to #3. Very few speak to the last, and that's what I'm looking for. I need to get out midday one of these days into a place that has a nice, balanced range of IR lighting and just shoot with all the lenses I have - same scene, same spot. That's the only way to truly see the difference. As for my current lenses, I find the 24-120mm f4, 16-35mm f4 and Sigma 15mm fisheye to be stellar performers in terms of 1-3 above. The 24-70mm Sigma and Nikon 24-85mm f3.5-4.5G are some of the worst I've seen for hotspots. Primes tend to be better, but I tend not to carry them when I'm carrying two cameras. I need to test them, but my old 50mm f2.0 Nikkor that I got with my FM is a stellar IR lens. [/QUOTE]

Verification