N
nsecomb
Guest
Thought I would share this experience, because I'm surprised a market hole exists today.
I have a Canon 50D which has been converted to near-IR-only (715nm), and for wide-angle shots I had intended to use my TSE-24 II (equivalent to 38.4mm on FF) and use shifts and stitching to cover wider angle shots. And that works fine... as long as you don't have things like wind-blown foliage, or waves, or a subject that moves.
So, for the last six weeks I have been going through reviews and lens manufacturer product lists and looking for a lens which has the following basic characteristics: 17mm (or shorter); does not "hotspot" or easily flare in near-IR wavelengths; excellent resolution in centre and out to frame borders (I don't put my subject matter in frame corners so I do not care if the corners are a bit soft); and takes front-mounted filters.
The large proportion of modern lenses produce a noticeable "hotspot" (discoloration and lower contrast in an isolated portion, centre frame), and many older designs just don't have the resolution capacity to match today's small-diode sensors. The closest I found was a Tokina 11-16mm, which I purchased. While mounted on a non-IR body, this lens was fine, but when put on a dedicated near-IR body with a shimmed sensor, the combination of the shimming + the Tokina 11-16's hard-stop at infinity, and near-IR wavelengths, meant that when set at infinity, the actual focus point was actually at a point only two feet in front of the lens. [A shame that Tokina and others do not take a leaf out of Canon & Sigma's books and put in lee-way at the infinity mark so their lenses will also focus at infinity in both near-IR and if there is significant thermal variation.]
My remaining option is a Samyang 14mm... which is great, except that with a bulbous front element you can not mount filters, either for protection or creative effect (e.g. graduated or 10x NDs).
Some may ask, "what about the EF-S 10-22mm"? Look for "10-22mm" on the following page for an explanation: http://www.maxmax.com/ircameraconversions.htm . Also, I have a 17-40mm... it is renowned for smearing near the borders and in the corners, and it is no different at near-IR wavelengths, even in the reduced image circle of a crop-sensor. Finally, I also have a Sigma 10-20mm... it is unusuable due to hotspot.
So, out of frustration and amazement, here is my plea to the lens-manufacturing ghods - seriously look at producing a prime lens that:
- has a focal length of 17mm (or shorter; 17mm is about 27mm equiv on a Canon APS-C body).
- does not "hotspot" or easily flare (when sun out of frame) in near-IR wavelengths.
- has excellent resolution in centre from f2.8 to f8.
- has very good border resolution between f5.6 and f8. (so low to moderate field-curvature)
- takes front-mounted filters (probably 77mm or 82mm).
- distortion less than 2.5% barrel, in a simple pattern (not wavy... that drives the architecture lovers nuts).
- vignetting <1.5 stops at f4.
- lateral CA <= 1px (as there seems to be a correlation between CA at shorter wavelengths and sharpness in near-IR).
- EF mount would widen the market base.
- $1000 or less will have a much wider market base than $1500 or more.
- weather sealing would not seem necessary for the majority of users, but may be very attractive for pros working outdooors.
Who'd buy it? Depends on price, but I expect that those who'd take a serious look at it would be:
1) anyone with a near-IR-dedicated body, regardless of brand.
2) anyone looking for a quality ultra-wide prime that can take front-mounted filters.
3) if it's "fast", any professional shooting ultra-wide in available light who would prefer not to have to regularly resell their UWA lens because the front element has accumulated too many "minor cleaning marks" on the front element.
Oh well... here's hoping the lens-manufacturing ghod are hearing the pleas of petitioners at the moment.
regards,
Nigel
I have a Canon 50D which has been converted to near-IR-only (715nm), and for wide-angle shots I had intended to use my TSE-24 II (equivalent to 38.4mm on FF) and use shifts and stitching to cover wider angle shots. And that works fine... as long as you don't have things like wind-blown foliage, or waves, or a subject that moves.
So, for the last six weeks I have been going through reviews and lens manufacturer product lists and looking for a lens which has the following basic characteristics: 17mm (or shorter); does not "hotspot" or easily flare in near-IR wavelengths; excellent resolution in centre and out to frame borders (I don't put my subject matter in frame corners so I do not care if the corners are a bit soft); and takes front-mounted filters.
The large proportion of modern lenses produce a noticeable "hotspot" (discoloration and lower contrast in an isolated portion, centre frame), and many older designs just don't have the resolution capacity to match today's small-diode sensors. The closest I found was a Tokina 11-16mm, which I purchased. While mounted on a non-IR body, this lens was fine, but when put on a dedicated near-IR body with a shimmed sensor, the combination of the shimming + the Tokina 11-16's hard-stop at infinity, and near-IR wavelengths, meant that when set at infinity, the actual focus point was actually at a point only two feet in front of the lens. [A shame that Tokina and others do not take a leaf out of Canon & Sigma's books and put in lee-way at the infinity mark so their lenses will also focus at infinity in both near-IR and if there is significant thermal variation.]
My remaining option is a Samyang 14mm... which is great, except that with a bulbous front element you can not mount filters, either for protection or creative effect (e.g. graduated or 10x NDs).
Some may ask, "what about the EF-S 10-22mm"? Look for "10-22mm" on the following page for an explanation: http://www.maxmax.com/ircameraconversions.htm . Also, I have a 17-40mm... it is renowned for smearing near the borders and in the corners, and it is no different at near-IR wavelengths, even in the reduced image circle of a crop-sensor. Finally, I also have a Sigma 10-20mm... it is unusuable due to hotspot.
So, out of frustration and amazement, here is my plea to the lens-manufacturing ghods - seriously look at producing a prime lens that:
- has a focal length of 17mm (or shorter; 17mm is about 27mm equiv on a Canon APS-C body).
- does not "hotspot" or easily flare (when sun out of frame) in near-IR wavelengths.
- has excellent resolution in centre from f2.8 to f8.
- has very good border resolution between f5.6 and f8. (so low to moderate field-curvature)
- takes front-mounted filters (probably 77mm or 82mm).
- distortion less than 2.5% barrel, in a simple pattern (not wavy... that drives the architecture lovers nuts).
- vignetting <1.5 stops at f4.
- lateral CA <= 1px (as there seems to be a correlation between CA at shorter wavelengths and sharpness in near-IR).
- EF mount would widen the market base.
- $1000 or less will have a much wider market base than $1500 or more.
- weather sealing would not seem necessary for the majority of users, but may be very attractive for pros working outdooors.
Who'd buy it? Depends on price, but I expect that those who'd take a serious look at it would be:
1) anyone with a near-IR-dedicated body, regardless of brand.
2) anyone looking for a quality ultra-wide prime that can take front-mounted filters.
3) if it's "fast", any professional shooting ultra-wide in available light who would prefer not to have to regularly resell their UWA lens because the front element has accumulated too many "minor cleaning marks" on the front element.
Oh well... here's hoping the lens-manufacturing ghod are hearing the pleas of petitioners at the moment.
regards,
Nigel
