Have you tried the Adobe Lens Profile Downloader? That would be my first idea. Failing that, there is a forum here where people have provided links for various lenses, but I can't remember which.
Yammer P wrote:
Failing that, there is a forum here where people have provided links for various lenses, but I can't remember which.
Adobe Lens Creator forum. BTW, the Adobe Lens Profile Downloader has several 18-200, what aperture?
Using v1.0 of the Lens Profile Downloader, I can now access the D90 18-200 profiles.
1. Will they be automatically recognized for my D300 as well?
2. Does anybody know whether they are better than the factory default profiles?
Judging by the profile set (seen on the upper right), this profile will be next to useless. Three focal lengths at f/11 isn't exactly a comprehensive lens profile. I'm told that the 18-200mm Nikkor is a nightmare in distortion terms, with plenty of barrel and pincushion distortion at the extremes, and "moustache" distortion in between. So, don't expect miracles, and don't expect any vignette correction at wider apertures either.
The profiles will work with any Nikon camera. The D90 sensor is almost identical to the D300, so it's well-matched anyway. I don't know how to open lens profiles, but a text editor shows that the two supplied raw profiles are quite big, so I reckon they probably the best available anyway.
Am I right in thinking there are two versions of this lens, or did I dream it?
I see what you mean. 18-200 is a monster of varied distortion / vignette "curves". The built-in profile leaves a *lot* to be desired, and I expect the downloadable alternative (so far) will not be much improvement, if any. I often correct 18-200 vignettes using a paint brush .
Note: I know the D90-created profiles will work identically on the D300, but I still don't know if they will be auto-detected - obviously I can just check and see. But it begs the question: why is the camera model included in the profile name if it makes no difference whatsoever?
And I still have the question:
Is it possible in ACR to have lens correction as good (or even nearly as good) as DxO? i.e. is it just a matter of taking sufficient samples, or is their some innate inferiority that even a large sample base would not overcome? (I've obviously never created my own profile).
Yes, the D90 profiles will work automatically on the D300. I have the same camera, and most of the DX crop profiles seem to have been shot on a D90 (or FX on a D3x). The crop factor is the thing that is matched, not the model. I don't know why the camera model is mentioned in the profile--it seems mostly irrelevant to me, although I remember someone once mentioned that microlenses differ on different sensors, so light falloff may vary from one model to another. Not so with the D90 and D300, which uses exactly the same sensor, afaik.
I have actually built my own lens profiles using the Adobe creator tool, so I know a little about it. It's not a task to take on lightly, but it's worth trying, if you a determined to get a good profile. You need to print out a large prepared chequerboard graphic, and photograph it from different distances at different focal lengths. The more the better--especially for a super-zoom like this. There's a good manual supplied with the software. You also need to shoot wide open at a few focal lengths, and maybe down a stop or two too, just so it can work out the vignetting.
Your main problem will be accuracy, as the lens suffers from complex distortions, and I will be surprised if the software will hande this properly. Still, it's worth a try. Nothing venured, and all that.