PTLens vs DA 17-70 F4

asdf · 05-01-2009, 06:30 PM

Correcting barrel/pincushion distortion is ridiculously simple with PTLens--it has presets for DA 17-70. I also used it to adjust the perceived perspective. For $25, it's a good argument against wide primes and/or tilt-shift lenses, imho.

The following one was shot through a dirty VIA rail window--I increased the contrast. I focused on the foreground: note (especially, you, RiceHigh) the corner sharpness.

*pcarfan* · 05-01-2009, 07:01 PM

Thanks.

But, can you also show the before images to see the changes.

Also, when you say "I also used it to adjust the perceived perspective", is there options to do different things with this software....I thought it is all programmed and you just press the button and PTlens does all the programmed changes with no user input?...Or can the user input any options to how this software corrects for distortions.

Thank you.

asdf · 05-01-2009, 07:14 PM

Originally Posted by pcarfan

Thanks.

But, can you also show the before images to see the changes.

Also, when you say "I also used it to adjust the perceived perspective", is there options to do different things with this software....I thought it is all programmed and you just press the button and PTlens does all the programmed changes with no user input?...Or can the user input any options to how this software corrects for distortions.

Thank you.

EDIT: Barrel/pincushion distortion are corrected automatically if there is a preset for your lens. Vignetting, perspective and chromatic aberration are corrected manually with sliders.

Here's the one where barrel distortion and perspective correction should be more apparent:

*k100d* · 05-01-2009, 08:25 PM

thanks for sharing. do you find w/ the perspective correction that you lose a lot of resolution?

asdf · 05-01-2009, 08:52 PM

Originally Posted by k100d

thanks for sharing. do you find w/ the perspective correction that you lose a lot of resolution?

In the most extreme case above, I started with 3104 x 4672 and ended up with (at most, around) 2646 x 3970, after cropping, while maintaing the aspect ratio. In the first pic, I started with 4672 x 3104 and ended up with 4532 x 3020.

As for acutance: In all of these photos, I'm stretching the top half--that's where I'd expect to lose perceived sharpness. But in all of these, the top half is--for the most part--detail free, anyway, so I can't say, yet.

stevebrot · 05-01-2009, 09:23 PM

PTLens is a great tool and a great value as well. It works best as a Photoshop plug-in (better file format support), but is still quite usable as a standalone program. There is a ton of information about the program here:

PTLens

Steve

*pcarfan* · 05-02-2009, 08:05 AM

asdf

Thank you very much for sharing the before image and answering my question, greatly appreciated....

Hythloday · 05-03-2009, 05:48 AM

Originally Posted by asdf

Correcting barrel/pincushion distortion is ridiculously simple with PTLens--it has presets for DA 17-70.

Tom Niemann calibrated the pictures taken with the DA17-70mm I sent him. The distortions are not too bad. Here is the picture at 17mm, uncorrected and corrected:

asdf · 05-03-2009, 08:34 AM

Originally Posted by Hythloday

Tom Niemann calibrated the pictures taken with the DA17-70mm I sent him. The distortions are not too bad. Here is the picture at 17mm, uncorrected and corrected:

Good job! I hope you got a free license.

Hythloday · 05-03-2009, 09:06 AM

Originally Posted by asdf

Good job! I hope you got a free license.

I have paid for my licence since he started with that system. He calibrated 5 lenses for which I supplied the images (Sigma 18-125mm, Sigma 18-50mm f/2.8 EX, Sigma 17-70mm for Canon cameras; the Pentax 28-70mm f/4 and the DA17-70mm).

In that way I quite sure that the profiles are correct:-)