17-50mm to 24-70mm?

[woof woof]

I usually use a 20mm, 30mm or 50mm prime or a 12-24mm zoom but on Saturday I went for a walk and attached my Tamron 17-50mm f2.8.

I haven't used this lens much but it's sharpness at the longer end has impressed me whilst I've found the distortion at the shorter end excessive but still better than the Canon 17-85mm it replaced.

Anyway, upon reviewing my shots I was disappointed with the level of distortion so I've been thinking of replacing it with a 24-70mm f2.8. I suppose I've been spoilt by using primes and the excellently corrected Sigma 12-24mm.

Can anyone comment upon the distortion performance on an APS-C body of the various Canon fit 24-70mm f2.8's that are available?

 

[LongLensPhotography]

Can anyone comment upon the distortion performance on an APS-C body of the various Canon fit 24-70mm f2.8's that are available?

I can't notice it at all, on FF there might be a little bit though. If you have a wider, and a longer lens then go for it.

 

[HoppyUK]

If you shoot Raw and process in Canon's DPP, there is custom distortion correction for all Canon lenses (also CA and vignetting). It picks up settings from the Exif (focal length, f/number, focusing distance) and sorts it perfectly with a mouse click.

You may need to upgrade your version of DPP (free) to v3.5 or higher to get all Canon lenses.

 

[The Matt]

If you shoot Raw and process in Canon's DPP, there is custom distortion correction for all Canon lenses (also CA and vignetting). It picks up settings from the Exif (focal length, f/number, focusing distance) and sorts it perfectly with a mouse click.

You may need to upgrade your version of DPP (free) to v3.5 or higher to get all Canon lenses.

do you know if there's a way to do this with a tamron lens?

 

[desantnik]

Photoshop distortion correction?

 

[jerry12953]

do you know if there's a way to do this with a tamron lens?

PTLens. This is a small piece of software which you can download at minimal cost. If you're working in Lightroom, for example, you need to open the image in PTLens as a separate action. Lightroom makes a copy and you work on that.

So its not as easy as Canoin DPP apparently is, but it works.

You can probably check on the website if it is compatible with your particular lens.

 

[woof woof]

I have the version of DPP that came with my 20D and I also have a 5DII version and I also have PTLens but I tend to use CS2. Yes I can correct the distortion to a degree (in CS2 I use "vertical perspective" or "remove distortion" whichever has the best effect but I then have to crop and therefore lose a percentage of the image. I haven't tried to correct the distortion using either DPP but I might give it a go)

I'm a bit worried about losing the wide end with a 24-70mm and even though I'm a bit cheesed off with the Tamron 17-50mm I don't want to rubbish it too much as it's a good lens once you can overcome (or aren't bothered by) the wide end distortion which is still better than some lenses in that range.

I'll revisit the distortion correction in CS2 and PTLens and I'll try out DPP and if I'm not happy I'll maybe take a look at a 24-70mm f2.8.

Thanks guys.

 

[HoppyUK]

do you know if there's a way to do this with a tamron lens?

I don't think DPP works with non-Canon lenses. The thing about it is that it is custom lens-specific, it is good, easy and free. It applies a sophisticated level of adjustment very quickly and easily (as Canon have done all the work). It knows which lens you've used, it knows how that lens behaves, and it knows exactly what focal length and f/number you've used. PT Lens is crude in comparison though it does work and covers a wide range of lenses. PTLens is here http://epaperpress.com/ptlens/

Correcting distortion is not very difficult anyway, so long as it is just basic barrel or pincushion. It's not so easy if you want to get a really good result with a lens that produces 'moustache' distortion with straight lines not only curved but also a bit wavy. Many wide angles are like this.

The other things DPP does very well are vignetting correction (which is easy anyway) and also chromatic aberration (CA) which is much more difficult. There's a good demo of DPP in action with the Canon 17-85 half way down this page from DPReview http://www.dpreview.com/lensreviews/canon_17-85_4-5p6_is_usm_c16/page3.asp