The Sigma shot really has a lot of purple fringing. Mine doesn't have a lot, just a little, hardly noticeable. Avoiding CA totally is not possible in the real world, where light is ruled by the laws of the rainbow :-). Some computer programs can even deal with this.
I believe my test serve me well. They tell me to do somthing about the Tokina AT-X (probably a new bayonet and a CLA), which used to be superior to the other lenses in my small test - or replace it. They also tell me that the two other lenses are not too bad, and can successfully be used at smaller apertures than F5.6. The lessons to be learned from the edges of the images do not really differ from those of the centre. I don't need sharp edges if the centre isn't sharp. I am not an artists, doing photographs for exibitions or sale. I just do photographs for books and presentations. No one, but me, will look at my photographs as such - only at the subjects they show, perhaps the composition and colours. So, I don't need expensive lenses, which i DK retails for what is similar to three weeks pay, before tax. I'd rather use a Tokina, a Sigma or a Pentax consumer lens - and then take 4 weeks leave! :-) Jens Bladt mailto:[EMAIL PROTECTED] http://hjem.get2net.dk/bladt -----Oprindelig meddelelse----- Fra: Rob Studdert [mailto:[EMAIL PROTECTED] Sendt: 16. november 2004 01:09 Til: [EMAIL PROTECTED] Emne: Re: Annother pile of test shots On 15 Nov 2004 at 20:01, Jens Bladt wrote: > Shel and Rob: I believe the Pentax SMC M 2.8 35mm is doing well, compared to the > zoom lenses. I appreciate your effort but your results don't actually surprise me, I hope the M28/2.8 would be better than the zoom. I like like your test compilation however if you also presented sections towards the edges of the frame I believe that it would prove a lot more useful and revealing. On your full frame image see the edge of the white fence to the left, there is significant CA even though it was shot at f8. This is often the type of thing that differentiates a good lens from a great one, a case in point being the FA24/2. It is razor sharp dead centre but it performs far worse than most other Pentax 24mm primes towards the edges at any aperture. A centre section wouldn't reveal this significant performance issue. To see just how badly CA can affect certain types of images check out the hideous sample image on the following Sigma page shot using a Sigma 18-50mm F3.5-5.6 DC at f9: http://www.sigma-photo.co.jp/sd10/english/photographer/miyake.htm Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
