85 f1.8 woe :-( "sniff"

[roanjohn]

HELP!!! I am in love with this lens. I finally had the courage and bought it 2 days ago. Looking at these photos, do I have reasons to be concerned?

First shot at f2

http://www.pbase.com/image/28058287/medium.jpg

crop

http://www.pbase.com/image/28058306/original.jpg

Second shot wide open f1.8





http://www.pbase.com/image/28058312/medium.jpg

crop

http://www.pbase.com/image/28058314/original.jpg

I did the same test with my el cheapo 50 f1.8 and it doesn't exhibit the same problem.

Is this problem expected or do I have a reason to return for a better copy?

Help!!!

Ro1[/i]

[Ballen Photo]

HELP!!! I am in love with this lens. I finally had the courage and bought it 2 days ago. Looking at these photos, do I have reasons to be concerned?


You're kidding, right? Does the lens seem to be TOO sharp? I'm confused here. :? :shock: :?
.......Bruce

[timmyquest]

I think he's refering to the purple hues he's getting around bright edges...the same ones i've come to expect from my crapola 70-300 $150 sigma junker special.

I belive it is caused by "chromatic aberration". It is when different wavelengths enter the lens and are not focused in the same spot.

© http://www.yorku.ca/eye/chroaber.htm
http://www.yorku.ca/eye/chroaber.gif


Also check out this site: http://194.100.88.243/petteri/pont/How_to/ha_Testing_lenses/a_How_to_test_a_lens.html

I do not own this lens but this is not a problem i would expect from very many canon lenses, let alone one of this quality.

**EDIT**

Good find. More on this topic in a review on dpreviews found here (http://www.dpreview.com/reviews/nikoncp885/page15.asp)

[roanjohn]

Also check out this site: http://194.100.88.243/petteri/pont/How_to/ha_Testing_lenses/a_How_to_test_a_lens.html

I do not own this lens but this is not a problem i would expect from very many canon lenses, let alone one of this quality.

**EDIT**

Good find. More on this topic in a review on dpreviews found here (http://www.dpreview.com/reviews/nikoncp885/page15.asp)

Thanks timmyq. I will read that article tomorrow.

I hope its a defect cuz this lens is really AMAZING!!

Ro1

[Ballen Photo]

I think he's refering to the purple hues he's getting around bright edges...the same ones i've come to expect from my crapola 70-300 $150 sigma junker special.


I see. For the amount of crop here on his photos, it really doesn't seem too bad though, especially when compared to the photos in the article Timmy Quest found. Still I'll keep an eye on this thread to see what you guys come up with.
.........Bruce

[Guillermo Freige]

It seems pretty normal to me. Fast lenses have those kind of problems wideopen. I know my 50/1.8 and Sigma 20/1.8 have a lot of purple fringing and softness wideopen. In fact I'm amazed how little fringing is actually present at 1.8 in your lens, and it's also very sharp!. Try to take the same shots at f/2.8 or up.
Do you take the same shot with the 50/1.8 wideopen or it was a different scene with less reflecting surfaces??

[drisley]

Roanjohn,
I finally got to try out my 85 f1.8, and I too get the same purple fringing.
I think only the L class lenses control CA and fringing.
Good news is that it can be reduced in post processing fairly easily.
If you use Photoshop CS for raw images, I think it has that option built in

[evilenglishman]

looks to me like those images have been sharpened.
look at the bike photo - particularly the cable, it has a definate halo around it.

[G3]

looks to me like those images have been sharpened.
look at the bike photo - particularly the cable, it has a definate halo around it.


That's what I was thinking. It's hard to tell if this is actually CA or if it's artifact from post-processing.

Roanjohn,
Can you tell us how these were shot and what processing was done?

[roanjohn]

looks to me like those images have been sharpened.
look at the bike photo - particularly the cable, it has a definate halo around it.

You're right, I used a very mild Lab Sharpening on these photos. The purple fringes are already apparent with the image unsharpened though.

I will do more test with the lens at 2.8.

Ro1

[Jim_T]

As far as purple fringing, I've found some lenses are far more prone than others.. I've never heard of the 85 mmf1.8 doing it..

I have a Canon 100-300 lens.. It's REALLY bad.

http://members.shaw.ca/jamestownsend/CA.jpg

I wound up getting the 100-400L.. It doesn't display any purple fringing..

Here's a side by side comparison.. I had the camera on a tripod and shot the same scene with both lenses @ 300mm f/8 The 100-400 is on the left.. You can see the purple fringe on the 100-300 image on the right.

http://members.shaw.ca/jamestownsend/CAcomparison.jpg

You might have to live with it..

[timmyquest]

Thats a fantastic compairison you made up there man.