Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-04-2013, 09:28 PM   #1
Pentaxian




Join Date: Nov 2008
Location: Bangalore
Photos: Gallery
Posts: 2,450
M Lenses - Purple Fringe Masters

Which are the M lenses known for producing bad PF.

I know M85/2 is one, just wondering about other M lenses

01-04-2013, 10:07 PM   #2
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,479
Lenses don't produce purple fringing, it is a digital sensor issue. It simply does not happen with color film. That being said, some lenses are more prone to encouraging the sensor to fringe. I can offer two Pentax-M lenses that I own that don't seem to be associated with that problem.
M 50/1.7
M 200/4

Steve

FWIW...I only own a few lenses that cause my K10D to fringe at all. Care to guess which ones?
01-04-2013, 11:32 PM   #3
Site Supporter




Join Date: Jan 2010
Location: Michigan
Photos: Gallery
Posts: 2,182
Hi Yusuf
Here is the offending lens SMC Pentax -M 1:2 85 mm you mention as being "bad PF" taking a shot wide open in the dark with bright lights !!, on aps-c , a pentax ist ds - no less !!

https://www.box.com/s/0ngldvkkw7w0relu0mh3

Here is your query for the lens on that shot in X
[root@localhost OlyRaw]# tca_correct -o cv *.jpg
here is the reply which you can feed to your gizmo whatever
-r 0.0000000:0.0000000:-0.0001282:1.0001706 -b 0.0000000:0.0000000:-0.0001529:1.0000598

Not too bad - Huh ??
You can post your "bad" image if you want ( needs 3000 pix across)
01-04-2013, 11:46 PM   #4
Pentaxian
Swift1's Avatar

Join Date: Sep 2009
Location: Oregon
Photos: Gallery | Albums
Posts: 4,003
QuoteOriginally posted by stevebrot Quote
Lenses don't produce purple fringing, it is a digital sensor issue. It simply does not happen with color film. That being said, some lenses are more prone to encouraging the sensor to fringe. I can offer two Pentax-M lenses that I own that don't seem to be associated with that problem.
M 50/1.7
M 200/4

Steve

FWIW...I only own a few lenses that cause my K10D to fringe at all. Care to guess which ones?
From my experience, fringing does happen on film. I imagine that major awareness of it didn't exist until pixel peeping though.
Here's a corner crop from a 2400 dpi scan of a Kodak Portra 400 VC negative shot with my SMC 6X7 45mm f/4 lens.


Unless this is somehow caused by scanning, I've definitely run across it a few times coming from this lens and different films.

01-05-2013, 12:41 AM   #5
Veteran Member
Jewelltrail's Avatar

Join Date: May 2008
Location: Rhode Island
Photos: Albums
Posts: 4,180
I owned several M-series lenses & shot them on my K20d. As Steve says above, the 50 f/1.7 & 200 f/4 were no problem. However, the most fringing/CAs I"ve ever seen on digital were with the M 300 f/4. It was a beautifully built lens, & I had a mint copy, but could not deal with the fringing/CAs. If you used it selectively, excellent shots were possible.

JT

EDIT:My apology, I left Pentax a couple of years ago & all my efforts have been in Nikon ever since. I made a mistake---It was not the M 300 f/4 which was so poor--It was the K 300 f/4. My experience with the M 50 1.7 & 200 f/4 is accurate.

Last edited by Jewelltrail; 01-05-2013 at 10:03 AM.
01-05-2013, 06:34 AM   #6
Veteran Member
maltfalc's Avatar

Join Date: May 2010
Location: Winnipeg
Photos: Albums
Posts: 394
QuoteOriginally posted by stevebrot Quote
Lenses don't produce purple fringing, it is a digital sensor issue.
wrong. pf is caused by a lens not focusing light at the far ends of the visible spectrum the same as light from blue to red. that's why pf varies from one lens to another and from one f-stop to another. digital is just usually better than film at "seeing" the pf produced by lenses.
QuoteOriginally posted by Swift1 Quote
From my experience, fringing does happen on film. I imagine that major awareness of it didn't exist until pixel peeping though.
Here's a corner crop from a 2400 dpi scan of a Kodak Portra 400 VC negative shot with my SMC 6X7 45mm f/4 lens.


Unless this is somehow caused by scanning, I've definitely run across it a few times coming from this lens and different films.
there may be a bit of pf in that photo, but it mostly just looks like blue/yellow ca.
01-05-2013, 06:50 AM   #7
Banned




Join Date: Jun 2012
Location: NY/Germany
Posts: 1,183
I've got an M85 and never really noticed any abnormally large amounts of PF. Very nice lens.
01-05-2013, 08:06 AM   #8
Site Supporter
Stone G.'s Avatar

Join Date: Jun 2010
Location: North Zealand, Denmark
Photos: Gallery | Albums
Posts: 1,516
QuoteOriginally posted by maltfalc Quote
wrong. pf is caused by a lens not focusing light at the far ends of the visible spectrum the same as light from blue to red. that's why pf varies from one lens to another and from one f-stop to another. digital is just usually better than film at "seeing" the pf produced by lenses.
there may be a bit of pf in that photo, but it mostly just looks like blue/yellow ca.
True. And one should recall that M-lenses were optimized to reduce aberrations otherwise visible on analogue film - and most films had and have a rather different spectral sensitivity than digital sensors, whether with or without blocking filters. See for example: Wikipedia:

Purple fringing - Wikipedia, the free encyclopedia

01-05-2013, 08:38 AM   #9
Veteran Member




Join Date: Nov 2006
Location: central Singapore
Photos: Gallery
Posts: 409
I don't find any of my M lenses particularly susceptible. The main culprit in my collection is the FA135/2.8 wide open. Even that's only a problem with really high-contrast edges.

(PS: I love the idea of a fridge master, OP. I know several people who could claim that title ... )
01-05-2013, 08:41 AM   #10
Pentaxian
Jonathan Mac's Avatar

Join Date: Apr 2009
Location: Madrid, Spain
Posts: 4,358
The M85 doesn't so much purple-fringe as blue-fringe. 80% of it is gone by f/2.8 and I've never found it to be a problem. It's a beautiful lens.

I've never seen any really bad purple fringing in my images and I have a lot of Ms and I like to shoot with wide apertures.
01-05-2013, 09:25 AM   #11
Site Supporter




Join Date: Jan 2010
Location: Michigan
Photos: Gallery
Posts: 2,182
SMC Pentax -M 1:2 85 mm
Pentax originally said
"Creates a soft focus effect in the areas just beyond the depth-of-field. Ideal for portraiture, indoors or out. The moderate distance between the photographer and the subject makes this lens particularly excellent for pictures of children, , night time street scenes, illuminated buildings, and for theater and ceremonial pictures."

I have never used this lens.
So here is a "fence test" wide open at f/2 showing the out of focus effect.
https://www.box.com/s/wefkg1ly4wmlu3m39zv2

A messy tree branch shot at f/11
https://www.box.com/s/pr1mvdsukww8xpixig0n

"portrait" (I don't put family members up)
At f/2 , difficult to focus so used the Magnifier M on the face.
https://www.box.com/s/i6nnfe3sdhnslsmpimn6

On the fence test full size on the 22 inch Eizo, , I do see some obvious purple fringe on the out of focus zone near to the camera, but I suppose the lens was not intended to be framed like that and Pentax said "just beyond...".
Maybe that is the origin of Yusef's query?
The fringing on the out of focus beyond the subject looks OK ??

Today I will try some family shots with SMC Pentax -M 1:2 85 mm on the MX with some Fuji 400.
But after the above lesson will stop it down f/5.6 or so to ensure focus.
01-05-2013, 10:21 AM   #12
Veteran Member
Jewelltrail's Avatar

Join Date: May 2008
Location: Rhode Island
Photos: Albums
Posts: 4,180
It is worth adding that DSLR sensors play a large role in "blooming" issues. Particularly with the CCD sensors found in many DSLRs does blooming become an issue, whereas CMOS sensors handle the issue much better. The subject can get complex, but there is some good discussion here, with endless more to be found in a Goolge search:

OK1000 Pentax Blog: Reducing Purple Fringing and Sensor Blooms
01-05-2013, 10:58 AM   #13
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 5,002
QuoteOriginally posted by Jewelltrail Quote
EDIT:My apology, I left Pentax a couple of years ago & all my efforts have been in Nikon ever since. I made a mistake---It was not the M 300 f/4 which was so poor--It was the K 300 f/4. My experience with the M 50 1.7 & 200 f/4 is accurate.
That's right -- I don't believe there is plain M 300/4, it only came in a green star(*) version. It is known as a fantastic lens, and is completely different than earlier K 300/4, which I don't think is that well-regarded, fringing or not.
01-05-2013, 11:04 AM   #14
Site Supporter
Jean Poitiers's Avatar

Join Date: Apr 2011
Location: Lost in translation ...
Photos: Gallery | Albums
Posts: 16,551
QuoteOriginally posted by stevebrot Quote
... Steve

FWIW...I only own a few lenses that cause my K10D to fringe at all. Care to guess which ones?
Please do tell ...
01-05-2013, 11:43 AM   #15
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,479
QuoteOriginally posted by maltfalc Quote
wrong. pf is caused by a lens not focusing light at the far ends of the visible spectrum the same as light from blue to red...
Wrong...PF is not the same as CA (what you described). CA can cause a purple "fringe", but not all purple is PF. The difference is readily apparent on inspection. CA does not "bloom". PF does. As I noted above, PF is a digital-only phenomenon. Read any lens test from the "film era" and you will see no mention of PF.

See:
Chromatic aberration - Wikipedia, the free encyclopedia

Steve
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
k-mount, lenses, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Purple Fringe crossmr Digital Processing, Software, and Printing 15 01-06-2013 06:22 AM
Purple fringe with Pentax DA 35mm f/2.4 AL Lens Noggin Pentax SLR Lens Discussion 7 10-19-2011 09:46 PM
purple fringe and noise plugins for LR3? dj_saunter Digital Processing, Software, and Printing 10 05-27-2011 07:33 AM
DA70mm purple fringe... why? GregX999 Pentax SLR Lens Discussion 16 04-20-2011 09:06 PM
used lens purple fringe ? kiwao Pentax SLR Lens Discussion 7 03-04-2010 08:14 PM



All times are GMT -7. The time now is 07:59 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top