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Vintage lenses and unwanted 'blooming'

Discussion in 'Adapted Lenses' started by DigitalD, Feb 8, 2014.

  1. DigitalD

    DigitalD Mu-43 Top Veteran

    505
    Jan 10, 2014
    Miami
    David
    From day one of owning my e-m1 I have been adapting my Canon FD lenses to it. I hadn't shot with my A-1 for almost 2 years and I was excited to retry my vintage glass on the MFT format. I have a 24mm, 35mm, 50mm 1.8, 50mm 1.4 and. 100mm. Most are the S.S.C versions so they really make some fabulous renderings. The 100mm is mind boggling sharp IMHO.

    But then the problem. The 50 1.4 was showing some serious CA and blooming wide open. I didn't notice it until post and was disappointed at first that my lens may have a problem I never noticed before. I shot only b&w film with it so it could have gone unnoticed.

    Here is a shot with the Canon 50mm 1.4 FD wide open. I processed it in b&w because the CA was too distracting. You can see the 'blooming' as a glow around the highlights of my daughter.

    arenuzeb.

    I searched around online (not extensively) and saw lots of adapted 50mm lens shots that looked sharp and wonderful so I was almost sure it was my lens.

    Last week there was a camera show in my area. Basically a swap meet for old film camera gear and I went hunting. I found a sweet deal on a minolta rokkor-pg 50mm 1.4 for $50 and snatched it up. Grabbed an adaptor and went to work again.

    Low and behold. Deep CA and blooming again.

    Here is a test shot in the worst conditions. Hot light on a reflective soda can.

    3esasa3e.

    Panic set in. I thought maybe my sensor was shot. I thought to myself "did I point the camera directly at the sun the other day in a zealous effort for a sunset shot?!!"

    So after some more digging I found that apparently blooming and CA can be a problem with fast vintage lenses. I never had the issue, as far as I can recall, when I adapted the lenses to my 7D but the experience was so poor with that camera I only did it once or twice. The blooming happens in high contrast areas and has to do with how the light is being interpreted by the sensor. The intense light at f 1.2 or 1.4 from a un-categorized lens can cause the contrast area to bleed over into other pixels on the sensor. I wonder if this is only a problem for high Megapixel MFT cameras because of the size of the sensor and tightly packed diodes?

    So the way to fix it? Stop down. After some more photos I found f2 to be sufficient to clean up the rendering and limit any CA and blooming. Here is a fav stopped down to f2.8

    sa7ugy7e.

    The funny thing is now that I know when it happens I plan on using the bloom in situations where it might make for a beautiful effect. For instance this shot is pretty neat with the glow around the face.

    beja9uge.

    Forgive all the kid photos. I haven't had the camera long enough to take out the vintage glass somewhere other than home. They also happen to be my favorite subjects ;)

    So if anyone has anything to share and discuss please do. I love 'slowing down' again with the old lenses and didn't realize how much I missed shooting 35 film until now. I plan on picking up more as I feel that these old lenses have characteristics you don't get in modern lenses. I happen to like flaws as long as I understand why they are happening (to some degree). What's been your experience?
     
  2. fortwodriver

    fortwodriver Mu-43 Top Veteran

    959
    Nov 15, 2013
    Toronto, Ontario, Canada
    Frank
    Sensors don't have the same properties as film. I have modern lenses that cause blooming on digital cameras. Heck, the modern Canon 50mm f1.4 USM lens, when placed on the Canon 7D had a few issues. Lenses designed before digital have at least different coatings on the rear elements. Unfortunately, that makes older lenses behave poorly in some conditions when mated to digital sensors.

    Some of the blooming can be due to light from the lens reflecting off the sensor cover glass, back to the lens, and then bouncing back to the sensor. It's a kind of recursive "halation" that can soften the image and produce longitudinal CA. LCA occurs when the CA appears green behind the focus point and shifts to purple in front of the focus point.

    A lot of my Nikkor lenses did this on my old D100. My 50mm, 85mm, and especially the 70-210 f4 did that. Most cameras companies tweaked the rear element coatings to reduce reflections and help minimize the problem - often without telling anyone. I believe some of the older pro D series Nikons had sensors with tweaked cover glasses to try and mitigate some of the issues related to using legacy glass on digital sensors - at least until they were able to re-work and release many of those lenses with modified coatings.

    I also have a 1976ish late model SMC Takumar screw-mount 50mm 1.4 (that still had the metal ribbed focus ring) which doesn't exhibit CA but does need to be stopped down to at least f2 to clear up the picture, otherwise it's much softer in front of a digital sensor than it ever was in front of film.

    So far my m.Zuikos seem to be much better behaved than older legacy glass.

    It may be a bit more obvious on m43 because of the crop-factor. You're essentially magnifying the aberrations of the lens due to the 2x crop factor. It certainly was obvious on APS-C cameras.
     
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  3. speedandstyle

    speedandstyle Mu-43 Hall of Famer

    Modern lenses have better coatings and glass and some of them are formulated specifically for digital. Some of my vintage Nikkors have similar issues to what you experience. I have found either avoid the conditions or use those conditions for an artistic rendering.
     
    • Like Like x 1
  4. mr_botak

    mr_botak Mu-43 Veteran

    222
    Dec 4, 2011
    Reading, UK
    David
    I've found pretty much anything faster than f3.5 or so glow/blooms when used wide open. It's much better on the E-M5 than the E-PM1, and also certainly on the OM lenses, the later the lens, the better - most got 3rd generation coatings in the 80s.

    I have put black foam around the inner skin of my adapters to dampen any reflections. I was suprised to see that most had a semi gloss paint finish rather then the matt you'd find in the mirror box of a camera or in the lens. I think it improved matters.

    I think the glow can be used to create a nice effect in subdued light,.
     
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  5. DigitalD

    DigitalD Mu-43 Top Veteran

    505
    Jan 10, 2014
    Miami
    David
    Really good feedback. Thanks!
     
  6. DigitalD

    DigitalD Mu-43 Top Veteran

    505
    Jan 10, 2014
    Miami
    David
    Thanks for this. I can't believe how long this info escaped me. The LCA is exactly what's happening on that coke can test shot. I'll have to try out that black tape method. I saw a post about it but didn't grasp what they were trying to do. I using the $20 Fotasy adaptors for both the MD and the FD. I'll have to check them in the morning but I thought they were pretty matte black.

    Again thanks for the info!
     
  7. MajorMagee

    MajorMagee Mu-43 All-Pro

    Feb 24, 2011
    Dayton, OH
    There are some pictures of my "Funky Foam" idea here.
     
  8. spatulaboy

    spatulaboy I'm not really here

    Jul 13, 2011
    North Carolina
    Vin
    It is unavoidable. However all is not lost. If you shoot in the right conditions you can actually use it to your advantage and give your portraits a wonderful soft quality. I find soft, diffused lighting really helps reduce the CA and will give your images a very acceptable level of sharpness wide open.

    These are from my Minolta MD 50mm f1.4 wide open. There is definitely that soft 'glow' there but I find it adds to the overall feel of the portrait and doesn't work against it. Shooting outdoors in bright direct light however... not recommended. :) Stopping down to f2 will sharpen it up considerably.

    10893502625_eb3fba9c28_c.
    Samantha: Model, Actress by Vincent-F-Tsai, on Flickr

    12409452785_0903d4c905_c.
    In the lobby by Vincent-F-Tsai, on Flickr
     
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  9. DigitalD

    DigitalD Mu-43 Top Veteran

    505
    Jan 10, 2014
    Miami
    David
    That's very encouraging. Yep definitely embracing it now that I understand the conditions a bit better. I really love your work Vincent!
     
  10. Pasukun

    Pasukun Mu-43 Regular

    30
    Aug 2, 2011
    It is my understanding that, no matter how good the adapter is.. there is always bit of misalignment, and that it can contribute to the problem you are describing.
    Having said that, some adapter is better than others, and it will greatly minimize the degree of misalignment.
    And with that bit of misalignment, some lens will have more issue(s) than other lenses, depends on how forgiving it is.
     
  11. DigitalD

    DigitalD Mu-43 Top Veteran

    505
    Jan 10, 2014
    Miami
    David
    That's a good point. What adaptor are you using Vincent?