My question is on the 8mm Fisheye, it appears to be flare or could be something else maybe fungus, take a look at the steps as you can see it has a white stripe (lightened area) this also happens on the bridge shot less noticable, when the light balance is more equal or that area darker it just blends in. Any thoughts what it might be just flare or fungus, something else? I can send back to KEH. Thanks for your opinions. ALl shots on Canon 5D.
What's the serial number on the Oly lens? There isn't a huge sample base from which to draw conclusions, but apparently some of the later 8mms were indeed given to fungus on the rear elements - see this url. If fungus is there it should be plainly visible and I'd be surprised if KEH missed it.
Which Sigma lens were you shooting against, and what apertures were you using?
The Sigma is the F3.5 version and the sample shot is at F3.5. All the Oly shots are F2.8.
The Serial number 100133 lens says OLYMPUS OM-SYSTEM ZUIKO AUTO-FISHEYE 1:2.8 f=8mm --- seems from the link it doesn't fully match single or double coated as it has the f=8mm which indicates single coated, but the capitalizing of AUTO-FISHEYE indicates double coating and the serial number indicates single coating.
The filter wheel has L39 (UV),R60(R2),O56(O2),Y48(Y2)
Interestingly from the link Lindy Stone mentioned he no longer has the Canon FD Fisheye, I was the one who bought it from him and he suggested later on to try the Olympus Fisheye.
Tommorrow I get my 5D MKII, though I don't expect any difference I'm going to try it on the 5D MKII.
It doesn't look like fungus as the circle seems to be too uniform and starts right at the edge of the blue CA, but doesn't show on every shot.
Capitalization means nothing as far as I know re: MC vs SC. It sounds like single coated, but you can usually tell by looking at the glass. f=8mm and whatnot sounds like SC, plus the early SN (#133 made). Still, a neat lens, no doubt! I'd look closely at the rear element area, for signs of that image issue. It's not going to be on the front or it will be obvious (huge front element would need a HUGE flaw for it to show up that much. Much smaller rear element can have much smaller flaw that would still affect things noticably. )
Thanks for further info Ed and olyacme . I was in contact with Lindy and he experiences the same image issues sometimes shows, other times nothe also confirmed his is also single coating, at least I now know that I'm not the only one. When I further looked at it through the camera I am now able to recognize when it shows, and it appears when the sun is in the feild of view, so I'll just have to accept the weakness learn how to shoot with it or return to KEH. I will do a closer inspection of the rear element.
burningheart wrote:
Thanks for further info Ed and olyacme . I was in contact with Lindy and he experiences the same image issues sometimes shows, other times nothe also confirmed his is also single coating, at least I now know that I'm not the only one. When I further looked at it through the camera I am now able to recognize when it shows, and it appears when the sun is in the feild of view, so I'll just have to accept the weakness learn how to shoot with it or return to KEH. I will do a closer inspection of the rear element....Show more →
Small community, the circular fisheye users seems to be...
You might try exploiting being able to see the whole image circle, and shoot the same scene while rotating the body. If the flare/shadow shifts position in lockstep with the body's rotation then it's either a smudge somewhere or possibly a shiny part of the lens's mechanics reflecting some light. If it doesn't shift position, and especially if, as your suspect, it remains tied down wrt the position of the sun, then it's probably inherent to the makeup of the lens. Tests against neutral fields at infinity and what amounts to close focus for the fisheye (heavily overcast skies or sides of large buildings), stopped down and wide open, might also help peg down its nature.
BTW, a smudge could even be toward the front elements. With its massive depth of field, it doesn't take much more than a mote for contamination to be imaged by a fisheye. Try a small thread-shaped slice of a post-it-note, crinkled in advance so that you can get it off without a finger nail, to see how little it takes.
If you have time, I'd be interested in seeing crops from shootouts at f/5.6 between whatever comparable fisheyes you have at your disposal.
Heres a couple shot with film via Eos-3 and same Olympus OM 8mm 2.8. I can tells its the Oly due to its distinctive shadow in one image. On film everyone always cut my circle because of their "Negative carrier". Mine has this shadowing issue Robert's concerned about. It is a lens from 1974 and designed for film some 35 years ago so I am not sure its a defect or simply the way it is, as good as it gets if you want a sample of only 1,500 or so made from 1973-1992ish.
Same location 15 months earlier via Eos-3 Film camera & Tamron 14mm/2.8 for eos mount. A Ultrawide 8mm versus Superwide comparision. Color Prints scanned on flatbed scanner
Did you try stopping the lens down to F:8 or F:11 to see if the artifact improves or gets worse? Sometimes using the lens wide open you will see artifacts that are eliminated when stopped down. However with a 8mm fisheye if the artifact is a scratch on the front element stopping down will make the issue worse.
Thanks again for all suggestions, I contacted KEH and returned the lens today. Stopping down it got worse, rotating the camera same result. it also shows on the opposite side. The lens is sharp even at 2.8. These shots are not the best they just empasize then problem encountered with the lens.
burningheart wrote:
The lens is sharp even at 2.8. These shots are not the best they just empasize then problem encountered with the lens.
Thanks for the follow up, those shots really show the problem. I still wonder if Olympus might have failed to notice the need for some black paint on a retaining ring or lens edge.
BTW, is it changing subject to lens distance in the close field (if the Siggy is shorter), or does the Sigma lens appear to be a bit wider than the Oly?
Sigma is a bit wider than the Oly, not by much. I noticed this on the two pictures that I took from tripod by changing the lens. The bridge shot and the house and step shots. I had hoped on doing more testing but with the problem it had to go back. I also found the Oly was sharper on the extremities/edges than the Siggy at least on the dreaded brick wall. The Sigma also suffers from reflections but these occur outside the picture area, at times you can see the inside of the barrel and occassionally you see red rings (Must mean it is an L lens ) but again this is outside the circular image so not an issue on the pictue as seen in picture below.
I sus[ect you may be observing an exaggerated effect of the lens design. The OM System Lens Handbook gives a clue. The example image shown on Page 111 is retouched around the edges to obscure anything that is not pure white (there is an unretiuched thumbnail on the same page). Also, the text on pages 100-111 speaks of the 8mm having been designed for such applications as meausrment of cloud cover over 180 degrees of the sky. For such an application the primary requirement is obviously distortion-free representation of the hemisphere, not coolour/exposure accuracy across the whole field.
Piers Hemy wrote:
Also, the text on pages 100-111 speaks of the 8mm having been designed for such applications as meausrment of cloud cover over 180 degrees of the sky. For such an application the primary requirement is obviously distortion-free representation of the hemisphere, not coolour/exposure accuracy across the whole field.
The issue certainly seems to be inherent in the lens's implementation, but I'm unsure if it's a strictly optical property, or flare due to insufficient baffling or edge blackening. I suspect the problem might not be noticeable in clear sky imaging at night, where the amount of light entering the lens would be much less. But for machine analysis of cloud cover, this lens would skew results near the horizon due to the changing intensity (especially after the lens was stopped down to avoid vignetting).
Also, looking at the test results burningheart's website, the lens delivers progressively lower contrast as it's stopped down. This is consistent with the amount of internal flare growing relative to the desired light passing through.
) but again this is outside the circular image so not an issue on the pictue as seen in picture below.