Oly 8mm f1.8 vs Pana 8mm f3.5

[Dann-Oh 40]

Hello all,

I cant wrap my head around this maybe its the lack of sleep right now.

I have the Pana 8mm F3.5 Fisheye, is there any benefit to looking at the Oly 8mm F1.8 Fisheye? Most of the time I have the lens stopped down to around F8. Does the Oly gather more light than the Pana is they are both at F8? If so would the Oly be a faster lens if both are set to F8?

[Tom_Kline 143]

At least theoretically any lens set to f/8 will transmit the same amount of light. Differences that occur are mainly due to differences in transmission of light by glass which is less than 100% as part of the light gets reflected, mainly at glass-air interfaces. Type of lens coating (from none at all for lenses made prior to the 1950s to the most recent coating types (very old uncoated lenses can be adapted to m43)) has the most pronounced effect on transmission. The number of lens elements as well because more lens elements results in less transmission - multi-coating as enabled far more lens elements than the past. The only practical way that we as photographers can detect differences in light transmission between two lens would be to take two identical exposures, one with each lens, and compare the resulting histograms in Lightroom or some other software (even the back of the camera could work but the graphs are tiny).

I would be more concerned with differences in autofocus ability between these lenses and this would depend on your camera model.

[ChrisRoss 150]

If you already have the Panasonic lens, I can't see any real justification for the Olympus.  You're shooting an Olympus camera so there is a slight difference in corner performance with a little purple fringing in the corners for the Panasonic, which is mostly correctable in post.  Both lenses are quite sharp and apart from the purple fringing there is not much to pick between them.

At f8 they both  pass the same amount of light to the sensor for all intents and purposes, there may be very minor differences but it is in pixel peeping territory.  There is a theoretical advantage for AF if the camera focuses wide open and then stops down for the exposure, but the AF on fisheye lenses is not challenging, so again no noticeable advantage.

[Rene Weterings 1]

I have owned the Panasonic for about 7 years and after that I switched to the Olympus 8mm. I can't really see any difference in terms of quality and I also shoot not wider than f8. 

The advantage for me was that you have to use a 20mm ring for the 4" minidome on my Nauticam housing. This is helpful when you want to put the neopreen cover on it after the dive.
Also...a little bit forward with the dome is helpful for CFWA.

But again....I don't see any quality issues in any of these lense.