micro four thirds: four fifties flare

For no apparent reason I decided I would test my lenses for flare. I'm not sure if this method is the most ideal, but I lined up the lenses against my kitchen wall under a fluro tube. I put a black circle with a hole cut in it on the left and a lens bottom cap (with the depth of the bucket facing me) on the right.

Lenses are:

• Canon FD 50mm f1.4 (top left)
• Canon FD 50mm f1.8 (top right
• Pentax 110 50mm f2.8 (bottom left)
• Olympus OM 50mm f1.8 (bottom right)

Method

all lenses were tested wide open and the camera (Panasonic G1) set to AWB and, camera on a tripod unmoving between each shot. (Note the Pentax 110 lens does not actually have any aperture control, so wide open is all you can pick from)

results

firstly lets look at the overview of each image, then zoom in for details:

overview

I find it interesting the colour renditions are quite different between the lenses. The lens absent from the group confirms which lens is on the camera at the time (to help me remember

the focus point
I used the following lens to confirm focus as best as I could using the magnifier to focus.

what is interesting here is at screen sizes the Pentax 110 looks to have the best contrast and sharpness, but when pixel peeping (click any image to load a full screen snapshot) I would have picked the FD 50 f1.4 ... just goes to show you need to evaluate things at something other than 100% magnification to see other factors than total resolution.

the rubber ring



The lower row seems to show better contrast to me than the top row, but the Pentax 110 lens (lower left) has significant CA purple fringing on the high contrast area, but mainly towards the outer side (away from the lens center). Makes sense.


the base cap

again purple fringing CA on the 110 lens shows up, but with better contrast than the two FD's

outside of the extreme contrast of being against the fluro the CA stops being obvious and you can get some detail in the blacks inside the caps.

Lastly, it was pointed out to me that perhaps my exposure was too short for reliable colour rendition on artificial light. Since its snowing outside and there is plenty of ambient light spill from all the street lights I would try one last thing.

On this I set the colour balance manually to be "cloudy" and manually focused the lenses to infinity. I used an exposure of 2 seconds for all of them and set all to f2.8 This puts the Pentax to a disadvantage as f2.8 is wide open. I then picked up my 3 led ultra-bright headlight so that it shone straight into the lens for the entire 2 seconds of the exposure. I tried to hold the torch in exactly the same spot.

Below are the results


Its interesting looking through the halo of light trying to see my face and how big the halo is. Then there is the secondary flare ... man the FD1.4 is really flaring. Interestingly there is a really large though less obvious purple flare on the 110 lens (lower left)

There are still colour differences, although its really hard to see colours in the outside in that sort of light.

conclusions

Well personally I like the OM and the itty bitty better and the FD's least. The FD 1.4 and 1.8 are almost dead ringers with the 1.8 showing better colour rendition in this situation to my eyes. I know from previous tests however that the FD 1.4 cleans up immensely when stopped down to 1.8 or 2 and shows itself as being much better than the 1.8 in a typical outdoor sunny day.


See my other tests of some of these lenses:

• FD 1.4 compared to OM 1.8
• FD 1.8 compared to OM 1.8
• Pentax 110 lenses

So, hope this was useful to someone (as it was to me). If you have a better suggestion for contrast and flare testing please put a comment in and I'll try to do that if I get time in the future (like I have now)

I think I'll have to try this again on a sunny day ...

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Post scriptum (today is sunny) so I thought I would repeat this with better "natural" light.

Please note that the order is:
Top row FD 50 1.4 left and 1.8 right
Bottom row OM50 f1.8 left and Pentax 110 50f2.8 right
(this is also visible on the frame in the names)

some 100% segments from the middle of the frame


and some 50% segments up closer to where the flare is stronger

Again I find myself liking the looks and contrasts of the Pentax 110 lens wide open better than the others.

Next I picked a strongly backlight scene and put the tree trunk to block the direct sun from hitting my lens:

overview


zooming in on the segment on which I focused ...

its clear that the Pentax (lower right) has better contrast (the FD1.4 is softer at 1.4) and the DoF is less (because its a f2.8 lens).

Throwing the Kit zoom into the mix:


which (being 45mm) has a smaller feature size and looks harsher and of course at 5.6 has different DoF ...

Lastly (for what its worth) there are complete image overviews of each of these images linked to a flickr account