Tuesday, June 07, 2011

FA 43 Limited Compared On Two Camera Systems

Here are some photos taken of the same subject at the same distance, with the FA 43 Limited lens. Shooting the same lens on different systems will not get us photographic equivalence. Nonetheless I was curious to see the overall image quality. On a full-frame camera 43mm provides a perfect normal field of view; on the Pentax K20D it provides the field of view of 64mm; on the Olympus E-P1 it is FOV equivalent to 86mm.

Here it is on the K20D, shot at ISO 200 and f/2.8. As always, click through for larger images in Flickr if you wish to examine in more detail.

K20D with FA43 Limited at f/2.8

Here is the shot on the E-P1, also at ISO 200 and f/2.8.

E-P1 with FA43 Limited at f/2.8

To aid in comparison I took a 100% crop from the centre of the image at various apertures. First the K20D.

K20D with FA43 Limited

And then the E-P1.

E-P1 with FA43 Limited

I will make three observations. First, I used Auto White Balance with no processing; the difference in colour is apparent. Second, the increase in noise in the E-P1 images is apparent.

Finally, the E-P1 produces smoother bokeh. I have no explanation for that.



Robbie said...

If anything it looks like the 43 on the E-P1 makes the DOF smaller instead of longer which is the opposite to what I expected. Perhaps the adapter is having an effect?

robin said...

The adapter is only a piece of plastic to keep the lens at the correct registration distance. this ensures that my sensor to subject distance is identical in both cases.

The only different factor is that of the "magnification" caused by the different size sensor.

I can only guess that the fact a smaller part of the lens image circle is being picked up by the sensor, somehow, for this particular lens, results in smoother bokeh. Or not. ;-)

Anonymous said...

Did you shoot jpeg? If so the difference could just be a result of different in-camera jpeg processing...

Technically, the lens rendition should be identical regardless of format, the only difference should be in the corners where the K20D uses more of the FA43's image circle.

robin said...

All shots taken in RAW, as is my standard practice.

Anonymous said...

why is the FOV equivalent to 56mm on the EP 1? wouldnt it be 84mm, or does the 43mm value not correspond to the 35mm format?

robin said...

It's because 43mm on the APS-C cropped sensor I am shooting in the Pentax K20D is equivalent to 56mm on the MFT sensor in the EP-1.

Anonymous said...

but 43mm is the focal length on a full frame sensor not the APS-C..

"Typical for all FA lenses it supports the full 35mm format so it can be used both on film and digital SLRs. On the Pentax K10D its field-of-view is equivalent to 64.5mm so it leaves its original scope as a "normal" lens towards a very moderate tele."
taken from photozone.de pentax FA43 lens review

that whould make it 84mm in the MFT format i think

robin said...

There was a typo in the original article. When I read the passage I misinterpreted my own writing, thus compounding the error. In short, you are totally correct! I have edited the article to remove the misleading statement.

Thanks for being persistent! Happy New Year!

Anonymous said...

Happy new year!
You're most welcome :) I actually found this thread because I am looking into buying the pentax FA 31mm to use on my EP 2 and wasn't sure what the FOV would be, i was hoping you were right in your post as i would rather have a wider FOV generally than what normal 35mm lenses give you on a MFT camera..
Do you have any suggestions for good lenses that give you an FOV of about 45-50mm on an MFT? The obvious ideal is the voigtlander 25mm .95, but that is a pretty serious investment..

robin said...

I have the excellent Panasonic 20mm (40mm eqv FOV) but perhaps that is too wide for you. The obvious choice then is the Panasonic Leica 25/1.4 which gets good reviews but is more expensive.

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