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Canon RF 135mm F1.8 is shipping …

Started 2 months ago | Discussions thread
Toothwalker Junior Member • Posts: 39
Re: Canon RF 135mm F1.8 is shipping …
1

RDM5546 wrote:

Use the tool at

http://howmuchblur.dekoning.nl/#compare-1x-135mm-f1.8-and-1x-85mm-f1.2-on-a-0.9m-wide-subject

Note the assumptions about subject distance, etc. For the case I tried the 85f1.2 was the blur winner. For closer than a head shot the 135 mm can be the winner

Note that the shown result is the absolute blur, i.e. the diameter of the blur disk on the sensor (here divided by 36 mm). If MarshallG intended to ask which lens yields a less distracting background, the situation is different.

On the one hand the 85/1.2 shows more of the background, which may contain distractions that the 135/1.8 does not show. However, because the background is less magnified with the 85/1.2, this adds to the relative blur. The relative blur is the size of the blur disk divided by the size of background objects. If we ask the question to what extent the license plate of a distant car is legible, or whether a group of people in the background are individually recognizable, then the F-number is decisive.

Provided we frame the object in the same way, the 85/1.2 yields 50% (1.8/1.2) more relative blur than the 135/1.8 and a less distracting background (within their common field of view).

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