MFT 25mm f/1.4 fails to blur background like Full Frame 50mm lens @ f/2.8

Started Feb 16, 2014 | Discussions thread
Fygaren
Regular MemberPosts: 169
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Re: Fygaren is on to something here ... FL and Crop!
In reply to Alex Notpro, Feb 16, 2014

With your cropping of the crop 2(mFT) and crop 1 (FF f2.8) you have made them in to crop 6.1 f1.4 and crop 2.9 f2.8

http://howmuchblur.com/#compare-6.1x-25mm-f1.4-and-2.9x-50mm-f2.8-on-a-0.9m-wide-subject

So what you are see in you pictures should be correct (I assume the 25mm is 25mm and 50mm is 50mm which they may not be exactly, and the focus is on the same spot)

If you could choose to shoot with 4:3 on the D700 (3776x2832 pixels, crop factor 1.1, or you crop in PP..), the lens/aperture to get the equivalent picture would be like this:

Standing in the same spot:

mFT - 4:3 - 25mm - f1.4 = FF - 4:3(cropped) - 46,2mm - f2.6

and

FF - 3:2 - 50mm - f2.8 = mFT - 3:2(cropped) - 24mm - f1.35

http://howmuchblur.com/#compare-1x-50mm-f2.8-and-2.08x-24mm-f1.35-on-a-0.9m-wide-subject

In other words:

Making the mFT look like the FF(3:2) picture you will need to use a factor of 2.1 (2.081)

Making the FF picture look like mFT(4:3) picture you will need to use a factor of 1.8 (1.848)

I rarely use anything other than 4:3 as I find 3:2 too narrow for family shots, I do crop to 1:1 every now and then. I havent gotten around to doing lots of landscapes yet.

At longer focal lenghs the difference is bigger(in mm), to get the equivalent picture with a FF-camera that I get with my 75mm f1.8, you will need a 138mm f3.3 FF lens (135mm) and not 150mm...

oh, mFT 4:3 - 25mm - f1.4 = APS-C(Canon) 4:3(cropped) - 28.5mm - f1.6, BIG difference!

Anyway, I recommend you forget all about it, crop 2 is so mutch easier to use!

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