DOF difference between the 85mm 1.2 and the 50mm 1.2

EOS 5Dmk3 X2, 60D, EF24-70mm f2.8L mk2, EF70-200mm f2.8L IS mk2, EF85mm f1.8, EF50mm f1.4, EF50mm f1.8 mk1(350D with 18-55mm Sh"kit" lens).
Speedlite 600EX-RT, 430EX II Flash. manfrotto 190XDB tripod, Giottos GTMML 3290B Monopod, B+W 77mm 110 Single Coated filter, Hama 77mm Variable Neutral Density Filter.

Gear: 7DII | 6D | Fuji X100s |Sigma 24A, 50A, 150-600C |24-105L |Samyang 14 2.8|Tamron 90mm f2.8 |and some other stuff
http://www.shutterstoc​k.com/g/copidosoma
https://500px.com/chri​s_kolaczan

gonzogolf wrote in post #16739631
http://www.dofmaster.c​om/dofjs.html Run your scenario here.

The 85mm seems to have less DOF.. I am wondering why. Maybe I calculated incorrectly

EOS 5Dmk3 X2, 60D, EF24-70mm f2.8L mk2, EF70-200mm f2.8L IS mk2, EF85mm f1.8, EF50mm f1.4, EF50mm f1.8 mk1(350D with 18-55mm Sh"kit" lens).
Speedlite 600EX-RT, 430EX II Flash. manfrotto 190XDB tripod, Giottos GTMML 3290B Monopod, B+W 77mm 110 Single Coated filter, Hama 77mm Variable Neutral Density Filter.

Copidosoma wrote in post #16739640
They will be the same.

But the rule is the further away you are the greater the DOF increases.. Or not??

EOS 5Dmk3 X2, 60D, EF24-70mm f2.8L mk2, EF70-200mm f2.8L IS mk2, EF85mm f1.8, EF50mm f1.4, EF50mm f1.8 mk1(350D with 18-55mm Sh"kit" lens).
Speedlite 600EX-RT, 430EX II Flash. manfrotto 190XDB tripod, Giottos GTMML 3290B Monopod, B+W 77mm 110 Single Coated filter, Hama 77mm Variable Neutral Density Filter.

gonzogolf wrote in post #16739631
http://www.dofmaster.c​om/dofjs.html Run your scenario here.

I calculated the 50mm at 5metres and the 85mm at 8 metres and the 85mm has less DOF.. Wow!!!

EOS 5Dmk3 X2, 60D, EF24-70mm f2.8L mk2, EF70-200mm f2.8L IS mk2, EF85mm f1.8, EF50mm f1.4, EF50mm f1.8 mk1(350D with 18-55mm Sh"kit" lens).
Speedlite 600EX-RT, 430EX II Flash. manfrotto 190XDB tripod, Giottos GTMML 3290B Monopod, B+W 77mm 110 Single Coated filter, Hama 77mm Variable Neutral Density Filter.

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gasrocks wrote in post #16739663
Be honest with us and yourself, how often are you going to shoot either lens at 1.2?

I am trying to understand the concept of it, the same rules would apply to shooting at 1.8 or 2.2 with both lenses

EOS 5Dmk3 X2, 60D, EF24-70mm f2.8L mk2, EF70-200mm f2.8L IS mk2, EF85mm f1.8, EF50mm f1.4, EF50mm f1.8 mk1(350D with 18-55mm Sh"kit" lens).
Speedlite 600EX-RT, 430EX II Flash. manfrotto 190XDB tripod, Giottos GTMML 3290B Monopod, B+W 77mm 110 Single Coated filter, Hama 77mm Variable Neutral Density Filter.

Nick_Reading.UK wrote in post #16739650
But the rule is the further away you are the greater the DOF increases.. Or not??

With the same FL, yes, DOF increases with distance. Once you change the focal length it isn't so clear.

Careful with the DOF calculator (not only because of the assumptions on which it is based). You need to know the exact distance difference to get the same framing.

A quick look shows the 50mm with a FOV of 39.35 degrees, the 85 has 23.54 degrees. Proportion is 1.67. So assuming (not 100% sure this is correct) that the distance to subject with the same framing for the 85mm is 1.67x the distance for the 50mm, I get a DOF of 0.86 vs 0.83 (at 10ft and 16.7 feet). That would be a hard difference to demonstrate in an image.

Gear: 7DII | 6D | Fuji X100s |Sigma 24A, 50A, 150-600C |24-105L |Samyang 14 2.8|Tamron 90mm f2.8 |and some other stuff
http://www.shutterstoc​k.com/g/copidosoma
https://500px.com/chri​s_kolaczan

sandpiper wrote in post #16739667
Yes, and the longer your focal length the more your DOF decreases. In general, if you are framing your subject the same, the extra DOF you get from moving further back is cancelled by the shallower DOF you get from using a longer lens, so the DOF remains more or less the same with no significant shift either way.

Nice one.. Cheers, I didn't know that !!!! Next time I am in Mathew street I will invite you for a beer

EOS 5Dmk3 X2, 60D, EF24-70mm f2.8L mk2, EF70-200mm f2.8L IS mk2, EF85mm f1.8, EF50mm f1.4, EF50mm f1.8 mk1(350D with 18-55mm Sh"kit" lens).
Speedlite 600EX-RT, 430EX II Flash. manfrotto 190XDB tripod, Giottos GTMML 3290B Monopod, B+W 77mm 110 Single Coated filter, Hama 77mm Variable Neutral Density Filter.

This is something I put together a long time ago, maybe it would be helpful here?

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TeamSpeed wrote in post #16739963
This is something I put together a long time ago, maybe it would be helpful here?

This is great! Thanks.

5D Mark III / 35L / 24-105L / 600ex-rt

Ladera wrote in post #16740385
This is great! Thanks.

+ 1

EOS 5Dmk3 X2, 60D, EF24-70mm f2.8L mk2, EF70-200mm f2.8L IS mk2, EF85mm f1.8, EF50mm f1.4, EF50mm f1.8 mk1(350D with 18-55mm Sh"kit" lens).
Speedlite 600EX-RT, 430EX II Flash. manfrotto 190XDB tripod, Giottos GTMML 3290B Monopod, B+W 77mm 110 Single Coated filter, Hama 77mm Variable Neutral Density Filter.