December 11, 2017, 04:42:27 AM

Author Topic: Need Source for Equivalent f-stops, pls  (Read 9941 times)

JumboShrimp

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Need Source for Equivalent f-stops, pls
« on: January 19, 2017, 02:31:05 PM »
Does anyone out there know of a reliable source for equivalent f-stops for 1"-type sensors? Thanks in advance.

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Need Source for Equivalent f-stops, pls
« on: January 19, 2017, 02:31:05 PM »

privatebydesign

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Re: Need Source for Equivalent f-stops, pls
« Reply #1 on: January 19, 2017, 02:39:59 PM »
Does anyone out there know of a reliable source for equivalent f-stops for 1"-type sensors? Thanks in advance.

As not all 1" sensors are the same size, just like APS, you need the actual sensor dimensions. Once you have that the factor is a constant.

Tell us what size your 1" sensor actually is and we'll give you the factor.
Too often we lose sight of the fact that photography is about capturing light, if we have the ability to take control of that light then we grow exponentially as photographers. More often than not the image is not about lens speed, sensor size, DR, MP's or AF, it is about the light.

neuroanatomist

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Re: Need Source for Equivalent f-stops, pls
« Reply #2 on: January 19, 2017, 02:42:27 PM »
As an approximation, the Sony RX100-type sensor has a crop factor of 2.72, so to get the equivalent f/number you just multiply by that (e.g. 50mm f/2 on an RX100 is equivalent to approximately 136mm f/5.4 on FF).   
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JumboShrimp

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Re: Need Source for Equivalent f-stops, pls
« Reply #3 on: January 19, 2017, 03:28:06 PM »
Thanks for the replies, gents. The camera in question is the Lumix FZ1000. It has a 1"-type sensor with dim's of 8.8 x 13.2 mm.

Mt Spokane Photography

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Re: Need Source for Equivalent f-stops, pls
« Reply #4 on: January 19, 2017, 07:00:12 PM »
Thanks for the replies, gents. The camera in question is the Lumix FZ1000. It has a 1"-type sensor with dim's of 8.8 x 13.2 mm.

Same as the Sony, 2.72 or some say 2.73.

http://www.digicamdb.com/compare/panasonic_lumix-dmc-fz1000-vs-sony_cybershot-dsc-rx100-iii/

JumboShrimp

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Re: Need Source for Equivalent f-stops, pls
« Reply #5 on: January 19, 2017, 08:41:37 PM »
Thanks !

privatebydesign

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Re: Need Source for Equivalent f-stops, pls
« Reply #6 on: January 19, 2017, 09:31:59 PM »
Hey Jumbo,

Obviously Mt Spokane is right.

If you want to know the way to do it for any sensor here is the formula.

Divide the diagonal of a FF sensor by the diagonal of the sensor you want a multiplication factor for.

So 'FF' sensor diagonal equals square root of 24mm sq plus 36mm sq. Or a 43mm diagonal. Now take your 1" sensor, 8.8mm x 13.2 mm at 15.9mm diagonal.  43/15.9 = 2.70 crop factor for focal length and aperture.

Any figure you want on a ff camera divide by 2.7 to get on your 1" sensor. A 200mm f2.8 on FF would be a 74mm f1.0 equivalent on the 1" sensor. To go the other way multiply your 1" sensor lens by 2.7 to get the FF equivalent, so an 8mm f2.8 on the small camera would be a 22mm f7.6 on FF.

This also works for sensors larger than the base sensor, so you can work out equivalence figures in the negative for say a medium format sensor in relation to a 'FF' sensor.

Hope this addendum helps.
Too often we lose sight of the fact that photography is about capturing light, if we have the ability to take control of that light then we grow exponentially as photographers. More often than not the image is not about lens speed, sensor size, DR, MP's or AF, it is about the light.

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Re: Need Source for Equivalent f-stops, pls
« Reply #6 on: January 19, 2017, 09:31:59 PM »

Mt Spokane Photography

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Re: Need Source for Equivalent f-stops, pls
« Reply #7 on: January 19, 2017, 10:40:56 PM »
Hey Jumbo,

Obviously Mt Spokane is right.

If you want to know the way to do it for any sensor here is the formula.

Divide the diagonal of a FF sensor by the diagonal of the sensor you want a multiplication factor for.

So 'FF' sensor diagonal equals square root of 24mm sq plus 36mm sq. Or a 43mm diagonal. Now take your 1" sensor, 8.8mm x 13.2 mm at 15.9mm diagonal.  43/15.9 = 2.70 crop factor for focal length and aperture.

Any figure you want on a ff camera divide by 2.7 to get on your 1" sensor. A 200mm f2.8 on FF would be a 74mm f1.0 equivalent on the 1" sensor. To go the other way multiply your 1" sensor lens by 2.7 to get the FF equivalent, so an 8mm f2.8 on the small camera would be a 22mm f7.6 on FF.

This also works for sensors larger than the base sensor, so you can work out equivalence figures in the negative for say a medium format sensor in relation to a 'FF' sensor.

Hope this addendum helps.

The equivalent aperture is why small sensor bodies can have a huge depth of field, and why autofocus can be easily made faster.  Focusing to 1/3 of the depth of focus for a f/7 aperture means fast focusing is easy.

stevelee

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Re: Need Source for Equivalent f-stops, pls
« Reply #8 on: August 23, 2017, 12:43:13 PM »
Plus in terms of exposure, f/2.8 is still f/2.8, not f/7, so you get the best of both. The trade offs obviously are elsewhere.

unfocused

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Re: Need Source for Equivalent f-stops, pls
« Reply #9 on: August 23, 2017, 02:22:50 PM »
Plus in terms of exposure, f/2.8 is still f/2.8, not f/7, so you get the best of both. The trade offs obviously are elsewhere.

Yes! As many on this forum know, I have a pet peeve about the way people throw around the term "equivalent" for f-stops when using different sensor sizes. The exposure is not only identical, but the truth is, the depth of field is as well if you shoot from the same distance to subject using the same focal length. All you are doing is cropping a portion of the full frame image in-camera instead of when processing the image. I know I won't win this argument, too many people are too invested in their own concepts to accept the reality, but I still have to try.

But, to the OP, please!!! Understand that we are ONLY talking about apparent depth of field, nothing else.

privatebydesign

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Re: Need Source for Equivalent f-stops, pls
« Reply #10 on: August 23, 2017, 02:36:54 PM »
Plus in terms of exposure, f/2.8 is still f/2.8, not f/7, so you get the best of both. The trade offs obviously are elsewhere.

Yes! As many on this forum know, I have a pet peeve about the way people throw around the term "equivalent" for f-stops when using different sensor sizes. The exposure is not only identical, but the truth is, the depth of field is as well if you shoot from the same distance to subject using the same focal length. All you are doing is cropping a portion of the full frame image in-camera instead of when processing the image. I know I won't win this argument, too many people are too invested in their own concepts to accept the reality, but I still have to try.

But, to the OP, please!!! Understand that we are ONLY talking about apparent depth of field, nothing else.

That is only because you refuse to accept that noise is part of the equivalence equation.
Too often we lose sight of the fact that photography is about capturing light, if we have the ability to take control of that light then we grow exponentially as photographers. More often than not the image is not about lens speed, sensor size, DR, MP's or AF, it is about the light.

unfocused

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Re: Need Source for Equivalent f-stops, pls
« Reply #11 on: August 23, 2017, 02:44:17 PM »
...That is only because you refuse to accept that noise is part of the equivalence equation.

Huh...what???

When have I ever said that? And what does that have to do with the OP's question? He/She is asking about equivalent f-stops. How does changing f-stops affect noise if the exposure remains the same?

privatebydesign

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Re: Need Source for Equivalent f-stops, pls
« Reply #12 on: August 23, 2017, 02:48:02 PM »
...That is only because you refuse to accept that noise is part of the equivalence equation.

Huh...what???

When have I ever said that? And what does that have to do with the OP's question? He/She is asking about equivalent f-stops. How does changing f-stops affect noise if the exposure remains the same?

I rest my case!

If he/she changes aperture because they have changed sensor size they have also changed the noise characteristics, that is equivalence, and is directly relevant to your post.
Too often we lose sight of the fact that photography is about capturing light, if we have the ability to take control of that light then we grow exponentially as photographers. More often than not the image is not about lens speed, sensor size, DR, MP's or AF, it is about the light.

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Re: Need Source for Equivalent f-stops, pls
« Reply #12 on: August 23, 2017, 02:48:02 PM »

neuroanatomist

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Re: Need Source for Equivalent f-stops, pls
« Reply #13 on: August 23, 2017, 03:02:16 PM »
The exposure is not only identical, but the truth is, the depth of field is as well if you shoot from the same distance to subject using the same focal length. All you are doing is cropping a portion of the full frame image in-camera instead of when processing the image. I know I won't win this argument, too many people are too invested in their own concepts to accept the reality, but I still have to try.

You won't win the argument...becuase you're wrong.  It has nothing to do with people being invested in their own concepts, and everything to do with optical physics. 

For clarity, and for the benefit of those who can understand and want to accept reality...if all else is equal and the only thing that differs is the sensor size, the DoF will be shallower with the smaller sensor.  The exact same thing would be true if you crop the image in post, instead of using a smaller sensor.  Note that 'all else being equal' assumes the other factors affecting DoF (output size, viewing distance, visual acuity) are also held constant.  Granted, the magnitude of the difference is relatively small compared to the difference you'd see changing focal length or subject distance to match framing, and note that the difference is in the opposite direction from that latter situation (where smaller sensors are said to have deeper DoF).  But there is a difference, and thus your statement that they are identical is wrong.

So please, stop trying...it would be unfortunate if you were to convince people of something that is not real.
 
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unfocused

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Re: Need Source for Equivalent f-stops, pls
« Reply #14 on: August 23, 2017, 04:16:39 PM »
The exposure is not only identical, but the truth is, the depth of field is as well if you shoot from the same distance to subject using the same focal length. All you are doing is cropping a portion of the full frame image in-camera instead of when processing the image. I know I won't win this argument, too many people are too invested in their own concepts to accept the reality, but I still have to try.

You won't win the argument...becuase you're wrong.  It has nothing to do with people being invested in their own concepts, and everything to do with optical physics. 

For clarity, and for the benefit of those who can understand and want to accept reality...if all else is equal and the only thing that differs is the sensor size, the DoF will be shallower with the smaller sensor.  The exact same thing would be true if you crop the image in post, instead of using a smaller sensor.  Note that 'all else being equal' assumes the other factors affecting DoF (output size, viewing distance, visual acuity) are also held constant.  Granted, the magnitude of the difference is relatively small compared to the difference you'd see changing focal length or subject distance to match framing, and note that the difference is in the opposite direction from that latter situation (where smaller sensors are said to have deeper DoF).  But there is a difference, and thus your statement that they are identical is wrong.

So please, stop trying...it would be unfortunate if you were to convince people of something that is not real.
 

Just to be clear. You are stating that if someone places a 5DS and a 7DII on tripods next to each other, places a 200 mm lens on both cameras, focuses on a target 50 feet away, shoots both images at f8 and then crops the 5DS image to exactly match the cropping of the 70D, that there will be a discernible difference in the depth of field?

I'm not afraid to be proven wrong, I'd just like to see the proof or a reliable source.

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Re: Need Source for Equivalent f-stops, pls
« Reply #14 on: August 23, 2017, 04:16:39 PM »