Confused with full frame lens vs APSC lens conversion

[harry2007]

I hope someone can explain this to me.

Recently, I asked this question "The new lens FE 28mm F2.0 on a6000?".

The new lens FE 28mm F2.0 on a6000?

I read about the new lens FE 28mm F2.0. Source: http://www.newsshooter.com/2015/02/13/newsshooter-at-cp-tokyo-2015-sony-fe-28mm-f2-lens-and-fish-eye-and-ultra-wide-converters-first-look/ This lens is for full frame mirrorless format. What would happen if I attach this to a6000? Will I see...

www.dpreview.com

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

But, when I read this:

Crop Sensor (APS-C) Cameras and Lens Confusion

It gives example:

50mm on full frame = 31.3mm on APS-C

Now, I am confused. Why not 50mm on full frame = 75mm on APSC? Like the answer on my question abous the FE 28mm F2.0 lens on A6000.

Thanks.

 

[le_alain]

I hope someone can explain this to me.

Recently, I asked this question "The new lens FE 28mm F2.0 on a6000?".

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

But, when I read this:

http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html

It gives example:

50mm on full frame = 31.3mm on APS-C

Now, I am confused. Why not 50mm on full frame = 75mm on APSC? Like the answer on my question abous the FE 28mm F2.0 lens on A6000.

Thanks.

"It gives example:

50mm on full frame = 31.3mm on APS-C"

NO:

A 50mm on APSC will have the same field of view as a 75mm on FF sensor.

he said the contrary, you need to have a 31.3mm lense on APSC to match the field of view of a 50mm lense on FF

 

[Digital Nigel]

I hope someone can explain this to me.

Recently, I asked this question "The new lens FE 28mm F2.0 on a6000?".

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

But, when I read this:

http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html

It gives example:

50mm on full frame = 31.3mm on APS-C

Now, I am confused. Why not 50mm on full frame = 75mm on APSC? Like the answer on my question abous the FE 28mm F2.0 lens on A6000.

It just means that to get the equivalent field of view of a 50mm lens on a FF camera, you'd need a 31.3mm lens on a Canon APS-C camera (or 33.3mm on a Sony/Nikon).

 

[harry2007]

I hope someone can explain this to me.

Recently, I asked this question "The new lens FE 28mm F2.0 on a6000?".

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

But, when I read this:

http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html

It gives example:

50mm on full frame = 31.3mm on APS-C

Now, I am confused. Why not 50mm on full frame = 75mm on APSC? Like the answer on my question abous the FE 28mm F2.0 lens on A6000.

Thanks.

"It gives example:

50mm on full frame = 31.3mm on APS-C"

NO:

A 50mm on APSC will have the same field of view as a 75mm on FF sensor.

I was referring to this article text:

 

[le_alain]

I hope someone can explain this to me.

Recently, I asked this question "The new lens FE 28mm F2.0 on a6000?".

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

But, when I read this:

http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html

It gives example:

50mm on full frame = 31.3mm on APS-C

Now, I am confused. Why not 50mm on full frame = 75mm on APSC? Like the answer on my question abous the FE 28mm F2.0 lens on A6000.

Thanks.

"It gives example:

50mm on full frame = 31.3mm on APS-C"

NO:

A 50mm on APSC will have the same field of view as a 75mm on FF sensor.

I was referring to this article text:

as i said above, you read it in the wrong way:

y=To match the 50mm field of view on an FF camera, you need a 31.3mm lense on an APSC sensor

 

[harry2007]

I hope someone can explain this to me.

Recently, I asked this question "The new lens FE 28mm F2.0 on a6000?".

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

But, when I read this:

http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html

It gives example:

50mm on full frame = 31.3mm on APS-C

Now, I am confused. Why not 50mm on full frame = 75mm on APSC? Like the answer on my question abous the FE 28mm F2.0 lens on A6000.

It just means that to get the equivalent field of view of a 50mm lens on a FF camera, you'd need a 31.3mm lens on a Canon APS-C camera (or 33.3mm on a Sony/Nikon).

Oh ...

I think it should be read like this:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm APSC lens when using full frame camera.

Damn confusing

Thanks.

 

[Pixel Pooper]

They're both saying the same thing. Sony APS-C needs 1.5 times less focal length to match the FF field of view. The second example is talking about Canon so he uses 1.6 instead of 1.5 because their APS-C sensor is slightly smaller.

 

[harry2007]

I hope someone can explain this to me.

Recently, I asked this question "The new lens FE 28mm F2.0 on a6000?".

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

But, when I read this:

http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html

It gives example:

50mm on full frame = 31.3mm on APS-C

Now, I am confused. Why not 50mm on full frame = 75mm on APSC? Like the answer on my question abous the FE 28mm F2.0 lens on A6000.

Thanks.

"It gives example:

50mm on full frame = 31.3mm on APS-C"

NO:

A 50mm on APSC will have the same field of view as a 75mm on FF sensor.

I was referring to this article text:

as i said above, you read it in the wrong way:

y=To match the 50mm field of view on an FF camera, you need a 31.3mm lense on an APSC sensor

Right ... I should read it like this:

To match the 50mm field of view on an FF camera, you need a 31.3mm lense on an APSC sensor, both are full frame lens (FE lens).

Thanks, I understand now.

 

[Pixel Pooper]

Oh ...

I think it should be read like this:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm APSC lens when using full frame camera.

No, it should read:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm lens when using an APS-C camera.

It doesn't matter if you have a full frame lens or APS-C lens.

 

[harry2007]

Oh ...

I think it should be read like this:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm APSC lens when using full frame camera.

No, it should read:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm lens when using an APS-C camera.

It doesn't matter if you have a full frame lens or APS-C lens.

You see, that's the confusion.

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

As you said the lens doesn't matter.

Why 42mm? and not 18.6mm?

 

[RGBaker]

Oh ...

I think it should be read like this:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm APSC lens when using full frame camera.

No, it should read:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm lens when using an APS-C camera.

It doesn't matter if you have a full frame lens or APS-C lens.

You see, that's the confusion.

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

As you said the lens doesn't matter.

Why 42mm? and not 18.6mm?

I'm hoping that the smiley face means you're not serious!



It is not unlike comparing discounts at the store -- an item that is on sale for '33% off the regular price' is the same as saying 'the regular price will be 50% more than the sale price' -- that doesn't translate into a sale price that is 50% off, nor does it mean that the price will increase by 33% when the sale is over.



So it is true that a 60mm lens on a crop camera delivers the same field of view as a 90mm lens on a FF camera; and that if you have a 60mm lens on a FF camera and want to match field of view on a crop camera you will need a 40mm lens. The separate issue of whether a lens is designed to cover a FF sensor or not has no bearing on the field of view -- as regards this point, you can summarize by thinking that all FF lenses will cover the sensor of a crop camera, but most crop lenses are designed too small and compact to cover the sensor of a FF camera ... but that focal length is not the issue, sensor coverage is.



HTH,
GB

 

[Pixel Pooper]

Why 42mm? and not 18.6mm?

Because the APS-C sensor is like a crop of a FF sensor, so you need a wider lens to get back the extra width that was cropped away.

 

[crudman]

Oh ...

I think it should be read like this:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm APSC lens when using full frame camera.

No, it should read:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm lens when using an APS-C camera.

It doesn't matter if you have a full frame lens or APS-C lens.

For those that don't understand this last comment see this pic:

http://www.borrowlenses.com/blog/wp-content/uploads/2013/05/LensCropFactor.png

An aps-c lens (e.g. 50mm) at the lens position on the diagram will project the light so that it covers the entire aps-c sensor. A FF lens at that same position (same focal length e.g. 50mm FE) will cover even more area however an aps-c camera will only collect light on the original area (where the sensor is), the rest is wasted. So you will still be stuck with the same field of view as aps-c(black dotted line as opposed to the red line or any other lines).

The below image shows why a shorter focal length in aps-c equals the same field of view for a given FF focal length. The above does too but this spells it out better.

https://imgur.com/6aHyX

 

[bugeyed]

Oh ...

I think it should be read like this:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm APSC lens when using full frame camera.

No, it should read:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm lens when using an APS-C camera.

It doesn't matter if you have a full frame lens or APS-C lens.

You see, that's the confusion.

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

As you said the lens doesn't matter.

Why 42mm? and not 18.6mm?

Just keep rereading the article you reference until you understand it! Some of the answers you will get on this forum will just confuse you more. Like the comparison with store discounts????? You must realize that some answers come from people that are as confused as you are or can't explain it as well as the article does.

kev

 

[RGBaker]

Oh ...

I think it should be read like this:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm APSC lens when using full frame camera.

No, it should read:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm lens when using an APS-C camera.

It doesn't matter if you have a full frame lens or APS-C lens.

You see, that's the confusion.

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

As you said the lens doesn't matter.

Why 42mm? and not 18.6mm?

Just keep rereading the article you reference until you understand it! Some of the answers you will get on this forum will just confuse you more. Like the comparison with store discounts????? You must realize that some answers come from people that are as confused as you are or can't explain it as well as the article does.

kev

 

[bugeyed]

Oh ...

I think it should be read like this:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm APSC lens when using full frame camera.

No, it should read:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm lens when using an APS-C camera.

It doesn't matter if you have a full frame lens or APS-C lens.

You see, that's the confusion.

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

As you said the lens doesn't matter.

Why 42mm? and not 18.6mm?

Just keep rereading the article you reference until you understand it! Some of the answers you will get on this forum will just confuse you more. Like the comparison with store discounts????? You must realize that some answers come from people that are as confused as you are or can't explain it as well as the article does.

kev

 

[RGBaker]

No worries Kev -- I'm the first to admit that photographers as a herd are among the worst communicators! And having worked professionally with and as one for nearly forty years, I can also attest they are a prickly bunch, myself almost surely included.



Cheers,
GB

 

[Abe R Ration]

Oh ...

I think it should be read like this:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm APSC lens when using full frame camera.

No, it should read:

To get the equivalent field of view of 50mm lens on a full frame camera, I need a 31.3mm lens when using an APS-C camera.

It doesn't matter if you have a full frame lens or APS-C lens.

You see, that's the confusion.

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

As you said the lens doesn't matter.

Why 42mm? and not 18.6mm?

The angle of view equation tells you the answer: α = 2arctan(d/2f) where α is the angle of view, d is the size of the diagonal/horizontal/vertical of the image sensor and f is the focal length of the lens.

More on comparing formats here.

 

[MrCPH]

I hope someone can explain this to me.

Recently, I asked this question "The new lens FE 28mm F2.0 on a6000?".

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

But, when I read this:

http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html

It gives example:

50mm on full frame = 31.3mm on APS-C

Now, I am confused. Why not 50mm on full frame = 75mm on APSC? Like the answer on my question abous the FE 28mm F2.0 lens on A6000.

Thanks.

As the APS-C sensor is smaller than the full frame sensor (also known as 35mm), the same lens will look different depending on which type of camera/sensor you mount it.

The Sony APS-C sensors are approx. 1.5 times smaller than a full frame and other manufactures (such as Canon) is 1.6 times smaller.

Therefore you have to multiply the focal lengt by 1.5 (for Sony) to get the equivelant on a full frame sensor.

Example:

Sony SEL50f18 50mm e-mount lens. This would be the full frame equivelant of 50mm x 1.5 = 75mm. So in order to get the same look on a full frame camera, you would have to get a 75mm lens.

It will also work the other way. If you have a 50mm lens on a full frame camera, and you want to know what that would be on a Sony APSC camera, you would divide the 50mm with 1.5, hence you would need to get a 33mm lens for your APSC camera.

Does it make sense?

 

[harry2007]

I hope someone can explain this to me.

Recently, I asked this question "The new lens FE 28mm F2.0 on a6000?".

http://www.dpreview.com/forums/thread/3798945

And the answer was:

"The FE 28mm f2.0 on the A6000 will have the same field of view and depth of field as a 42mm f3.0 lens on FF sensor."

But, when I read this:

http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html

It gives example:

50mm on full frame = 31.3mm on APS-C

Now, I am confused. Why not 50mm on full frame = 75mm on APSC? Like the answer on my question abous the FE 28mm F2.0 lens on A6000.

Thanks.

As the APS-C sensor is smaller than the full frame sensor (also known as 35mm), the same lens will look different depending on which type of camera/sensor you mount it.

The Sony APS-C sensors are approx. 1.5 times smaller than a full frame and other manufactures (such as Canon) is 1.6 times smaller.

Therefore you have to multiply the focal lengt by 1.5 (for Sony) to get the equivelant on a full frame sensor.

Example:

Sony SEL50f18 50mm e-mount lens. This would be the full frame equivelant of 50mm x 1.5 = 75mm. So in order to get the same look on a full frame camera, you would have to get a 75mm lens.

It will also work the other way. If you have a 50mm lens on a full frame camera, and you want to know what that would be on a Sony APSC camera, you would divide the 50mm with 1.5, hence you would need to get a 33mm lens for your APSC camera.

Does it make sense?

Yes, it does.

At the end, the full frame camera and it's lens are "wider" than APS-C, as I understood it now.

I own SEL35F18 and a6000, I found it quite difficult when using it indoor. I need to make some distance.

For the same 35mm focal length, with full frame camera and full frame lens, I would "see" the field of view like 24mm on my current camera and lens

I was thinking to switch to full frame in the future (thinking A7000), but I wasn't sure with the full frame lens selection. I was afraid that the "tight" situation as I have now with SEL35mmF18+a6000 will be the same or worse. Granted, I have never held a full frame camera and lens, so I don't know the experience.