FS7: Cinema lens advice for FS7 film shoot

You are conflating “sensor crop” with “image circle”.

Image circle is a factor of the design of the lens. A 50mm designed for FF will produce an image circle large enough to cover a FF sensor. A 50mm designed for APS-C will produce an image circle large enough for APS-C, but will vignette on a FF sensor. Worth noting, the image circle will vary in size between different designs, even for lenses designed for the same format. Take 10 different 50mm lenses and I’ll bet they all produce slightly different sized image circles. But, importantly, their magnification will be the same.

Your A7 is performing sensor crop ‘in camera’. It’s simply using the central portion of the sensor to capture the image. It’s the same as taking the lens and using it on a 5D (FF) and a 7D (APS-C). Again, the magnification performed by the lens remains unchanged.
 
Donny 123 said:
if you are used to what a 1000mm APS-C lens will give you on an APS-C camera.. you have used it 100 times this month.. you know the shot you will get.. BUT you drop that lens in the lake and rush to rent another 1000mm lens but this time they only have a FF 1000mm lens.. which you have never used before.. you put it on your camera.. and its not the same shot had with the 1000mm APS-C lens..from the same camera position ..the FoV is narrower .. as per your lovely diagram.. surely this is correct
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No. It is wrong. The image will be the same. They are both 1000mm lenses. They produce the same magnification. The fact that one lens produces a larger image circle and can be used on a FF camera, with a wider FOV, is immaterial.
 
FoV=lens mm+CAMERA sensor size

Pretty simple?

Add to that the lens need to cover the given sensor size with its image circle.
 
Liam Hall said:
You are conflating “sensor crop” with “image circle”.

Image circle is a factor of the design of the lens. A 50mm designed for FF will produce an image circle large enough to cover a FF sensor. A 50mm designed for APS-C will produce an image circle large enough for APS-C, but will vignette on a FF sensor. Worth noting, the image circle will vary in size between different designs, even for lenses designed for the same format. Take 10 different 50mm lenses and I’ll bet they all produce slightly different sized image circles. But, importantly, their magnification will be the same.

Your A7 is performing sensor crop ‘in camera’. It’s simply using the central portion of the sensor to capture the image. It’s the same as taking the lens and using it on a 5D (FF) and a 7D (APS-C). Again, the magnification performed by the lens remains unchanged.
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But the FoV does change .. a 50mm FF lens will not be the same shot as a 50mm APS-C lens ..from the same position.. on an APS-C camera.. surely this is empirically true.. besides any hair splitting or semantics.. there is a term crop factor and its a physical thing.. and it exists to compare the difference in FoV.. surely you agree to this at least ..
 
Donny 123 said:
But the FoV does change ..
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No. It doesn't. It really doesn't. The image projected by the lens remains EXACTLY THE SAME. The image circle produced by the FF lens will be larger but it is not recorded by the APS-C camera.

Again, you are conflating SENSOR CROP.
 
Donny 123 said:
But the FoV does change .. a 50mm FF lens will not be the same shot as a 50mm APS-C lens ..from the same position.. on an APS-C camera.. surely this is empirically true.. besides any hair splitting or semantics.. there is a term crop factor and its a physical thing.. and it exists to compare the difference in FoV.. surely you agree to this at least ..
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Donny you are wrong.

'Crop factor' comes from stills. Stills had standardised on the 35mm film used in landscape format.. 'vista' 'full frame' - whatever - then the first digital DSLRs were release with smaller sensors and known to have a 'crop factor' because you existing lenses did not see the width they did with a FF film DSLR.

For example when I 'went digital' I was using a nikon F4 with a 24mm as my standard wide.. when I bouht the D1 I had to buy a 17mm to replicate that FOV because of the 'crop factor' for the nikon D1.
 
Liam Hall said:
No. It doesn't. It really doesn't. The image projected by the lens remains EXACTLY THE SAME. The image circle produced by the FF lens will be larger but it is not recorded by the APS-C camera.

Again, you are conflating SENSOR CROP.
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But that un recorded image area.. then makes the recorded image appear to be on a longer lens..there is less image.. the FOV does change..in practice looking through a EVF.. semantics aside.. are we not talking in circles of confusion.. mine Im sure.. but at the end of the day .. there is a crop effect .. of 1.5.. where ever it comes from.. by magic or aliens or divine intervention .. there its a change in the EVF.. !! say it's so.. please ...
 
OK lets down to basics.. you have an fs7 I believe.. I have a 50mm ff lens.. I deftly attach it to your beast.. you shoot a chart.. lining up the edges .. I then change that lens.. with a lot of care and attention.. to a 50mm APS-C lens..camera position is nailed into the floor.. will the charts edges still line up.. ?
 
Donny 123 said:
OK lets down to basics.. you have an fs7 I believe.. I have a 50mm ff lens.. I deftly attach it to your beast.. you shoot a chart.. lining up the edges .. I then change that lens.. with a lot of care and attention.. to a 50mm APS-C lens..camera position is nailed into the floor.. will the charts edges still line up.. ?
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They will be the same. Exactly the same. A 50mm is a 50mm is a 50mm...
 
Donny 123 said:
The what is crop factor.. why or where doers the 1.5X come from.. why does it even exist if there is no difference between FF /APS-S lenses.. when used on an APS-C camera .. ?
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The crop factor comes from the size of the sensor. It is independent of the lens. It's simply the relative size of the sensor compared to 135 stills format.
 
morgan_moore said:
Donny you are wrong.

'Crop factor' comes from stills. Stills had standardised on the 35mm film used in landscape format.. 'vista' 'full frame' - whatever - then the first digital DSLRs were release with smaller sensors and known to have a 'crop factor' because you existing lenses did not see the width they did with a FF film DSLR.

For example when I 'went digital' I was using a nikon F4 with a 24mm as my standard wide.. when I bouht the D1 I had to buy a 17mm to replicate that FOV because of the 'crop factor' for the nikon D1.
Click to expand...

But its now used in Video.. where as before the 5D it just wasn't a thing.. its used to "understand " the difference in FoV between FF and s35mm lenses /sensors .. either way you look at it.. its 1.5x factor or there abouts depending on manufactures .. although now even today Arri releases a FF Mini.. so as I said before.. within 10 years APS-C /s35mm sensors could be a thing off there past ..
 
Liam Hall said:
The crop factor comes from the size of the sensor. It is independent of the lens. It's simply the relative size of the sensor compared to 135 stills format.
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Yes I know.. ?? but the physically larger FF lens .. won't cover the APS_C sensor.. you are saying that has no effect on the image you see in the VF..between two 50mm lenses one being FF the other s35..on the same APS-C sensor sized camera.. Im still not getting your groove sir.. Im going to have a large Gin ..
 
Donny 123 said:
Sigma Cine primes are all FF.. will still work of course but your FoV will be different.. the Sigmas cine zooms are s35mm .. they are the basically the cine -ized versions os the Art series stills zooms..
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Gonna wade in for s*%ts and giggles...

I think it was a small slip of terminology that you're getting pulled up on, Donny.

You're right in that the different versions (FF and S35) of a 50mm (for example) will present different image circles - but not different Field of Views. One will cover the sensor adequately and the other won't and will cause a degree of vignette/drop-off around the edges.

But, if you ignore the vignette effect, the two different images from the 2 different lenses - aspect, content, size etc etc - are the same.

Ben.
 
Donny 123 said:
It would vignette .. ? its the opposite situation .. the back element cannot project a big enough image to cover the larger sensor..
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Nearly right:-) The image will be the same size, in terms of magnification, as one produced by FF lens but the APS-C lens won’t produce a big enough IMAGE CIRCLE to cover the larger sensor, so will vignette. By how much will depend on the design of the lens.
 
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Liam Hall said:
Nearly right:-) The image will be the same size, in terms of magnification, as one produced by FF lens but the APS-C lens won’t produce a big enough IMAGE CIRCLE to cover the larger sensor, so will vignette. By how much will depend on the design of the lens.
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Ok so how does it work the other way round.. a ff lens on an APS-C.. sensor.. the image is too large for the sensor .. its a narrower / tighter image .. ? in comparison to the same focal length APS-C sensor lens..
 
Donny 123 said:
Ok so how does it work the other way round.. a ff lens on an APS-C.. sensor.. the image is too large for the sensor .. its a narrower / tighter image .. ? in comparison to the same focal length APS-C sensor lens..
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With a FF lens on on an APS-C sensor the image will look the same as an APS-C lens of the same focal length on an APS-C sensor.

The FF lens will look narrower/tighter on an APS-C sensor compared to the same FF lens on a FF sensor. The APS-C lens will vignette on the FF Sensor, but the image contained within the ‘porthole’ will be the same size as the FF lens.

I now officially give up as I have to go pack for my shoot.
 
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