How to simply calculate CL vocal lengths on SL cameras?

[lct]

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1 hour ago, Robert E said:

Bingo! That's the correct answer. 

 

 

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[jaapv]

On 4/1/2021 at 4:10 AM, lct said:

In APS-C mode you must multiply by 1.5x so it gives 82-202mm equivalent FoV in your example. Think of your SL2 as a bulky CL when you use a TL lens on it. It is just another APS-C camera then. 

Guys., FOV is the width of a view at a given distance - usually 100 meter. If you really must confuse the issue of an unchanging focal length on different sensor sizes, please use the correct parameter: Angle of View. At least that makes sense, which FOV does not.

[lct]

29 minutes ago, jaapv said:

Guys., FOV is the width of a view at a given distance - usually 100 meter. If you really must confuse the issue of an unchanging focal length on different sensor sizes, please use the correct parameter: Angle of View. At least that makes sense, which FOV does not.

Would you say that you disagree with this article then?

https://photographylife.com/equivalent-focal-length-and-field-of-view

[beewee]

22 minutes ago, lct said:

Would you say that you disagree with this article then?

https://photographylife.com/equivalent-focal-length-and-field-of-view

Or this one for that matter.

[jaapv]

5 hours ago, lct said:

Would you say that you disagree with this article then?

https://photographylife.com/equivalent-focal-length-and-field-of-view

Yes. I would agree with Leica, who define the field of view of their binoculars as  "feet at 100 yards"

https://us.leica-camera.com/SPORT-OPTICS/Lifestyle-Leisure/Leica-Binoculars/Leica-Trinovid/Models

And with all camera manufacturers defining their lens coverage as "angle of view" for the sensor format.

 

And with:

https://www.techradar.com/how-to/photography-video-capture/cameras/photography-basics-angle-of-view-1325784/1

And this guy sorted the thing out (note that he calls the Internet  "befuddled" - and he is right-.

https://shuttermuse.com/angle-of-view-vs-field-of-view-fov-aov/

[jaapv]

On 4/1/2021 at 8:03 PM, oldwino said:

If I remember correctly, Leica printed the equivalent focal lengths on the barrel of the X-Vario lens. 
For us old guys, who grew up using 35mm film cameras, seeing “28-70” on the lens made a whole lot more sense than “18-47”. I know what the FOV of 28mm lens looks like, or a 50mm. When I put my 50mm Summar on my (digital) CL, it’s not a “50” anymore..

So they did on the Digilux 2. It is just a simple reference for photographers that are used to the 135 format, but confusing for those who think in the focal lengths of for instance medium format, MFT, etc.

[lct]

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4 hours ago, jaapv said:

Yes. I would agree with Leica, who define the field of view of their binoculars as  "feet at 100 yards"

https://us.leica-camera.com/SPORT-OPTICS/Lifestyle-Leisure/Leica-Binoculars/Leica-Trinovid/Models

 

Not sure to see the link between Trinoids and crop factors but you would disagree with exif data referring to "field of view" and reviewers like Sean Reid referring to "equivalent field of view" (EFOV)  then i guess. Now would you agree with Leica when they say that the frame lines of the M8 "show the correct field of view" when taking crop factors into account? Just curious.

[Robert E]

OK guys, then answer this question:  If Leica manufactures a lens made for the APS-C cameras (TL & CL) and they label it "55-135"mm: then what is it on the camera?

Is it a 55-135 or is it a "82-202" mm lens? Forget the FOV or AOV confusing stuff, stick to the mm's. There must be a reason it's labeled 55-135 and NOT 82-202, right?

This formula everyone seems to apply to an APS-C sensor camera of multiplying by 1.4 or 1.5x should not even come into play when the manufacturer labels the lens a specific MM in length.  It should only apply if you put a non-APS-C lens on the camera; IE: put a Leica VE 24-90 zoom on a CL camera. It's no longer a 24-90 because that is it's designation on a SL.

😃

 

[BernardC]

13 minutes ago, Robert E said:

If Leica manufactures a lens made for the APS-C cameras (TL & CL) and they label it "55-135"mm: then what is it on the camera?

Is it a 55-135 or is it a "82-202" mm lens? Forget the FOV or AOV confusing stuff, stick to the mm's. There must be a reason it's labeled 55-135 and NOT 82-202, right?

That is right. The lens is always a 55-135, on any camera, or even on its own (used as a magnifier, or to project an image of the Sun on a piece of paper).

[lct]

33 minutes ago, Robert E said:

OK guys, then answer this question:  If Leica manufactures a lens made for the APS-C cameras (TL & CL) and they label it "55-135"mm: then what is it on the camera?

Is it a 55-135 or is it a "82-202" mm lens? Forget the FOV or AOV confusing stuff, stick to the mm's

Impossible to forget them sorry. 55-135 is the focal length (or lengths) of the lens. Remains the same on any camera. Now when you put your 55-135 on an APS-C camera, it remains a 55-135 lens as far as focal length but its field of view is cropped by 1.5x. 88-202mm is then the translation of such cropping in terms of field of view. As for AOV (angle of view) calculations, ask Jaap to explain please i'm sure it will be interesting.

Edited April 3, 2021 by lct

[pop]

vor 59 Minuten schrieb Robert E:

If Leica manufactures a lens made for the APS-C cameras (TL & CL) and they label it "55-135"mm: then what is it on the camera?

Is it a 55-135 or is it a "82-202" mm lens? Forget the FOV or AOV confusing stuff, stick to the mm's. There must be a reason it's labeled 55-135 and NOT 82-202, right?

Right.

The focal length is the distance of the lens from the film (or sensor, of course) when taking a photograph of the sun (don't!) or the moon, that is, of things that are very far away. You can observe the focal length of a lens even without any camera: just hold it over a sheet of paper and look how far it is from the paper when the image of the moon is sharp; or of the sun, of course. Beware, however, of playing with images of the sun; you'll soon find out why it's called the 'Brennweite' in German (that is, the 'burning distance').

All lenses of the same focal length will make pictures of the same objects at the same scale. The image of - say - your house, your car or your spouse will be exactly the same size whenever you use a lens with a focal length of 55mm from the same distance, regardless of the size of the film or sensor in the camera. Using a camera with a large film format might show the entire house, car or spouse. Using a camera with a smaller sensor might only be able to depict the chimney, the steering wheel or the face of the spouse. Using a camera with a larger film will get more of the environment into the image. My grandfather used a traveling camera which took pictures of about 120mm by 80mm on plates of glass. A lens with a focal length of 55mm would be wide-angled lens.

Calling a 55mm lens "equivalent to 82mm" is an attempt to make it simple for people accustomed to using cameras for 35mm films. It makes life hard for people accustomed to other formats, like the 60mm by 60mm Hasselblad. It says that you will get about as much of the landscape in your picture as you would with a 82mm lens when using a 35mm film camera.

Edited April 3, 2021 by pop

[lct]

Not sure what is more difficult on medium format. The S2 must have a crop factor of 0.8 or something, then a 80mm lens has an equiv. FoV of 80 x 0.8 = 64mm on the S2. Correct me if i'm wrong as i have no experience with MF cameras.

[Jeff S]

One factor that complicates MF (or LF) comparisons is different aspect ratios.  The S system maintains the 3:2 ratio from 35mm format. Large and medium format aspect ratios come in a wide variety of flavors, making 35mm comparisons difficult. Add to that DOF differences, typical print size differences, etc, and rendering comparisons  become obscure. 
 

As I wrote early on, similar to Pop’s comment, one gets used to how certain focal lengths render on certain formats and and ignores format comparisons and math.  The eye sees what the math often can’t easily explain.

Jeff

 

[pgk]

The problem we have is that we think of focal length as defining 'angle of view'. It doesn't, because it is the combination of both focal lenth and sensor/film format size which do, so the whole concept of 'equivalent focal lengths' is somewhat flawed. What we need to appreciate is the a 'crop factor' is just that, it crops the image produced by a lens to reduce the recorded 'angle of view' (by for example 1.5x which equates to 2/3 of the 35mm full frame angle of view, and so on). All that said, most of us have got used to appreciating the angle of view of a focal length on the full frame 35mm format (24x36mm), so it is very tempting to equate other formats to our understanding of the 'field of view' of images produced by the focal lengths on this format. Providing it is understood that we are merely referring to 'angle of view' equivalence then this is ok. Confusion kicks in when we try to think beyond this.

[lct]

23 minutes ago, Jeff S said:

One factor that complicates MF (or LF) comparisons is different aspect ratios.  The S system maintains the 3:2 ratio from 35mm format. Large and medium format aspect ratios come in a wide variety of flavors, making 35mm comparisons difficult. Add to that DOF differences, typical print size differences, etc, and rendering comparisons  become obscure. 
 

As I wrote early on, similar to Pop’s comment, one gets used to how certain focal lengths render on certain formats and and ignores format comparisons and math.  The eye sees what the math often can’t easily explain.

Jeff

It should not be obscure IMHO. 3:2 and other aspect ratios are taken into account in the calculation of the crop factor given that the latter is based on the diagonal of the sensor. Same for DoF which depends on CoC (circle of confusion) which depends itself on the crop factor. Easy to check on a DoF calculator. 

[Jeff S]

14 minutes ago, lct said:

It should not be obscure IMHO. 3:2 and other aspect ratios are taken into account in the calculation of the crop factor given that the latter is based on the diagonal of the sensor. Same for DoF which depends on CoC (circle of confusion) which depends itself on the crop factor. Easy to check on a DoF calculator. 

I don’t bother with DOF calculations or crop factors when I’m out photographing.  I just know how my lens and focal length works on any given format.  That’s my point. Using a S 30mm lens and thinking that it acts just like a 24mm lens on full frame misses some key points, for me. It still has the optical characteristics of a 30mm lens. I don’t waste my time with equivalencies.  YMMV.

David Farkas expresses it better...

https://www.reddotforum.com/content/2020/04/the-definitive-guide-to-leica-s-lenses/

And that’s without getting into different aspect ratio comparisons.

Jeff

Edited April 3, 2021 by Jeff S

[lct]

Nobody has to be interested in equivalences but as far as FoV and/or DoF calculations are concerned, some calculation must be made anyway. My point is just that there is nothing obscure in them. 

[ravinj]

I like it how Sony does it on their compact cameras, RX100VI in this case. FL of the lens imprinted on front, but you see the 35mm equivalent FoV or Angle of view or whatever you want to call it on the screen.

 

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Hallo,

Look here: Leica L-Mount

[ravinj]

Alternatively, skip all other cameras and lenses - just use the Leica Q2 and you are assured that is a 28mm lens with a 28 mm "Fov" or "AoV". Always. All the time, crop function not withstanding

 

[pgk]

I've always thought of a 20mm lens (on 35mm format) as having a Field of View of about 90 degrees. Its the easy one. I can't remember any others.