Is the 2X zoom on an iPhone 8 Plus digital or optical zoom

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Stanley
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Joined: Sun Aug 02, 2009 2:34 pm

Is the 2X zoom on an iPhone 8 Plus digital or optical zoom

Post by Stanley »

Hi everyone,

I recently took some macro shots using my iPhone 8 Plus at 2X zoom. I thought that 2X on the iPhone 8 Plus was optical zoom.

But the EXIF information on my photographs called my 2X “DigitalZoomRatio.” So, please, is the 2X zoom on my camera optical or digital?

Thank you.

Stanley

Stanley
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Joined: Sun Aug 02, 2009 2:34 pm

Post by Stanley »

Hi everyone,

No one answered by question regarding digital versus optical zoom, and of course none of you nice people were obligated to respond. So I continued to further investigate this issue.

I was not finding definitive answers, so finally I contacted Hunter Research & Technology (let’s call it HRT). Why this company? Because I took the photograph, which prompted my question to begin with, using the theodolite app that they produce. Just to be clear, I have no financial interest in HRT at all, but some time ago I purchased a bundle containing four excellent apps that they make. This package, for which I paid about $11, contains a theodolite (which you can just use as a camera), an altimeter, and a compass. Although the theodolite does not have its purpose to take close-up photos, I did use it for that purpose. In particular, I took a close up of a small, empty wasp nest that I found while doing some cleaning around my house, and I used the 2X zoom on my iPhone 8 Plus to take the wasp-nest picture.

What confused me was the fact that the EXIF information on my photograph refer to the 2X zoom on my picture as “DigitalZoomRatio.” Now, in a previous inquiry that I sent to HRT, the owner of the company told me that “devices with dual camera have optical zoom for 2X and digital zoom for 4X and 8X.” In case you did not know, the iPhone 8 Plus does have a dual camera. So, then, why did the EXIF data call the zoom ratio digital zoom?

Here is the answer that HRT sent me to that second question. I am sure that I may cite the response, since I am not saying anything negative, and in fact I am praising the apps that HRT produces. For clarity, I am editing the answer slightly:

“We use that tag because it’s the only EXIF tag available to store zoom information. It doesn’t imply anything about whether it’s optical or digital in the case of an iPhone. In fact, the Apple camera sensor doesn’t report whether an image is optical or digital zoom either, nor does it act like it has multiple lenses — as far as the software is concerned, it’s just a black box digital camera that delivers image data with certain metadata tags. The only reason we know certain devices use optical zoom is based on independent knowledge of the hardware. Interestingly, I don’t believe all digital cameras can report optical zoom — certainly not the Nikon digital SLR I own. The manual zoom optics on that lens have no electronic connection to the camera, and the image sensor captures the pixels as a 1X image regardless of the lens zoom.”

So there we have it. According to HRT, when you take a picture at 2X on a cell phone with dual camera (such as the iPhone 8 Plus), you are using optical zoom and not digital zoom. That is the case whether you use the iPhone’s native camera app or HRT’s theodolite app.

Stanley

Pau
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Post by Pau »

Interesting... :smt017
In fact if your dual camera phone has two cameras of different focal length likely you're no using a zoom at all, just the "tele" lens camera
Pau

Stanley
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Joined: Sun Aug 02, 2009 2:34 pm

Post by Stanley »

Hi Pau,

OK. That's an interesting thought, that I may just be using the telephoto lens.

Stanley

Troels
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Post by Troels »

I suppose Pau is right. Modern cellphones often have several separate cameras of different focal length.
Apart from that it should be rather simple to know if a certain camera uses digital zoom: At 2x digital zoom the width of the picture measured in pixels should be half that of the non-zoomed picture.
Troels Holm, biologist (retired), environmentalist, amateur photographer.
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Chris S.
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Post by Chris S. »

Stanley,

Thanks for alerting me to the existence of Hunter Research & Technology's Theodolite app. I took a look at it and decided it would be well worth the $6 price for things I do. I also like their other apps, such as Professional Compass, professional altimeter, Nav Camera, and Weather. I ended up paying $11 for their whole bundle, and like it a lot. I have several other weather apps, but don't like any of them. I can delete them now, as this one does everything I want, and nothing I don't want. Perfect.

--Chris S.

grgh
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Post by grgh »

Stanley

Had the package from HRT for nearly ten years, got it just after they first bought it out.

you should really get into all its usage as its fascinating just how powerful it can be.

All the best.
used to do astronomy.
and photography.
Zeiss Universal Phase contrast.
Zeiss PMII

ohdeeremee
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Post by ohdeeremee »

FWIW, I was looking at some images in my Lightroom, knowing I took both 1X and 2X pix with a iPhone XS Max. They all show up as 3024 x 4032, but one has a Focal Length of 6mm and the other as 4.25mm.

That means it is really Optical, not digital 2X.

Should be the same for you iPhone 8 Plus.

George

Stanley
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Joined: Sun Aug 02, 2009 2:34 pm

Post by Stanley »

Chris S. wrote:Stanley,

Thanks for alerting me to the existence of Hunter Research & Technology's Theodolite app. I took a look at it and decided it would be well worth the $6 price for things I do. I also like their other apps, such as Professional Compass, professional altimeter, Nav Camera, and Weather. I ended up paying $11 for their whole bundle, and like it a lot. I have several other weather apps, but don't like any of them. I can delete them now, as this one does everything I want, and nothing I don't want. Perfect.

--Chris S.
Hi Chris,

First, I am sorry I am so long in responding to you. I was on vacation for a few days, so I was away from my computer.

Second, I am glad that you like the apps.

Stanley

Stanley
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Joined: Sun Aug 02, 2009 2:34 pm

Post by Stanley »

grgh wrote:Stanley

Had the package from HRT for nearly ten years, got it just after they first bought it out.

you should really get into all its usage as its fascinating just how powerful it can be.

All the best.
Hi grgh,

Well, with your credentials, then I know that the apps are good.

Stanley

Stanley
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Joined: Sun Aug 02, 2009 2:34 pm

Post by Stanley »

ohdeeremee wrote:FWIW, I was looking at some images in my Lightroom, knowing I took both 1X and 2X pix with a iPhone XS Max. They all show up as 3024 x 4032, but one has a Focal Length of 6mm and the other as 4.25mm.

That means it is really Optical, not digital 2X.

Should be the same for you iPhone 8 Plus.

George
Hi George,

First, I am sorry I am so long in responding to you. I was on vacation for a few days, so I was away from my computer.

Now, your response truly intrigues me and pleases me to confirm that the 2X is in fact optical zoom.

But please explain the logic a bit more so that I understand it. Does the 6 mm focal length indicate the 2X zoom and the 4.25 mm indicate the 1X zoom? Or is it the other way around?

And in general, how do the numbers work, please? Since the 3024 x 4032 is fixed, then why does the change in focal length demonstrate a change in zoom. I have a vague idea, but I would like to understand this in greater detail.

Thank you.

Stanley

Stanley
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Joined: Sun Aug 02, 2009 2:34 pm

Post by Stanley »

Hi George and anyone else,

Now I understand my confusion on the focal-length issue. I can formulate the question, but I don't know the answer.

The 2X optical zoom should produce an image twice as large as does the 1X optical zoom. To test this, I used my iPhone 8 Plus to take a picture of my house, standing from a fixed point. This way I could make an easily measurable, apples-to-apples comparison.

And indeed, when I took the picture at 2X, it produced an image exactly twice the size both vertically and horizontally as the 1X picture.

And here is my confusion. One of the lenses on my iPhone has a focal length of 3.99, and the other lens has a focal length of 6.60. Well, 6.60/3.99 is approximately 1.654, and that is not even close to 2.

So, please, why the discrepancy?

Thank you.

Stanley

Pau
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Post by Pau »

Perhaps the sensor size is different.
Pau

Stanley
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Joined: Sun Aug 02, 2009 2:34 pm

Post by Stanley »

Pau wrote:Perhaps the sensor size is different.
Hi Pau,

Could you please explain in a bit more detail what you mean by that.

Stanley

Bob-O-Rama
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Its comparing apples to oranges

Post by Bob-O-Rama »

Both of the iPhone 8+ cameras are 12MP cameras, and both share a common die size, however the wide camera has has a larger pixel pitch ( 1 vs ~1.22 um ) . So the ratio will not be 2:1. It should be something like 2 * ( 1 / 1.22 ) = 1.64:1 which is certainly close enough to your observed value.

-- Bob

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