Is digital zoom a worthless gimmick?

Started Jul 25, 2013 | Discussions
bssfujifan
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Is digital zoom a worthless gimmick?
Jul 25, 2013

I might well be wrong, but I cannot see the need to use digital zoom for taking a picture. It seems to me that   post capture cropping would do the same job, but without the increased possibility of camera shake due to the effective increase in focal length obtained by using digital zoom. Could someone please tell me if the following reasoning is correct:

X2 digital zoom would double the effective focal length of the lens, but use 1/(2x2) = 1/4 of the sensor. Shutter speed would need to be twice as fast to cope with effectively doubling the focal length of the lens (or use double the ISO setting). Alternatively you could forget digital zoom and crop the picture post camera. Cropping to double the linear image size (equivalent to doubling focal length of the lens) would again result in 1/4 of the sensor being used. However, as this was done post capture there would be no need to use a faster shutter speed (or double the ISO).  Also cropping would give more flexibility and fine tuning with composition than when using digital zoom at the point of image capture.

The only possible advantage I can see with digital zoom is that the image will look bigger in the viewfinder/screen, although there will be no additional resolution of detail as there would be when using optical zoom.

If I've misunderstood or overlooked something, I'm sure someone out there will be able to put me right. Thanks for taking the trouble to read this!

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Aldersyde
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Re: Is digital zoom a worthless gimmick?
In reply to bssfujifan, Jul 25, 2013

I have never used digital zoom, I agree it seems pointless.

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bssfujifan
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Re: Is digital zoom a worthless gimmick?
In reply to Aldersyde, Jul 25, 2013

Thanks. I've never used it either!

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Alexander Meredith
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Re: Is digital zoom a worthless gimmick?
In reply to bssfujifan, Jul 25, 2013

bssfujifan wrote:

I might well be wrong, but I cannot see the need to use digital zoom for taking a picture. It seems to me that post capture cropping would do the same job, but without the increased possibility of camera shake due to the effective increase in focal length obtained by using digital zoom. Could someone please tell me if the following reasoning is correct:

X2 digital zoom would double the effective focal length of the lens, but use 1/(2x2) = 1/4 of the sensor. Shutter speed would need to be twice as fast to cope with effectively doubling the focal length of the lens (or use double the ISO setting). Alternatively you could forget digital zoom and crop the picture post camera. Cropping to double the linear image size (equivalent to doubling focal length of the lens) would again result in 1/4 of the sensor being used. However, as this was done post capture there would be no need to use a faster shutter speed (or double the ISO). Also cropping would give more flexibility and fine tuning with composition than when using digital zoom at the point of image capture.

The only possible advantage I can see with digital zoom is that the image will look bigger in the viewfinder/screen, although there will be no additional resolution of detail as there would be when using optical zoom.

If I've misunderstood or overlooked something, I'm sure someone out there will be able to put me right. Thanks for taking the trouble to read this!

See here

http://www.mediacollege.com/video/camera/zoom/digital-vs-optical.html

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bssfujifan
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Re: Is digital zoom a worthless gimmick?
In reply to Alexander Meredith, Jul 25, 2013

Thanks for that. It looks like the article confirms my thoughts on the matter.

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PAUL TILL
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Re: Is digital zoom a worthless gimmick?
In reply to bssfujifan, Jul 25, 2013

I find it very useful, I get to see my subject 2 times larger in the EVF/LCD so I can compose my shot easier. I shoot RAW + JPEG so I always have the RAW file to work with and that obviously stays at the proper size as the digital TC doesn't affect the RAW file.

The shot below is the RAW file converted to JPEG so I can show it here, shot at 300mm which is 600mm equivalent on micro 4/3rds.

This shot is the JPEG with the 2X digital TC turned on 1200mm equivalent. Straight out of the camera.

This one is a crop of the RAW file in CS5.

As you can see the shot with the digital TC turned on is not bad, remember that is a SOOC JPEG I'm sure it would look even better with a little PP.

So, is digital zoom worthless? I say no, it can be very useful.

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PAUL TILL
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Re: Is digital zoom a worthless gimmick?
In reply to PAUL TILL, Jul 25, 2013

You can also see that on the original RAW I focused on the birds eye, the 2X digital shot shows how I recomposed knowing how I wanted the shot to turn out.

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seilerbird666
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No it is not a worthless gimmick?
In reply to bssfujifan, Jul 25, 2013

You are not the target audience for digital zoom. If you know how to PP then digital zoom is a worthless feature. However for the 95% of the camera users that don't PP then digital zoom is wonderful. Is it technically as good as cropping in PP? It doesn't matter. Most of the people who use it have no clue what PP is.

It is really quite simple if there is a feature on your camera that you don't like then don't use the feature. Starting a thread to slam the feature just because you don't understand it is pretty pointless.

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Aldersyde
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Re: No it is not a worthless gimmick?
In reply to seilerbird666, Jul 25, 2013

Not such a pointless thread, Paul Till makes an interesting point.

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AdamT
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In reply to bssfujifan, Jul 25, 2013

Not to Tourists who just upload everything to Facebook or plug the SD card into a Photobooth when they get back off holiday and churn a buch of 6X4s out .

to anyone who edits their images then its of little value (usually worse than cropping and upsizing yourself) but to the shoot`n`blog brigade it`s a no lose scenario and cuts time out.

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Trevor G
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Re: Is digital zoom a worthless gimmick?
In reply to PAUL TILL, Jul 25, 2013

PAUL TILL wrote:

I find it very useful, I get to see my subject 2 times larger in the EVF/LCD so I can compose my shot easier. I shoot RAW + JPEG so I always have the RAW file to work with and that obviously stays at the proper size as the digital TC doesn't affect the RAW file.

You're a clever man, Paul Till.  Sometimes 

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jcmarfilph
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Re: Is digital zoom a worthless gimmick?
In reply to bssfujifan, Jul 25, 2013

bssfujifan wrote:

I might well be wrong, but I cannot see the need to use digital zoom for taking a picture. It seems to me that post capture cropping would do the same job, but without the increased possibility of camera shake due to the effective increase in focal length obtained by using digital zoom. Could someone please tell me if the following reasoning is correct:

X2 digital zoom would double the effective focal length of the lens, but use 1/(2x2) = 1/4 of the sensor. Shutter speed would need to be twice as fast to cope with effectively doubling the focal length of the lens (or use double the ISO setting). Alternatively you could forget digital zoom and crop the picture post camera. Cropping to double the linear image size (equivalent to doubling focal length of the lens) would again result in 1/4 of the sensor being used. However, as this was done post capture there would be no need to use a faster shutter speed (or double the ISO). Also cropping would give more flexibility and fine tuning with composition than when using digital zoom at the point of image capture.

The only possible advantage I can see with digital zoom is that the image will look bigger in the viewfinder/screen, although there will be no additional resolution of detail as there would be when using optical zoom.

If I've misunderstood or overlooked something, I'm sure someone out there will be able to put me right. Thanks for taking the trouble to read this!

Pointless unless you are IDing very distant subject or you want to make sure the subject is in focus.

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PAUL TILL
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Re: Is digital zoom a worthless gimmick?
In reply to jcmarfilph, Jul 25, 2013

jcmarfilph wrote:

Pointless unless you are IDing very distant subject or you want to make sure the subject is in focus.

Hardly pointless then! You've just given two very useful reasons for using it.

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evannole
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Re: Is digital zoom a worthless gimmick?
In reply to PAUL TILL, Jul 25, 2013

PAUL TILL wrote:

I find it very useful, I get to see my subject 2 times larger in the EVF/LCD so I can compose my shot easier. I shoot RAW + JPEG so I always have the RAW file to work with and that obviously stays at the proper size as the digital TC doesn't affect the RAW file.

The shot below is the RAW file converted to JPEG so I can show it here, shot at 300mm which is 600mm equivalent on micro 4/3rds.

This shot is the JPEG with the 2X digital TC turned on 1200mm equivalent. Straight out of the camera.

This one is a crop of the RAW file in CS5.

As you can see the shot with the digital TC turned on is not bad, remember that is a SOOC JPEG I'm sure it would look even better with a little PP.

So, is digital zoom worthless? I say no, it can be very useful.

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Very nice shots, all three. I will have to give this function a try.

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jcmarfilph
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Re: Is digital zoom a worthless gimmick?
In reply to PAUL TILL, Jul 25, 2013

PAUL TILL wrote:

jcmarfilph wrote:

Pointless unless you are IDing very distant subject or you want to make sure the subject is in focus.

Hardly pointless then! You've just given two very useful reasons for using it.

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It would be only useful if you can shoot RAW while digital zoom is ON with these HS and X-S1 cameras.

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tomhongkong
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Re: Is digital zoom a worthless gimmick?
In reply to bssfujifan, Jul 25, 2013

There are some potential good reasons for using it, quite apart from Paul Till's comment on composition.

First, you are wrong about needing a faster shutter speed if you use it.  Either in camera or in PP you are cropping the image (effectively getting the same FOV as a longer lens) so both techniques will show any shake equally.

Then there are two claimed advantages which could do with testing out

Fuji claim that there is some special interpolation going on when you use it, which is different from just cropping the image in PP and gives a better result.

Then, if you are using any area averaging technique for exposure, the important part of the image (presumably that which you are cropping down to) should set the exposure chosen by the camera.  So, as an example, if you crop out the sky using in camera digital zoom you should get better exposure of what would otherwise be a backlit subject.

Perhaps someone with time to spare could check (unfortunately I can't right now)

tom

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bssfujifan
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Re: Is digital zoom a worthless gimmick?
In reply to tomhongkong, Jul 25, 2013

Thanks to all those who have replied. As a result of the responses, I've discovered some new advantages of digital zooming that I hadn't considered. Also I've been corrected on my misunderstanding about digital zooming requiring a faster shutter speed to cope with increased camera shake. That was a surprise to me! This must be different from using a  teleconverter to increase the effective focal length of a lens. I assume this would require a faster shutter speed. My reason for starting this thread was not to slag off digital zooming, but to ask a question (admittedly in a provocative way!) which I hoped folks more knowledgeable than I am would be able to answer for me ( which you have). I don't think it's been pointless. Thanks again to everyone for your contributions.

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Lloydy
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Bssfujifan ...
In reply to bssfujifan, Jul 25, 2013

... Typically, I shoot Raw + Jpeg, which setting precludes the use of digital zoom. That being said I have experimented with digital zoom on all my Fuji digital cameras - Seven to date.

Reality is that if you are shooting solely Jpeg then digital zoom has a place in the tool kit and with modern sensors does not necessarily harm the output..

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Bill Donnell
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Re: Is digital zoom a worthless gimmick?
In reply to Aldersyde, Jul 26, 2013

I have programmed the FN button on  my X20 for digital zoom. There are occasions when I unexpectedly need it. A quick press of the button turns it on and off without going into the menu.

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Futax
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Re: Is digital zoom a worthless gimmick?
In reply to bssfujifan, Jul 26, 2013

I haven't posted on this forum for ages, but I thought I'd join in because it's an interesting subject.

Firstly, as has been pointed out, there is no advantage or disadvantage in using digital zoom (or digital TC) as regards shake or shutter speed.  They'll all suffer the same amount of blur as cropping.  A real TC won't affect the shake issue either (assuming it hasn't affected aperture value or light transmission), you just need to trade off the resolution/noise advantage versus image degradation due to optical limitations.

Paul Till makes a good point that digital zoom can help getting the correct focus.  However, it can also work against getting the right composition, if the image on the screen or in the viewfinder is bouncing around a bit.  In these situations cropping allows you to get the best composition at your leisure.

The other issue regarding digital zoom is that the camera uses a cropped image and upsamples this to the same resolution as a normal image.  I think this is where the term "interpolation" comes in: the extra pixels are added by interpolating between neighbouring pixels.  However, I think this is all a bit counter-productive.  You're not going to print or display the image at full resolution anyway; the image has to be downsampled before it can be printed or displayed at any sensible size, so all the interpolation is doing is adding approximation to the original image.  (Mind you, in practice, I rather doubt the image will be substantially degraded by this, because I've not seen much difference when I've looked at test images on this and other forums.)

In conclusion, I don't think there's much to choose between digital zoom or cropping, really.  But if you're using digital zoom and finding it difficult to keep the camera steady enough to get the right composition, don't be afraid to use the cropping route...

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