Difference between optical and digital zoom?

[Guinness]

On the lens of a lot of cameras, you see (number)mm - (number)mm, along with either digital or optical zoom info.. Since I'm familiar with my old Kodak C433, I'll use it as an example.. The lens says 3X optical zoom, and 36mm - 108mm equivalent. From what I read, supposedly I can use it as close as 36mm to the object, but that's not at all true.. 100mm is a bit more realistic. I don't need to have my camera right on top of an object, but I do need a camera I can use to capture objects as small as 3mm x 3mm x 10mm in length. The largest objects I need to capture are about 75mm x 75mm x 400mm across. If I understood how the "X" Zoom relates to the (number)mm - (number)mm, maybe I'd be able to start looking at the camera or lens I need to buy.. I most likely can't afford a brand new camera, so I have to include optical zoom capability in my searches even though it's a bit outdated. Can anyone explain this to a novice with limited photography terminology knowledge? I don't mind looking things up, but if there's more than one common abbreviation, such as SLR or DSLR, please include both acronyms... My budget is a bit low, around $250 USD/$250 Euro... Thank you..
Guinness
I fear the day my hunger for knowledge is satiated..

[DanK]

An optical zoom changes focal length, magnifying the image. (To be more accurate, it is narrowing the field of view.) With a longer focal length, the total number of pixels on the sensor cover a smaller area. A digital zoom simply spreads pixels out, so as you zoom out and magnify more, you have fewer and fewer pixels in the frame.

[Guinness]

So, if I were to take a photo of a cricket on a leaf, one a 10X optical zoom, the other a 10X digital zoom, most likely the better poster size picture would be the optical zoom?

[rtbaum]

As I understand it, you have hit the nail on the head, Guinness

[Guinness]

If optical zoom is that much better than digital, why would anyone want digital zoom? I have to be missing something here.. And by the way, are those yellow and red flowers under your username perennials in Mn? If they are, what are they? They'd look beautiful surrounding a monstrously large rose bush in my yard.. I need really good ground cover around it to keep weeds out, because weeding by hand near it is dangerous, it'll swallow you whole and no one would ever find you. Pretty sure it ate a rabbit this past summer..

[DanK]

Because digital zoom is cheap.

[Manfred M]

I hate to say it, but is really is nothing more than a marketing ploy that makes the camera performance look better than it really is.

"10x Digital Zoom" printed on the camera box or spec sheet sure sounds impressive, even if it not.

[jcuknz]

Since digital zoom is an in-camera means of enlarging a portion of the image with resulting loss of quality it is probably undesirable. Though these days with the profusion of pixels in even bridge cameras it becomes a reasonably viable option to increase magnification of the subject. Though 'custom' based on small pixeled cameras has it as a NO-NO.

If your needs are small, such as posting on the web then it is a viable option to a degree and in changing from a bridge camera to Micro Four Third I accepted a reduction in zoom reach because by cropping [ digital zooming in editing] I could get the same reach with similar image quality .... though most of the time I get better quality by using the limited optical range. With bridge cameras I have 430mm reach but with MFT only 280mm but a 17x13mm sensor compared to much smaller in the bridge. [also 16Mp instead of 10Mp ]

But I enjoy editing for what I have learnt to do with the process but for some with say a x3 zoom and no editing skill they would/might want/use the digital zoom.

My personal practice as I work with my x10 zoom and MFT is to use my two dioptre CU lens whenever I go near the close focusing distance of my rig so that I have the freedom to tightly frame the subject ... it is a practice I started with my bridge cameras and prefer .... though when I want even tighter framing I use extension tubes as a superior way of working ... anew skill I have learnt with my transition to MFT ... But that seems out of your budget so the long reach bridge seems to be the financial answer for you and so long as you shoot what you will want you can compete on this forum with alomst anybody

As to your desire for a camera to make tightly framed shots of subjects I would look at the Panasonic range of 'FZ' cameras where you get a long zoom which with the addition of a moderate close-up lens enables you to get tight framing ... NOT BY GOING IN CLOSE ... but by working from some way back from the subject. For example with my FZ50, an older model these days It has a 430mm zoom and adding a moderate two dioptre [ 500mm ] CU lens I with the focusing power of the lens can work at about 13 inches from the subject but fill the sensor with a 1.5" subject .

This is how bridge camera folk with their fixed in position lenses work but the principle is followed by interchageable lens camera users when they buy expensive macro lens in the 150-200mm range.There are a number of advantages to keeping back from the subject and you neither loose or gain Depth of Field working this way.

Infor regarding the camera you are familiar with the 36-108mm is a way of describing the angle of view the lens will give you. I cannot find a reference to the C433 camera but you would find that AF will click into focus closer at wide angle [36mm] than at telephoto [108mm] and this is common to all zooms.... my 430mm zoom of its own accord can only focus to two metres but adding the two dioptre CU lens enables it [ makes AF 'think' that something at 20" 500mm is at infinity and it focuses so. But since it can focus closer than infinity it will focus down to about 13 inches. Closer and it goes out of focus or AF doesn't work.
This practice of adding a moderate CU lens only works with longer lens [ I will not bore you with the maths ] and is a waste of time with short lenses such as your 36-108mm zoom.
The Panasonic FZ70 seems to be the budget priced camera within your expressed limits though if you are prepared to deal on Amazon I expect the range to be wider .. it has a longer zoom than I have so should be able to get tighter for the smaller subject .... bear in mind in all this getting tight framing that DoF is marginal to nothing ... an unfortunate fact of life.

Carpet beetle with insert of the full frame back when I had a Nikon 5700 camera ...



More recent spider in my sink MFT x10 zoom with CU lens



Neither quite as small as you want but with longer zoom you should fill the frame with that subject.

[rtbaum]

If optical zoom is that much better than digital, why would anyone want digital zoom? I have to be missing something here.. And by the way, are those yellow and red flowers under your username perennials in Mn? If they are, what are they? They'd look beautiful surrounding a monstrously large rose bush in my yard.. I need really good ground cover around it to keep weeds out, because weeding by hand near it is dangerous, it'll swallow you whole and no one would ever find you. Pretty sure it ate a rabbit this past summer..

Primrose from a conservatory in St Paul, Mn. Rabbit would find it tasty, gotta keep the rabbits well fed for rabbit eating rose bushes

I may get hammered for saying it but digital zoom is marketing ploy, essentially it is cropping the image to imitate zooming. Anytime you crop an image you lose pixels.

[Dave Humphries]

Hi Guinness,

Warm welcome to the CiC forums from me.


In the original post; you had several misconceptions, so let's dispel these one-by-one.

On the lens of a lot of cameras, you see (number)mm - (number)mm, along with either digital or optical zoom info.. Since I'm familiar with my old Kodak C433, I'll use it as an example.. The lens says 3X optical zoom, and 36mm - 108mm equivalent. From what I read, supposedly I can use it as close as 36mm to the object, but that's not at all true.. 100mm is a bit more realistic.

No, that's not how these figures work at all I'm afraid - and you have discovered this yourself.

Those mm figures are the 'focal length' of the lens (from 'wide angle' to 'telephoto') and do not relate in a practical way to lens to subject distances.

Let's also cover off something else;
Zooming is about image 'magnification' or the 'angle of view' you see through the viewfinder and on the LCD (or final image).
Focusing (distance) is how close the camera gets to the subject - in normal photography it is unimportant, but in macro and close up photography, it is relevant.
I'll admit that in macro and close up photography, the two do kinda become more interchangeable, but the figures you see for advertising cameras are not usually written with macro in mind. As John has said, you'll find the camera can focus closer at the wide angle end of the zoom range than at the telephoto end of the range.

I most likely can't afford a brand new camera, so I have to include optical zoom capability in my searches even though it's a bit outdated

You should not think in this way; the technology of zoom is not like the technology of photography as a whole.
You should be thinking like this: optical zoom is good, digital zoom is bad.

Digital zoom can always be done in Post Processing, by cropping the image - it achieves exactly the same result by the same means; throwing away pixels around the edge of the subject. What you end up with is an image with less detail.
When buying a camera for general and telephoto (think of small birds in trees at a distance) photography, you always want to consider only the optical zoom figures. Discount digital figures, in fact if you're going to do any post processing, I'd strongly recommend disabling digital zoom on the camera (there's usually a menu option for it), so it doesn't use digital zoom at all. That's what I do.
If you do not intend to do any Post Processing (PP), only then might it be worth you using digital zoom, if you cannot get the subject big enough in the image (and focused) when you have explored whether the best result is obtained by zooming in more and shooting from further away, or using wide angle and getting really close. The downside to getting too close to the subject is that you'll find that the subject begins to look odd, with the bits closest to the lens seem really big compared to bits slightly further away.

If I understood how the "X" Zoom relates to the (number)mm - (number)mm, maybe I'd be able to start looking at the camera or lens I need to buy. ~ Can anyone explain this to a novice with limited photography terminology knowledge?

The figure of "3x" is simply mathematically derived from the telephoto figure (108 mm) divided by the wide angle figure (36 mm), so 108/36 = 3, hence the "3x" (or 3 times) zoom.

However, that understanding alone is not sufficient to necessarily buy a camera that will do all you need.

I don't need to have my camera right on top of an object, but I do need a camera I can use to capture objects as small as 3mm x 3mm x 10mm in length. The largest objects I need to capture are about 75mm x 75mm x 400mm across.

This sounds like what we'd call 'product photography' - it would also help us to know what your subjects are going to be? We may then be able to help with lighting suggestions.
It ranges from close up (what most camera manufacturers have 'macro mode' on their lenses for).


Could you do me a favour please?
Could you click Settings (right at the top),
then Edit Profile (on left)
and put your first name in the Real Name field
and where you are (roughly) in the Location field,
then click the Save Changes button below and to right,
this helps everyone give you more personal and relevant answers - thanks in advance.

Cheers, Dave

[DanK]

Guiness,

Since you seem to be starting pretty much from scratch, I have a suggestion for you. This site has superb tutorials. I suggest you look at some of them. For example, under the first "concepts" link, you will find one that explains focal length. It's a lot more efficient to start with some of the tutorials, and they will give you a more comprehensive overview than things that we write on the fly. Once you have looked at them, post questions about things they don't explain or that aren't clear. Folks here are very helpful and will chime in to help fill the gaps.

Dan

[Manfred M]

Primrose from a conservatory in St Paul, Mn. Rabbit would find it tasty, gotta keep the rabbits well fed for rabbit eating rose bushes

I may get hammered for saying it but digital zoom is marketing ploy, essentially it is cropping the image to imitate zooming. Anytime you crop an image you lose pixels.

You won't get hammered by me. Check out what I said in Post #7.

[AlwaysOnAuto]

Guinness - All the advice given above is good. For a beginner it may still be a bit confusing. The way I interpreted the difference between 'optical' and 'digital' zoom when I was starting out was a little simpler. 'Optical' meant the camera used the physical glass of the lens for zoom whereas 'digital' meant the camera used software to do the zooming by manipulating the image inside the camera.
For your intended purposes, as I understand them to be, if you were here in the States I'd sell you my Micro Nikkor 55mm lens and help you find a used Nikon D80 to put it on. With help, I think you could get the shots you're after for your modeling of the trains.
I've got LGB myself, so am not too worried about the small stuff.