PDA

View Full Version : Why everyone wants 3x optical zoom



hari
08-31-2004, 04:22 AM
I own Powershot A75 which has 3x optical lense/zoom. But I do not know whether I can take any close up photos. The subject does not come closer. I was trying to shoot a Crow 10 feet away, but hardly it was close when I used the Zoom ? How best I can use this ?

Any correction of my misunderstanding of this topic.

speaklightly
08-31-2004, 04:55 AM
The function of a zoom lens, such as you have on your A-75 is to utilize the optics within the lens to bring things closer to you in the viewfinder, quite like binoculars would do. In the A-75 as you rotate the ring around the shutter release towards your body, the image within the viewfinder will be enlarged, or appear to grow larger.

In your own example of the crow on the fence some ten feet away from you: by actuating your zoom control (as described above) you woulld enlarge the image of the crow within your viewfinder. Therefore the crow would essentially appear closer to you, while you had not moved at all.

When you have the crow as large as you desired within your viewfinder, you would then take your digital photo. I hope that helps.

Sarah Joyce

hari
09-01-2004, 01:30 AM
Thanks for the reply. But what I meant was that the 3x zoom is not that great at all. As everyone says I have disabled the digital zoom for quality. I use the 3x zoom lever. I have read somewhere that by 3x mean, it will devide the distance by 3. If your subject is 9 feet away by using 3x means, your subject will be as close as 3feet. Is it ok. I cannot see that close. Even for this 10 feet objects, what lense is supposed to be used. 3x, 10x or ???

David Metsky
09-01-2004, 06:41 AM
3x means that the difference between the full zoom and full closeup of your lens is a factor of three. In 35mm camera-speak, that would be like a zoom that goes from 38mm to 105mm. It will NOT bring you three times closer to your subject for a variety of reasons.

For most 3x zoom digitals the range is roughly 38-105mm equivilent. The low end of the range (38mm) is wide angle, it effectively moves you further away from the subject and allows you to get more in the image frame. 50mm is essentially no zoom, this is the same as looking at your subject exactly as you see from your eye. At the far end of the zoom (105mm) you have the equivilent of being slightly less than half the distance to your subject.

Different 3x zoom lens give you different results. Some give you more wide angle at the tradeoff of giving up some telephoto. You have to look at the specific lens. But the range of 38-105mm equivilent is a great general purpose zoom range that meets the needs of many users.

-dave-

hari
09-03-2004, 02:09 AM
Many thanks, Dave.

Your explanation goes very easy. Though we may get things in books, but they are not as clear as the ones what we find from members of this type of forums. Thanks once again for clearing my doubts.

I am little bit confused when I read terms - WIDE ANGLE AND TELEPHOTO. Now your explanation makes it easy to understand. Wide angle covers more space in the frame. For example Group Photos. I can get more people in the frame by using Wide Angle. AM I RIGHT ?

I do not know anything about TELEPHOTO :D

-Hari

David Metsky
09-03-2004, 06:53 AM
I'm no photog expert. I'm still hoping that someone with real knowledge will come along to point out my mistakes or assumptions.

In 35mm photography, for a variety of reasons, a 50mm focal length lens offers no magnification or wide angle, it's just exactly what you see with your eye. If a lens is larger/greater than 50mm it is a telephoto meaning that it brings things closer. If it is smaller/less than 50mm it is a wide angle, meaning it allows you to get more in the image. Fixed lenses have only one length, zoom lenses can change focal length. People often use zoom to mean telephoto, but zoom really means that you can change focal length, not that it is a telephoto.

Digital cameras have different geometry than 35mm SLRs, but it's helpful to keep using the same terminology. The CCDs are different size than a 35mm negative, and closer to the lens, but we still talk of 38-105mm "effective" lens. This means that if you were using a 35mm SLR it would act like a 38-105 lens, when if fact the lens is probably something like a 8-24mm. People rarely use the actual focal length on a digital camera, it makes more sense to most folks if you use the 35mm effective length.

All that explains the terminology. In real life, it's good to have a wide angle lens so you can get more into a shot. This allows you to take a full family photo without backing up all the way into the kitchen. However, the wider the lens (smaller focal length, like 28mm or 24mm) you get more distortion. When you get very wide you get a fish-eye lens, which makes things look like they are bulging in the center. Most digital zoom cameras have around 35-38mm on the wide angle end. I'm not sure which ones go wider.

The 10x and 12x ultrazoom digital cameras have roughly the same wide angle, approximately 35-38mm, but have huge telephoto capabilities. If you start with 38mm and have a 10x lens, that will bring you to 380mm effective, which will bring you very close to your subject.

I hope this makes sense.

-dave-

yonco
09-04-2004, 08:16 AM
David, thank you so much for your two posts!
I myself didn't know much about the whole zoom, wide-angle and telephoto subject, and as photography and digital cameras interest me a lot, I am always eager to learn more. I came across this thread, and your explanations really helped me understand! Thank you.

D70FAN
09-04-2004, 08:42 AM
I'm no photog expert. I'm still hoping that someone with real knowledge will come along to point out my mistakes or assumptions.

In 35mm photography, for a variety of reasons, a 50mm focal length lens offers no magnification or wide angle, it's just exactly what you see with your eye. If a lens is larger/greater than 50mm it is a telephoto meaning that it brings things closer. If it is smaller/less than 50mm it is a wide angle, meaning it allows you to get more in the image. Fixed lenses have only one length, zoom lenses can change focal length. People often use zoom to mean telephoto, but zoom really means that you can change focal length, not that it is a telephoto.

Digital cameras have different geometry than 35mm SLRs, but it's helpful to keep using the same terminology. The CCDs are different size than a 35mm negative, and closer to the lens, but we still talk of 38-105mm "effective" lens. This means that if you were using a 35mm SLR it would act like a 38-105 lens, when if fact the lens is probably something like a 8-24mm. People rarely use the actual focal length on a digital camera, it makes more sense to most folks if you use the 35mm effective length.

All that explains the terminology. In real life, it's good to have a wide angle lens so you can get more into a shot. This allows you to take a full family photo without backing up all the way into the kitchen. However, the wider the lens (smaller focal length, like 28mm or 24mm) you get more distortion. When you get very wide you get a fish-eye lens, which makes things look like they are bulging in the center. Most digital zoom cameras have around 35-38mm on the wide angle end. I'm not sure which ones go wider.

The 10x and 12x ultrazoom digital cameras have roughly the same wide angle, approximately 35-38mm, but have huge telephoto capabilities. If you start with 38mm and have a 10x lens, that will bring you to 380mm effective, which will bring you very close to your subject.

I hope this makes sense.

-dave-

Good expalination Dave. Without mucking things up with the technical jargon.

Keith
10-01-2004, 07:23 AM
I own Powershot A75 which has 3x optical lense/zoom. But I do not know whether I can take any close up photos. The subject does not come closer. I was trying to shoot a Crow 10 feet away, but hardly it was close when I used the Zoom ? How best I can use this ?

Any correction of my misunderstanding of this topic.

Keith said:

My Fuji s5000 has 10x, the s7000 that I am wrestling with buying has less x and so my problem, I need power when shooting scenes, and animals.

I have approximately two years of digital experience and 4 decades with 35mm slr cameras, I understand your problem well, as I have used a lot of zoom during that time.

Without getting too technical, I really do not understand a lot of this jargon anyway, you are right in your understanding of digital zoom and staying away from it, three power is not much and probably will not do you so well with distant shots, so, like I have done when I first started shooting nature I learned by experience that I had to get as close as I could or use fine grain film or in digital one can use a high 8,? meg ccc and cut the heck out of your final picture.

I first bought a Sony dsc pocket and it was very good for what it was meant for.

I hope I have got the gist of your question and this has helped in some way.

Keith