Explanation of numbers on camera lens: Looking for a fairly simple explanation of lens information. I have a Fuji FinePix S1800 - on the lens is: 18x Zoom f=5.0-90.0mm 1:3.1-5.6 I know...

PhotoMeThis Loc: Southern California

Looking for a fairly simple explanation of lens information. I have a Fuji FinePix S1800 - on the lens is:
18x Zoom f=5.0-90.0mm 1:3.1-5.6
I know it all has to do with the viewing range. So, if I was taking a picture of an object 100 ft. away, zoomed all the way in, how much closer would the object appear ??
I usually leave it in auto mode, then zoom if desired. Thx.

haroldross Loc: Walthill, Nebraska

Here is the lens info: Fujinon 18x optical zoom lens, F/3.1 (Wide) - F/5.6 (Telephoto). The lens focal length is 5.0-90mm, in 35mm equivalent numbers the lens is 24mm to 505mm.

You can get 18 times magnification from the wide end to the telephoto end.

PhotoMeThis Loc: Southern California

Harold - thx for the explanation - is that a decent lens ?
I somewhat understand the magnification part, but I was looking for a foot/distance measurement -- at 18 x with the object 100 ft. away am I now like only 50 ft. away ?
I'm trying to get a ratio of distance -- as you can already tell I'm on the amateur side :-) .

bhfranklin Loc: Boston Area / Cape Cod

Wouldn't you be more like 6 feet away? or am I missing something?

PhotoMeThis Loc: Southern California

That's what I'm trying to find out -- it doesn't appear that way when looking in the camera -- I can see that I am closer but I don't know the approx. feet when I am on total zoom. How did you come up with the 6 ft. ? Thx.

haroldross Loc: Walthill, Nebraska

From the 35mm equivalent numbers, at 50mm- that is roughly what the human eye sees. Zooming into 500mm would give to 10 times magnification from what your eyes see.

'Is this a good lens?' That is a difficult question to answer. Does it give you satisfactory results? The Fuji camera is a fairly decent camera in its class. The zoom range is adequate for most uses. In my opinion, the lens is a good match for the camera's sensor and will yield pretty good photos.

I will be happy to try to answer any specific questions about the camera.

Roger Hicks Loc: Aquitaine

PhotoMeThis wrote:

Harold - thx for the explanation - is that a decent lens ?
I somewhat understand the magnification part, but I was looking for a foot/distance measurement -- at 18 x with the object 100 ft. away am I now like only 50 ft. away ?
I'm trying to get a ratio of distance -- as you can already tell I'm on the amateur side :-) .

There isn't any very meaningful ratio of distance. You could calculate the angle subsumed on the sensor by an object of given height with a given focal length, but what good would it do you? For example, your thumb at arm's length may be as tall as a truck 20 yards away, an angle at the eye of maybe 4 degrees, but what does this actually tell you?

If you double any given focal length, the subject will be recorded twice the size on the sensor. If you double the distance between you and the subject, it will be half the size.

All the rest depends on the magnification of the lens and the size at which you view the image. A wide-angle makes things look further away. A telephoto makes them look closer. And at a particular focal length, when the angle subsumed at the eye by the subject on the final image is the same size as the angle subsumed at the eye by the actual subject, you may have a sort of 'magic window' where the perspective looks uniquely natural. You may (or may not) find the following useful: http://www.rogerandfrances.com/subscription/ps%20perspective%201.html

Cheers,

R.

PhotoMeThis Loc: Southern California

haroldross wrote:

From the 35mm equivalent numbers, at 50mm- that is... (show quote)

Harold - again thx. for all the good info. -- I am learning from this site and its weatlh of knowledge from the memebers. It's like having an expert sitting next to you. I've attached two photo's in zoom and non-zoom mode - the mountain range is at least 10 miles from where I was standing - just to give u an idea of the distance. I also added a pic of a "night blooming" cactus, it is in the cereus family, another subject I am limited with. Am repeating but I mainly use the auto setting, sometimes change to a specific "scene" mode, i.e. landscape, beach, yadda yadda.
I guess you would call me a just point & shoot person. I would appreciate your honest thoughts of the pic's. These days it seems like camera's are upgraded/advanced faster than computers. Have a fine day.

Roger Hicks Loc: Aquitaine

DUH! Subtended, not subsumed (in my earlier post). Too much Vouvray with lunch!

Cheers,

R.

PhotoMeThis Loc: Southern California

Roger Hicks wrote:

DUH! Subtended, not subsumed (in my earlier post). Too much Vouvray with lunch!

Cheers,

R.

R --- I have no clue what u r saying in your message/note but appreciate the response.

Julian Loc: Sarasota, FL

Roger Hicks wrote:

DUH! Subtended, not subsumed (in my earlier post). Too much Vouvray with lunch!

Cheers,

R.

You were not too far off: 'Subsume' also means comprise, contain, consist of; however, 'subtend' is the geometrically correct terminology. It was refreshing to see your revision. I was ready to jump on it.

As an engineer, I find it disturbing to read technical discussions in this forum containing incorrect spelling or terminology. It makes one question the validity and accuracy of the rest of the subject.

PhotoMeThis Loc: Southern California

Julian wrote:

quote=Roger Hicks DUH! Subtended, not subsumed (i... (show quote)

I so appreciate the comments -- I must ponder all of this, but am very grateful -- thanks to all

bvm Loc: Glendale, Arizona

I live in AZ. What kind of cactus is that ? I'd like to get one.
thanks

Roger Hicks Loc: Aquitaine

PhotoMeThis wrote:

R --- I have no clue what u r saying in your message/note but appreciate the response.

Think of a telegraph pole. Draw imaginary lines from the top and bottom of it, to your eye. The angle between those lines is the angle subtended. The closer you are, the bigger it looks, and the bigger the angle between the lines.

Now think of a photograph of the same telegraph pole. Look at the picture from varying distances. Again, the angle subtended will vary. When the angle subtended by the pole (and everything else) in the photo is the same as the angle subtended by the pole (and everything else) in the original subject, the picture should appear uniquely three-dimensional.

BUT -- everything depends on (a) the focal length of the lens you used to take the picture, (b) the size of the picture and (c) how far away you are from the picture.

This isn't exactly answering your question but it should, I hope, help to explain why there isn't a 'feet and inches' answer.

Cheers,

R.

Roger Hicks Loc: Aquitaine

Julian wrote:

You were not too far off: 'Subsume' also means comprise, contain, consist of; however, 'subtend' is the geometrically correct terminology. It was refreshing to see your revision. I was ready to jump on it.

As an engineer, I find it disturbing to read technical discussions in this forum containing incorrect spelling or terminology. It makes one question the validity and accuracy of the rest of the subject.

Dear Julian,

I quite agree with your second para, and for the first, all I can say is, wait until you get older. Two words, both equally familiar and well understood, can craftily change places for paragraphs at a time. Yesterday I remembered 'abridged' for 'infringed' in the second amendment to the US constitution.

Cheers,

R.