Camera Lenses - Tilted Forum Project Discussion Community

Gatorade Frost · 05-05-2005, 06:54 PM

I suppose this could go under the Tilted Photography, but this is more of a knowledge question since I'm not posting anything pretty.

When you buy a camera with lenses that can be switched out, what do the numbers mean? I've read through some 'technical' website on it, but it just leaves me a bit dumbfounded.

What exactly is the different between a 18-70mm f lens and a 55-200mm f lens?

Locobot · 05-05-2005, 08:27 PM

ok there should be a number coupled with the "f" this refers to the f-stop of the lens, this is often more important to a lens' value than the mm. F-stop refers to the maximum aperature (the hole that lets light through the lens) that the lens is capable of. A lower number for f-stop (1.4,1.8,2.8,3.5,etc.) means that the lens is able to take pictures in lower light situations. This is often spoken of as the "speed" of the lens because aperature (f-stops) and shutter speeds are mathematically equivalent. One f-stop equals one shutter speed increment. A lower f-rating is better.

mm refers to the shape or strength of the lens and depends on the size of the film or type of sensor in the case of digital cameras. For 35mm film an 18mm will be quite wide-angled with a fair amount of distortion on the periphery of the image. 50-70mm is a standard focal length for 35mm film corresponding to how your eye generally sees things. Beyond 70mm the lens will have a telescopic effect, bringing things closer.

If you're having trouble picking between these two lenses I would ask what kind of photography you plan to use it for. Assuming both have the same f-rating, the 18-70 lens will be better for wider landscape photos or in close quarters, the 55-200 lens will be better for taking wildlife or other instances where you will want to zoom in on a specific feature from a distance. But 55mm is fairly wide so either lenses could work as an all-arounder. I would prefer the 18-70 lens, it probably has a wider aperature (lower f-stop) and suits the type of photography that I do mostly. It's a question of preference.

In the case of digital SLRs, the lens sizes correspond typically to a 35mm film format.

TM875 · 05-05-2005, 09:44 PM

Ditto for what Locobot said. The only thing is, with Digital SLRs, you might want to check to see if there's any "negative crop" or whatever the manufacturer calls it. Because the image sensor is slightly smaller than 35mm film, the image will be more "zoomed in" with the lense than comparable to 35mm.

In other words, an 18-55mm lense might produce the same zoom as a 28-88 (I have a Canon Digital EOS - I think the multiplyer is 1.6). In reality, it doesn't matter - just realize that it's not the same as what you'd expect from a film SLR (but digital is still way better).

Gatorade Frost · 05-08-2005, 04:19 PM

Here are the two lenses in their completeness:

18-70mm f/3.5-4.5G ED IF AF-S DX
55-200mm f/4-5.6G ED AF-S DX

paddyjoe · 05-09-2005, 03:58 AM

What these guys stated is spot on, but let me add my 2 cents.

With the 18-70 f/3.5-4.5 lens, when you have the lens set at 18mm, your max (or widest) aperature will be 3.5. Not the fastest, but not too bad. When the lens is zoomed out fully to 70mm, the max aperature will only be 4.5. Sorry, not very fast at all.

It's the same with the 55-200mm lens. Your max aperature when zoomed to 200mm is only 5.6.

This is not to say that the lens quality and edge to edge sharpness won't be good, but be prepared to shoot at faster speed films, or faster ISO's if digital. Things will just be a bit grainier (or noisier). Probably won't be the least bit of a problem, unless you're trying to make a living with photography.

Gatorade Frost · 05-09-2005, 01:45 PM

This is going to be a digital camera.

I'm not trying to make it a living, I've just got some old digital cameras that arent' satisfying me so I thought I'd take the dive and invest in something a bit expensive and learn to use a DSLR, so I'm looking at the Nikon D70s big kit.

This will basically be for me fooling around, travelling, etc.

paddyjoe · 05-09-2005, 05:30 PM

That's a damn fine camera, Gator. Those two lens' will work just fine with it. Have fun man, and post some of the pics over in photography.

shakran · 05-09-2005, 05:50 PM

if you really want good lenses, get a D70 body-only package, then go buy the lenses seperately. . . Package deal lenses are always middle-of-the-road glass at best. The good stuff is a good deal more expensive, but much more flexible.

The big advantage, at least to a rookie, to having a faster lens is that you can shoot with less light without having to resort to the flash. The flash is the enemy of good photography - it flattens everything out and makes the scene unnatural.

05-05-2005, 06:54 PM	#1 (permalink)
Gatorade Frost Rookie	Camera Lenses I suppose this could go under the Tilted Photography, but this is more of a knowledge question since I'm not posting anything pretty. When you buy a camera with lenses that can be switched out, what do the numbers mean? I've read through some 'technical' website on it, but it just leaves me a bit dumbfounded. What exactly is the different between a 18-70mm f lens and a 55-200mm f lens? __________________ I got in a fight one time with a really big guy, and he said, "I'm going to mop the floor with your face." I said, "You'll be sorry." He said, "Oh, yeah? Why?" I said, "Well, you won't be able to get into the corners very well." Emo Philips

05-05-2005, 09:44 PM	#3 (permalink)
TM875 Addict Location: Amish-land, PA	Ditto for what Locobot said. The only thing is, with Digital SLRs, you might want to check to see if there's any "negative crop" or whatever the manufacturer calls it. Because the image sensor is slightly smaller than 35mm film, the image will be more "zoomed in" with the lense than comparable to 35mm. In other words, an 18-55mm lense might produce the same zoom as a 28-88 (I have a Canon Digital EOS - I think the multiplyer is 1.6). In reality, it doesn't matter - just realize that it's not the same as what you'd expect from a film SLR (but digital is still way better). __________________ "I've made only one mistake in my life. But I made it over and over and over. That was saying 'yes' when I meant 'no'. Forgive me."

05-08-2005, 04:19 PM	#4 (permalink)
Gatorade Frost Rookie	Here are the two lenses in their completeness: 18-70mm f/3.5-4.5G ED IF AF-S DX 55-200mm f/4-5.6G ED AF-S DX __________________ I got in a fight one time with a really big guy, and he said, "I'm going to mop the floor with your face." I said, "You'll be sorry." He said, "Oh, yeah? Why?" I said, "Well, you won't be able to get into the corners very well." Emo Philips

05-09-2005, 01:45 PM	#6 (permalink)
Gatorade Frost Rookie	This is going to be a digital camera. I'm not trying to make it a living, I've just got some old digital cameras that arent' satisfying me so I thought I'd take the dive and invest in something a bit expensive and learn to use a DSLR, so I'm looking at the Nikon D70s big kit. This will basically be for me fooling around, travelling, etc. __________________ I got in a fight one time with a really big guy, and he said, "I'm going to mop the floor with your face." I said, "You'll be sorry." He said, "Oh, yeah? Why?" I said, "Well, you won't be able to get into the corners very well." Emo Philips

05-05-2005, 08:27 PM	#2 (permalink)
Locobot is awesome!	ok there should be a number coupled with the "f" this refers to the f-stop of the lens, this is often more important to a lens' value than the mm. F-stop refers to the maximum aperature (the hole that lets light through the lens) that the lens is capable of. A lower number for f-stop (1.4,1.8,2.8,3.5,etc.) means that the lens is able to take pictures in lower light situations. This is often spoken of as the "speed" of the lens because aperature (f-stops) and shutter speeds are mathematically equivalent. One f-stop equals one shutter speed increment. A lower f-rating is better. mm refers to the shape or strength of the lens and depends on the size of the film or type of sensor in the case of digital cameras. For 35mm film an 18mm will be quite wide-angled with a fair amount of distortion on the periphery of the image. 50-70mm is a standard focal length for 35mm film corresponding to how your eye generally sees things. Beyond 70mm the lens will have a telescopic effect, bringing things closer. If you're having trouble picking between these two lenses I would ask what kind of photography you plan to use it for. Assuming both have the same f-rating, the 18-70 lens will be better for wider landscape photos or in close quarters, the 55-200 lens will be better for taking wildlife or other instances where you will want to zoom in on a specific feature from a distance. But 55mm is fairly wide so either lenses could work as an all-arounder. I would prefer the 18-70 lens, it probably has a wider aperature (lower f-stop) and suits the type of photography that I do mostly. It's a question of preference. In the case of digital SLRs, the lens sizes correspond typically to a 35mm film format.

05-09-2005, 03:58 AM	#5 (permalink)
paddyjoe through charlatans phone Location: Northcoast	What these guys stated is spot on, but let me add my 2 cents. With the 18-70 f/3.5-4.5 lens, when you have the lens set at 18mm, your max (or widest) aperature will be 3.5. Not the fastest, but not too bad. When the lens is zoomed out fully to 70mm, the max aperature will only be 4.5. Sorry, not very fast at all. It's the same with the 55-200mm lens. Your max aperature when zoomed to 200mm is only 5.6. This is not to say that the lens quality and edge to edge sharpness won't be good, but be prepared to shoot at faster speed films, or faster ISO's if digital. Things will just be a bit grainier (or noisier). Probably won't be the least bit of a problem, unless you're trying to make a living with photography.

05-09-2005, 05:30 PM	#7 (permalink)
paddyjoe through charlatans phone Location: Northcoast	That's a damn fine camera, Gator. Those two lens' will work just fine with it. Have fun man, and post some of the pics over in photography.

05-09-2005, 05:50 PM	#8 (permalink)
shakran Tone.	if you really want good lenses, get a D70 body-only package, then go buy the lenses seperately. . . Package deal lenses are always middle-of-the-road glass at best. The good stuff is a good deal more expensive, but much more flexible. The big advantage, at least to a rookie, to having a faster lens is that you can shoot with less light without having to resort to the flash. The flash is the enemy of good photography - it flattens everything out and makes the scene unnatural.