Trenger litt hjelp til å "forstå" objektiver

[GBOne]

Hei!

 

Jeg skal fremover kjøpe objektiver, men sliter litt med å forstå alle de betegnelsene som står på objektivene og hva det innebærer i praksis. Jeg forstår hva f.eks "18-200" betyr, of samme med f.eks "f4-5,6", men så blir det verre. Jeg har et Samsung GX 10. Hvilke forkortelser på ojebtivet er egentlig relevante for meg???

 

Og hvordan kan jeg se om et ojektiv er for digital eller "vanlig" speilrefleks???

 

Håper noen kan hjelpe meg å knekke denne koden, slik at jeg vet litt mer om hva det bør stå (evt ikke stå)...på objektivene jeg ser på!

 

På forhånd hjertlig takk!

[von-schnellfahrer]

https://www.diskusjon.no/index.php?showtopic=845036

[pederk]

Jeg tror jeg fant noe relevant med litt googling: http://digital-photography-school.com/foru...read.php?t=4115

 

67mm is the filter size. It's usually not actually used as part of the description of the lens.

 

16-45 is the focal length range (i.e. zoom range) in millimeters -- one would usually say 16-45mm.

 

"DA" is Pentax's designation for lenses designed for digital SLRs -- they don't necessarily fill a full film frame (so they can be smaller and lighter), they have designed-for-digital optical coatings, and (unrelated to digital but a feature of all DA lenses) they have a quick-shift features where you can tweak the autofocus manually without switching the body into MF mode.

 

1:4 is usually the way one specifies magnification, or how good it is at being a macro lens. 1:4 isn't that exciting -- so you know macro isn't really the point of the lens if you see that. (You want 1:2 or better.) But this lens is actually 1:3.8, so either that's just rounded, or more likely, it's a typo for:

 

f/4 -- this is a constant-aperture zoom, which means the widest aperture of f/4 is available over the entire focal length. The kit lens, by contrast, is "f/3.5 - f/5.6", which means it starts out a fraction of a stop faster at the very wide end, but in the middle is slower and at the telephoto end is much slower. This is a huge advantage of the lens you have -- it makes autofocusing faster, the viewfinder brighter, and allows a narrower depth of field if you want to use selective focus in your composition.

 

The (22) is the smallest (slowest) aperture the lens can use. 22 is pretty normal. (On a point & shoot camera, by contrast, f/8 is usually the minimum.)

 

ED means that at least one lens element uses extra-low dispersion glass, which reduces chromatic aberration, so your picture has fewer color artifacts and is sharper.

 

AL means that at least one lens element is aspherical -- this generally is a part of the design used to reduce distortion, and can replace multiple normal lens elements, making the overall lens smaller and lighter.

 

So now you know. The upshot is: this is a much better lens than the kit lens.

 

Edit: Oi, der var det et mye bedre svar. Jaja!

Endret 22. juni 2008 av pederk

[GBOne]

Takk begge to!

 

Jeg tror jeg fant noe relevant med litt googling: http://digital-photography-school.com/foru...read.php?t=4115

 

67mm is the filter size. It's usually not actually used as part of the description of the lens.

 

16-45 is the focal length range (i.e. zoom range) in millimeters -- one would usually say 16-45mm.

 

"DA" is Pentax's designation for lenses designed for digital SLRs -- they don't necessarily fill a full film frame (so they can be smaller and lighter), they have designed-for-digital optical coatings, and (unrelated to digital but a feature of all DA lenses) they have a quick-shift features where you can tweak the autofocus manually without switching the body into MF mode.

 

1:4 is usually the way one specifies magnification, or how good it is at being a macro lens. 1:4 isn't that exciting -- so you know macro isn't really the point of the lens if you see that. (You want 1:2 or better.) But this lens is actually 1:3.8, so either that's just rounded, or more likely, it's a typo for:

 

f/4 -- this is a constant-aperture zoom, which means the widest aperture of f/4 is available over the entire focal length. The kit lens, by contrast, is "f/3.5 - f/5.6", which means it starts out a fraction of a stop faster at the very wide end, but in the middle is slower and at the telephoto end is much slower. This is a huge advantage of the lens you have -- it makes autofocusing faster, the viewfinder brighter, and allows a narrower depth of field if you want to use selective focus in your composition.

 

The (22) is the smallest (slowest) aperture the lens can use. 22 is pretty normal. (On a point & shoot camera, by contrast, f/8 is usually the minimum.)

 

ED means that at least one lens element uses extra-low dispersion glass, which reduces chromatic aberration, so your picture has fewer color artifacts and is sharper.

 

AL means that at least one lens element is aspherical -- this generally is a part of the design used to reduce distortion, and can replace multiple normal lens elements, making the overall lens smaller and lighter.

 

So now you know. The upshot is: this is a much better lens than the kit lens.

 

Edit: Oi, der var det et mye bedre svar. Jaja!