Why does my 17-55mm 2.8 take a different picture than a 16-35mm 2.8?

[Mike_E]

I'm familiar with "hyperfocal distance" for focusing but what is "hyperfocal length" and how does it relate to Drewski's issue?

That was just me mangling the terminology. :lmao:

I was trying to point out a use for the lens he bought. Setting the lens to it's hyperfocal is great for street shooting and makes nice landscapes too.

 

[Seefutlung]

oh, and not everyone likes Ken

many of his opinions are good ... but his photography and reviews pretty much suck.

Gary

 

[Socrates]

That was just me mangling the terminology. :lmao:

I was trying to point out a use for the lens he bought. Setting the lens to it's hyperfocal is great for street shooting and makes nice landscapes too.

OK. Thanks.

 

[kundalini]

I'm familiar with "hyperfocal distance" for focusing but what is "hyperfocal length" and how does it relate to Drewski's issue?

Maybe this will help, but of course, it also could be regurgitated info you already have.

 

[Dubious Drewski]

That was just me mangling the terminology. :lmao:

I was trying to point out a use for the lens he bought. Setting the lens to it's hyperfocal is great for street shooting and makes nice landscapes too.

Ohh, ok. Because I was going to come on here and admit that I had no idea why you were pointing me to the concept of the hyperfocal when my issue was in relation to length of the lens.

But even still, is there something special about a 28mm prime's hyperfocal distance that my kit zoom can't achieve? I'm still not convinced that I didn't waste my money here.

(Especially because I'd rather have an 18mm prime, but now buying one is going to break the wallet)

 

[GTHill]

As an update to my situation, I tried the Nikon 12-24mm F4 Lens today and I think it is what I'm looking for. A bit higher cost than I would like to spend, but I'll get it eventually. Thanks for the education!

Gene

 

[Stratman]

Ohh, ok. Because I was going to come on here and admit that I had no idea why you were pointing me to the concept of the hyperfocal when my issue was in relation to length of the lens.

But even still, is there something special about a 28mm prime's hyperfocal distance that my kit zoom can't achieve? I'm still not convinced that I didn't waste my money here.

(Especially because I'd rather have an 18mm prime, but now buying one is going to break the wallet)

What 28 MM did you get? I have a fully manual Tokina that I really like, but I would love to get one with the "A" on the aperture ring. A sample of the Tokina 28...

 

[Dubious Drewski]

That's a nice picture of an even nicer car, but it doesn't make me feel any less stupid. I'm not bummed because I think the lens will take bad pictures, I'm bummed because it's going to be a redundant lens. Your posted picture confirms it - that's not a very wide angle at all.

This is a picture of it, by the way:

 

[Stratman]

It IS wide angle on a film SLR, or, a full frame DSLR, Just as wide as your 18-55 is on your cropped DSLR, but don't think it is useless, it is a Prime, has nice IQ, and it is fairly fast, will be good for indoor available light shots. Trade that K1000 in on something you need, I got $60 for the one I bought, traded it even for an old Manfrotto tripod !! Unless you want to keep that classic, I kind of wish I would have kept mine, it was in mint condition, and worked flawlessly.

 

[Tasmaster]

All these pages claiming to explain the crop factor only show cropped photos... duh. None of them show how it works, how the light passes through the lens and falls on the sensor and how this affects the image perspective with a normal lens and with a DX one. Any links on that would be appreciated.

Trying to work this out i would say that DX lenses don't focus light in a different way to make the whole image fit in the smaller sensor, but rather they produce the same image as a normal lens would, only there isn't enough light to reach the outer edges because of the smaller lens - so there is still cropping, the only benefit being the size and cost of the lens.

Is that correct?

 

[Alex_B]

Trying to work this out i would say that DX lenses don't focus light in a different way to make the whole image fit in the smaller sensor, but rather they produce the same image as a normal lens would, only there isn't enough light to reach the outer edges because of the smaller lens - so there is still cropping, the only benefit being the size and cost of the lens.

Is that correct?

Sounds like you mean the right thing
I guess by don't focus in a different way you just mean that the focal length is the same as with a non-DX lens, hence 18mm are 18mm (that is why it reads 18mm on the lens barrel after all).

The light does not reach the outer edges of a full frame sensor, since the image circle (the area light shines on) is too small.

 

[Tasmaster]

What i meant (what i said i think the lens does not do) is "condensing" the image so that it would fit onto the DX sensor without cropping. Making the light beam narrower while carrying the same information. As you can tell, i am not exactly sure how this works or if it would even be possible to do while keeping focal length the same and without getting a distorted image. Pardon my makeshift terminology too, if i could i would rather draw it!

 

[Alex_B]

What i meant (what i said i think the lens does not do) is "condensing" the image so that it would fit onto the DX sensor without cropping. Making the light beam narrower while carrying the same information. As you can tell, i am not exactly sure how this works or if it would even be possible to do while keeping focal length the same and without getting a distorted image. Pardon my makeshift terminology too, if i could i would rather draw it!

the ratio between object size and image size given by a lens is only defined by the object's distance and the focal length of the lens, nothing else.

so there is no "condensing" of the image possible, except when you go to shorter focal lengths.

 

[Lugs77]

the ratio between object size and image size given by a lens is only defined by the object's distance and the focal length of the lens, nothing else.

That's right!

 

[Tasmaster]

So this is where i should hit the information superwighway (old school cool term for the internet) and maybe a book store in search of more knowledge.


Here is a thread from another forum with some more info on DX vs FX: http://www.stevesforums.com/forums/view_topic.php?id=587336&forum_id=9&jump_to=862330