Nikon lens for D100 that lack 1.5 x effect ?

[diana]

Any chance that anyone out there is manufacturing lenses for the

D100, etc. that doesn't have that 1.5 x zoom effect?<P>

 

I want a 28mm lens that acts like a 28mm lens.<P> Is that too much

to ask? <P>

 

Thanks! <P>

 

Diana<P>

 

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[hkbmac]

Its the size of the sensor that gives the 1.5, not the lens.

[douglas_greenberg]

To get a "28mm. lens" on a D100 you are going to need a lens of focal length 19mm. or so (19mm. x 1.5 = 28.5mm). Sorry, that's how it works.

[mark_scheuern]

<P>Because of the size of the sensor, you will <EM>always</EM> get a field of view equal to that of a lens of 1.5x the focal length mounted on a 35 mm camera. For example, a 20 mm lens on the D100 will give you the field of view of a 30 mm lens on a 35 mm.</P>

[olivier_reichenbach]

Yes, Diana, as you can see, it IS too much to ask. But what about the very good Nikon

20 mm AF-D f/2.8? It will give you the close enough cropping (not the focal length)

of a 30 mm. Which, by the way, does not exist, making the solution even more fun ;-)

Or does it?

[diana]

Can't the lens designers just change the size of the barrel, etc. to aim the image for a smaller target/image sensor ?

[todd peach seattle, washi]

<i>

Can't the lens designers just change the size of the barrel, etc. to aim the image for a smaller target/image sensor ?

</i>

<p>

Sure, they can, and that's what Nikon's 'DX' lens line is. But then it's no longer a '28mm lens'. Nikon's 12-24mm DX lens gives an angle of view similar to an 18-36mm lens on a 35mm camera.

<p>

Take a close look at a digital P&S specs sometime. They may say things like '35-105mm lens (35mm equivalent)' but down in the fine print they're actually sporting more like '5-15mm' lenses. The lens has to be sized appropriately to the image sensor to give 'wide angle' or 'telephoto' affect you desire.

[mark_scheuern]

They can design lenses that throw a smaller image circle, like Nikon has done with the 12-24 mm, but focal length is a physical property of the lens and isn't a function of on what the lens is mounted. It's determined by where parallel rays focus. The field of view is smaller than the same lens used on a 35 mm camera because the sensor covers a smaller portion of the image circle. You'll see people say that, for instance a 20 mm lens "becomes" a 30 mm lens on a digital with a 1.5x cropping factor but that's sloppy language. The lens is what it is and doesn't "become" anything, but the field of view is reduced due to the sensor size.

[ky2]

Diana, a mm is a mm is a mm. Whether you shoot with a 50mm lens on a D100, 35mm or Medium Format, Nikon, Canon, or Hasselblad, a 50mm lens would still be 50mm.

 

So how does a 28mm lens act?

[dave_schneider]

It's sure a good thing Diana doesn't shoot with a large format 4x5 camera. She would be looking a long time for a 28mm lens that would work with that camera.

[stephen hazelton]

So get the 20mm or the 12mm-24mm lens as indicated above. If that's too much money, you might check into a Vivitar 19mm (assuming it can mount on the camera, I'm not a Nikon guy). Obviously, you'd expect to lose some quality, but the worst quality would most likely be in the parts of the image that get cropped off.

 

Diana, the problem with the crop factor is that the camera is made to use standard 35mm lenses. That means they can't just set the lens in closer to the sensor like they can with a point-n-shoot- it has to mount at the same distance as on a film camera. That makes it a lot harder to design good wide angle lenses that fit the sensor. (They COULD have designed it to use little teensy interchangeable lenses up close to the sensor, rather than 35mm lenses, but then people with a lot of Nikon lenses couldn't use them).

[diana]

>(They COULD have designed it to use little teensy interchangeable lenses up close to the sensor, rather than 35mm lenses, but then people with a lot of Nikon lenses couldn't use them).

 

Thank-you for explaining this. So Nikon made both routes available - point and shoots with mini-lenses and SLR's that use Nikkor lenses but with a catch or two.

 

Why not use a 35mm sensor? It is a price issue?

[erick_lamontagne]

<i>It is a price issue?</i><p>

 

Canon makes a full-frame 35mm sensor camera. It costs 7300$ USD. Wether it's a price issue or not is yours to decide. It is for me! :-)

[robert_rudeski]

Why design a new digital camera with full frame exposure when digital camera backs are available. Sure they're expensive as hell, but as has already been mentioned, Canon's full frame digital is quite expensive too.

[majid]

The Kodak DCS-14n is the Nikon F mount compatible full-frame DSLR. It "only" costs $4000 or so...

[jwenting]

this might seem a bit controversial, but there is NO 1.5x effect!

At least there isn't in the way in which it is normally described to mean that the focal length of your lens magically gets 1.5x as long when using a DSLR.

 

Your lens will still behave exactly the same, a 28mm lens will still be a 28mm lens.

The difference lies in the part of the image circle projected by the lens that is used to form the image (iow the sensor size).

As this is a lot smaller in a DSLR (about APS sized) compared with a 35mm camera the image looks cropped in comparison.

Were you to take the negative/slide from a 35mm SLR and crop out an APS sized area from the exact center you'd get exactly the same as you get on a DSLR.

 

Therefore: ALL Nikon lenses lack the 1.5x effect since the effect simply does not exist.

 

The misunderstanding is sadly perpetuated by marketeers who know full well that long focal lengths attract people to cameras. That's also why so much effort is put into enormous (and completely useless) digital zoom ranges. It's useless in real life but it looks good in the marketing brochures.

[raczoliver]

Focal length is a physical property of the lens, and not the way you see the image. A 28mm lens acts like a 28mm lens, no matter what you put it on. The reason why they say "it is equivalent to 28X1.5" is because most people use 35mm cameras, and this way they can relate it to something. Check out this place:

 

http://www.photo.net/learn/optics/dofdigital/index.html

 

It helped me a lot with understanding this thing.

[charles_twiss1]

Yaron....try and follow the plot! Yes a mm is a mm and 28mm is 28mm etc,etc. But on a digital camera IT IS THE SIZE OF THE SENSOR that determines the focal length, not the lens. The focal lens of ALL lenses on ALL digital is increased by a factor of 1.5. So, 28mm is still 28mm but yeilds an image as though taken with a 28mmx1.5=37.50 or approximately 35mm. To obtain a "true" 28mm effect you have to allow for the 1.5 extension so need to use an 18mm for a "near enough".

Diana, it can't be done. Manufacturers are not going to invest hundreds of thousands on your spec of lens when what they sell is selling. This is how digital works along with many other drawbacks. The need to download, file, orientate, correct density, colour balance, sharpen, crop, size, etc,etc,etc! And all this to produce something still not as good as a professionally well printed neg. Phew!!!

[david_h._hartman]

A better term than 1.5x extension factor or multiplication is 1.5x cropping factor.

 

---

 

Consider this: a 135mm lens is a super wide angle lens on 8x10" format, wide-normal on 4x5", long-normal on 6x7cm, medium-short telephoto on 35mm and medium telephoto on near APS-C digital format. This provided that the lens is designed to cover the format mentioned.

 

If the subject to lens distance does not change the perspective for all formats will be unchanged. If you crop an APS-C sized image out of the center of an 8x10" negative it will have the same perspective and angle of view as the APS-C format DSLR.

[joe_cottam]

Sorry not an answer, another question. Ok i was not aware of the above effect, but do understand what people are saying. However what is not clear is whether the crop effect can be seen through the viewfinder. i.e. if you use the optical view finder and not the tft on the back of the camera which will be cropped as the image comes from the ccd.

[plattro]

Answer to Joe Cottam: Yes, the cropping is visible in the viewfinder. To date, all of Nikon's DSLR's have the same viewfinder magnification as their film counterpart, so the picture in the viewfinder of the DSLR looks a bit smaller. Say you put a 50mm lens on both a F80 and a D100, or on a F100 and a D1, and hold both cameras up to both eyes, you will easily see that both viewfinders have the same magnification, but the DSLR viewfinder has more masked away.

[joe_cottam]

ok so no problem, you just need to change your thinking a little, so what is the big deal with the nikon DX series lens's. they claim better edge to edge corner to corner performance on DX cameras. But my 24mm nikon afd was designed to do just that onto a larger projection area, the best part of the image is normally the center anyhow so is this just an excuse for nikon to cheapen up the optics?

or is there some other smoke and mirrors going on?

[ilkka_nissila]

It's possible to optimize lenses with digital sensors in mind, by minimizing colour aberrations and increasing MTF at those spatial frequencies which the digital sensor can record, instead of pushing resolution. Also, flare is reduced when compared with those wide angles able to image a 24x36 mm frame. The price and size of the 12-24 mm DX Nikkor are quite attractive when you compare with the 14 mm or 18 mm AF Nikkors. Not to mention the zoom may give better image quality as well. According to Bjorn Rorslett, the 12-24 at 24 mm is better than any 24 mm Nikkor prime. At 18 mm he also rates it better than the primes. So if you want a wide angle for a digital SLR, this seems to be quite a good choice.

[ShunCheung]

Joe, it is not smoke and mirrors. Digital sensors work better when the light hits them from more a perpendicular angle to the sensor plane. That is why older wide-angles lenses designed for film, long before digital was even possible, don't work as well on DSLRs. As I mentioned a couple of times, I recently tested an older 24mm/f2 AI-S on my D100, and the images have very serious color fringing problems. Just because the image circle is big enough to cover the sensor area is not sufficient.