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Yes, from price point of view, 50mm prime makes a lot of sense. The AF-only lens option without AF-S makes the lenses cheaper.

To be sure of what I am talking about, I used my 18-105 lens on D90 to photograph the same human subject from a fixed distance of 3m.
Zoom positions used were 18, 25, 35, 50, 75 and 105.
- I personally liked the 25mm photo (effective 37mm on D90) which covered enough of the surroundings without compromising on the facial expression of the subject.
- Next best was 35mm (effective 52mm on D90).
- 50mm (effective 75mm on D90) was too close to the subject, IMO.

Basically I am talking about the angle of view. When this requirement is married with the price factor, AF-S DX NIKKOR 35mm f/1.8G is the best bet IMO.

Is this argument convincing? Or would you step back a couple of meters and achieve the same angle of view with a 50mm?

I assume your 18-105 is a FX lens..am I right? If it is a DX lens then your conversion to D90 focal length is not required. A 50 mm setting on a DX lens is, well, equal to a 50 mm setting on a D90. OTOH, it would be equal to about approx 30mm on a FX camera.

I'd say all other things being equal, a prime lens is faster & would provide you better quality pictures with lower distortion than a zoom specially in low light.

So to answer your question, no I would not step back to frame the subject with a zoom. Much rather use a prime. But since you have an option of a 35mm F/1.8 DX lens that would my choice.

Rgds,

Oops, my mistake. It is a DX (Nikkor AF-S VR 18-105mm f/3.5-5.6G DX ED).

Now I understand from where I am talking.:D A full frame upgrade (if at all there is one) is a long way away for me. Even D90's capabilities are still to be explored in full.

Clarifies. It is going to be that lens for me then.

Not quite the focal lengths even on lenses meant for cropped bodies are always mentioned in terms of FF focal lenght and you need to calculate the equivalent. So you still need to multiply by 1.5 to get the FF equivalent focal length.

In DX format Nikon has reduced the diameter of optical elements so the lens has become lighter and cheaper , If you mount DX on FX you will get actual Focal length but vingineting due to smaller diameter.

Canon does the same on EF-S.

Ah, it doesn't work that way. Even a pro can't get 100+ well framed shots in 5 hours. He will be lucky to get 10 great shots. I suggest you start composing using your mind instead of the camera every time.

Look the following the post and a few that follows: http://www.team-bhp.com/forum/gadget...ml#post1692793

The image seen on my office wall is a 24"x36" blowup of a photograph shot in 1.5MP in jpg mode in a P&S, one can hardly makeout. :)

Uh uh..nopes. I am not sure what Canon does but I am sure that Nikon DX lens markings are not their equivalent on 35mm/FX cameras. Read here:

18-200mm AF-S DX VR Lens Review by Thom Hogan

I quote:

"The 18-200mm focal range gives you angle of views from ~8 to 76 degrees on a DSLR; it's effectively the same as using an 28-300mm lens on a 35mm body."

End quote

Therefore an 18-200mm lens on a DX camera is marked with graduations that start with 18mm and extend to 200mm. This is equal to a 28-300mm zoom on a FX body.

As you will notice the 18-200 does not have markings that begin from 28 and extend to 300 mm to denote FX equivalent. There is no conversion factor involved when using DX lenses on a Nikon DX body.

Incidentally Nikon recently introduced a 28-300mm FX lens that offers the same zoom range as the abovementioned DX lens but at a higher price. :)

I have been reading about the crop factor on DSLR viz-a-viz 35mm / Full Frame Camera and understand that Canon DSLR's have a 1.6 Crop Factor. This means that a 100MM lens while attached to the body will give you a field of view equivalent to a 160mm lens. But will the 100 MM lens show magnification equivalent to 160mm as well?

If so then wouldn't make better sense to have a high end consumer DSLR rather than a full frame whereby you get a better magnification.

I think most people misunderstand crop factor. Crop factor is NOT magnification. It is essentially cutting or cropping of a portion of the FX or 35mm frame to depict a smaller part. Therefore a cropped frame is a subset of an FX frame.

Thats what I wanted to clarify. So what you are saying is that only the field of view gets cropped.

So how come in P&S compact cameras, which have high crop factors of 5-6, give you magnification of 200mm with only a 30mm lens?

The answer probably lies in the camera's digital zoom. Optical zoom is much lower.

My doubt got cleared with this article Andre's Blog • Crop factor vs. magnification

Good explanation about Crop Factor vs Magnification

Hmm, may be I was expecting too much from a PRO grade shooter :).

Is it not 27-300 equivalent (Nikon)?

In practice, it will give higher magnification for a macro work purely because every lens on a DX body will give 1.5 times more reach ! I am giving an example below, its taken with my 200mm zoom lens on D90, so in effect its in 300mm, but would have remained 200 itself on a FX body. If I dont reveal it, it would look like an image shot with a dedicated macro lens.

Shaju, I must compliment you on that photograph and your skills! :) Dare I say I see the next Rudra da here?

Yes if we were go down to the accuracy of a mm then it would be 27-300. But Nikon AFAIK does not makes zoom lenses that start from 27mm.

I think magnification and crop are two different things well illustrated by the author of the page whose link was provided by milecruncher.

Exactly that is what I am saying Dear R2D2.

An 18mm on DX / EF-S gives similar angle of view as 28mm on full frame.

So if you are buying a 50mm Canon or Nikon Lens then the focal length is ofcourse 50mm but due to crop factor "effective" Focal length is 50X1.6= 80mm so what was a walk-around lens on FF body works for portraits.
35mm lens is the one which will give equivelence of 50mm prime on APS-C sensor body.

This is exactly what was meant earlier and sbraj is right in his calculations
However all this matters if and only if you have some experience on FF and you are in comparison mode. For someone who has only APS-C body 18mm gives only that much and for any wider angle of view an ultrawide angle lens such as 10-20mm is required.

Ah! Then what you were referring to was the crop factor (equivalent to FX) instead of the focal length of the lens.

Focal length denoted by markings on the DX lens barrel would be the same...which is what I was referring to.