What makes a lens so cheap/expensive?

[jbainesy]

Hi everyone, I can't seem to figure this one out...

There's a LOT of different codes / types of lens out there. I'm looking at buying something which will go beyond my kit 28-55 VR lens that came with my nikon D3100, to do the more long-distance bird / wildlife shots.

First up, what would be the drawbacks of a lens such as this one from our sponsors:
http://www.qualitycamera.com.au/niko...6g-p-4584.html

First up, I realise the F4-5.6 is fairly "general" and this really is all I'm after at this stage, for the price it seems like an absolute steal, I just want to make sure I'm not missing any deal-breaking info here.

Is it "DX compatible" (what IS DX?)

Is it AF-S Compatible? do I need to manually focus this lens on my D3100?

Is there a good reason why I should avoid this lens (as a beginners lens)

And HOW can a noob like myself tell if a lens such as this one:

http://www.qualitycamera.com.au/tamr...ro-p-4244.html

... will be useable/compatible with the D3100 body that I have? I would hate to order something like this and then go to use it and my SLR say "incompatible lens" on the screen or something like that!

Would the tamron lens work with the autofocus on the nikon? would the apeture controls work?

Sorry if I seem a bit paranoid about this - the guy in the camera shop I visited last told me that "the one big thing with a nikon camera is that you need to buy the right lens for it, or else....." well, he didn't exactly say what, but I'm guessing it's bad! lol!

Thanks anyone who can shed some light on this for me
I'd LOVE to grab one of these lenses if they're not too "cheap'n'nasty"

-Jazz

[I @ M]

Don't consider either of those lenses, save your money for something not a great deal more expensive but a hell of a lot better quality wise.

DX is the term for Nikon cameras with an APSC sensor ( 1.5x crop factor ) and apart from a very small number of old lenses all Nikon lenses will mount on a DX body whether they are designed for DX or FX.

Not all Nikon lenses ( FX or DX ) will autofocus on your D3100, they must be an AFS lens with a built in motor and neither of those lenses are AFS lenses.

One lens that does have a good reputation, a reasonable price and will work on both DX and FX bodies is the AF-S VR Zoom-Nikkor 70-300mm f/4.5-5.6G IF-ED . It will provide you with the reach you want, pretty fast accurate autofocus and very good quality images.
Hunt around for a bargain price on one.

[pcbermagui]

I agree with Andrew, if you can get a Nikon ED lens without to great a price jump they are invariably superior and you'll have much less likelihood of wanting to get rid of it in 12months time. The difference more often than not is in effects like colour fringing on the cheap lenses (a different colour where there is a change of colour or brightness)
Hope this helps - pcbermagui

[jbainesy]

Thanks so much guys, that's helped A LOT... I now know that DX is in relation to the type of sensor which I didn't before, and the AFS would almost be considered "crucial" for myself (unless we're talking 3x - 4x the price, but we're not!)

A bit of searching found this... (shhh! don't tell anyone before I buy it!)
http://www.adorama.com/NK55200VRR.ht...e=rflAID021866

This is only a 200 whereas the others were 300 - It's also a refurbished lens, I've bought many refurbished things in the past and see no problem with that....
That.... is a steal..... correct?

There's also the 300 which you were suggesting:

http://www.adorama.com/NK70300AFVRR....e=rflAID021866

Now my next question: the 300 will give exactly 50% more "zoom" than the 200, is this correct? And that's about the only difference? or are there other benefits / considerations I should take into account here? This will only be my second lens so as you can imagine, I still really don't know what to expect from ANY lens but my 28-55 at this stage!

Thanks again guys - Really has been a help!

[macrocephalic]

70-300 lenses can be had for about $200 from Sigma and Tamron (and canon, and probably other OEMs). They are fairly cheap optics, fairly slow (f4 at the wide end), slow to focus (although they are autofocus), sometimes have rotating front elements (which is a problem if you're using filters), extend when you zoom but arent well sealed (so they are sometimes called dust pumpers), tend to get soft from 200-300, etc.

I've no experience with them as I'm a newbie, but they don't seem to be very well respected. You can get them for about $70 used on ebay - and I might pick one up at around that price just because it's not much to lose. If you buy it for $70, don't like it and sell it for $50 then you've only lost $20 and maybe the photos that didn't come out.

[Blueywa]

I'm not saying this man is always right, but this review might help you decide.
Good Luck


http://www.kenrockwell.com/nikon/70-300-vr.htm

[jbainesy]

One 55-200mm "Dust pumper" on its way ;-)

Thanks everyone, sounds like I'll get my $200 worth out of this lens (at least!)

Was out taking shots of the city last night, from about 50km away :-P this lens would've been great to have on me.... I'll be taking it next time ;-)

One last question, not really still on topic, but:
How do you know, (I don't know what it's called, but I'm going to call it the "focussing length" - meaning the subject must be at LEAST "x" away from the camera, any closer and you cannot get it in focus)

But how do you know what this "x" is? for my 28-55 lens it seems to be 100mm, give or take a bit.... meaning even if I zoom all the way in on a thistle, I CANNOT get it to take up the full frame (unless I allow it to be out of focus).

How would I know before buying (too late on this one...) what this "x" is? would it be listed as the "focal length" or is it called something else? or they usually don't tell you what it is? I'm not sure what to expect with this new lens, will I be able to focus on the thistle and have it come up as full-frame? or will the 55-200mm make matters worse?

I'm thinking with extra zoom, I can only make things better, but if the "x" doubles or triples from the "x" of my 28-55mm, It's not going to help!

Cheers ppl ;-)

-Jazz

[ricktas]

The x is the 'minimum focusing distance' and that information will be available in the data about the lens. It basically wil say something like "minimum focusing distance : 27cm". meaning that if the subject is closer than 27cm from the front element of the lens then you will not be able to get the subject in focus. So look through lens information, either in the lens paperwork that comes wit the camera, or online, under the technical data for the lens, on the manufacturers website

[fillum]

How do you know, (I don't know what it's called, but I'm going to call it the "focussing length" - meaning the subject must be at LEAST "x" away from the camera, any closer and you cannot get it in focus)

It's usually referred to as "minimum focus distance" or "closest focus distance" and can usually be found by looking up the lens specs. Example.


Cheers.

Edit: Rick beat me to it...

[arthurking83]

To add further to what Rick said about MFD, in the 'good ol days' lenses focusing rings used to have marked distance scales. Whilst not perfectly accurate in some cases(but accurate enough!) this at least helped the operator to see on the lens whilst in use that MFD is x(or 24cm, or whatever...)

Have a look at the very front end of the 55-200VR lens you've chosen(a modern lens) and note that the very front focusing ring, which is ribbed, is not marked with any distances, is very thin and Nikon(and other manufacturers) simply assume that the people that use these lenses are not interested in marked distances. That's why manufacturers omit these markings nowadays.
By comparison, both the Nikon and Tamron lens linked to in the first post both have these markings on the focusing ring, where the distances are lined up with a moving white mark. Once you auto focus, you then check to see where the white mark is lined up against on the distance scale and that's your focused distance. You can also preset the focus in that manner too.
With the 55-200R lens, to find out what the MFD is, you need to 'research it', which usually means that you do a quick search on the net or you read the manual(which is usually just a folded up piece of paper) that came with the lens.

More expensive lenses almost always have these distance scale markings on them, BUT! some cheaper lenses, will have them too.
I'm pretty sure Nikon is either planning on phasing them out on all of it's new consumer/cheap/kit designs, or have already ceased to mark them. It costs money and every dollar they save on these lenses, means larger black figures on their Profit and Loss sheets

[swifty]

Just quickly... isn't MFD measured from the sensor/film plane as oppose to front element of the lens?
I though from the front element would be minimum working distance.