Lens Selection & Why?

Thanks everyone, there is a lot of good information here.
Also, thank you for the link http://www.the-digital-picture.com/.

The camera I was looking at was a Canon EOS 7D. But that is out of my price range. Right now I am looking at a Nikon D90.

Concerning lenses, I am prioritizing quality over convenience. If a Zoom lens of 18-200 has less quality then an 18-55.
Is there a rule of thumb of how many mm not to go over?
I mean the 18-200 has difference of 182, while an 18-55 has difference of 37.
Is there a maxim mm difference that I should not go over?
Or is there a percentage not to go over?

Not really, and some folks love the super zooms....If you're getting a crop camera like the d90 you might want to look at a 3rd party walkaround zoom like the Tamron 17-50, It's 2.8 and sharp as a tack.

FallGuy2005 wrote in post #9178205
Thanks everyone, there is a lot of good information here.
Also, thank you for the link http://www.the-digital-picture.com/.

The camera I was looking at was a Canon EOS 7D. But that is out of my price range. Right now I am looking at a Nikon D90.

Concerning lenses, I am prioritizing quality over convenience. If a Zoom lens of 18-200 has less quality then an 18-55.
Is there a rule of thumb of how many mm not to go over?
I mean the 18-200 has difference of 182, while an 18-55 has difference of 37.
Is there a maxim mm difference that I should not go over?
Or is there a percentage not to go over?

Some might say that about a 3:1 maximum ratio of the longest to the shortest focal length is a good rule of thumb (24-70, 70-200 for example). However there are some very well-regarded zooms that do not adhere to that "rule".

I've upgraded lenses quite a few times over the years.. but here is my current setup and their typical uses as requested in your original post... It's not the typical way we recommend lenses for people. I'm including my upgrade paths that got me where to where I am.

10-22 Wide angle used for landscapes. Not good for Panoramas when < 14mm
18-55 -> 17-40 -> 16-35 2.8L Typical wide angle lens used for anything indoors with flash, outdoor architecture car shots and vertically for Panoramas.
50mm 1.8 -> 50mm 1.4 Indoors no flash, portraits with bokeh in the background, night photography
70-200 F4 -> 70-200 2.8 -> 70-200 2.8L IS Indoor sports. Depending on lighting sometimes used with 1.4x
70-300 -> 100-400L IS If it moves and is outdoors; this is THE lens. Airshows, zoos, outdoor sports, paintball and some car photography

If I were on a budget and just starting out now, I might cover the range with a 10-22 and an 18-200/250. Once I figure out where most shots fell in the range, I might pick up a lens to cover that range, e.g. 17-50/55, 24-105, 70-300 etc.

thatkatmat wrote in post #9178555
If you're getting a crop camera like the d90

Sorry but could someone please define what a crop camera is and what this is as compared to what?

majipoor wrote in post #9170216
To summarize things, you can categorize lenses based on focal length:

Ultra Wide (<24mm) : landscape, scenic
Wide (24-35) : landscape, street, people groups, environmental portrait
Standard (50) : general purpose, indoor, portrait
Short Tele (85-135) : tight portrait, indoor sport
Tele (200-300) : candid portrait, outdoor sport, landscape details
Long Tele (400-800) : wildlife, birds

These focale lengths are for a FF camera: you need to multiply everything by 1.6x on a APS-C DSLR.

I think you were thinking the right way but expressed it in reverse. Divide by 1.6, rather than mulitply.

Multiplication is for determining what the FF equivalent is for a lens used on APS-C, therefore dividing by 1.6 is what the APS-C equivalent is based on FF .

Apart from the focal length, it is important to choose the lense based on its maximum possible aperture. Typical values are:

Fast (< f/2) : allows indoor shooting without flash
Quite Fast (f/2.8 ) : bare minimum for indoor without flash
Normal (f/4) : requires flash indoor
Slow (f/5.6+) : avoid whenever possible (except for ultra long tele)

The maximum aperture is also important for background isolation using shallow depth of field : this is an important point to consider for portraits.

And obviously, a zoom is a lot more versatile than a prime lens, but this is at a cost.

A good kit could include one walk-around zoom covering the most common focal lengths as well as 2 fast primes. If you want a general purpose kit, you should probably choose a standard or moderately wide prime (35 or 50) and a short/mid tele (135 or 200). You can add a lot of versatility to your kit by adding a 1.4x TC and a 25mm extension tube.

Canon 24-105 f/4 + Canon 50mm f/1.4 + Canon 135L f/2 + 1.4 TC would be for example an excellent general purpose kit. But I don't know if you would consider it as "affordable"

Kind regards, Wim

FallGuy2005 wrote in post #9203530
Sorry but could someone please define what a crop camera is and what this is as compared to what?

A crop or APS-C camera is the most common dslr, with a sensor much smaller than a 35 mm negative. Actually, it has a sensor, on Canon, which is 1.6X smaller in diameter than a FF (35 mm negative size) sensor.

APS-C or crop cameras are the xxxD series, like the 450D (or XSi in the US), xxD series, like the 40D, and the 7D.

These are much cheaper to produce than a FF sensor camera, like the 5D, 5D II or 1Ds Mk III, which makes these crop cameras very popular.

They are called crop cameras, because in a way, when you use FF lenses, EF lenses in Canon-land, such a sensor only images a crop of the full (35 mm) image, hereby giving the apparent or equivalent view of a photograph taken with a lens that has 1.6X the focal length, compared to FF. This is where the 1.6X "crop-factor" stems from.

This also means that in order to have the same Field or Angle of View on APS-C as compared to FF, you need a lens that is 1.6X shorter than such a lens on FF. F.e., a 24 mm lens on FF would require a 15 mm lens on APS-C to give the same AOV or FoV, taken from the same exact point, that is.

As Canon wanted to provide shooters with similarly short lenses as on FF, with regard to AoV, they introduced the EF-S mount, a variant of the EF mount with lenses that can only be mounted on APS-C cameras and which provide the most common shorter FLs and wider AoVs one expects to have with a dslr. Standard zooms (15-xx, 17-xx, 18-xx(x), an UWA zoom, 10-22, and a macro lens, 60 mm, were added in EF-S mount to the exisiting arsenal of EF lenses in order to supply APS-C shooters with the missing shorter lenses.

HTH, kind regards, Wim

Ok I am by no means an expert and will answer this based on my knowledge and my kind of shooting, I started with crop sensor and was very happy with the first 3 lenses below, now I have both crop and full format, but I buy lenses for full frame and take advantage of the crop sensor when needed:

Crop sensor:
10-22 landscape, interior, carinterior
17-55 walk-around lens, travel
70-200 motorsport and all other events

24mm Group shots
85mm portraits
100mm Macro

Full format:
17-40 landscape, interior, carinterior
24-70 walk around lens, travel
70-200 motorsport, all other events
100-400 (same as 70-200 with more reach, less light)

35mm group shots, low light indoor small rooms
135mm portraits
100mm Macro