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02-02-2008, 08:34 PM   #1
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Couple of basic lens questions

Hello all,

the kit lens for my K100D Super is 18 - 55mm. I'm looking to buy a wide angle lens & found one that's 24mm. Does this mean my kit lens at <24mm is 'wider' than the 'wide angle' lens?

There's no menton of the lens hood in the owners manual (that I can find). When should I be using it (or not using it)? I've read some conflicting suggestions on the Web & would like clarification.

Cheers!

AP

02-02-2008, 08:39 PM   #2
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QuoteOriginally posted by arthur pappas Quote
Hello all,

the kit lens for my K100D Super is 18 - 55mm. I'm looking to buy a wide angle lens & found one that's 24mm. Does this mean my kit lens at <24mm is 'wider' than the 'wide angle' lens?
Yes. What speed is the 24mm lens (maximum aperture, which is to say lowest f/stop)? It probably has other advantages while the kit lens is relatively nice, it's weak at the widest end of its range.

QuoteQuote:
There's no menton of the lens hood in the owners manual (that I can find). When should I be using it (or not using it)? I've read some conflicting suggestions on the Web & would like clarification.
Use it whenever light might otherwise strike the front element of the lens directly. (Particularly obvious when shooting facing the sun.) But it's also good to have as protection at all times.
02-02-2008, 08:47 PM   #3
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Thanks Matt. I don't know what speed it is but will find out. Why do I need lens protection & what am I protecting it from?
02-02-2008, 08:55 PM   #4
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The idea of a lens hood as Matt said is to shade the front of the lens from Sunlight which will cause lens flare. That looks like yellow/orange/blue/purple "spots" on the pictures. The protection is to keep the lens free from scratches, fingerprints etc that could impair or damage the lens.

Many use UV or Skylight filters to protect the lens as well. For critical shooting, it's better without a filter.


Last edited by Peter Zack; 02-02-2008 at 10:34 PM.
02-02-2008, 09:51 PM   #5
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QuoteOriginally posted by arthur pappas Quote
Hello all,

the kit lens for my K100D Super is 18 - 55mm. I'm looking to buy a wide angle lens & found one that's 24mm. Does this mean my kit lens at <24mm is 'wider' than the 'wide angle' lens?

There's no menton of the lens hood in the owners manual (that I can find). When should I be using it (or not using it)? I've read some conflicting suggestions on the Web & would like clarification.

Cheers!

AP
A good reason for the lens hood is to protect against physical damage to the front element of the lens. I scratched the hood on my 12-24 the other day. I can live with a scratch on the hood, particularly on the outside.
02-02-2008, 11:09 PM   #6
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QuoteOriginally posted by arthur pappas Quote
the kit lens for my K100D Super is 18 - 55mm. I'm looking to buy a wide angle lens & found one that's 24mm. Does this mean my kit lens at <24mm is 'wider' than the 'wide angle' lens?
Arthur,

18 < 24, so yes, the kit lens can go wider than the "wide angle" lens you've found.

But note that 24 isn't very wide these days. Have you read yet about what is commonly called "crop factor"? The sensor in cameras like the Pentax digital slrs (all of them, including the K10D) is smaller than the sensitive area of an old 35mm film camera and this makes a difference to the EFOV ("effective field of view"). A 24mm lens on an old film SLR (or on a full-frame digital SLR like the Canon 5D or the Nikon D3) is fairly wide. But the same lens, when used on a Pentax K10D or K100D or similar camera, has an effective field of view equivalent to the EFOV of a 32mm lens on a film SLR, which is to say, wideish, but not what I'd call very wide. To give you a concrete example, say, you're photographing a house from the street out front. The 24mm lens on a Pentax K10D might let you see the entire width of the house, from the left side to the right side. But the same lens on a film SLR would let you see a good bit more, the yard on the sides of the house both on the left and right. So if you're using a Pentax digital SLR with a 1.5x "crop factor" and you are thinking of photographing, oh, wide buildings, or large groups of people, or the Grand Canyon, you'll probably want to do better than 24mm. When I need to go wider than that I put on my Sigma 10-20, which on my K10D is an honest-to-gosh wide angle.

As for lens hoods, they serve two purposes. They help prevent "flare" in your photos, which can occur when stray light hits the mouth of the lens from the side rather than from more or less directly ahead of you. And as Matt and others have noted, the lens hood provides quite effective protection of the lens in many instances, particularly protection from knocks. Many people use a neutral density filter for protection, but I think it's less effective than a lens hood. Last year I took a nasty spill while hiking with my K10D. AS I was going down, I did my best to protect the camera, but it took a bang on the rocks nonetheless. If I'd had only a filter on the camera, the business end of the lens would have taken the hit directly. But I had a lens hood on, and it took the hit instead of the lens. The hood got a nasty scratch from the rocks, but otherwise, no harm done. Well, I limped for a week, but the camera was fine.

Will
02-02-2008, 11:50 PM   #7
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Thanks to all for clearing the fog. I have to say this is a great community. I go to Steves Digicams & Dpreview for review & upcoming news 'n stuff & almost joined one of those forums.

I'm so glad I found this place.
02-03-2008, 04:34 AM   #8
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QuoteOriginally posted by mattdm Quote
... while the kit lens is relatively nice, it's weak at the widest end of its range.
unless you don't stop it down significantly (f11-f16) than it's pretty good, especialy for what it is. IMO

QuoteOriginally posted by arthur pappas Quote
Hello all,

the kit lens for my K100D Super is 18 - 55mm. I'm looking to buy a wide angle lens & found one that's 24mm. Does this mean my kit lens at <24mm is 'wider' than the 'wide angle' lens?

There's no menton of the lens hood in the owners manual (that I can find). When should I be using it (or not using it)? I've read some conflicting suggestions on the Web & would like clarification.

Cheers!

AP
Yes, DA18-55 is wider than 24mm. The lower mm number, the wider the lens (with exception of fisheyes! 17mm fisheye is still wider than even 10mm corrected lens!). As Matt said, the 24mm can have some advantages... All depends on what you want the lens for...

02-03-2008, 05:29 AM   #9
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As others have said Yes the 24 mm is a wide angle lens but not as wide as the 18-55 can give. I have found in doing landscape photography there are times when you want more latitude and area in the shot. Thinking of what it looks like in the lens and what it will look like after the shot and how much you can crop out later.
Using a 24mm will allow a wider shot but the crop factor of the lens limits you in how much of the shot filling the lens you will want to keep. A wider angle lens (or even a fish eye) will give you the most bang for the buck in landscape and wide angle photography.
The use of fish eye lenses for this purpose and knowing how the fish eye will work on angles will give you better results than a narrow crop 24mm.
I know I have used the 16mm Zenitar many times for landscape shots and have gotten beautiful results. Knowing how to shoot to get the fish eye effect using the straight on angles is one thing but learning to use the lens to not render this effect by shooting off angle and getting the wide angle results you want takes just a little practice. (not much) If this is what you want to use a wide angle for then I would recommend using (or finding ) a 10-17mm or a straight 14-17 mm focal length lens. Remember all lenses have their use but using a straight focal length is limiting. I know since I got the Zenitar I have not used it much in the way I shoot, but when I want (or the need arises) I have it. When I'm limited in space I can move back for a wider shot with a 18-55mm lens I use a fixed focal length 14-17mm lens for the best results.
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