** Noobs DSLR Lens guide **

[just Touge]

For those of you out there thinking of getting a new lens, or for those of you shooting digital and may not know, a little information about using lenses on a digital body. Obviously we all know that digital cameras work in much the same way as a 35mm with the exception of the digital sensor replacing the film to capture the image. However, that sensor is smaller then 35mm film physically so you loose part of your image shooting digital unless your a baller and can afford one of the newer pro slr bodies with full frame sensors. This is sometimes refered to as "Crop Factor" or "Magnification Factor". Here are some quick reference figures: 35mm film size 24mm x 36mm by diagonal 43.27mm Standard digital sensor size 15.5mm x 23.2mm by diagonal 27.9mm This makes your 28mm lens with an AOV(angle of view) of 79 degrees turn into a 28mm with an AOV of 52 degrees. Nikon and Canon use a 1.5 or 1.6 crop. To figure your lense difference simply multiply one of these to your lens focal length to get the "new lens". Focal length reamains the same, AOV is the only thing that changes. Example 28mm x 1.5 = 42mm 18-200mm x 1.5 = 27-450mm Remeber, this does not make it a different zoom or focal length, only a difference in AOV.

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[awang]

allow me to add:

When you purchase a lens, you'll notice next to the mm distance, a number in the following format f/XX

This is referred to as the len's f-stop. F-stop is a measurement of a len's aperture.

When one looks at an F number, there are a few basics:
the larger the number, the smaller the aperture (hole that allows light into the camera)
the smaller the number, the larger the aperture

All lens are able to close down to a minimum of f/22. However, there is a maximum that each lens can open up. The notation on the lens tells of the maximum size that the aperture can open up.

Examples:

Canon EF-S 18-55mm f/3.5-5.6
When you have the camera zoomed to the minimum (18mm), the largest f/# that can be achieved is 3.5. As you zoom further, to 55mm, the aperture will close down and get smaller. At 55mm, the max size that the aperture can be opened to is 5.6

Canon EF 24-70mm f/2.8L
This lens has a constant aperture. Zoom lengths from 24mm all the way to 70mm can have a aperture of 2.8.

General comments:
- Lens that have a constant aperture are more expensive because of the way they are constructed.
- Usually lens that can open wider are more expensive. For example, a camera with a max aperture of f/2 will be more expensive than one that is f/4
- Lens that have a large max aperture are referred to as fast lens. This is because of the inverse relationship between shutter speed and aperture. More light going through the hole, allows the photographer to use a faster shutter speed. Smaller hole requires a slower shutter speed.
- It often appears to be a good idea use the lowest f-stop (largest aperture), but this has a few disadvantages:
- depth of field (DOF) shrinks with a larger aperture
- brokeh is not always the best
- image quality is not always the sharpest



Modified by awang at 12:37 PM 1/25/2008

[KhMerEatRice]

Great Topic guys, just what I needed. Couple of questions...I understand that prime lenses are those that have a fixed focal length, I've seen users with a 18-55mm kit and another lens that is 50mm F/1.8, now whats the point of having those two lens when the kit lens can also have a focal length of 50mm? Is it that the 50mm lens have a lower F-stop,therefore resulting in a faster and sharper lens? Second question, What's the biggest difference between a Nikon 28mm and a Sigma 30mm beside the fact that they're only 2mm difference and they're both different brands? Does that 2mm really makes the difference? Please fill me in for I am in the process of purchasing a new lens. Thanks

[darkspector2.0]

Originally Posted by KhMerEatRice

Great Topic guys, just what I needed. Couple of questions...I understand that prime lenses are those that have a fixed focal length, I've seen users with a 18-55mm kit and another lens that is 50mm F/1.8, now whats the point of having those two lens when the kit lens can also have a focal length of 50mm? Is it that the 50mm lens have a lower F-stop,therefore resulting in a faster and sharper lens? Second question, What's the biggest difference between a Nikon 28mm and a Sigma 30mm beside the fact that they're only 2mm difference and they're both different brands? Does that 2mm really makes the difference? Please fill me in for I am in the process of purchasing a new lens. Thanks

And the 2mm makes very little difference, but you may want that difference. The build quality and image quality of both may differ slight or significantly. Lenses are exactly like cars. Some go fast some are slow, some are built like tanks, some are POS' etc, etc. Good rule of thumb is generally, "you get what you pay for"

[just Touge]

I highly suggest the Nikkor 28mm f/2.8 over the Sigma. The Nikkor is uber sharp at f/4 and pretty sharp at f/2.8. If you really want a sick prime I'd go with the Nikkor 20mm f/2.8 or mega baller 18mm f/2.8.
Im actually getting the 20mm, its sick!

Taken with the 28mm f/4 1/80th SB-26 speedlight

http://farm3.static.flickr.com...3.jpg

Taken with the 20mm

http://farm2.static.flickr.com...7.jpg

[KhMerEatRice]

Nice photos, would that lens be great for an everyday use? I believe that should be wide enough. I was looking into a lens that can cover my everyday shooting from portraits to basically autos.

[Tinh Ngo]

For that kind shoots get a tamron 17-50 that would cover up for everyday shooting. I hope this help, and the wide is perfect for what you're looking for. I hope this help

-Tinh

[Miracle]

Originally Posted by KhMerEatRice

Great Topic guys, just what I needed. Couple of questions...I understand that prime lenses are those that have a fixed focal length, I've seen users with a 18-55mm kit and another lens that is 50mm F/1.8, now whats the point of having those two lens when the kit lens can also have a focal length of 50mm?

I have both the 18-55 kit lens and the 50mm 1.8, and here is the reasoning behind why I bought the 50mm prime:

-Fast lens (due to the WIDE 1.8 max aperture)
-Great for night shots, when I don't have my tripod handy.
-Shallower DoF when I want it.
-Smaller and lighter than the 18-55 kit lens
-It's a great walk-around lens
-Great for portraits

There's a couple others... but I won't bore you.

[KhMerEatRice]

Originally Posted by Miracle

There's a couple others... but I won't bore you.

No not at all. I'll be happy to hear it. Why did u think the topic of this tread was for NOOBS? I also have the kit lens 18-55, now how much of a difference is that from the tamron 17-50? And also, if I zoom into 50mm on my kit lens that would give the same affect as if I had the prime 50mm? I know these questions sound silly. Please help

[Miracle]

Originally Posted by KhMerEatRice

And also, if I zoom into 50mm on my kit lens that would give the same affect as if I had the prime 50mm? I know these questions sound silly. Please help

Technically, in ways of focal length, yes... it will be the exact same thing. BUT... you would have more control over the aperture if you wanted a Shallow DoF, or it was a low light shot...

EXAMPLE:

I just set my tripod up in my room... and had my camera and the kit lens on it. At it's widest aperture, a picture of my dark bedroom (I keep it like that, ) needed .8 seconds to get a +/-0 exposure. The SAME LOCATION, same lighting, with no changes, except the 50mm 1.8 lens, set to an aperture of 1.8 only needed a 1/5th of a second shutter to make a perfect exposure.

THAT much of a difference can mean you have obvious camera shake or not without a tripod.

Originally Posted by KhMerEatRice

I also have the kit lens 18-55, now how much of a difference is that from the tamron 17-50?

You lose more focal length with the Tamron, but it is 1mm wider at it's widest setting.

Just another "kit lens" if you ask me... just 1mm narrower and 5mm narrowwer at it's max zoom.

[just Touge]

For a walk around prime you probly want a 50mm. The Nikon is quite good and cheap.

Tinh, is your Tamron the constant 2.8?

[KhMerEatRice]

Originally Posted by Miracle

Technically, in ways of focal length, yes... it will be the exact same thing. BUT... you would have more control over the aperture if you wanted a Shallow DoF, or it was a low light shot...

EXAMPLE:

I just set my tripod up in my room... and had my camera and the kit lens on it. At it's widest aperture, a picture of my dark bedroom (I keep it like that, ) needed .8 seconds to get a +/-0 exposure. The SAME LOCATION, same lighting, with no changes, except the 50mm 1.8 lens, set to an aperture of 1.8 only needed a 1/5th of a second shutter to make a perfect exposure.

THAT much of a difference can mean you have obvious camera shake or not without a tripod.

You lose more focal length with the Tamron, but it is 1mm wider at it's widest setting.

Just another "kit lens" if you ask me... just 1mm narrower and 5mm narrowwer at it's max zoom.

Great, just as I thought. If I was looking into a prime lens the 50mm at 1.8 being its widest aperture isn't all that bad. Camera shake is one of my concerns as well as low light shooting.

[Miracle]

Originally Posted by KhMerEatRice

Great, just as I thought. If I was looking into a prime lens the 50mm at 1.8 being its widest aperture isn't all that bad. Camera shake is one of my concerns as well as low light shooting.

And that is mostly why I picked it up... the capabilities in low light. I haven't really gotten the chance to exerise that premise... because i have been fairly busy since I got it... but it works really well from when I HAVE used it.

[just Touge]

Originally Posted by Miracle

And that is mostly why I picked it up... the capabilities in low light. I haven't really gotten the chance to exerise that premise... because i have been fairly busy since I got it... but it works really well from when I HAVE used it.

Think about the 28mm or 30mm too. You will be closer to true 50mm with crop factor.

[Miracle]

Originally Posted by just Touge

Think about the 28mm or 30mm too. You will be closer to true 50mm with crop factor.

yeah true... the 50mm 1.8 is more like a 80mm on my XTi...

Sucks.

[just Touge]

Originally Posted by Miracle

yeah true... the 50mm 1.8 is more like a 80mm on my XTi...

Sucks.

The 28 is like 42 and 30 is like 45 or 47.

[usdm97DC4]

Originally Posted by just Touge

I highly suggest the Nikkor 28mm f/2.8 over the Sigma. The Nikkor is uber sharp at f/4 and pretty sharp at f/2.8. If you really want a sick prime I'd go with the Nikkor 20mm f/2.8 or mega baller 18mm f/2.8.
Im actually getting the 20mm, its sick!

would you suggest a 10-20mm sigma? im looking for very sharp pics. i dont really know if nikkor has a 10-20mm, but im pretty sure they dont. the sigma caught my eye because of its price.

[Miracle]

Originally Posted by just Touge

The 28 is like 42 and 30 is like 45 or 47.

44 on the 28 lens, and the 30 comes out to a 48, according to my math skillz...

And for those of you that don't understand what we are talking about... here is a tutorial I took the time to write up myself... enjoy...

http://www.honda-tech.com/zerothread/2209039

[just Touge]

Originally Posted by Miracle

44 on the 28 lens, and the 30 comes out to a 48, according to my math skillz...

And for those of you that don't understand what we are talking about... here is a tutorial I took the time to write up myself... enjoy...

http://www.honda-tech.com/zerothread/2209039

Your shooting Canon so the crop factor is different, and I also did a short write-up about this here.

[usdm97DC4]

just Touge help me out

[just Touge]

Originally Posted by usdm97DC4

just Touge help me out

pm me then.

[A's 94 GSR]

Now, I currently have a 50mm f/1.8 lens and the only problem I have with it is that it isn't wide enough for indoor shots, parties, etc. This is the only lens I've owned/used. What lense would I need to get a wider angle? 17-35mm lens? or would a prime lens at like 28mm be better? Like everyone else asking questions, I'm new to photography and want a crisp, sharp picture.

[Dr.Zoidberg]

Originally Posted by A’s 94 GSR

Now, I currently have a 50mm f/1.8 lens and the only problem I have with it is that it isn't wide enough for indoor shots, parties, etc. This is the only lens I've owned/used. What lense would I need to get a wider angle? 17-35mm lens? or would a prime lens at like 28mm be better? Like everyone else asking questions, I'm new to photography and want a crisp, sharp picture.

I suggest taking a looking at the Sigma 24-60 2.8 or 24-70 2.8 and also the Tamron 28-75 2.8. All three produce sharp pictures (assuming you get a good copy) and cost less that $350.

Tamron and Sigma also make 18-50 2.8 for a little bit more money if you want a lens with a wider angle. I used to use a 28-300 for my camera and found that even 28mm was sometimes not wide enough for indoor shots.

[just Touge]

Originally Posted by Dr.Zoidberg

I suggest taking a looking at the Sigma 24-60 2.8 or 24-70 2.8 and also the Tamron 28-75 2.8. All three produce sharp pictures (assuming you get a good copy) and cost less that $350.

Tamron and Sigma also make 18-50 2.8 for a little bit more money if you want a lens with a wider angle. I used to use a 28-300 for my camera and found that even 28mm was sometimes not wide enough for indoor shots.

It really depends on if you want zoom. I guess Im old school and I like prime lenses. I love my 28mm, I shot all of JDM Theory with it and at f/4 with a speedlight the pictures were super crispy. I'll probly end up owning like 4 primes and one wide range zoom like an 18-200.

[A's 94 GSR]

Originally Posted by just Touge

It really depends on if you want zoom. I guess Im old school and I like prime lenses. I love my 28mm, I shot all of JDM Theory with it and at f/4 with a speedlight the pictures were super crispy. I'll probly end up owning like 4 primes and one wide range zoom like an 18-200.

Yeah, I hear that primes are sharper because it uses one piece of glass, instead of a few for zoom lens'. But do you understand what I'm talking about with the 50mm lens. Would you recommend the 28mm lens for a indoor/group gatherings because its wider or should I look into a different focal length?