Confused by DSLR lens terminology

[FloridaGal]

Hi everyone,

I am very confused by lens terminology and would really appreciate it if someone could give me the "lenses for dummies" answer to my question.

I presently have an Olympus SP 500UZ; a 6 megapixel point & shoot with a 10x zoom which the documentation says is equivalent to 38 mm to 380 mm. On the lens itself it says AF zoom 6.3 - 63mm 1:28-37. So I really don't know what that means, but it has never mattered ... I just know that when I use the zoom button, things get closer, but cropped.

But now I am thinking about a camera that would take better pictures with more zoom and so I am looking at the entry level DSLR's ... specifically the Olympus E-510 (10 megapixel) ... but when I look at lenses I realize that I do actually need to understand this "mm" thing. :eek:

There is a 2 lens kit for the E-510 that includes a 14-42mm f3.5-5.6 and a 40-150mm F4.0-5.6 ... but I don't really know what this means. I take a lot of pictures of birds and sometimes the pesky little fellows don't let me get too close ... hence my desire for a sharper picture taken from a greater distance. Is there any easy way to calculate how much zoom I get at a certain distance? i.e. will a certain lens number give me a zoomed in shot of a bird that is 25 ft away? 50ft? 100 ft?

Also, if anyone knows of websites or books that really "dumb down" the terminology I'd appreciate it.

Thanks!
:)

[Codebreaker]

Beth....

Expressing lens characteristics in 'mm' is defining the the Focal Length of the lens. What's that I hear you say? :)

Well rather than get technical I'll answer the second question which will explain about Focal Length. In a nut shell the longer the Focal Length the close the subject will appear. So a 200mm lens will get you closer than a 50mm lens.

Focal Length is a physical characteristic of the lens, so for DSLR lenses no matter what camera you put them on the Focal Length is always the same.

However, confusion now creeps in because most Digital Cameras can have sensors that are physically smaller than 'olde' 35mm film. This means that if you put the same lens on a 35mm film camera and a typical digital camera, the digital camera 'appears' to have zoomed in because you're seeing less of the scene. It's like having an image and cropping something out of the middle. Which is why digital camera sensors are often called Crop Sensors.

So your 6.3 to 63mm is equivalent to a 35mm camera using a lens of 38 to 380mm.


Hope this helps.

Colin

[msbrad]

Thank you Colin,
Your answer helped me.
m

[FloridaGal]

Thank you! Do I get a follow-up question?:)

Since the E-510 kit lens of 40-150mm is the 35mm equivalent of a 300mm 35mm, and my present point & shoot is a 380mm equivalent, doesn't that mean that I will end up needing to be closer to the subject with the new camera than I presently do with my old camera? And so the solution to that would be a "zoomier" lens? Like the ED 70-300mm f/4.0-5.6 which is the 140-600mm 35mm equivalent? And is there a formula that says if the distance from your subject is X, and your subject size is y, then to get a decent shot your mm# should be z?

Thanks again!
Bye,

[Codebreaker]

Hi Beth....

If the 510 equivalent is 300mm and your P&S equivalent is 380mm then you'll need to stand closer.

As for a formula I don't think it's that simple because the missing factor is how much do you want to fill the frame. Maybe some one else can shed some light on this.

As an example though I used a 300mm on my Canon which gave an equivalence of 480mm. A Goldfinch only appeared about 2/3rd of the height of the frame (in Landscape mode) when taken at a distance of about 4m.

Colin

[Chuck S.]

Colin, the factor for adjusting lens focal length from film SLR to digital SLR is confusing. It gives the impression that somehow that lens magnifies more when attached to a DSLR; as you know, it doesn't. A 300 mm lens mounted on either camera projects an image to the film or sensor that's exactly the same magnification; a 300 mm lens is approximately a 6-power magnifier. However, in the case of the film SLR, you have a relatively large surface onto which the image is projected, so more of that 6 power image is caught on the film. However, the smaller sensor on a DSLR only captures the heart of the image, leaving out a bunch of stuff that was captured on the film. In effect, the DLSR is cropping the image in-camera.

However, if I then develop the images from the film and digital, then print 4-by-6's, the DSLR image appears to be at a higher magnification. In reality, the DSLR image is a crop of the film image that has been upsized.

Again, probably not worth a whole lot of discussion, but I just keep telling myself that my long lenses didn't truly get longer just because they're now attached to a DSLR!

[Codebreaker]

Hi Chuck....

That's really what I was saying - just using different words :):)

Colin

[Chuck S.]

Hi Chuck....

That's really what I was saying - just using different words :):)

Colin

And fewer words - which is a good thing!:D

[Big AL]

I'm not familiar with the Olympus lenses...I use Canon, but as far as how you would use the lenses you mentioned....The 14-42mm would be for close up shots like maybe a car show or of flowers and normal family shots. It would probably be a good wide angle shot for scenery. If it has macro settings thats what you would use to get really close like for bugs or close up flower shots. The 40-150mm is a good everyday range or for if you are on a hike....enough for a close animal but with enough zoom for that bird 50 feet away. It also would work well for portraits and family shots. If you are specifically into birding, you will need probably a minimum 300mm. I use a 70mm-300mm lens which works well, but I would really like a 500mm. Of coarse the bigger and better the lens means the more cost. Since my wife laughed when I gave her my Xmas list I guess I will be waiting a little longer for that lens :)

[GaryK]

Hi Beth

Without getting into it too much, there is a bit more to lenses than just the mm comparisons. You are correct though, that the bigger the number the zoomier it is.
If you are new to DSLR terminology as well as technology, ask questions before spending the money. Loads of people here will be willing to help without the egos and brand bashing you find on some photography sites.

It is not hard to pick up the slang and pretty soon you will be throwing jargon around like a pro.:)

[FloridaGal]

Thanks to everyone for your answers! Here's where I am in my "quest for understanding". :)

Last night I bought "Get the Most from Your Digital Camera (new 2007 edition) by Simon Joinson and thus far it has been extremely helpful because he starts out at a VERY basic level on numerous subjects, not just lenses. So for anyone who is following this thread, and is also confused by basic terminology, I would definitely recommend this book.

I think my confusion stems from the fact that I am trying to understand DSLR technology from the viewpoint of a digital point & shooter rather than a person who has a background in film photography ... so when I Google for the answer to a question, I am not understanding the basic language the answer is written in ... truly, it is "all Greek to me" and I want to make it "all geek to me"! And I think where I am getting frustrated is that I am trying to understand, specifically, what is happening between me (point A) and my subject (point B). When I get in my car and drive from point A to point B, the fact that I am clueless as to how the engine works does not bother me ... I never ask how or why the car got me to my destination. But with photography, I have a strong "need to know" ... I want to understand what happens after I push the button on the camera ... what is happening between me (A) and subject (B) ... why do I sometimes get a really good shot and sometimes I don't. And yes, I do understand that it has to do with many other factors besides this "mm" thing that I am presently really hung up on ... it's just that since the good shot I am after is of a bird that is not very close, I thought I'd start with my "mm" confusion and then move on to other areas of confusion afterwards (assuming you all don't get so fed up with me that you quit reading my posts! :D)

So I believe that I have definitely decided to ask Santa for the Olympus E-510 ... I have loved the SP500 UZ, am very happy with the reviews for the 510, and completely comfortable with the four thirds standard ... it comes with the 2 kit lenses I previously mentioned and I'll probably add the "zoomier" 70-300mm (600mm equivalent) ... and then start taking pictures of something small that doesn't move and see how far I can back up from it and still get the detail I want.

So thanks for letting me share my frustration & confusion ... till next time ...

Bye!
:)

[GaryK]

Beth

Glad you have a book to get you on your way.

Don't mind asking questions if you have them. sometimes a bit of clarification goes a long way to helping understand.:)

I don't know the Olly lens line up, but as a general rule, 300 mm is about the top end of the lower priced lenses. Once you get over 300 mm you will typically find that the prices jump quite a bit. A 400 mm may cost as much as your zoom.

One thing, it you are really thinking you might want a really long (500 mm) type lens in the future make sure that Olympus makes one. Or that at least one of the other lens companies make one for your camera. (Sigma, Tamron comes to mind).:)

[ljameso1]

I'm going to try to give a "nongeeky"(is that a real word?:eek:) answer to your distance explanation request. Say you are standing in 1 spot with a 50mm lens on your camera. Then without moving you change to a 100mm lens. The object you were photographing will now appear twice as large as with the 50mm(as if you had walked half the distance closer with the 50mm). You get the same jump going from 100mm to 200mm. 200mm-400mm etc. I hope this helps grasp the gist of the differences between the lenses. I have gotten frame-filling shots of larger birds with the focal lengths your looking at. Smaller birds need either a blind, habituation to your presence, a remote trigger for the camera, or a lens so big neither your back nor your pocketbook will be overly enthused.;)

[lexcell]

With all the different formats of digital out there now it really can be confusing. Each camera has a different focal length magnification factor. The 35mm equivalent is what we have all understood for years (those of us who have been shooting for years that is).

So, in 35mm terms, 50mm was always considered normal...that is the magnification and angle of view that we see with our eyes (approximately).

Anything smaller becomes wider angle, including more in our picture. The smaller the number the wider the lens.

Anything larger than 50mm is considered telephoto. The bigger the number the greater the magnification.


The greater the magnification, the closer the subject appears or the more it fills the frame. A pair of 10X binoculars is approximately equivalent to a 500mm lens. (50X10=500)

Now, you introduce, smaller sensors and all that sort of goes out the window. True, a 300mm is a 300mm no matter what format but on different cameras you get a crop factor which makes the lens appear to be even longer when in actuality, the sensor is effectively cropping the image.

Manufacturers put an equivalent to 35mm focal length in their specs so that you can get a good idea of what the new lenses will equate to.

[Codebreaker]

I often wonder if the manufacturers include the 35mm equivalent because the bigger numbers look more impressive. Marketing hype!!! :)

Colin

[Clayton]

Thanks Laurie for the explanation (and to everyone else). I have been looking at the Nikon 18-200 lens. It says it is equivilant to 27-300mm in 35mm format, so I assume this means it gives the appearance of 1.5 times of what I would see on my 35mm camera with a 18-200 lens. Is this right? Also the specs say it has a 11.1x zoom lens. My slow mind can't figure out what this means in the terms we have been discussing.:eek:

[lexcell]

Your camera has a 1.5X multiplier due to the size of the sensor so, any lens you look at will be multiplied by 1.5X if you want the 35mm equivalent.

The 11.1x zoom means that at 200mm the lens is 11.1X greater than it is at 18mm. If your lens went from 18-180 it would be 10X ( an easy one to do the math )

[Codebreaker]

Just a word of caution before you buy your zoom lens. I'd advise you to read up on some reviews. Zoom lenses, especially those with very large zoom ratio's try to be all things to all people, for the convenience of just having one lens. They often do not have the same overall performance as lenses with smaller zoom ratios.

Colin

[FloridaGal]

Hi Everyone,

I found a website that I believe has the type of lens distance calculator I was looking for: http://www.cambridgeincolour.com/tutorials/camera-lenses.htm

In the tutorial it is referred to as a "required focal length calculator". Since the camera I am interested in is an Olympus which has a 2x multiplier, and since that is not one of the choices in the calculator drop down box, I am choosing 35mm instead and then dividing the calculated result by 2.

There are also quite a few tutorials on other subjects at this site. For me, this site has been very helpful, though at this point in my camera education I would not recognize inaccurate information ... I just try to judge how correct I believe the information is based upon how professional the website looks. So if anyone else takes a look at the site I would be interested in your opinion ... especially an opinion on the validity of the required focal length calculator.

Thanks to everyone for all the posts to this thread!

Bye,
:)

[hotstuff]

Hi Floridagirl.

I recieved my first Dslr at the weekend, and guess what it an E510. I upgrade from an oly mju 300 piont and wait for the sensor to wake up and shoot. not had chance to play with it yet, I got the two lens kit should keep me going for a while.
Here's a link you may have seen it before, only one problem it will make Xmas seem ages away lol.

http://www.cameralabs.com/reviews/OlympusE510/video_review.shtml

:)