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Photography Question 
Dale Ann Cubbage
BetterPhoto Member Since: 3/4/2004
 

Faster Lenses?


First of all I need to admit to using auto mode a lot on my Fuji FinePix 4900Z, mainly because I am still a beginner and find that although I know the difference between shutter speeds and aperature, I get better results from auto than when I try to do it manually. I do want to learn how to do it better though. I know I could buy a book and read it, but I don't learn that way very well. My question is really about lenses. I want to shoot portraits, and someone suggested I get a faster lens. Will someone explain to me what that is in English, in a slow learner kind of way, so I can figure out what I need to get better?

Thanks in advance,
da


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7/15/2004 11:11:18 PM

 
Jon Close
BetterPhoto Member Since: 5/18/2000
  A "faster" lens is one with larger maximum aperture. For 35mm film the term generally refers to maximum apertures of f/1.4 to f/2 for lenses under 100mm, f/2.8 for zooms and lenses from 100mm to 400mm, f/4 for 500mm to 600mm. The wider aperture allows faster shutter speeds (hence the name) in low light, and shallower depth of field (to separate your subject from distracting backgrounds). These lenses generally use exotic glass elements and are much better corrected for chromatic and spheric aberrations, so they are sharper than typical consumer lenses and are better suited for larger print sizes and slide projections.

Not really relevant to your FinePix 4900Z as it has a permanently mounted lens that you cannot change. Also it's digital sensor is much much smaller than 35mm film. Its zoom lens has maximum aperture of f/2.8-3.1 and seems relatively "fast" for getting higher shutter speed exposures. However, it's lens focal length is very short. While it gives a view equivalent to a 35mm camera with 35mm-210mm zoom, its lens is actually on 7.6mm-46mm. Depth of field at f/2.8 is the same as the equivalent 35mm zoom set to f/12.8. It will be very difficult to get the shallow depth of field typical in portraits (face in focus, background creamy blur).

Typical rig for portraits would be a 35mm SLR with 85 f/1.8 or 100 f/2 lens. In digital the equivalent would be a digital SLR (Digtal Rebel, 10D, D100, D70) with 50mm f/1.4 lens.


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7/16/2004 7:42:31 AM

 
Dale Ann Cubbage
BetterPhoto Member Since: 3/4/2004
  John, thank you for answering my question. So if I understand correctly, I cannot purchase a "faster" lens for my finepix, correct?

Q. Also, I'm sure this is probably explained elsewhere, but I still don't understand what all those mm's are about. Anyone care to school me on that? I don't have a clue about focal length and all that technical stuff. I really desire to learn about it, everything I've read is so technical I can't grasp it.

Q. Also on the back of my external flash for hotshoe, it has a chart on it for flash and distance. What is that all about?

I appreciate anyone taking time to help me out.


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7/16/2004 9:09:25 AM

 
Jon Close
BetterPhoto Member Since: 5/18/2000
  Right, you cannot purchase a faster lens for your FinePix.

mm is millimeter. Lenses are categorized by their focal length, measured in millimeters. In the most general terms, shorter focal lengths give a wider angle of view than longer focal lengths.

Re: the chart on your flash, do you not have the instruction manual? Generally, the flash will give a good exposure only if your subject is at a specified distance (ex. 8 ft), or range of distance (ex. 4-20 ft), from the flash. That distance or range will vary depending on the ISO setting (light sensitivity of the film or digital sensor) and the lens aperture.

There are many good books or websites for learning the basics and ease into the technical. Try Kodak's "Joy of Photography", their online "Taking Great Pictures" (http://www.kodak.com/US/en/nav/takingPics.shtml), this website's online courses for beginners (http://www.betterphoto.com/home.asp#courses), Agfa's free online courses (http://www.agfanet.com/en/cafe/photocourse/cont_index.php3), etc.


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7/16/2004 9:55:52 AM

 
Dale Ann Cubbage
BetterPhoto Member Since: 3/4/2004
  Thank you John. Please forgive my ignorance, but I need to talk this out to figure it out. Is this correct:

I get a longer focal length when I zoom in on my subject staying the same distance from them. A shorter focal length would be zoomed out, actually showing more detail in the bg?

My camera has 48.6 mm, that is a shorter focal length than a 55mm, right?

Thank you for the link's. I have already been to agfanet.com and am going to take the free courses. I really appreciate your time and walking me through this.

da


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7/16/2004 12:37:36 PM

 
Jon Close
BetterPhoto Member Since: 5/18/2000
  Yes, the longer focal lenght gives greater magnification at the same distance.

>>"A shorter focal length would be zoomed out..."<< Yes.
>>"..., actually showing more detail in the bg?"<< ??? What is the "bg"? Shorter focal lengths give wider field of view, showing more of a scene farther to the left and right, above and below you subject. That's not the same as "more detail."

Yes, the smaller number is the shorter focal length.


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7/16/2004 1:22:52 PM

 
Gregory LaGrange
BetterPhoto Member Since: 11/11/2003
gregorylagrange.org
  Come on Jon. Don't know any slang do you. BG is typo talk for VF, as in view finder. Just slide your hand to the left a little, so you can be on point with the rest of us.


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7/16/2004 1:43:41 PM

 
Jon Close
BetterPhoto Member Since: 5/18/2000
  LOL!
qp-r, good buddy!


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7/16/2004 1:51:26 PM

 
Dale Ann Cubbage
BetterPhoto Member Since: 3/4/2004
  Actually, I was referring to the background (bg?) Which is what you said, just another way. By saying background, I'm referring to everything else in the VF besides my subject. LOL!

So a shorter focal length would show more of what surrounds my subject, and a longer focal length would bring me into a tighter crop with my subject.

Another question: if I use a longer focal length, and larger aperature (F2.8) then what is showing in field of view should be more blurred, correct?

Thanks again for helping me grasp it. I'm a slow learner! (duh)

da


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7/16/2004 8:24:08 PM

 
Gil Batzri   Using a 35mm or other "real" lens camera combination (medium or large format) a 2.8 or any fast lens will give you blur or "bokeh" on anything that is in the focus range (depth of field in focus) The larger the aperture is the shallower the "in focus" range is. A good example of this can be seen looking a professional sports photography of say a baseball game,

The DOF of the shot they frequently use of the pitcher on the mound has a range of focus of about 5' from about 100' away, shot with a 400mm lens at f2.8 (you can do a web search on DOF or Depth of Field for more info on this)

Back to your question...
I am not sure the point and shoot camera will behave the way a real lens does because the 2.8 aperture they refer to is nominal only, there is no actual aperture involved, and my understanding is that it is more a measure of light sensativity then the physical properties a f2.8 lens has (which include light transmission and DOF shallowness among other things)

If you really want to learn about photography with a digital camera that "obeys the rules" I would recommend looking into a used D-SLR the lower end cameras have dropped in price to below what you probably paid for your Fuji. you could get something like a D30 and a couple lenses for $700 or so.

All the "Rules" of photography will apply, and even an older body like a D30 is FAR superior to every P/S available, based purely on the sensor size and ability to control all facets of the camera.

Good Luck!
gil


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7/16/2004 9:45:20 PM

 
Gil Batzri   Ahh typos... Anyone for an EDIT function?

The Blur mentioned in the first graf is going to be on the portion of the scene NOT in the focus range

That's the most egregious, I won't correct myself agin..

Gil


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7/16/2004 9:48:41 PM

 
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