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Old Sep 18, 2006, 2:14 PM   #11
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Thanks for the responses. Please keep up the discussion.

So kit lens at 50mm(50mm equiv?) is not the same focal length as the FA 50mm(75mm equiv)? I previously thought that the crop calculation was supposed done on all the lenses and was trying to keep my kit lens at 50mm to test out if I could live with the FA 50mm. Guess I have to reevaluate that.

One of the things that I wanted to avoid is camera shake, since at 50mm(75mm), my camera shake will be magnified. I don't really have a feel for "fast f1.4" lens, so I don't know how much this will help me.

I don't plan on purchasing many lenses and this lens may be the 1 that I buy and keep on the lens for a few years. I don't mind so much using my feet as zoom as long as the pictures come out clear and with minimal noise.

I'm glad to hear that other lenses are way better than the kit lens, because I haven't seen much improvement over my P&S, other than in the noise arena.
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Old Sep 18, 2006, 2:23 PM   #12
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The kit lens set at 50mm is the same at the FA50mm. They both give the equivelant of 75mm campared to a 35mm film camera. The crop fact on a Pentax DSLR is 1.5, so multiply the focal length of any lens by this.A 50-200mm becomes a 75-300 instantly,shazam. Now if I put a 2x converter on it, what do I get? Wow- Bruce
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Old Sep 18, 2006, 2:29 PM   #13
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To get the equivalent angle-of-view in 35mm you need to multiply by 1.532. This applies to all lenses.
Here is a calculator for you: http://www.dcviews.com/lenses/Digital-SLR-lenses.htm

Just enter the focal length in the left-most column on the *ist D line, hit the X and see the equiv at right.

At around 50mm, the kit lens is quite decent. Allow for some higher ISO (400, 800)
and you should see a big difference compared with P&S. Shake Reduction works wonders at that focal length.

At 50mm the kit lens is F5.6 which is not even close to what FA can. At F2.8 you could have really nice portraits with great background blur. Moreover, the viewfinder is much brighter and it will help a lot in low-light situations.

Here is one example with the kit lens handheld: 55mm F5.6, at 1/100s, ISO400, SR on, in relatively low-light.

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Old Sep 18, 2006, 2:44 PM   #14
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Here is a 100% crop of it.
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Old Sep 18, 2006, 3:05 PM   #15
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Hi ksurfer,

"So kit lens at 50mm(50mm equiv?) is not the same focal length as the FA 50mm(75mm equiv)? I previously thought that the crop calculation was supposed done on all the lenses and was trying to keep my kit lens at 50mm to test out if I could live with the FA 50mm. Guess I have to reevaluate that."

Focal length is focal length. You'll get the same Field of view with any lens that can be set at 50mm.

One of the things that I wanted to avoid is camera shake, since at 50mm(75mm), my camera shake will be magnified. I don't really have a feel for "fast f1.4" lens, so I don't know how much this will help me.

The biggest difference between your kit lens at 50mm and the FA 50/1.4 is max aperture. The FA 50/1.4 will gather 16 times the amount of light that the DA 18-55 will with a max aperture of f5.6 at that focal length. That's 4 full stops. In practical terms, this means that if you have a situation where you can get a correct exposure at 1/10 sec wide open with the kit lens, you could shoot the same scene with the FA 50/1.4 (again wide open) at 1/160 sec. That'll make a big difference in camera shake. Up the ISO, and you could shoot the same scene at 1/300 @ ISO 400, and pretty much be assured that there would be very little shake involve, and the subject could even move some without it effecting the shot.

Add to that the sharpness of the FA 50/1.4, and there's a distinct advantage to having one in addition to the kit.

Scott
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Old Sep 18, 2006, 4:06 PM   #16
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I'm convinced that FA 50mm is what I'm looking for.
I think I'll start shopping for this lens.

Thank you all for helping!
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Old Sep 18, 2006, 6:46 PM   #17
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Not to go off topic on the 50mm, but I saw the comment Bruce (?) made on putting the 50-220mm on and then a 2x converter. I am new to all this lens stuff. Have the K100D with the kit lens and am considering the 50-200 lens for the rebate right now. The sales people are trying to talk me into getting the 75-300 for the extra zoom saying I will want it later. But, if I can get the 50-200 and just use a converter if I want more, why not? I like the size of the 50-200 for general walkaround camera.

Also, the 75-300 is $50 less. It makes me wonder why. And, why are they trying to get me to buy the less expensive lens in a commission field.

I had a Canon Rebel before with the 35-90 kit lens and never bought a higher zoom. It satisfied my basic needs, but was wishing I had more. Now with the 1.5 ratio, and getting to 200 (300) I think that would be more than sufficient.

Anyway, like I said, sorry to go off topic, but it had never crossed my mind to put a converter on the end of the zoom. Any potential problems with this?
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Old Sep 18, 2006, 7:34 PM   #18
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I don't think you'll go wrong having a 50mm lens. Id love an FA 50mm 1.4 but can't afford it right now. However I did pick up a new A 50mm f2.0 for about thirty bucks on Ebay a few weeks back. Not as nice Bokeh as the 1.4 or 1.7 but it does take nice pics when I get the focus right I have a Sigma 24-135 coming this week and my next lens purchase will be the auto focus 50mm 1.4.

Pic taken with the A 50mm 2.0 wide open in decent light in a wodded area.
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Old Sep 19, 2006, 12:21 AM   #19
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About Teleconverters - I had started thinking about that myself (after those *300mm lenses went through the roof on ebay this weekend). I'm no expert, but from what I've figured out, some are better than others (I converted a particularly worthless one my father had bought many years agoto an extension tube by taking out the glass - the glass degraded the picture THAT much). Any time you introduce more glass elements, you reduce the capability of the lens (whether it be a filter or an add-on lens). I got a photographybook out of the library Saturday that was written in 1976 (Field Photography)and ittalks about lens resolution vs. film resolution - the principles would still apply to digital sensors. He has a number of mathematical formulas in the book that are way over my head, but the bottom line conclusion he came to is that TCs can be quite useful, assuming that the lens you start with is really good quality - he recommends using a better prime lens with it set to a small aperture because there's a tendency to have less focus at the edges of the picture, and a smaller aperture would help, along with allowing additional unused space around your subject. I don't know if there's been any big strides in glass/lens optics to correct this curvature.

The other thing to think about is that not all TCs will work with the DA 50-200.The lensdoesn't have an aperture ring and so can only be stopped down if it communicates with the camera electronically. I don't know enough about modern TCs (hadn't gotten that far in my research) to know which ones would work with the DA lens, and I would assume (but don't know) that modern, good quality,TCs with the appropriate electronic contacts would be expensive. Not sure if it would save me enough to make up for the loss in quality, so I'd prefer to get a 300mm prime lens.

We probably should start a separate thread on Teleconverters if there is enough interest and knowledge here, since it's a big topic all by itself, and I've only scratched the surface of it!
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Old Sep 19, 2006, 7:45 AM   #20
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Thank you, Sarah. A new discussion topic would be fine with me to help me understand the whole thing. I do think, from reading other threads last night, I may just buy the 50-200 and be satisfied with it for now. I know if I had a long lens I would be less inclined to use it as often.

200 (300) zoom would be so much more than I've ever had (most is 90mm) I should be happy with that.

Patty
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