[EyeSpy]

sure i could google my ? but I rather hear it from you guys and gals. I purchased an F 80-200 and a FA 50-200 from fellow pentaxians to build my af lens collection at decent prices. I used the FA 50-200 today. Well, now to satisfy the LBA or ahem,cough, build my collection.. another forum member is selling the tamron af 75-300 LD. A screaming deal and I calls it. Maybe. So before I decide... just how much distance do I gain with a 300mm?

[Macario]

to put it simply, alot of distance. But I do not know how good the tamron is at 300mm. I have the 80-200 myself, and have to say that the results at 200mm are pretty good

[EyeSpy]

Thanks for answering a dumb question. my fuzzy math would indcate a 50% increase. I've read the reviews and this lens at 300 is not so sharp, but a decent lens at lower apertures.

[stevbike]

I do not own any of these lenses but I wrote a review of my 75 to 300mm zoom I had gotten as part of a used ME-Super package that was bought. I like the range of this type of lens over the shorter 50 to 200mm myself. They are heavier relative to the shorter counterparts depending on the age and brand but I find myself getting a lot of use out of it.

I found myself in the past using a 80 to 200mm range lens only to use the longer settings most of the time. I bought a fixed Pentax SMC-M 200mm f4 telephoto lens and was far happier with this over the zoom with the same long end focal length.

For a shorter lighter zoom in I bought a used 75 to 150mm SMC-M f4 that gets used when the 75 to 300mm zoom is not needed. The 75 to 150mm has been around for many years and never regretted buying it.

[mysticcowboy]

You gain a lot of distance with the 300, but the Tamron gets softer past 200mm. If you want the longer focal length, sell the 80-200 and take the extra cash you were going to spend on the 70-300 and go for the Pentax 55-300. It's more expensive but worth every penny.

[SpecialK]

"Distance" is not the correct term as all lenses can see to infinity :-) You are asking about magnification. and, yep, the math is simple - 50% increase. The Pentax 55-300 is the way to go (for a consumer zoom).

[RioRico]

For less money, look for an old FA100-300/4.7-5.8 (silver). Probably around US$100 and very good at the long end.

[sterretje]

The maths is simple; a subject that wlll be 1cm high on the sensor with 200mm, will be 1.5cm high with a 300mm when at the same distance. Or a subject at 20 meters being 1cm high on the sensor can now be at 30 meters (with the 300mm) giving the same height on the sensor.

[wsteffey]

I have two favorite lenses, one a 50-200 (Pentax) and one a 70-300 (Sigma). I shoot a lot of horses, cats, and wildlife during their natural daily lives, and the 50-200 is just too short. I could not function without the 70-300. Most of my photos are in the 200-250 range, and the results are excellent. On the other had, the 50-200 is physically much shorter, lighter and faster handling, and I can actually carry in around for hours, something I've tried with the 70-300 and regretted.

[Marc Sabatella]

Another way of looking at it - a subject taken at 300mm will be the same size in the frame as a subject taken at 200mm and then cropped down so that two-thirds of the frame remains. Unless you are regularly shooting small birds similar subjects and are already cropping extensively to achieve more magnification, I personally find the difference between 200mm and 300mm inconsequential inpractice, given that cropping is free and all modern DSLR's have resoltuion to spare.

[Just1MoreDave]

Don't overlook camera shake. You get more magnification but need a faster shutter speed too, otherwise your 300mm shots are blurry. Camera shake will have a much larger effect on IQ than lens quality. If your typical use is in less than good light, you might not get to use the full 300mm without a tripod.

Some zoom lens designs also only reach 300mm at infinity focus, and actually have less magnification at across-the-room distances than some 200mm zooms.

[EyeSpy]

focus to infinity...visualize my realization of "that was a dumb question" when I "woke up". but the answers not so dumb. thanks everyone. good advice and comments all round.

[RioRico]

focus to infinity...visualize my realization of "that was a dumb question" when I "woke up". but the answers not so dumb. thanks everyone. good advice and comments all round.

The only dumb question is an unasked question -- or a troll, but we don't have THOSE here, eh?

Lots of what happens in optics isn't intuitive unless you've soaked-up a lot of info. Are many kinds of lens designs that behave differently. Not all zooms are created equal, nor are they labeled and marketed equivalently. Some zooms shift the focal length with a focus change or vice-versa, but you can't tell this from the labels and specifications. Magnification and focus numbers are measured at the extremes, not across their whole working range. The stories are incomplete.

And then there are peculiarities. Some zoom designs are so off-the-wall that they just can't be compared to common zooms. (My Schneider Betavaron 50-125/4-5.6 enlarger zoom is a good example.) Some zooms have splendid optics but quirky or bothersome construction. (Zoom creep, ick!) Some just feel better or worse to use. My Lil'Bigma 150-500 is splendid but a huge beast. I'm much more likely to carry the much smaller FA100-300 (silver). A lens must be usable as well as brilliant.

We can't just look at the numbers of a couple zooms and compare them meaningfully. So besides doing lots of research and memorizing the lens review database here, we ask questions. Those too dumb to ask questions get what they deserve, eh?

[EyeSpy]

Rio, I just found a listing on ebait and placed a bid on the silver bullet you mention. wish me luck.

[RioRico]

Rio, I just found a listing on ebait and placed a bid on the silver bullet you mention. wish me luck.

G'luck indeed! If When you get it, you'll like it!