which telephoto lens??

[Pentaxian1992]

I'm looking for an inexpensive telephoto lens for my Pentax K100D. I want a telephoto so I can start photographing wildlife. I've been looking at the Tamron 70-300mm f/4 Di. is this lens good? is there a better lens that isn't too expensive?

[TheWengler]

It's actually a f/4-5.6. I'm starting to like it more than when I first got it. It does however, give me some problems with chromatic aberrations. People also like the Sigma 70-300 APO. Here are some shots I got with the K100D and the Tamron...

http://picasaweb.google.com/lswenger/Animals/photo#5128698674488942338
http://picasaweb.google.com/lswenger/Animals/photo#5128698678783909650
http://picasaweb.google.com/lswenger/People/photo#5128699662331420786
http://picasaweb.google.com/lswenger/Macro/photo#5128699232834690994

[pas49ras]

The Sigma Zoom Telephoto 70-300mm f/4-5.6 APO DG Macro is about the best lens under 200 dollars

http://www.sigma4less.com/sess/utn;jsessionid=15460ac2878e832/shopdata/0010_Lenses/0010_Zoom/0040_Tele+Zoom/product_details.shopscript?article=0380_Sigma%2BZo om%2BTelephoto%2B70-300mm%2Bf%3D26slash%3D3B4-5%3D252E6%2BAPO%2BDG%2BMacro%2BAutofocus%2BLens%2B for%2BPentax%2BAF%2B%3D28SG70300F4ADPX%3D29

[TheWengler]

The Sigma shows pretty poor border resolution on photozone. That's why I decided to just go with Tamron. It does seem odd that so many people like the Sigma as a budget telephoto if it really did have poor border resolution. Maybe photozone got a bad copy.

[BBPhoto]

What sort of wildlife are you shooting? 300 is pretty short for a lot of subjects.

[DonSchap]

The problem is that Pentax is severlely limited with newer long telephoto lenses. There are a few older lenses that are out there ... one being the kind I personally have a copy of for my SONY/Minolta. It took me a couple years to get one, but it has proven to be a pretty good long lens.

The Tokina AF 80-400m f/4.5-5.6 AT-X, which hasn't been produced for a couple years, is a great nature lens. It may be just what you are looking for. It'll probably be around $400-$500 (I got mine for around $300), but the focal range is outstanding on a APS-C sensor camera.



30480


It, effectively, is 120-600mm on a 35mm film-camera body. That's impressive. Not only that, it doesn't weigh all that much for a lens of this type, so toting it around is a lot easier.

Just a suggestion.

[Pentaxian1992]

I mainly want to shoot larger wildlife and birds. my camera has a 1.5x conversion factor, which gives a 300mm lens a focal length of 450mm. and I can always buy a 1.4x teleconverter, increasing it to about 630mm.

[BBPhoto]

300 with a 1.4x TC is respectable for a lot of wildlife stuff on a crop-sensor body. You will find serious birders shooting a minimum of 400mm but more often than not at 500 or 600 on crop-sensor bodies.

I have been shooting recently with a 300mm lens, 1.4x TC with a crop factor of 1.6 and it's still quite short for timid subjects. If it is within budget, Don's suggestions with a TC may serve you better for birding. I am not sure how the TC will affect the auto focus on the camera as I am not familiar with Pentax but I'm sure Don could give you the details if you need some.

[DonSchap]

Okay, a 1.4x T/C will lop off a full f-stop of light from the lens (and forget about using a 2x T/C ... because it instantly lops 2-f/stops) ... so your 300 or 400mm @ its widest f/5.6 aperture will actually become an f/8 lens and autofocus will cease to exist or become rather unstable. You also may lose the infinity focus in the offing.

Some may disagree, but I believe that your best bet is always getting the longest lens width the widest available aperture and avoiding the use of a T/C altogether.

In fact, if you should decide an AF 200-500mm f/5-6.3 lens is on your short list, using any T/C is extremely unwise, because it will eliminate your infinity focus and restrict you down to about 23 feet, making your beautiful and sharp lens nothing more than some kind of oversized macro. :rolleyes:

My personal suggestion is that if you rely on autofocusing, do not use a T/C on a lens with a maximum aperture less than f/5. f/5.6 will be very suspect ... and your "keeper" rate will decrease significantly ... but you usually won't reaalize that until you get back home and start reviewing your work. It's then the sadness sinks in. :(

[Pentaxian1992]

what do people think of the Pentax 75-300mm f/4-5.6??

[Telecorder]

I mainly want to shoot larger wildlife and birds. my camera has a 1.5x conversion factor, which gives a 300mm lens a focal length of 450mm. and I can always buy a 1.4x teleconverter, increasing it to about 630mm.

Sad to say but -- for your desires, I'd highly recommend saving a bit and going with a used Bigma 50-500 or Tamron 200-500. It took me a while but I was able to snag my non-DG Bigma for $535. For wild life, a 300 lens is usually just too short unless you go for a blind and/or feeder station to cut the subject distances.

In most all cases, use of a TC will degrade the IQ; especially when you attach a 1.7 - 2.0X TC to an inexpensive consumer lens. Also, IMHO, having to crop an image more than one-third to one-half to get frame-filling subjects is where one starts to see IQ degradation issues.

Distance to subject, subject size and IQ of the lens are all inter-related. -- The first two correlate to determining the long end needs and the latter is strongly related to cost.

Mothman13 did a chart for a Nikon D80 with a 1.5X crop Factor for different FOV image sizes (18mm - 500mm)...

http://www.pbase.com/mothman13/image/74511515 (5 - 30 feet)
http://www.pbase.com/mothman13/image/74511517 (35 - 60 feet)

Evaluate your intended subjects' sizes v distance in light of his FOV chart above.... Also evaluate how much of the FOV would need to be cropped to get the subject to near full image FOV.

At 300mm (450mm EQ) and subject at 60' -- the FOV is ~4.6' x 3.1' vert. A perched Bald Eagle stands ~2' +/- tall so you'd have to be within 60' of the subject to mostly fill the frame.

My tests indicate that my Bigma at 100' subject distance & 500mm (750mm EQ) my FOV is ~40" vertical so I could get a near half-frame-filling BE image at 100'. At 200', the Bigma's FOV is ~6' vertical so, with a crop of 1/2, I could nearly fill 2/3rd of the frame.

If you're anticipating a 'birding/wild life' lens for use out and about without a blind/feeding station, then at least 500mm should, and eventually will probably be, your goal.

Moderate-priced alternatives would also include the Tamron 200-500. Its been my experience that any inexpensive consumer 300mm lens will be very problematic in obtaining any number of 'keepers' due to the lack of lens's inherent IQ, AF speed etc unless your subject is very close and/or very cooperative.

As an added illustration, the following 500mm (750mm EQ) image with my Bigma on a tripod, 50' away from the tape measure, shows a vertical FOV of 20" -(11" at top to 31" at bottom)- the tape has 1/16" marking on the right side. One can imagine how much cropping of a small songbird would be needed to get any frame-filling detail if it was only 3-5" tall...
http://i33.photobucket.com/albums/d73/Telecorder/DSC_5818Medium1.jpg

My 2-cents, FWIW -- Others, of course, have their own valid opinions....