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07-28-2011, 01:12 PM   #1
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Which lens should i buy

I went to Abe of Maine shop to buy K-R body and thought of shopping for lens online. The shopkeeper gave me a good bundled deal. He advised me to take the 18-200 mm sigma AF for pentax saying its a very good lens and convenient as i dont need to change 2 lenses. i also bought with the bundle high speed SD card and also UV filters ( Nikura).

I have started taking picutres and learning step by step. To me the pictures look good but not sure if i got a good lense. I tried to take picture to blurr the background and focus on the object but i am not getting it. Not sure if this lense is no good or do i need 2 seperate lenses....i am very confused. please advice

07-28-2011, 01:16 PM   #2
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Well there are more way's to get that isolated subject and blurrey background.

- Buy an expensive lens with wide open diafragma's like DA*55mm/f1.4.
- Make a close-up picture with your current lens so that the background will be blurred.
- Take with your lens a picture and make shore that in the background there is nothing in close range so that things further away will get blurrey.

Best to take some photography classes.
07-28-2011, 01:52 PM - 1 Like   #3
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Welcome to PF.

The starting point is to use your K-r with 18-200mm. Do read the Instruction manual. This is essential. Use your camera as you read and discover its functionalities. It tok me 2 months to read in-depth the K-7 manual and I saw a rapid jump in my skills as I learned to use the camera. (The K-7 was my first dSLR.)

Do not worry about the lens(es) until you master your camera. The 18-200mm is an all-around lens. It covers a wide range of fical lengths and this is not a bad idea for a starter.

Learn to PP your shots. The pentax software PDCU 4.33 is a good start. The outputs are excellent, event if the software is not the most-user friendly.

Lastly do post your shots in PF.

Then in 6-12 months you may consider to add a few new lens(es) to you setup.

Hope that the comments will help.
07-28-2011, 02:09 PM   #4
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QuoteOriginally posted by RonHendriks1966 Quote
Well there are more way's to get that isolated subject and blurrey background.

- Buy an expensive lens with wide open diafragma's like DA*55mm/f1.4.
- Make a close-up picture with your current lens so that the background will be blurred.
- Take with your lens a picture and make shore that in the background there is nothing in close range so that things further away will get blurrey.

Best to take some photography classes.
I'd like to add one to Ron's advices:
-Use your current lens at telephoto focal lenghts (lets say over 100mm) and get to your object as close as possible. Shoot wide open. This way you should be able to separate object from background (provided that background is far enough from object)

07-28-2011, 02:12 PM - 1 Like   #5
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Blurring the background depends on a couple things including your aperture (F number), how far your subject is from the background, and how far away you are from the subject. Although not one of the best lenses, your Tamron 18-200 can certainly achieve the blur.

It's pretty easy to practice. Setup a subject or object about 6 feet away from a contrasting background (i.e. trees, shrubbery, wall, etc) Set your lens to a fixed length like 70mm. Move the aperture to the lowest it will go. Stand 5 feet away from the object, focus, and take a photo.

Look at the output you have. Step one foot back and try again. Look at the results. Now try stepping forward so you're about 4 feet away, take a photo. Keep repeating at different distances, but don't change your focal length by zooming or your F-number.

The idea is to look at the results so you can understand how distance affects the depth of field and how things will be blurred. Typically, the longer the focal length the easier it is to blur the background. Once you get the hang of it, try the same exercise with other focal lengths (i.e. 85mm, 100mm, 200mm, etc).
07-28-2011, 02:48 PM   #6
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I'm not sure the bundled deal was a win. At least the UV filter is essentially useless. My advice is not to use it - it doesn't help, it only deteriorates the image quality.
Definately buy one fixed focal lens, DA35 is a good one for low price. If you like it, you will add more primes to your kit.
07-28-2011, 04:18 PM   #7
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check this link. It also has a video that explains how.

DSLR Tips Workshop: How to take portraits with blurred backgrounds
07-28-2011, 04:33 PM   #8
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It really only applies to my copy and my k-x -- but I have the 18-200 Sigma and really like it for when I'm not certain what I will be shooting. I feel it's a talented enough lens to handle the 12Mpixel sensor, but of course copies vary.

It's all been said: for more blur in general, you want more telephoto and more separation from focused object to background, and lower f/ratio (f/8 or lower number). Keep us informed on things as you learn!

07-28-2011, 04:48 PM   #9
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You may want to being experimenting with thin depth of field (to blur the background) with a cheap manual focus lens such as the variety of 50mm lenses available that have maximum aperture settings of f/1.8 or greater. Then you'll find you can get the results you want for very little money.
07-28-2011, 04:51 PM   #10
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Tips Tips Tips

I'd recommend scott kelby's book "The Digital Photography Book"

The first half of it or so is all about what you need to buy to take sharp photos, which is theoretically true, but hardly necessary. But the latter half of the book has lots of good tips similar to the type of question you are asking... Basically, he answers many "How do I get my photo to look like this?" Its cheap and you'll learn a bunch. And no, I'm not scott kelby.

I second the recommendation, Read the manual! You'll learn about your camera and about photography.

Finally, I think you've got a good lens. You'll always have a place for such a versatile lens, travel especially, or those days when you only want to bring 1 lens and you aren't sure what you will be shooting. Take pictures of what you find interesting!

Over time, you'll accumulate a nice collection of photographs, then start looking at the EXIF data, which any decent photo management/editing software can show you. Then you can see what focal lengths you tend to shoot at and you can consider buying a prime lens at one of the more commonly used focal lengths.
07-28-2011, 08:11 PM   #11
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QuoteOriginally posted by rr4562 Quote
The shopkeeper gave me a good bundled deal. He advised me to take the 18-200 mm sigma AF for pentax saying its a very good lens and convenient as i dont need to change 2 lenses.
I'm not sure I understand this advice. I thought the whole point of a DSLR is that you could change lenses. If you didn't want to change lenses, why not just use a P&S?

I agree with some of the others that have suggested adding a prime. Primes not only are easier to isolate subjects with, but being suck at a single focal length forces one to think more about composition, which is good for learning photography.
07-29-2011, 06:09 PM   #12
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Respectfully, I think there is more to a DSLR than simply the ability to change lenses. You have faster shutter speeds, it is more responsive, the images themselves are higher quality due to the larger sensor, better handling compared to the majority of point and shoots, better high iso performance... The list goes on.

I think it is perfectly acceptable to start out with one multipurpose zoom. Consider how many people buy a dslr and stick with the kit lens for a very long time. The OP is at least in the position where he has a much more versatile lens than the kit zoom.
07-30-2011, 10:48 AM   #13
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All good advice given here, rr4562.

I'd like to add my own suggestions if I may.

1.) Use a tripod if you can. A tripod will help with two very important things:
A - It will eliminate all or most problems associated with slow shutter speeds.
B - It will give your images consistent composition frame to frame.

Try the soft drink still-life experiment.

Try this outdoors at first to avoid the very slow shutter speeds you'll get indoors.

Buy a six pack of your favorite soft drink.

Arrange the cans from left to right using a ruler, so that each can to the right in your viewfinder is one half an inch further back from the line than the can next to it.

Start at 50mm and your widest aperture, and take a photo. Then, take another photo at the next smallest aperture, and so on, until you've reached f22.

Now, repeat this procedure at 70mm, 100mm and so on, until you've reached your lens' maximum focal length of 200mm.

Also, take one set of photos at 50mm focusing on the far left can, then repeat by focusing on the can which is second from the left, then third from the left an so on.
This will take some time, but I think it will be worth it.

This should give you a good starting point of seeing the different depth-of-field results (blur) you'll get from different focal lengths at different apertures.

The reason I suggested soft drink cans, is that they are uniform in size, and have writing on them, which I think will help in judging the differences in depth-of-field and perspective at differing focal lengths.

You can either write down the focal length, aperture and frame number on a piece of paper or use the exif data that the camera will assign each shot.

Good luck.

Mike
07-30-2011, 10:55 AM   #14
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rr4562, I forgot to add that after you do this experiment with your 18-200mm lens, you can repeat it with the next lens you buy to compare the differences.

Mike
07-30-2011, 12:24 PM   #15
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Thanks for all the suggestions. I am going to try all these trics. Already i tried couple of them and it worked. I am now able to appreciate the differences by taking lot of pictures and comparing them......Thanks a lot guys
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