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09-02-2012, 03:08 PM   #1
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which lens for me?

Soon, i'll be a proud owner of a K-r, won the auction earlier and just paid.
It's coming with the stock 18-55, but i'm looking for something to be a better all-rounder.
There's nothing specific I shoot but I do like a good bokeh effect, and I know I won't be able to pull that off with the kit lens, so am looking for a zoom lens and the main few out there are the sigma and tamron 18-200's or 18-250's, but the 250's are out of my price range.
reading through the lens reviews here have left me confused. the general consensus is that the tamron 18-200 is a little soft, the IQ is okay, but 92% would recommend it!
the sigma seems to fare slightly better on the sharpness and IQ fronts, but only 86% would recommend it!
Then I read other reviews which say it's basically a toss-up which one you buy
And then, of course, to throw in a curve ball is the sigma 18-125 (pentax 18-135 is too pricey)
basically, the questions are:

do I really need a 200mm lens, what do you use 200mm+ zoom for?

If the 125mm is zoom enough for me, will I be able to achieve a shallow DoF at 125mm?

If I say I can get the 18-125 for 150
the sigma 18-200 for 220
the tamron 18-200 for 100, would that change peoples opinions and recommendations?!

09-02-2012, 04:55 PM   #2
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I used to own the Sigma 18-200 and thought it was pretty good until I tried a 200 prime and realized that the IQ was not even comparable. Ok IQ and soft features are definitely something you will find in just about any zoom lens. People are still willing to recommend it due to the compact size, light weight, versatility, and price.

You have to weigh all of those options to find a lens that best suits you. As for 200mm being enough- you will always want a little more. 300mm, wish you had a 400, 400 wish you had a 600, or wish you were able to get a tad closer without disturbing the subject...

200mm is great for distant portraits or reaching out in the audience to something nearby.

I use a 300mm for birding but sometimes use a TC as well. I like the reach for maximum IQ without having to crop. Even from 10 yards away shooting Chickadees it's just not enough to get full IQ. Typically I like to be within 15 feet or so from the subject and you will end up getting all the feather detail. With that being said, 200mm can be enough for that as well just need to take a few steps closer and exude a little more patience.

I guess really you just need to ask yourself what you like to shoot to see what kind of focal length you want..

It might be a good idea to get a wide ranged zoom to begin with to see what areas you shoot the most. Take a few weeks photos and go through them to see your most used focal lengths.

Perhaps an older used zoom on ebay for 30-50 bucks might be the way to go. You can get a good understanding of the lens you want to buy before throwing too much money in.

Kind of a ramble there... hope you can decipher my thoughts.

cheers and grats on the new camera
09-02-2012, 04:58 PM   #3
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Sigma Zoom Lens 70-210mm F/1:4.5 K-II Macro Lens with Case Fits Pentax | eBay 15 bucks on ebay for 70-210 in an older Sigma. That should cover some longer range to pair with the kit lens.

Between the kit and something like that you can get quite a bit of practice in.
09-02-2012, 07:01 PM   #4
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Rather than more zoom range, which generally hurts image quality, look at similar zoom range with faster maximum aperture (or some lenses which have better image quality if not necessarily much faster). Some of the more affordable choices are:

Sigma 18-50mm f/2.8 (there were macro and regular versions, both now discontinued, macro is better)
Sigma 17-70mm f/2.8-4.5
Tamron 17-50mm f/2.8

All of these will be somewhat sharper than the kit lens, and have a much wider maximum aperture (which will help you in getting your stated goal of blurred backgrounds).

09-02-2012, 09:05 PM   #5
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There is currently for sale a Pentax FA 24-90 for $275 in Market Place. Snatch that up and have great range and a f3.5-f4.5 zoom that is also full frame ready!
09-02-2012, 10:49 PM   #6
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QuoteOriginally posted by Franky2step Quote
There is currently for sale a Pentax FA 24-90 for $275 in Market Place. Snatch that up and have great range and a f3.5-f4.5 zoom that is also full frame ready!
I've never used that lens, but it is a good price according to the reviews. I have had a Tamron 28-105mm 1:4-5.6 (and a Pro Master branded version) that were very sharp, I gave my daughter the ProMaster and recently sold the Tamron after acquiring a DA 18-135. I purchased both of them used, for around $40 each. Don't put a lot of money into a lens until you really know what you want. I have not had an 18-200 zoom, I had had some 28-200 zooms, and I can say there seems to be a lot of "variation", meaning you might get a good one. If you don't care about sharpness and detail, they are OK. I would assume the 18-200s are similar, but that's a total assumption on my part. A lot of lenses can produce a good bokeh, or shallow depth of field, you should look into the review section. Lots of manual focus primes can give you a great bokeh, 136/2.8 can go pretty cheaply since there are so many of them. One thing to remember, if you don't overpay on a used lens, you can probably sell it later without a loss.
09-03-2012, 03:54 AM   #7
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QuoteOriginally posted by wes k Quote
There's nothing specific I shoot but I do like a good bokeh effect, and I know I won't be able to pull that off with the kit lens
All depends on what you mean by "good bokeh effect" and at what focal lengths you want to achieve it. The quality of bokeh is largely subjective, and I think the kit lens has pretty good bokeh. Of course it's not a very fast lens, so you can't get an ultra-thin depth of field except at very close focus. As msatlas says, look for a faster lens. Or just stick with the kit lens for a while. You said:

QuoteOriginally posted by wes k Quote
There's nothing specific I shoot
which makes it rather hard to make recommendations.
09-03-2012, 05:10 AM   #8
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I know, one of those newbie questions which is unanswerable without specific information.

I'll try and narrow down, I don't shoot anything specific, but I suppose you could say i'm after a "travel" lens, something to replace the kit lens, I know it somewhat defeats the point of buying a dslr on some levels by wanting a lens that does it all, but yeah, i'm one of those people!
I mainly take a camera when i'm travelling or out and about, so landscapes, buildings, sunsets, sometimes people and anything else that looks cool is usually what I shoot, which is why I asked if i'd even need a 200mm+ lens
I usually use my mates nikon d90 and his 55-200 for the DoF, but he keeps taking credit for my shots as it's his camera, so thought i'd get in on the dslr action myself

I don't know if this little chart is accurate:

but this is what made me think i'd probably not need 200mm zoom, the difference between 135 and 200mm there isn't that significant to me, and I don't see why i'd need to zoom that far for anything over than birds, i'm probably wrong though

some samples:

so what do you reckon, 200mm or 125mm should be good for now?
I imagine at some point I will amass a lens collection, but for now, i'd love an all rounder...

09-03-2012, 10:15 AM   #9
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If you aren't particularly interested in sports or wildlife, or any other such subject where one of the main challenges is getting close enough to the subject, then you will probably do fine with 125 as the long end. I can't speak for these particular lenses, but as a rule you can expect a superzoom (~10x zoom range) to be less sharp and have more distortion than a standard zoom (~ 3x) and so the 18-125 might be higher quality within that range.

Shallow depth of field? Yes, if you're close to the subject. Just remember that aperture is one of the main variables controlling this, and no inexpensive zoom is going to have a particuarly large aperture. If you really want narrow DOF effects you will have to spend more for a fast (f/2.8) zoom, or a prime (fixed focal length) lens (many good options for less than a fast zoom).
09-03-2012, 10:37 AM   #10
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Use your kit lens for a while and take as many pictures in as many diverse situations as you can. Then analyze the focal lengths you used more often. If you find that you are stuck at 55mm you will know that you need a longer lens. If you have several at 18mm then you need something wider.

If you find that most of the images are at 35mm and longer, then the SMC-F series lenses are far superior than the kit lens and dirt cheap (less than $100). Take a look at SMC-F 35-70 F3.5~4.5, SMC 35-105 F4~5.6, SMC-F 35-135 F3.5~4.5 or if you need wider the SMC-F 24-50 F4 (a bit pricier than the others).

Image quality depends on many factors and the lens is just one. Even with the same lens you get very different IQ when you use different F-stops (most perform their best closed down 1 or 2 f-stops typically around F8). Other factors that significantly affect IQ is accurate focusing, good lighting and use of a tripod.
09-03-2012, 10:54 AM   #11
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thanks for all the input guys!
i've just stumbled across a 35-135(f3.5/4.5) I like the look of at a very reasonable price, buy a brand called miranda, any thoughts?

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