Budget High-Performance Pentax Lenses

Started Nov 10, 2013 | Discussions thread
jamesm007 Veteran Member • Posts: 5,654
Re: Budget High-Performance Pentax Lenses

Hello kriztian!

This is not directed to you only. Its a fact that copies (same model) lens vary in IQ. But there is a fairly wide tolerance range before we start calling parts of a picture not so good. And there are two factors in that tolerance. First and foremost is its IQ you see when taking a picture through your dSLR through out the frame; does it get blurry, soft, sharp.... Next is manufactures tolerance; of course to make it short that is, is it a good copy or bad. Most people don't get bad copies. But that means folks do get bad copies! Just to note, how bad the lens quality is (IQ) varies as well.

Now the first factor can be controlled somewhat by the photographer. Are you out of focus, are you in a bad spot of the zooms range. Most zooms have one or more spots in the focal range that give poor performance. A first time dSLR user may have a good copy but not know where and how to set shutter speeds, f/stops.

I assume you know all in the paragraph above.

So that leaves a copy that's not up to par. How does a person know they have a copy not up to spec? You don't unless you can get copies from all over the country or world and compare them! So no one lens review can ever hope to be even close to accurate. No one can say look at Photozones review. Nope one copy tested to manufactures spec or not is not anywhere near scientific. Its all elementary school stuff that we all know.

"Scientific facts are generally believed to be independent of the observer: no matter who performs a scientific experiment, all observers will agree on the outcome. In addition to these considerations, there are the social and institutional measures, such as peer review and accreditation, that are intended to promote factual accuracy (among other interests) in scientific study"

Quoted from - http://en.wikipedia.org/wiki/Fact#Fact_and_the_scientific_method

Its a quote but most of us learned this in elementary school. So one person testing a lens is no where close to giving enough info on a lens to help you decide to buy it or not. Even the camera test body the reviewer owns might be on the edge of manufactures tolerance and when the reviewer uses that body to test a manufactures lens, the results will vary. Want proof of this? Read lens reviews from one web site to another. A lens review is closer to a personal opinion than a fact.

There is the obvious. If a lens tests good at a web site. Readers make comments and most like the lens (note there will be some who don't) being tested. You buy a copy and it works for you as you expected. You in your mind just verified the findings of the review. This is what happens most of the time as most lens are within spec. So the odds favor this scenario.

Sometimes I see a lens on eBay for example, that I may want to bid on, but what's its IQ. I have no idea how a normal copy of the lens performs. I look at reviews and test pictures and aggregate the results to form about 40% of my decision. Next and most important I look at user reviews and full size pictures taken with that lens in conditions I would want to use it (landscape, indoors, portrait). Try to find websites with lots of user reviews on the lens your looking at. I use that for about 60% of my decision. Sometimes its surprising how much user reviews will go against the official review of the lens at that website. Its also very surprising in what we individually consider a good picture. It varies person to person by more than you would think! For example the DA50-200mm WR I bought this year. Its review it pretty bad at some site. But user reviews are more mixed and overall more positive. I went with that and that is what I got. The lens is not bad at all. No its not a DA55-300mm, but its small size and WR along with really being the replacement for a 70-300mm in FF makes it a nice little package with decent enough IQ. Users where more accurate then reviews.

Now with all of the above. If I get a lens and it does not perform like I thought. Well I assume I got a below average copy and send it back to the seller (if not eBay). I am not saying the DA18-55mm is a great lens. I am not saying its a bad lens.

I was going to post a pic from it but what good would it do?

 jamesm007's gear list:jamesm007's gear list
Pentax K20D Pentax K-5 Sigma 10-20mm F4-5.6 EX DC HSM Pentax smc DA 55-300mm F4.0-5.8 ED Sigma 17-70mm F2.8-4 DC Macro OS HSM +13 more
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