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07-11-2010, 10:50 AM   #1
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thanks for lens reviews and a suggestion

hello all,
I am still very new into my new passion which is photography. i know enough already to be sure that pentaxian is the way to go if old lens compatibility is important. i am in the process of getting some starter lenses and have found the lens reviews on this site extremely helpful. i am thankful enough that i donated $20 to the forum to keep it going.

all that said, i have found the process of screening potential lenses through forum reviews lacking. the lenses posted here are for the most part decent lenses. i have heard a comment (dont know if here or elsewhere) that 90% of all lenses made are poor. if that is indeed the case, it would be very helpful for the (90%) bad lenses be posted as well with confirmation that they are poor and why. finding a review on the forum that helps me avoid a bad lens is just as important as one that tells me a potential lens is a good one. perhaps (good/bad) categories of third party lenses would be useful.

I think that perhaps the reason most lenses reviewed are decent is that those who post lens reviews are pretty knowledgeable and have avoided the bad ones. it would be nice for the lens review forum to give us beginners some insight into that knowledge. if a given lens manufacturer, for instance, should be avoided, tell us.

I welcome comments from other beginners
thanks

07-11-2010, 11:02 AM   #2
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90% of lenses made may be poor--but not those by certain manufacturers. If it's from Pentax, Nikon, Canon...it's the good stuff. And a lot of third party lenses are good as well.

Also, you have lens reviews all wrong. "Regular" people who own a lens have a tendency to give it positive ratings--it's just human nature. So unless the lens really stinks, all you're going to see are good reviews. In addition, opinions are like you-know-what. Everyone has one.

Lens reviews posted by users are inherently weak, including those on this site. They're not scientific. Instead, go the Lens Club forums here to get accurate assessments of particular lenses, as well as SHOTS taken with them.

And make reviews no more than 50% of your purchase decision-making process.
07-11-2010, 11:08 AM   #3
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I think you just need to read a lot more lens reviews to get a handle on what you want.
07-11-2010, 11:14 AM   #4
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Original Poster
thanks for the help. i will indeed use the lens clubs as you advise. this process is, however, inclusive, meaning you only consider that group of lenses. the "other manufacturers which are also good" info you mentioned would be useful as and equally other manufacturers to avoid.


thanks

07-11-2010, 11:51 AM   #5
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I'd take issue with the basic assumption here that 90% of lenses are poor.
07-11-2010, 11:53 AM   #6
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Hi Glenn,
Welcome to the Pentax Forums and thank you for the positive words.

Regarding the lens reviews and the "90% of all lenses are poor" comment. You may have read this somewhere, but it is not quite true. My opinion is that probably 90% of all lenses that fit a Pentax camera are good or better and that few are true stinkers. This even includes "off-brand" or store-brand lenses. See the Off-Brand Club thread for many examples of lenses that should be crap, but aren't. (There are also a bunch posted there that are sub-par, but what the heck...they are all cheap.)

Here is my short guide to bad lenses:
  • If it feels cheap in the hand, it is probably crummy on the camera
  • Russian lenses can be incredible performers, but QA is spotty (my best shots have been made with Russian glass)
  • Made in Japan is usually good for off-brand...Made in Korea, Indonesia, India, etc. are not so good (apologies to fans of current Samyang/Bower/Vivitar users...the tide may be turning...)
  • Off-brand and store-brand consumer zooms with f/4.5-f/5.6 maximum aperture are often not so hot
  • An "excellent" lens (by review) in poor condition (on the shelf) is a poor lens
Here is my short guide to high value lenses:
  • Russian glass, if you find a good copy is great, but never overpay
  • Non-AF Vivitar is usually good (pre-1990 by serial number)
  • Tamron is good
  • Kiron is good
  • Tokina is good
  • Current generation Sigma is good, but older models not so much
  • Takumar-A and Takumar Bayonet have a reputation on this site as being crummy lenses, but at $20 or less per copy, they might be worth a look see.
  • Even lenses that have red flags might be OK if the price is low
In regards to the ratings in the lens reviews...It may seem like an artificial skewing, to have so many lenses ranked 7 or better, but the truth is that in the broad spectrum of lens quality, 5 is not the middle of the road. There are many more gradations of bad than there are of good. For example the lens on a Holga might rank a 3-5 due to its unique qualities. Ditto for the various Lensbaby models. Do the 1-2 rank lenses exist? Oh, yes...but you seldom see them on the market used. Most hit the trash.


Steve

Last edited by stevebrot; 07-11-2010 at 12:12 PM.
07-11-2010, 01:12 PM   #7
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The problem with reviews is that something that is a big deal to you (say, lack of auto focus or harsh bokeh) may be something that doesn't bother me or I figure out a way to work around. A fair review will mention these issues and then say that they didn't bother the reviewer.

The other thing to remember is that people often grade a lens in relationship to what they paid for that lens. That is to say, a Sigma 70-300 that cost me 75 dollars, I will not grade as hard as a DA *300mm that cost me 1100 dollars. So, the grading ends up being on some kind of curve. A 1200 dollar lens that is given a 7 will likely shoot circles around a 200 dollar lens given a 7, everything else being equal.
07-11-2010, 02:07 PM   #8
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The lens reviews on this site are partial listing. There probably really is 90% more lenses out there. So there's already a significant filtering done. Pentax is renowned for it's glass, so you're pretty sure to get quality. There are some lemons, but you'll know it by the reviews.
I've been using the reviews to find interesting lenses, and it's been quite helpful.

By the reviews themselves, it can give an idea of the experience of the user. Some go into details. One lens has a 4 rating in a review, bringing the whole average down because the person obviously didn't know how to use it., and you could know it right away by reading his review.

As for the lenses themselves, I've seen good results from most lenses when the person shooting knows how to use them. The suggestion of the https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/31353-off-brand-club.html and there's also the https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/32688-dcl-dirt...lens-club.html is a great one, as you'll be able to see them in action.

07-11-2010, 02:25 PM   #9
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If you read reviews of most standard zooms from the F and FA line (think 28 or 35 to 70 or 80, in those ranges) you'll see that poor lenses are reviewed accordingly. I'd steer away from a lens evaluated below 7.5 on average.

As for CURRENT lenses, honestly they are all at least "good" (with Pentax, that is). By reading the reviews here, you'll learn how users use their lenses, how they evaluate them, they will list strengths and weaknesses, in most cases. Reading the text is more important than looking at the rating. for instance, in my case rating is linked to the price paid, to some extend. It is strongly linked to how I use the lens (a good but not grat lens will get a high rating if it's weather resistant, light, reliable, so I can bring it hiking and camping. That's how I will use it, so I evaluate it as grat for that purpose).

Also remember that most older lenses are prime, and that most primes are very good, because desiging a good prime is relatively easy.
07-11-2010, 05:42 PM   #10
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The reviews database has meaningless scores, almost all in the high 8's or 9's. This when supposedly a 5 is a good lens.

Though your priorities will of course dictate how you rate them, almost no lenses Pentax has ever produced were poor. I value small size, light weight, excellent handling, solid build and great IQ. No zoom lens is going to get the highest possible rating on my scale.

DECENT
DA 10-17mm
DA* 16-50mm
DA 18-55mm II
DA 50-200mm

GOOD
DA 17-70mm
DA 55-300mm
DA 21mm

VERY GOOD
DA 12-24mm
DA 16-45mm
DA* 50-135mm
DA* 60-250mm
DA 14mm
DA 15mm
DA 35mm
DA 40mm
FA 50mm
DFA 50mm
DA* 55mm
DA 70mm
DFA 100mm
DA* 200mm
DA* 300mm

SUPERLATIVE
FA 31mm
FA 43mm
FA 77mm

(And no, I haven't used all of them.)
07-11-2010, 05:46 PM   #11
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Interesting that you rate the 16-50 so low, Robin. Others would put it the "superlative" category, along with a couple of the "very good" lenses. Just goes to show the extremely subject nature of these things.
07-11-2010, 06:17 PM   #12
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QuoteOriginally posted by Marc Sabatella Quote
Interesting that you rate the 16-50 so low, Robin. Others would put it the "superlative" category, along with a couple of the "very good" lenses. Just goes to show the extremely subject nature of these things.
The MTF has been tested (Photozone after three copies) to be significantly worse than either the DA17-17 or the DA16-45. For example, border MTF goes down to 1160 while the DA16-45 is never less than 1740. That's not a small difference, it's huge! My own photos with the lens bore this out. I am happier using the DA16-45 for landscapes, my shots of street art (yes, some shoot walls!) etc.

I would not rate a lens that costs much more, has no better CA, worse distortion, is far too huge, heavy and has a failing SDM motor that Pentax have refused to say anything official about. I am tempted to rate it even lower, to be honest. I would prefer the WR version of the kit lens. This is not based on subjective but objective measures of usefulness.

In terms of personal bias, I put my cards on the table when I said that "I value small size, light weight, excellent handling, solid build and great IQ. No zoom lens is going to get the highest possible rating on my scale." If I was a Canon-type shooter I might rate some of the telephoto lenses in the superlative category. But I have never had a use for them. Further, I would seriously have to question why anyone would use the Pentax system if birding, sports, etc. was their primary interest.

I simply don't think any other lenses belong in the same category at the FA Limiteds.
07-11-2010, 06:35 PM   #13
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I've never used the lens, so I can't say from personal experience. All I can do is reiterate what I said before - others (including PopPhoto who run their own controlled tests and have numbers to back up their opinions just as you do) have a different opinion of the 16-50. There's really no point in wondering which opinion is "right", since it is just an opinion. MTF might be an obejctive measure, but it's not the only measure - and it's opinion that places relative important on different factors. I personally have preferences not unlike yours - I wouldn't rate the 16-50 highly simply because it's way too big and heavy for what I want to do.

Anyhow, my point wasn't really to nit-pick on that specific lesn, but to use it as an example to show how subejctive these things really are. I have no opinion on the lens personally, but if PopPhoto calls it "Best In Class" (which they do), that goes to show it's possible to rational and well-informed informed people to come to different conclusions about things like this. One person might say 90% of lenses arne't "good", but chances are excellent that many other others would *love* some of the lenses that person said weren't good.
07-11-2010, 07:17 PM   #14
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You already received some excellent comments and suggestions. Let me add my own and limited experience.

When I am looking for a lens, I do my research using both independent reviews (Welcome to Photozone!, www.lrgear.com, dpreview.com) and users' reviews in this forum. The former are very useful and usually more objective. Also the comparative comments in the same site (eg photozone.de) of several comparable lenses are very valuable. For example, www.slrgear.com always includes a discussion of similar lenses on the market, while Welcome to Photozone! provides some useful quantitative results.

The users's reviews are complementary. They provide you with the opinion of Mr and Mrs Smith on their lens(es): why is it good, what is not that good. These subjective comments are less consistent but also valuable.

The last source of information is the discussion forums. By reading relevant threads, you start to learn of some issues or peculiarities, as well the strengths of some lenses. You may also learn about other products that could suit you.

All in all, the forum reviews are one set of information that adds to the topic but cannot be taken independently of independent reviews nor the forum discussions.

Last edited by hcc; 07-11-2010 at 07:18 PM. Reason: Typos
07-11-2010, 07:32 PM   #15
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Marc:

There are indeed many different measures of a lens. Personally, I have found MTF to say something that translates to images I produce. It is certainly not the only measure, and some things simply are not measurable... true!

I was sceptical as always, but Photozone have earned my trust for their measurements. However, their conclusions are often rather arbitrary and do not take into account those intangibles. So I use their values but make my own conclusions, largely based on other trusted opinions and images I can find online.

This is not to say one cannot argue the worth of one judgement, review, or measure against another. I think one can. To flog this particular horse some more, I am not sure when PopPhoto rated the DA*16-50 "Best In Class". In any case it's not a phrase that has much meaning; I don't judge lenses according to arbitrary marketing classes. As I know you don't!

In the review that is available, they seem to be in love with the build and SDM, readily admitting that even the Sigma is superior optically. This seems to be an instance of "big fat lens" syndrome, in which a lens more likely to stun an ox with its size and feature set gets a better review because "that's what professionals use". I have little confidence in this opinion based on the minimal data in this review with that provided by Photozone. And even if I did, their recommendation seems to really be for the Sigma lens after all!
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