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09-21-2011, 07:36 AM   #1
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Predictable lenses I can trust?

I've only had my K-x (my first DSLR) for a year, and I've taken about 8500+ pics so far. So, I'm still fairly new, but I've learned a lot. I'm still trying to figure out what lenses I do use and want to use most, but I'm finding it hard to identify what lenses I can trust to deliver predictable results. I realize some lenses are better than others, and I realize that focal length and aperture can affect picture quality, but it seems that some of my lenses are more reliable than others. I'm mainly talking about sharpness, contrast, proper brightness... (I am aware of shutter speed and ISO and shake issues, but that's not the issue here.) I tend to do most of my shooting using aperture priority, so I'm able to control most of the parameters.

Some I do trust:
  • Primes: I have a Vivitar 28 f2.8 (nice enough), a Pentax M 50 f1.7 (very nice), and a Tak 135 f2.5 (nice enough). Primes seem to be quite predictable.
  • Zooms: I love my DAL 55-300. Almost impossible to take a bad (quality!) picture with it. I have a F35-70 which always can be counted on to do a good job for me.
I cannot trust:
  • The DAL 18-55. Sometimes good, sometimes poor. I know it's weak all the way wide and open, but I can't figure out a predictable pattern of what works best on this lens.
  • The DA 16-45. I like this lens, and it's usually quite good. Maybe I'm expecting too much from it, but some of the pics come out soft and low contrast. I can't figure out why...
  • In my search for a reasonably priced walk around lens (I'd love to have the DA 18-135, but I've been shopping in the $100 range), I've tried:
    • FA 28-105 f4-5.6: Frustrating... I'm thinking this one may be a lens issue (slight decentering?), but I can't count on it.
    • Vivitar 28-105 f3.5-4.5 Macro Focusing Zoom: Actually a decent lens, but changing the aperture seems to have significant affect on the color and contrast. I'd have to work a lot more to be confident I'm getting the shot I think I'm getting.
So, is it me or the lenses? Is this what people talk about when they describe a lens' IQ? Are there quality control issues w/ lens? (E.g., the DA 16-45 and FA 28-105 get much better reviews here than I'm inclined to give them.) Do you simply have to spend more to get a good lens?

Okay, so partly I'm just expressing some frustration here, but thanks for playing along! (I'm still looking for that reasonable walkaround lens. I'm going to be trying a Tamron 24-135 next.) If you have any suggestions or advice, I'd be glad to hear it.


Last edited by mgvh; 09-21-2011 at 07:51 AM.
09-21-2011, 07:50 AM   #2
axl
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I'd say it's more of a question: how well do you know your gear?

Sure, there are folks who will tell you you canot take a bad shot with certain lenses (usually the FA ltds and sometimes DA ltds and some *s) but I personally say it's a myth.

The point I'm making is, if you know your gear well enough to predict or expect how it will behave in certain situations you'll be able to select the right lens for the right shot.

This, of course, assumes the gear is prfect techical condition. But since QC is a B!?*h you'll never know...

My 2p
09-21-2011, 08:06 AM - 1 Like   #3
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Perhaps it is another issue with your wider lenses. What time of day do you tend to shoot? If you're always out mid-day, shooting wide landscapes is going to end up looking flat and dull regardless of the lens - that is a light issue though, and certainly not a lens issue.

My experience with the 16-45mm was definitely not poor, I really enjoyed owning that lens, it was my first 'serious' lens purchase and probably the lens I held onto longest!

Do you have a link or some examples showing what you're considering poor performance from that lens in particular? Even the 18-55 isn't terrible, but its output can vary greatly depending on shooting conditions. So, some examples would be great!
09-21-2011, 08:17 AM   #4
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Do you use hoods? Are you sure your focus is on? Are you shooting at the right time of day?

09-21-2011, 08:17 AM   #5
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DA Limiteds, get one.
09-21-2011, 08:27 AM   #6
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I had a Tamron 28-75/2.8 practically glued to my K7 for a long time... Sharp, fast, good range (especially for portraits), and quite cheap compared to other similar offerings...
09-21-2011, 08:51 AM - 1 Like   #7
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I think i can generalise here a little, and it may help, but you really need to know your gera too:

Primes are quite predictable, you will generally get consistent results, and
- they will all benefit in sharpness a little from stopping down, some more than others.
- they may have better contrast and sharpness than zooms at the same aperture
- their bokeh is more predictable

Zooms can be quite different as a function of focal lenght, but zoom quality is generally benefiting more from new optical elements than primes, because the new materials are making it easier to resolve design conflicts as the lens is zoomed. Additionally note
- kit zooms while not "bad lenses" are relitively cheap, slow and can be soft wide open
- older kit lenses, like the FA 80-105 (power zoom) have very loose front elements that wiggle back and fourth and are prone to some decentering as a result
- larger faster zooms, (towards pro models) are generally very very good, especially telephotos
- bokeh can be all over the place as a function of lens design.

The other thing to note, is that not all lenses expose perfectly. My tamron 28-75F2.8 has a tendancy to expose perfectly (middle of histogram for uniform surface) wide open but drift to +1 stop at F32. you need to really map your lenses to be aware of things like this, every lens may be different.

many lenses, especially older ones benefit greatly from the use of a hood, and note that the stock hoods were for film and not any where near long enough to prevent flare or loss of contrast for digital
09-21-2011, 09:12 AM   #8
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+1 Lowell! I'll add that except for stark malfunctions, all lenses deliver reliable results in the same conditions. As mentioned, those conditions change with various lightings, zoomings, hood usage, etc. But what's most critical IMHO is metering. Slightly different metering points and techniques can give very different results in dynamic range, contrast, saturation, etc.

For real consistency, meter the incident (ambient) light -- light reflected from the subject can vary. Or use a modified zone system: meter the brightest and darkest points in a scene, then expose midway between those. If metering reflected light, make sure your metering points are actually on the subject and not somewhere else that's differently lit.

Our cameras capture light, not subjects. The meter sets exposures for 18% gray reflectivity. Be aware how your scenes are lit and meter accordingly. Focus points are important too. Good luck!


Last edited by RioRico; 09-21-2011 at 10:16 AM.
09-21-2011, 09:43 AM   #9
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QuoteOriginally posted by axl Quote
I'd say it's more of a question: how well do you know your gear?

Sure, there are folks who will tell you you canot take a bad shot with certain lenses (usually the FA ltds and sometimes DA ltds and some *s) but I personally say it's a myth.

The point I'm making is, if you know your gear well enough to predict or expect how it will behave in certain situations you'll be able to select the right lens for the right shot.

This, of course, assumes the gear is prfect techical condition. But since QC is a B!?*h you'll never know...

My 2p
I agree with that. The supporting evidence is from the original post. He can trust the DA-L 55-300, which most people like but some have trouble with. And he has trouble with the DA 16-45, which most people like but some people have trouble with. It's going to be tough to suggest a lens in this thread without qualifying it with "a good copy should..." Also, since I suggested originally that the OP buy a 16-45, I have no more great ideas.

It is useful to analyze some failed shots to narrow down the problem, instead of deleting them right away. For example, out of focus shots are rarely usable, but you might learn why they are out of focus. It could be the AF system, the diopter, focus screen, motion blur, camera shake or just user error. One photo won't show the exact answer, but you may see a pattern of camera shake that you can address.

Sometimes you just stumble on the solution. I have always tried to take shots for a stitched panorama, even on film. I got better at some obvious details, like using M mode for the same exposure for each shot, keeping the lens from refocusing, use a smaller aperture, etc. But I kept trying with the kit lens at 18mm. Software would never really join these shots properly. When I got and used the DA 16-45, the shots fell together like magic. It was not clear to me that the kit's uneven performance at 18mm was the problem.
09-21-2011, 10:05 AM   #10
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QuoteOriginally posted by pxpaulx Quote
My experience with the 16-45mm was definitely not poor, I really enjoyed owning that lens, it was my first 'serious' lens purchase and probably the lens I held onto longest!

Do you have a link or some examples showing what you're considering poor performance from that lens in particular? Even the 18-55 isn't terrible, but its output can vary greatly depending on shooting conditions. So, some examples would be great!
I agree. The 16-45 should be a hair behind a good prime in sharpness and colour/contrast, and the current 18-55 lenses are pretty decent. How exactly is the IQ lacking in your photos? Post some examples, it could be a lens problem or it could be technique. Taking a wide angle photo with lots of bright sky and dark earth is different than shooting telephoto, where the frame is often filled with the subject.

My 16-45mm was exemplary for over a year, then went off, couldn't get a sharp photo. I had it repaired under warranty and it's all good again.
09-21-2011, 11:29 AM   #11
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+1 to the Tamron 28-75. It is my have to get the shot lens. I also really love my FA35/2.0 (Samsung version). The Helios 44-2 58mm is my favorite portrait lens for color and pixie dust.
09-21-2011, 12:31 PM   #12
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There's been some very good advice given here. I started with my Kx about the same time as you. The best thing I've done as a learning experience was to do some Single in... challenges. Take photos everyday with the same lens for a month and post a photo everyday. https://www.pentaxforums.com/forums/mini-challenges-games-photo-stories/15697...er-2011-a.html You'll learn your lens and it's idiosyncrasies as well as see what a bunch of other lenses can do under a bunch of different conditions. Food for thought...
Bruce
09-21-2011, 07:57 PM   #13
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Original Poster
OP here: Thanks, all! Some helpful insights... A few things:
  • From what I gathered on this forum, the majority opinion is that it is better to use a hood than a filter. So, yes, I usually use a hood.
  • I'll have to pay more attention to whether time of day/light is an issue.
  • @Lowell Goudge: Yes, you identified one thing that seems to be an issue. On some lens, as I change aperture, it seems the exposure level changes. I suppose that's why some photographers are professional; they probably have little booklets on each lens with adjustments to make for each focal length and aperture setting... That's where the amateur side of me, especially when I'm needing to hurry a bit to get a shot, just wants something a bit more predictable.
  • @just1moredave: Ha! I am glad I got the 16-45. It served me well on my trip to Turkey/Greece. Here are some pics: Picasa Web Albums - Mark Hoffman - Aphrodisias &... I am definitely keeping this lens as my wide angle lens, but it just seems to go extra soft and have more CA at certain focal lengths and apertures. I'll just have to try to catalog when that happens...
  • Other than the 18-55 and 55-300 kit lens, all my other lenses have been bought used. I suppose that adds another possibility for problems...
  • @wwifa: Good suggestion. I've actually kind of tried doing that in a less disciplined way by going out for bike rides with just one lens. It's helped me get a better feel for focal lengths and how to go about framing shots.
I'll keep trying and learning. Thanks again.
09-22-2011, 01:08 PM   #14
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Lenses are not inconcistent. Only photographers are. If a lens is ever capable of great pictures at a given aperture and focallength, then it is always capable of it, and any disappointing pictures can't be blamed on the lens.
09-22-2011, 02:16 PM   #15
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Mgvh

I have in fact mapped out about 1/3 of myy lenses at each exposure indent or e-dial serting
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