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06-27-2012, 10:51 AM   #1
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How to assess 55-300 specimen quality

HI,
I have purchased a 55-300 DAL a few months ago, expecting to get the excellent IQ the different reviews here give it. The lens was new, but bought separate from bundle.
However, I have been somehwat disappointed with the sharpness of the lens, used in trips mainly in variety of appretures/ exposure times/etc.. (Body is k10d).
I know there might be some variance due to the manufacturing and wanted to ask what is a simple way to check that the lens quality I have is similar to other lenses ?
i.e. to photograph somthing using pre-defined setting, etc...

thanks in advance
daniel

06-27-2012, 11:15 AM   #2
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Can you post some samples, with EXIF intact?
06-27-2012, 11:20 AM   #3
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QuoteOriginally posted by koraldon Quote
HI,
I have purchased a 55-300 DAL a few months ago, expecting to get the excellent IQ the different reviews here give it. The lens was new, but bought separate from bundle.
However, I have been somehwat disappointed with the sharpness of the lens, used in trips mainly in variety of appretures/ exposure times/etc.. (Body is k10d).
I know there might be some variance due to the manufacturing and wanted to ask what is a simple way to check that the lens quality I have is similar to other lenses ?
i.e. to photograph somthing using pre-defined setting, etc...

thanks in advance
daniel
Don't forget, it's a long lens.

If you're shooting at 250mm, you will pretty much need to be @ 1/250 sec or 1 stop lower with SR.

It's the most common problem with long zooms and IQ.
06-27-2012, 02:16 PM   #4
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QuoteOriginally posted by Aristophanes Quote
Don't forget, it's a long lens.

If you're shooting at 250mm, you will pretty much need to be @ 1/250 sec or 1 stop lower with SR.

It's the most common problem with long zooms and IQ.
Or be really, really, really, steady.(Almost tripod-like)

Though I'm willing to bet this is the major issue. Past 100mm, shutter speeds start to matter a lot more.

06-27-2012, 02:44 PM   #5
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Check front/back auto focus issues also. Mine was rather soft at the long end but after adjusting the auto focus front/back settings it improved dramatically.

Stopping down even to F6.3 or F7.1 improves noticeably from wide open at F5.8.
06-27-2012, 05:16 PM   #6
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Like others mentioned stopping down on the long end offers a huge improvement with this lens. Here's some samples I have online. I'm pretty happy with mine, at least with enough light to use F8 on the long end.

http://jaywallphotography.smugmug.com/Photography/Pentax-Lens-Sample-Shots/17003181_7LL7fX#!i=1286569377&k=xjJhJnN
06-27-2012, 06:14 PM   #7
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wide open should be soft..I think that is normal for this lens.
try f8...
in the review of da*300 f4. there is comparsion to 55-300
at 300mm f8..it is identical...super sharp..but at 5.8..really soft
06-27-2012, 08:21 PM   #8
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I've been interesting in testing for decentering on my own lenses (I suspect none are decentered, but it seems like fun to try).

The bottom of the article has a home method of testing using white rings on poster board.

LensRentals.com - Testing for a Decentered Lens: an Old Technique Gets a Makeover

Other forms of lens defects exist and this may not find every defect.

06-27-2012, 08:55 PM   #9
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QuoteOriginally posted by liukaitc Quote
wide open should be soft..I think that is normal for this lens.
try f8...
in the review of da*300 f4. there is comparsion to 55-300
at 300mm f8..it is identical...super sharp..but at 5.8..really soft
Are you talking about this review? Pentax-DA* 300mm F4 Review - Sharpmess and Angle of View - PentaxForums.com

The DA*300 is sharper at f4 than the 55-300 at f8. With both at f8 there's really no comparison.

The 55-300 is OK if you don't crop it too hard at 300mm. I find the In-Depth review on this site is highly overstated. It is not excellent at 300mm, even when stopped down and on a tripod.
06-28-2012, 03:14 AM   #10
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QuoteOriginally posted by audiobomber Quote
Are you talking about this review? Pentax-DA* 300mm F4 Review - Sharpmess and Angle of View - PentaxForums.com

The DA*300 is sharper at f4 than the 55-300 at f8. With both at f8 there's really no comparison.

The 55-300 is OK if you don't crop it too hard at 300mm. I find the In-Depth review on this site is highly overstated. It is not excellent at 300mm, even when stopped down and on a tripod.
Well, it's not that bad, but it certainly does lose sharpness past 200mm. That said, I can't really afford the DA *300 and so I make do with the DA 55-300 and it is pretty decent. Stopped down to f8 is your best bet and definitely using something to steady you like a tripod or monopod.
06-28-2012, 06:01 AM   #11
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QuoteOriginally posted by audiobomber Quote
Are you talking about this review? Pentax-DA* 300mm F4 Review - Sharpmess and Angle of View - PentaxForums.com

The DA*300 is sharper at f4 than the 55-300 at f8. With both at f8 there's really no comparison.

The 55-300 is OK if you don't crop it too hard at 300mm. I find the In-Depth review on this site is highly overstated. It is not excellent at 300mm, even when stopped down and on a tripod.
yeah sorry about that
I was comparing the wrong test pic.......
but I think da55-300 at f8 still look pretty good
06-28-2012, 06:37 AM - 1 Like   #12
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QuoteOriginally posted by koraldon Quote
I know there might be some variance due to the manufacturing and wanted to ask what is a simple way to check that the lens quality I have is similar to other lenses ?
i.e. to photograph somthing using pre-defined setting, etc...
Do you have any other lenses with similar focal lengths? That's the best way to compare. If you only have the 18-55 you should be able to compare it to the 55-300 at 55mm. At the same aperture, the 55-300 should have better resolution. I usually shoot a cereal box to test lenses. It's a good size for testing at medium and longer distances and the print on the box shows up differences very readily. You can also use a cereal box (or anything similar) see how aperture, shutter speed & ISO affect IQ.


(I can't remember what lens I was testing here, it's posted for reference only).

I have a Tamron 70-300mm and a Pentax A*300mm to compare with my 55-300 at 300mm. A tested a couple of times because I thought my 55-300 was off, but the Tamron showed me that the Pentax zoom hasn't changed. What changed is my expectations after shooting with the prime.

To test for back-focus and front-focus, I use the chart at the bottom of the page posted below. Lay the printed chart on a flat spot that's well lit by natural light (warning, artificial light may affect focus, use daylight for testing). Set the focal length you want to test (usually the longest), use the widest aperture, hold the camera at a 45 degree angle and shoot several times to see if there is a trend to BF or FF. The directions rightly state that a tripod should be used, but I find it unnecessarily clumsy. Just make sure you have good shutter speeds and take several photos. Reset the focal length each time so the lens has to look for the target. If there is a trend, you should see it.

http://focustestchart.com/focus21.pdf
06-28-2012, 11:02 AM   #13
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The 55-300mm is not a bad lens but is a bit over-rated. If you aren't happy with your sample then send it back to wherever you got it from - persevere until you get a good one. My second copy is much better than the first one I got. Pentax QC in Vietnam is terrible and hopefully if enough lenses bounce back to them they might get the point.

A quick play with mine at infinity (or thereabouts). Similar shots taken with my other lenses are there also. Some more test shots. And a few real life shots.

Overall, I'm not too keen on this lens, mainly because of its size and weight. I prefer the 50-200mm.

Last edited by kh1234567890; 06-28-2012 at 11:07 AM.
06-28-2012, 11:27 AM   #14
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QuoteOriginally posted by kh1234567890 Quote
The 55-300mm is not a bad lens but is a bit over-rated.
I agree, the 55-300 is a bit overrated, but I can see why. I have a Tamron 70-300mm Di, which is supposed to be sharper than the Sigma 70-300mm. My 55-300mm is actually a bit sharper than my Tamron at 300mm wide open, and has noticeably better colour & contrast. From anything I've heard, the 55-300 also beats the older Pentax telezooms.The 55-300 is on a pedestal because it is best in class. Compared with a premium lens, it understandably does not hold up.

It's possible that Daniel has a poor or defective copy, or his technique is not good, or he's cropping hard and expecting higher resolution than the lens can deliver. Until he does some testing and posts some results, we can't know which. Overly exhuberant statements like the one below, from the In-Depth review on this site, can lead to false expectations:

Surprisingly, the images at 300mm, wide open are incredibly sharp. Granted, 300mm wide open is f5.8. But the images are tack sharp, corner to corner. Examine the mortar on the edges in the f5.8 image taken at 300mm. Check out those individual sand grains! WOW!

Overall, If you are using shorter focal lengths, it is advisable to stop down 1 or 2 stops if at all possible to maximize sharpness. At 300mm, clearly there is no need to stop down. Rather, shoot away and enjoy those razor sharp pictures.
06-28-2012, 12:43 PM   #15
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Original Poster
Hi everybody,
Wow, that's a lot of data, I'm still trying to go over it, but first I will attach some photos.
Most of my photos are f/8, with long exposure times, and handheld (w/SR).

Squirrel, not happy with:
http://i470.photobucket.com/albums/rr67/koraldon/photos/IMGP2726.jpg

Swan, so-so:
http://i470.photobucket.com/albums/rr67/koraldon/photos/IMGP2717.jpg

Swan, now this one looks sharp:
http://i470.photobucket.com/albums/rr67/koraldon/photos/IMGP2677.jpg

Seagulls, short distance but still doesn't resolve well
http://i470.photobucket.com/albums/rr67/koraldon/photos/IMGP2538.jpg

Long distance buildings over the thames, doesn't resolve well
http://i470.photobucket.com/albums/rr67/koraldon/photos/IMGP2832.jpg

So let me know what do you think - Lens IQ not as it should be or I just need to improve. I have seen some of the samples here and around the web and to my eyes it seems like a different league.
I will say that I'm quite happy with the results from my FA50 and DA18-55WR.

p.s. okay, photobucket reduced the resolution, how / where can I upload full res?
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