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01-12-2011, 05:17 PM   #31
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QuoteOriginally posted by normhead Quote

Darn, now I feel bad again, it was listed on Kijiji for $500. I should have jumped.
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what do you feel so sad about? >>> smc PENTAX FA 100mm f/2.8 MACRO Exc+ - eBay (item 380306500610 end time Feb-08-11 22:00:33 PST)

01-12-2011, 06:01 PM   #32
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QuoteOriginally posted by climit Quote
Come on Bramela. Where do I say that da 35 ltd is not a sharp lens? What I say is that it is not THAT sharp (compared to other lenses). Check Photozone. It is soft in borders compared to FA35 or FA43 for example.
I don't own the 43, but I do own both the FA35/2 and DA35/2.8. The DA lens is definitely the sharper of the two in my usage.
01-12-2011, 08:13 PM   #33
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Back in my manual focus days, before my eye went down the crapper, I used take a shot 3 times if I really wanted it. Now I'm taking 5. I think this article explains why.
08-09-2011, 01:17 PM   #34
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I'm fairly new to Pentax Digital (Got a K5) Have used Pentax equip for many years (Film cameras, it was my living) Now reading this forum, which has many odd and unqualified comments posted. Re lenses, in my experience the Pentax own lenses ALWAYS beat the other brands. But I have the two "Bundled" lenses, 18-55 and 55-200mm both good, and have recently added a Pentax 50-300 which seems inferior and quite soft. Does anyone else have this opinion? David Dunn

08-09-2011, 01:21 PM   #35
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QuoteOriginally posted by Urkeldaedalus Quote
The main thing that surprised me was how low the DA*16-50 scored.
Well I wasn't overwelmed by that lens.

There are some new lenstests. Da14 is one of them.
08-09-2011, 02:09 PM   #36
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QuoteOriginally posted by VK3DBD Quote
I have the two "Bundled" lenses, 18-55 and 55-200mm both good, and have recently added a Pentax 50-300 which seems inferior and quite soft. Does anyone else have this opinion? David Dunn
The 55-300mm is pretty universally acknowledged to be superior to the 50-200mm. I don't have a 50-200, but when I compared my 18-55 and 55-300mm at 55mm, the 55-300 was easily the sharper lens.
08-10-2011, 08:57 AM   #37
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It's funny to see superzooms like the 28-300mm above Pentax lenses. I wish it automatically filtered it by sensors.

QuoteOriginally posted by Wheatfield Quote
Compare the lenses on cameras with more similarly specified sensors. The Pentax lenses look a little better, though still not as good.
If they test wide open, I'm not surprised. I don't think (in general) Pentax lenses are quite as sharp wide open as they could be.
They test at all apertures when you look at the measurements.
08-10-2011, 09:22 AM   #38
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how is produce DxO marks score :

QuoteQuote:
DxOMark Score
The DxOMark Score is the performance of a lens (with a camera body) for its best focal length and aperture combination. It does not show how the lens behaves over its entire focal range. Other lens scores, such as Use Case and Optical Metric Scores, report average performances over the whole focal length and aperture ranges.
However, the DxOMark Score is reported using a gauge that shows the score itself as well as the range of scores over the focal range. WIth this gauge, photographers can view the homogeneity of the lenses image quality over their focal range.

DxOMark Score
The DxOMark Score is measured for defined exposure conditions corresponding to low-light scene with 150 lux illumination and an exposure time of 1/60s. These conditions were chosen as we believe low-light performances are very important for today’s photography and it is also important for photographers to know how well lenses perform at the widest aperture.
Read more about the DxOMark Score for lenses and how it is designed.
(first thing : in the 100 first "best lense" 98 are at least f2.8 or bigger aperture. the only 2 that are f4 are the Samyang wide angle)

Then if you keep digging on the "Read more about the DxOMark Score for lenses and how it is designed" :

QuoteQuote:
Here we detail the motivations behind the DxOMark Score and the rationale for its conception.
Motivation behind DxOMark Score for lens with camera
A camera consists of many different components. Because so many factors related to all these components have to be taken into account, it can be difficult to choose between models. To make it easier for photographers to choose, we wanted to design an objective numerical quantity to globally represent the highest image quality a given camera can achieve.
To fully embrace the complexity of the camera, however, it is necessary to go back and forth between several levels of detail for different parts of the system, analogous to looking at something under a microscope. When looking inside a camera, for example, the data in lens with camera and in camera sensor reveal many details about their respective target components. Taken together, they provide a more global view of the camera’s image quality performance.


Information Capacity

The idea of DxOMark Score is to quantify the amount of information captured by the camera, taking into account all the optical aberrations and sensor characteristics measured by DxO Labs. This quantity is called the information capacity of a camera.
Information capacity can also be defined as the product of the number of effective bits sampled at each position and the effective resolution of the camera. It is expressed in Megabits (Mbits). The higher this number, the better the camera.
These two numbers (effective bits and resolution) depend on the characteristics of the camera, including such parameters as focal length and f-number, along with the amount of light coming into the camera.

To compare different kinds of cameras, we choose a low-light use case in terms of illumination and exposure time. More precisely, we choose the scene illumination to be 150 lux and the exposure time 1/60s. Such conditions were chosen as we believe low-light performance is particularly important for today’s photography and it is also important for photographers to know how well lenses perform at widest aperture.
Information capacity is an open scale. However, for a given sensor, it is usually about twice the sensor pixel count.
How do camera characteristics influence information capacity?
Optical aberrations depend on image field position, which means that information capacity is first locally computed then summed over the whole image. Optical aberrations such as blur, lateral chromatic aberration, distortion (barrel and pincushion), and lens shading all influence the quality of the signal at each point, and result in reduced information capacity.
In addition to optical limitations, a camera’s T-stop setting determines the amount of light that crosses the optical system and eventually reaches the sensor. In general terms, less light means a noisier (or less useful) signal. The signal-to-noise ratio (SNR) determines the number of useful digital values needed to describe the luminance at each point.
A final characteristic to consider is the way each sensor "sees" color, or its spectral response. These responses are different from one sensor to another, and are also different from the response of the human eye. In order to output an image with similar rendering, independently from the sensor, the color space of the sensor is mapped to a standardized color space (as sRGB for instance). This mapping usually enhances noise, and therefore decreases the information capacity.
Here is the point :
Those test are very "Body-dependant", the FF of Canikon have a very good SNR, that's explain a bit why any lense tested on those body gets better score. There is nothing more to look at.

simple example :
the 85 f1.2L II USM got 27 points on a 5DmkII and only 16 with a 7D (and 18 pts with the 1DmkIII)
-> Very depend on the sensor size / spec.


To finnish, 90% of the people even photog, will hardly see the difference between the 10 best 50mm at their best aperture, on the same body.


Last edited by aurele; 08-10-2011 at 09:32 AM.
08-10-2011, 09:24 AM   #39
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QuoteOriginally posted by Eruditass Quote
It's funny to see superzooms like the 28-300mm above Pentax lenses.
Do you mean the Canon EF 28-300mm f/3.5-5.6L IS USM? That's a $2600 lens.
08-10-2011, 09:41 AM   #40
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QuoteOriginally posted by audiobomber Quote
Do you mean the Canon EF 28-300mm f/3.5-5.6L IS USM? That's a $2600 lens.
price is not everything, especially in the lense market.

on the best lenses ranked, click on it, then change the body it was tested with, from a FF (like 5dmkII or D3x) and put a APS-C body, it will almost halve the score, and it will be very close of the Pentax one

Last edited by aurele; 08-10-2011 at 09:50 AM.
08-10-2011, 02:39 PM   #41
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Dpreview always gives Pentax high marks

Ken Rockwell typically p1sses on Pentax, which I feel is a real shame.

Dx0 mark ? Maybe they are paid to p1ss on Pentax ?
08-11-2011, 02:44 AM   #42
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QuoteOriginally posted by spystyle Quote
Dx0 mark ? Maybe they are paid to p1ss on Pentax ?
i don't know, but as long as DxO test a "full system" (i.e.: Lense + body) and as long as Pentax doesn't have FF, Pentax will be mark far behind the big two.
08-11-2011, 03:29 AM   #43
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their claims about macro lenses are weird
they say that micro nikkor 105 on D200 reaches 44 lp/mm at f/2,8...while test on lenstip with D200 shows only 39
then on D7000 it has 55 lp/mm at f/2,8...while DFA 100 WR on K5 has only 46lp/mm at f/4 and on lenstip on K5 it has 51 lp/mm at f/4
I`d say they could not get proper focus with pentax lens

the same goes when comparing canon EF 100mm f/2.8L Macro IS USM to DFA 100 WR

Last edited by stanic; 08-11-2011 at 11:02 AM.
08-11-2011, 04:05 AM   #44
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QuoteOriginally posted by stanic Quote
their claims about macro lenses are weird
what they clame about lense in general is weird.

Whatever, some very few mm of miss-focus and the full test is false. Don't give too much importance to DxO. they didn't even take the pain to test on of the 50mm f2/1.9/1.8/1.7/1.4 that Pentax made for the last 30 years.
08-11-2011, 06:27 AM   #45
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QuoteOriginally posted by stanic Quote
they say that micro nikkor on D200 reaches 44 lp/mm at f/2,8...while test on lenstip with D200 shows only 39 then on D7000 it has 55 lp/mm at f/2,8...while DFA 100 WR on K5 has only 46lp/mm at f/4 and on lenstip on K5 it has 51 lp/mm at f/4
Even if all tests used the same sensor, you cannot compare lp/mm figures between different testers. Unless someone performs aerial image lens tests, they are all performing system tests. And part of the system is what sharpening is applied (e.g., to counteract the fuzziness introduced by Bayer pattern sensors).

Look at Bojidar Dimitrov's published resolution tests for an older example of how one and the same lens can yield different results depending on the tester.

Regarding the performance of the 16-50: I believe the DxOMark results are correct. This lens isn't as great as it is often purported to be. In a comparison (sadly no longer available) it frequently lost in individual disciplines to either the Tamron 17-50/2.8 or the Sigma 18-50/2.8. In one or two results it was ahead but in the vast majority it came second or third.

Maybe the 16-50's strength is its rendering. Maybe it just doesn't measure that well, but produces images with a special touch. I couldn't see that in the comparison test (which included many real world images) at all -- in fact I often preferred either Tamron or Sigma -- but I'm not excluding that possibility.

However, the 16-50/2.8 certainly isn't an optical wonder, let alone the SDM (Surely Dying Motor) issues.
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