Pentax DA18-250 vs DA18-55&DA50-200, DA18-250 Testing


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fengwei

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As some of you already knew that I got this DA18-250 lens last week. It's a lens w/ very wide focal range, good option for travel or some casual snaps. I bought it because my kids are old enough to go to the beaches, or play some water. Sometimes I don't want to bring very expensive gear to those places ;)

Anyway, I'm sure some guys here want to compare this lens with the dual kit lenses. I borrowed the dual kit lenses from a good friend and did some simple comparison over the weekend.

Here are the lenses:



Specification Comparison:

1. SMC DA 18-250/3.5-6.3 AL ED [IF]
Optical Formula: 16 elements in 13 groups (including 2 ED and 2 AL elements)
Angle of View: 76-6.5 degrees
Diaphragm: Fully Automatic
Minimum Aperture: f/22-45
Number of Aperture Blades: 7
Metering System: TTL Open Aperture Metering
Minimum Focus Distance: 1.48’ (0.45m)
Filter Diameter: 62mm
Maximum Magnification: 0.28x
Maximum Diameter: 3.0” (75mm)
Minimum Length: 3.4” (85.5mm)
Weight (w/o Hood): 16.0 oz (455g)

2. SMC DA 18-55/3.5-5.6 AL
Optical Formula: 12 elements in 9 groups (including 1 AL element)
Angle of View: 76-29 degrees
Diaphragm: Fully automatic
Blades: 6
Min Aperture: F22 at 18mm, F38 at 55mm
Metering: TTL open-aperture metering
Min Focus Distance: 9.84 inches (0.25m)
Max Magnification: 0.34mm
Size Max Diameter Length: 2.7 inches
Weight: 7.9 oz.
Filter Diameter: 52mm

3. SMC DA 50-200/4-5.6 ED
Lens Construction: 11 elements in 10 groups (including 1 ED element)
Angle of View: 31.5 degrees to 8.1 degrees
Diaphragm: Fully Automatic
Blades: 6
Min Aperture: F22 at 50mm, F32 at 200mm
Min Focus Distance: 1.1m
Max Magnification: 0.24x
Size Max Diameter Length: 2.6" x 3.1"
Weight: 9.2 oz.
Filter Size: 52mm

Did some simple test, and found the aperture values in certain focal ranges for all three lenses (these are approximate values, might vary abit) as following:
DA18-250
18~21mm:F3.5
22~35mm:F4
36~65mm:F4.5
66~155mm:F5.6
156~200mm:F6.2
201~250mm:F6.3
DA18-55
18mm:F3.5
29~34mm:F4
35~45mm:F4.5
46~55mm:F5.6
DA50-200
50~62mm:F4
63~138mm:F4.5
139~200mm:F5.6

You can see the DA18250 has faster or same aperture values when comparing with the DA1855, while it has slower or same aperture values comparing w/ the DA50200. Not too bad for a mega zoom lens like this one :)


Overall feeling of the DA18-250 after some try:

The three lenses are built pretty much the same, look and feel similar. But the DA18250 has bigger filter thread size, the barrel is thicker, which makes it feel a bit more solid. The lens barrel will extend out by itself if I shake the len/camera a bit when pointing downward, but it won't extend if not shaking it. This might become worse after some use. Luckily there is a lock switch on the barrel as some Sigma/Tamron 70-300mm lenses.

There is no silver "DA" tag on this lens as the other two, and there is no small open window on the hood either. QuickShift is definitely not there as reported, but I don't expect to use MF anyway w/ such a lens (which has very short MF turn from min to max distance). The lens does marked "Made In Japan", not like all the other DA lenses.

AF speed is about the same as the DA50-200, and AF w/ both lenses are much slower than the DA18-55. Noise level is pretty much the same w/ three lenses. Overall the AF speed with the DA 18250 is pretty okay, good enough for normal use.

One thing to mention though, most if not all mega zoom lenses normally won't reach as long as their specified focal lengths, especially on the tele end. This is certainly the case w/ the DA18-250. It's the way these lenses are designed and made, not some cheating from the manufacturer. They'd reach their specified focal length when focused at infinity, but they won't have the same magnification ratio as fixed or non-mega zoom lenses on close target. This can be seen from the following testing photos between the DA18250 and the DA50200.

Enough said. I'll post the comparison photos in the following replies. I only compared the center sharpness, the color, and CA of these lenses. Didn't do any other test. You can click on the small photos to open their full size ones.


Setup for the test:
1. K10D camera set to average matrix metering, Av mode, ISO100, RAW, AF on center point, SR off, 2sec mirror up
2. Tripod
3. All lenses w/ no filter, no hood
4. RAW files are converted by SilkyPix w/ same color temperature, no sharpening, 100% JPG output, then resaved to quality 8 by PhotoShop CSII. No other post processing.
5. All small or crop versions are done by CSII

Here is the test scene:

 

fengwei

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#12
There are all full sized JPG output directly from K10D+DA18250. All photos were taken at wide open apertures. Only rotated to portraits in PhotoShop CSII and saved to quality 8 jpg. No other post processing. Please click on the small photos to open up their full sized unprocessed ones:

 

fengwei

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#15
Here are some random photos taken by K10D+DA18250, processed either by SilkyPix or PhotoShop CS2 as usual:









 

fengwei

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#16
Overall I quite like this DA18-250 lens. It offers very good range w/ good optical performance over the entire focal length. Sharpness is good even comparing with the two kit lenses. It is certainly capable of making good photos when used well.

My suggestion? If you are planing to buy the dual kits, I'd suggest you to get this one instead. Optically it is as good if not better than the dual kit lenses, and you don't need to change lenses when you are out in the field :)

Hope this thread would be some help to some guys here.

Cheers!
 

istDeS

Senior Member
Dec 7, 2005
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#17
Thanks fengwei for taking the time to do the test shots and comparison.:thumbsup:

Looking at the comparison with the kit lens range of 18-55mm, personally i find the DA18-250is slighty better there in central sharpness and the kit lens looks a tad underexposed also. When compared with the 50-200, both quite on par.

Looking at your testing shots. Looks like the DA 18-250 is quite a decent lens for general use. :)

btw, nice shots of your kids with the lens.:D
 

fengwei

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#19
Thanks fengwei for taking the time to do the test shots and comparison.:thumbsup:

Looking at the comparison with the kit lens range of 18-55mm, personally i find the DA18-250is slighty better there in central sharpness and the kit lens looks a tad underexposed also. When compared with the 50-200, both quite on par.

Looking at your testing shots. Looks like the DA 18-250 is quite a decent lens for general use. :)

btw, nice shots of your kids with the lens.:D
Thanks Desmond, glad you found these are helpful.

Yes, I do feel this DA18250 can be as good as the kit lens and the DA 50-200. If you are happy with these two lenses, you won't be disappointed with the DA18-250 lens :)

But of course it's still a mega zoom lens, a consumer level lens. We can't expect too much except what it really can do. Overall it's a good alternative to the dual kit lens solution, and probably better option than the Sigma/Tamron 18-200.
 

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