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06-23-2011, 02:42 PM   #1
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Just got my 50mm 1.7 prime!

Just bought this today for my K5 from another Pentax'r -Thanks Rob.

I am loving this lens. Compared to the kit 18-55mm it appears to give a sharper shot and a lovely controllable background blur for portrait. Not sure on how it compares for landscape on F22 but will see in time.

What I really like about the lens is that it is manual focus. This makes it quite challenging to get a perfect focus on a moving 2 year old! However, if you can get it right, the results are worth it.

The build quality is also amazing, all metal, and a nice smooth weighted action to the focus ring. Can't wait to do some outside portraits.

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06-23-2011, 02:56 PM   #2
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Congratulation !
It is a wonderful lens. And so compact !
06-23-2011, 03:07 PM   #3
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Nice lens and beautiful little child you have there!
06-23-2011, 03:08 PM   #4
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I've got the same lens - Did a few tests of sharpness, and it seems sharpest at 8 +/- one stop. At F1.7, it's quite soft even in the center. For bokeh, I usually go to 2.8 for reasonable bokeh and sharpness. At F16+, it goes soft again.

At 50mm, compared to the kit lens, this is sharper but not by too much (a testament to the kit lens I think). However, I get odd colors out of the kit lens, especially in low light, overlit, or very colorful situations.

50mm prime



18-55mm at ~50mm setting


I believe I shot the prime at F8 for best sharpness, and the zoom at F10 for sharpness as well. The actual color of the time is seen in the prime shot. The kit lens for some reason is very very off. I had AWB on for both shots, and I do believe AWB works on a manual lens, so I don't know if it can be attributed to that.

06-23-2011, 05:16 PM   #5
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You don't need f22 for landscapes.

At f8 you can get a DOF from 8m to infinity if you focus at 16m

Online Depth of Field Calculator


06-23-2011, 06:38 PM   #6
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With regard to color....I have both FA and A50/1.4 and love both but the A50 is definitely cooler as JinDesu's shots indicate. Just something to remember when I use them as I don't know that either is specifically wrong, just different.
06-23-2011, 06:46 PM   #7
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In some circumstances, I would like the 18-55 color in the pictures above, but as far as "true to life" goes, the 50mm wins that aspect.
06-24-2011, 01:17 AM   #8
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Thanks for the feedback guys. The DoF and sharpness info is useful to know. I am not familiar with the concepts yet. Will check the calculator. Is there a printable version of the DoF I can get for my 50mm 1.7? This would be useful.

Thanks again. Paul


Last edited by 10speeduk; 06-24-2011 at 01:23 AM.
06-24-2011, 01:28 AM   #9
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If you've got an iphone, theres a couple of free apps around that do DoF calcs for you. DoFMaster I think is one of them. Theres ones around for Android as well.
06-25-2011, 06:24 AM   #10
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and a killer in video

If you wanna give a try to the video mode with that lens, you'll enjoy....and learn a lot about focusing...especially with a 2 years old kid.
06-25-2011, 07:20 AM   #11
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QuoteOriginally posted by 10speeduk Quote
Thanks for the feedback guys. The DoF and sharpness info is useful to know. I am not familiar with the concepts yet. Will check the calculator. Is there a printable version of the DoF I can get for my 50mm 1.7? This would be useful.

Thanks again. Paul
Learn to read the scale on your lens. Each aperture has 2 lines drawn to the focus ring scale. When you are at a given aperture, look at the scale and the distance range that falls between the two markings, is your DOF (or about there). You don't need printable charts or calculators to figure it out, you carry it with you every time you put one of these lenses on the camera.

Note that DOF changes with Format. That is, different sized film/sensor will affect the end result. The smaller the format at a given focal length, the larger the apparent DOF (that's one reason why point and shoot cameras with tiny sensors seem so sharp). So if your scale indicates 10 feet (or 3.3 meters depending on where you're at), figure it's a little more. This is one reason some wish for a full frame sensor camera.


Last edited by JeffJS; 06-25-2011 at 07:27 AM.
06-25-2011, 03:46 PM   #12
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Thanks Jeff, great info! So if my focus ring says 0.45m at say, F4, my total DoF will be 45cm deep? If so, where does this 45cm start from? Is it the nearest point of focus to me? Ie, what I see as sharp focus through the viewfinder?

Thanks

Paul
06-25-2011, 04:47 PM   #13
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Paul

There's a red mark that shows where your focal point is. On either side of that mark are your aperture numbers going to the right and left. When you are in focus, and have selected your aperture, you look at the total distance between the aperture marks as they point to the focus scale. I don't have an M50 in front of me right now.

http://pentax-manuals.com/manuals/mf/pentax_k1000_manual_s.pdf

Open this up (password is Pentax with the capital P) and go to page 20. It explains the DOF range there. The text explains it with an M50 f2.0 but the information is valid regardless of the lens.

You can see the effect of DOF in your viewfinder if you activate the Optical Preview. You pull the power switch lever to the right (if it snaps a photo set it for optical preview instead of digital preview). That will stop the lens down to your chosen aperture, the viewfinder will darken but you will be able to see what is in focus and what is not. Hint: This will Also activate the Meter with a manual lens. You can then make your adjustments using the meter instead of screwing around with the green button (which only centers the meter). These cameras are PACKED with nice features. Don't be afraid to explore them.

DOF is affected by both aperture and focal distance. The closer you are to your subject, the more narrow the DOF (focus in front and back of subject). The further away you are, the wider that apparent range will be. If you study the focus scale for a second, this will become obvious to you. Some lenses will have 3 red marks. One of the aperture numbers will be red, the obvious focal length pointer, and one of the focal lengths on the scale will be red. If you Have one of those lenses (don't remember if the f1.7 is such a lens), you line those 3 points up and just about Everything will be in focus with a few exceptions. All lenses have such a range but they aren't all marked that way.


Last edited by JeffJS; 06-25-2011 at 04:59 PM.
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