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11-04-2007, 11:24 AM   #1
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My new FA 50 1.4


I'm new here. i live in graz (austria) and use a pentax k100d with the kit lens, the 50-200 and now, a fa 50 1.4.
yesterday i only shot photos with this lens on a birthday party. it is an other variety to photograph just only with one lens, äh i mean, with a fix focal lens. it makes fun.
the bokeh is very fine and it balanced very well on the k100d. it's a great little combo.
but some photos were not so sharp as i hoped.
maybe it's my fault because of the small depth of field.

today i made a few test shots to test the sharpness. at 1.4 is only a small area in the center sharp. at 2.0 it's the same. first at 2.8 it will be sharp.

the attachted first image is with f 1.4 and the second with f 2.8.

are these pictures okay or is my example not as sharp as it could be.

maybe i'm too critical with it. but for me is sharpness very important.

thanks and greetings

ps: my english is not so well. i hope you understand what i wanted to say.

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11-04-2007, 12:00 PM   #2
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That is a normal phenomina called "Depth of Field". The 50 f1.4 effectively becomes a 75mm f1.4 lens and DOF seem s more exagerated even if it is not. Precise focussing is essential when shooting wide open.


PS..The Pentax f1.4 lens falls in to my brutally sharp category...

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11-04-2007, 12:25 PM   #3
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Online Depth of Field Calculator
11-04-2007, 12:54 PM   #4
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okay, thanks for the good news.
now i'm again very very happy with that lens!

11-04-2007, 12:58 PM   #5

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Here is another tool that allows you to "play" around and get to understand DOF a little better. Basically it shows the same information but provides a slightly different point of view. (redudant huh) The links off of the help menu go to sites that should be bookmarked too.

I have the FA 50mm f1.4 and it is glorious.

The Elitist - formerly known as PDL
11-05-2007, 03:40 AM   #6

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I thought the question was that the area in focus (in the first picture) only is a small elliptical spot, shouldn’t it have been more of a horizontal row, spanning the entire picture?
11-05-2007, 06:39 AM   #7
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yes, that was my question. after the posts i thougt this is normal.
but now, i'm unsure again.
11-05-2007, 07:03 AM   #8
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Hi Mario. First of all welcome to the forum. Your English is just fine and I think well understood by everyone here.

Me thinks the second shot is the sharpest - hands-down.

11-05-2007, 10:01 AM   #9
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hi JCSullivan!

thanks for your encouraging words! my second open windows is .

i made the second photo with f 2.8.
but i'm confused on the picture with f 1.4, because of the not available layer outside the center.
the center is really sharp.

as written above maybe i'm to critical.
11-05-2007, 11:59 AM   #10
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It's normal. Looking at your f/1.4, it appears to me like there was some rotating camera shake, which would cause a sharp center and exaggerated blurred edges.

Do the same test in the sunlight sometime, I'm almost sure that won't happen.
11-05-2007, 12:40 PM   #11
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i think you are right. i made other test shots and these are better at 1.4.
11-05-2007, 12:44 PM   #12
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I'm very jealous! I hope this is my next lens.
11-05-2007, 01:49 PM   #13
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As shallow as the depth of field is at f1.4, if that page of type isn't perfectly parallel with the back of the camera, the edges will go soft because they're no longer in the plane of focus.
11-05-2007, 03:14 PM   #14

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But since the photo is taken with an angle to the page, the right distance has to appear somewhere, even at the edges.
11-06-2007, 03:46 AM   #15
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Congrats on owning the 50 1.4. Personally, I feel that anyone who's into SLRs (regardless of brand) should have a fast fifty. It's just that useful.

I just got mine yesterday, and I must say that it's brutally sharp like what Ben said, even wide open. The bokeh's also wonderful, and the best part is that it costs far less than other 50's of similar aperture from other companies. Even then, those aren't as sharp wide open.

Pentax sure knows how to do primes. Also, the 50 reaffirms what I like about Pentax - value for the money, as well as outstanding quality.

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