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04-06-2014, 05:25 PM   #1
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My new Pentax 50 DA f1.8 lens with Pentax K30

Hello people,

I took my new 50mm DA f1.8 lens for a spin with my K30 camera this weekend and I got mixed results. May be its something that am not doing right.

Sharpness : I dont find this lens sharper than my 18-135mm WR for portraits. I really thought the 50mm lens to be tad sharper as per the reviews. I tried with aperture settings from f2 to f8.


Autofocus : The autofocus seems to be fast but bit noisy which did not bother me. But the issue that I had is focussing multiple people. For example I tried to focus my wife and her friend close to each other and only the person on the left seems to be fully focussed. In other words the sharness is good. I tried with multiple fstop from f2 to f10 and even changed my angle. I even tried the auto focus settings from multi to spot and even focussed on the subject eyes but still the same. I dont have this issue when taking portrait of an individual. Not sure what am making wrong here.


Bokeh : This lens has very good bokeh compared to my 18-135mm WR lens.

I have not tried the lens indoor on low light which I believe should be better than my 18-135mm WR lens.


Regards,
Jai

04-06-2014, 05:45 PM   #2
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QuoteOriginally posted by jaikumarr18 Quote
Hello people,

I took my new 50mm DA f1.8 lens for a spin with my K30 camera this weekend and I got mixed results. May be its something that am not doing right.

Sharpness : I dont find this lens sharper than my 18-135mm WR for portraits. I really thought the 50mm lens to be tad sharper as per the reviews. I tried with aperture settings from f2 to f8.


Autofocus : The autofocus seems to be fast but bit noisy which did not bother me. But the issue that I had is focussing multiple people. For example I tried to focus my wife and her friend close to each other and only the person on the left seems to be fully focussed. In other words the sharness is good. I tried with multiple fstop from f2 to f10 and even changed my angle. I even tried the auto focus settings from multi to spot and even focussed on the subject eyes but still the same. I dont have this issue when taking portrait of an individual. Not sure what am making wrong here.


Bokeh : This lens has very good bokeh compared to my 18-135mm WR lens.

I have not tried the lens indoor on low light which I believe should be better than my 18-135mm WR lens.


Regards,
Jai
Could you post a sample pics? It sounds like some of your subjects may be blurry because of the shallow DOF at wider apertures.

It could also be FF/BF, but it's hard to say without seeing some pics.

Adam
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04-06-2014, 05:52 PM   #3
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QuoteOriginally posted by Adam Quote
It sounds like some of your subjects may be blurry because of the shallow DOF at wider apertures.
My guess as well. It is a real wake-up call for many people used to shooting at f/3.5 maximum aperture to suddenly see that f/2 and wider is a whole 'nother game.


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04-06-2014, 06:16 PM   #4
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QuoteOriginally posted by jaikumarr18 Quote
I dont have this issue when taking portrait of an individual. Not sure what am making wrong here.
Since you don't have this issue with only one person in photo, that's the Shallow DoF!
to get two people in focus, it would be better to use f/5.6 I think.

And I have this lens, it's soft wide open, but once you stop it down to f/2.4 it is super sharp (but DoF is still so shallow, so you won't see the whole photo to be sharp! just the point of focus)

04-06-2014, 06:49 PM   #5
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I actually tried aperture settings from f 2 to f10 but still did not get much improvement. My wife is bit reluctant in posting her pictures and unfortunately I did not have a chance to take my picture. Will see if I can take any this weekend and would post it out.
04-06-2014, 06:54 PM - 1 Like   #6
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That's one of the picture I took using the lens. Am still trying to learn Lightroom and hence it would help if you could provide some tips.
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04-07-2014, 11:47 AM   #7
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Looks like a great shot with a wonderfully shallow depth of field. At 50mm wide open (or near to it) your depth of field is much shallower than what you may be used to with your 18-135mm when it is stopped down. I love the bokeh in the background. Nice work!!
04-07-2014, 05:08 PM   #8
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QuoteOriginally posted by 6BQ5 Quote
Looks like a great shot with a wonderfully shallow depth of field. At 50mm wide open (or near to it) your depth of field is much shallower than what you may be used to with your 18-135mm when it is stopped down. I love the bokeh in the background. Nice work!!
Thanks Boris. But am not getting consistent results though. Especially when it comes to portrait, the sharpness is not great. Am really not sure what am doing wrong. In some pictures, although the autofocus locked the subject (focus priority mode), the tree next to the subject seems to be bit sharper. But until now, I did not experience any pictures with WOW factor for the sharpness. Apart from Bokeh, I find the sharpness similar to the 18-135mm WR lens.

Regards,
Jai

04-07-2014, 06:33 PM   #9
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QuoteOriginally posted by jaikumarr18 Quote
Thanks Boris. But am not getting consistent results though. Especially when it comes to portrait, the sharpness is not great. Am really not sure what am doing wrong. In some pictures, although the autofocus locked the subject (focus priority mode), the tree next to the subject seems to be bit sharper. But until now, I did not experience any pictures with WOW factor for the sharpness. Apart from Bokeh, I find the sharpness similar to the 18-135mm WR lens.
Did you test if it has Back focus/front focus issue?
When I found my DFA50 f/2.8, I found that wide open it's not that sharp as everyone talk about. but later I tested and found it has focus issue, and a slight (+2) AF tuning made it super sharp wide open.
However the DA50 f/1.8 isn't sharp wide open, but can compete with DFA50 @ f/2.8
04-09-2014, 02:02 AM   #10
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QuoteOriginally posted by jaikumarr18 Quote
Thanks Boris. But am not getting consistent results though. Especially when it comes to portrait, the sharpness is not great. Am really not sure what am doing wrong. In some pictures, although the autofocus locked the subject (focus priority mode), the tree next to the subject seems to be bit sharper. But until now, I did not experience any pictures with WOW factor for the sharpness. Apart from Bokeh, I find the sharpness similar to the 18-135mm WR lens.

Regards,
Jai
Hmm.... I'm happy to inform you that Pentax is extremely generous in providing users with a large surface area as auto focus points!
Welcome to the world of digital manual focusing!
04-09-2014, 04:08 AM   #11
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I need to check on the focus issue and have to do it over the weekend. I got to print the focus chart to get started. This picture is straight out of the camera without any post processing. Am not sure if the focus was spot on the flower or not.

@Syncguy, I tried to manual focus on 18-135mm lens and 50 f1.8 but did not get any good results. I tried focus peeking but am still not getting hang of it.
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04-09-2014, 04:28 AM   #12
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One more to add....I have slightly processed this picture with LR....
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04-27-2014, 07:46 AM   #13
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QuoteOriginally posted by mtux Quote
Did you test if it has Back focus/front focus issue?
When I found my DFA50 f/2.8, I found that wide open it's not that sharp as everyone talk about. but later I tested and found it has focus issue, and a slight (+2) AF tuning made it super sharp wide open.
However the DA50 f/1.8 isn't sharp wide open, but can compete with DFA50 @ f/2.8
How do you test this and how do you fix it if there's a problem?
04-28-2014, 02:34 AM   #14
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QuoteOriginally posted by allexinwonderland Quote
How do you test this and how do you fix it if there's a problem?
My post is already linked to proper article! Check it here.
04-28-2014, 03:16 AM   #15
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You are getting very good results with your lens at f/1.8 - especially the bag and the magpie. Ignore the flower shot; it can be very difficult to select the right spot to focus on with such a three-dimensional subject.

Remember, this is an aperture you should only be using occasionally for specific reasons (very low light or desire for extremely shallow depth of field). Relax and enjoy your lens. Don't expect to become an expert overnight.
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