Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-20-2010, 02:11 AM   #1
New Member




Join Date: Apr 2010
Location: Delhi
Photos: Albums
Posts: 22
Confusion DOF, Sharpeness, Detail, Saturation, Hue....!!!!

Hi,

After night shots, tried out a lot of combinations to understand aperture\shutter settings and DOF .....seems ended up getting confused if it was an issue of lack of my understanding, wrong settings or a problem with my camera (Mirror slap or some other issue.

Am posting three pics taken with different f numbers and shutter speed

1stPic: DAL 50-200mm f4-5.6ED, 50mm, f4.0, 1/1600, multi metering, daylight WB, ISO 200, Natural image tone

2nd Pic : only change from pic 1 is 1\320 sec, f9.0

3rd pic : only change from pic 1 is 1/100 sec, f18.0

The problems:

1) The DOF does not seem to be very different in all three
2) Detail\Clarity is not too great. The name on the racks appear fuzzy. Hope it is not because of mirror slap or some other defect with my pentax k-x
3) Not sure if the colors have come out good. Seem to be too bright. Is it because of wrong image tone selection? Can some one guide me to some material on how to learn about Hue, sharpness, contrast settings etc.

Any other suggestions on improvements are welcome!

Thanks in advance for all your advice.




Last edited by alokaga; 04-20-2010 at 11:26 AM.
04-20-2010, 02:22 AM   #2
Senior Moderator
Loyal Site Supporter
Nass's Avatar

Join Date: Aug 2009
Location: The British Isles
Photos: Gallery
Posts: 2,251
Hello Alokaga,

There should be more depth of field on the third picture (f18) than the first (f4); these images are too small to take be able to take a good look though.
04-20-2010, 03:24 AM   #3
Veteran Member




Join Date: Aug 2007
Photos: Gallery
Posts: 1,563
Hi Alokaga,

Perhaps you can start reading this: PENTAX DSLRs: The Pentax K-x e-book is actually completed and ready to download.

To comment on your pictures, you should post much larger pictures or links to a photo site where you show them with detail.

I do not have a K-x, but do understand that the mirror slab issue is particulary noticable with shutterspeeds between 1/50 and 1/100.
So the image taken with 1/320s should be fine.

To understand the DOF of a picture, you could experiment with: Online Depth of Field Calculator

Cheers, Bert
04-20-2010, 11:31 AM   #4
New Member




Join Date: Apr 2010
Location: Delhi
Photos: Albums
Posts: 22
Original Poster
Guys sorry,.....did not realize that the thumbnails cannot be expanded...I have edited the snaps to their original size....

Even I thought it should give me more DOF at f18.....other thing is I am not sure if there is a mirror slab issue.....it there is one how do I find it out and does that mean I will always have to live with it unless I decide to change my equipment?

Also is the mirror slab an issue with Canon & Nikon too or is it just a k-x issue?

04-20-2010, 12:33 PM   #5
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,484
QuoteOriginally posted by alokaga Quote
Guys sorry,.....did not realize that the thumbnails cannot be expanded...I have edited the snaps to their original size....

Even I thought it should give me more DOF at f18.....other thing is I am not sure if there is a mirror slab issue.....it there is one how do I find it out and does that mean I will always have to live with it unless I decide to change my equipment?

Also is the mirror slab an issue with Canon & Nikon too or is it just a k-x issue?
I assume you mean mirror SLAP issue. That aside, to begin with, you're over exposed in all 3 shots. Try getting that right and I think you'll find that your DOF cleans up quite nicely. Second, DOF is a function of not only lens aperture but Distance from subject. At Infinity for instance, you'll be hard pressed to tell the difference in most situations. That is unless you have Some specific detail to compare.

04-20-2010, 01:38 PM   #6
Senior Member
Itai's Avatar

Join Date: Sep 2009
Location: Montreal
Photos: Gallery
Posts: 211
A few things to know:

- Depth-of-field is relative to display/print size. At reduced sizes, images
may appear to have the same depth of field but will be different when
seen larger up to full size.

- F/8 gives you more depth-of-field than F/4

- F/18 theoretically gives more depth of field but due to a phenomenon
called diffraction makes the whole image softer which hides the increased
depth of field. On the K-7, the diffraction limit is F/11. On the K-x is is most
likely F/13.

- You definitely needed to apply negative exposure-compensation here because
there is a darker area near the center of the frame, which cameras tend to
prioritize, causing the area around to be over-exposed. Try -1/2 EV if you work
in half or -2/3 if in thirds.

- At the shutter-speeds you used, shake should not be an issue.

- Your saturation seems to have blown out the yellow of the chip rack and packages.
At least it looks this way on my sRGB color-accurate display. It make look different in
yours. Start with the default settings for Bright and if you need more saturation, add
one until you are satisfied. I do not own a K-x but my K-7 is slightly undersatured at
the default and slightly over at +1, so I stuck with +1.

- Have you seen my sharpness demo? You can try all the settings interactively, to see
what difference it makes. Look at both sides of the image as sharpnining affects
fuzzy edges differently than sharp edges:

Pentax K-7 Image Sharpness | Neocamera.com

That should get you started on finding the settings which please you. Personally, I am
a maniac for representing reality, so I test the cameras against a standard color target
and choose the most accurate settings possible. I have never seen a camera get it 100%
correct but the K-7 can get very close.

- Itai
Neoluminance | Fine Art Photography by Itai Danan
04-20-2010, 03:01 PM   #7
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by alokaga Quote
Hi,
1) The DOF does not seem to be very different in all three
Sure it does. Check out the distant plants juis below the "Pepsi" sign at the far right - just a blob of green at f/4., fairly well defined at f/18.

QuoteQuote:
2) Detail\Clarity is not too great. The name on the racks appear fuzzy.
Which racks, and where exactly did you focus? DOF doens't guarantee *perfect* focus everywhere in the range, just in focus "enough". presumably you are viewing these images at 100% and finding the spot you are lookng at is not quite in the most perfect focus. or you're just expecting to much of your lens (neither f/4. nor f/18 would be as good as f/8 for sharpness).

QuoteQuote:
3) Not sure if the colors have come out good. Seem to be too bright. Is it because of wrong image tone selection?
That's subjective. If *you* don't like them, then by all means, play with settings until you do. But don't expect the same settings to work equally well for all pictures. That's why people do post-processing on their images - to tune each individually as necessary.

I would agree they are too bright in the sense of being a bit overexposed, though.
04-20-2010, 08:31 PM   #8
Site Supporter
jmschrei's Avatar

Join Date: Apr 2010
Location: Calgary, AB
Photos: Gallery | Albums
Posts: 3,959
QuoteOriginally posted by Marc Sabatella Quote
Sure it does. Check out the distant plants juis below the "Pepsi" sign at the far right - just a blob of green at f/4., fairly well defined at f/18.



Which racks, and where exactly did you focus? DOF doens't guarantee *perfect* focus everywhere in the range, just in focus "enough". presumably you are viewing these images at 100% and finding the spot you are lookng at is not quite in the most perfect focus. or you're just expecting to much of your lens (neither f/4. nor f/18 would be as good as f/8 for sharpness).



That's subjective. If *you* don't like them, then by all means, play with settings until you do. But don't expect the same settings to work equally well for all pictures. That's why people do post-processing on their images - to tune each individually as necessary.

I would agree they are too bright in the sense of being a bit overexposed, though.
I am still on the steep end of the learning curve myself but these comments make sense. I attended a workshop with a professional nature photographer who suggested that we experiment to find the optimum range for DOF for the lens we are using starting about mid-range in the apetures for that lens and judging images at 50% magnification. For example the lens I use most often has a constant range of f/2.8 to f/22 and I find that f/8 to f/11 tend to produce the most consistently satisfying depth of field to my eye, given the subject and conditions. I also tend to shoot outdoors with a polarizing filter.

Does that make sense? I found that for a while I was obsessed with trying to produce scenes that were focused from near to the distant horizon. The more comfortable I become the more I am starting to play with what I do or do not want to be in focus.

Joe

04-21-2010, 02:10 AM   #9
Veteran Member




Join Date: Aug 2007
Photos: Gallery
Posts: 1,563
To come back to your orginal question and having better pictures now:

It is hard to estimate the subject distance of your photos.

Let's say the nearest subject is around 6 meters and the farthest is around 12 meters away?

Suppose your AF is at.... 8 meters?

The DOF calculator gives you at 50mm and f4 on a K-x:
+++++++++++++++++++++++++++++
Subject distance 8 m

Depth of field
Near limit 6.38 m
Far limit 10.7 m
Total 4.35 m

In front of subject 1.62 m (37%)
Behind subject 2.73 m (63%)
+++++++++++++++++++++++++++++

Note that there is not an absolute border but the DOF field fades away.
That would at f4 have almost everything in focus.

The DOF calculator gives you at 50mm and f18 on a K-x:
+++++++++++++++++++++++++++++
Subject distance 8 m

Depth of field
Near limit 3.73 m
Far limit Infinity
Total Infinite

In front of subject 4.3 m
Behind subject Infinite
+++++++++++++++++++++++++++++

With smaller apertures than f4, the DOF would only get wider not making a lot of difference as you can see.

I hope this helps.

- Bert
04-21-2010, 03:02 PM   #10
New Member




Join Date: Apr 2010
Location: Delhi
Photos: Albums
Posts: 22
Original Poster
Hi Everyone,

Really thanks for all the replies...I think these put a lot of thing in perspective.

I agree on all of them and am sure if I keep in mind the points enumerated, I will be able to take a better shot next time in similar situations

Can I have some clarifications on the following two points:

1) In case the whole picture is in the DOF range the word pepsi (Smaller letters and not the bigger ones only) on the rack should have come out clearly. What is the reason for that not coming out clearly.

2) The natural image tone settings for hue, saturation & contrast all are +4.One thing I am struggling with is the Image tone settings. Is there some rule of thumb as to which default settings to use and when to make adjustments to these defaults and how much?

Thanks again to everyone for the analysis!
04-21-2010, 05:20 PM   #11
Pentaxian
Clarkey's Avatar

Join Date: Jan 2008
Location: Brampton, ON, Canada
Photos: Gallery
Posts: 1,767
QuoteOriginally posted by alokaga Quote
Hi Everyone,

Really thanks for all the replies...I think these put a lot of thing in perspective.

I agree on all of them and am sure if I keep in mind the points enumerated, I will be able to take a better shot next time in similar situations

Can I have some clarifications on the following two points:

1) In case the whole picture is in the DOF range the word pepsi (Smaller letters and not the bigger ones only) on the rack should have come out clearly. What is the reason for that not coming out clearly.

2) The natural image tone settings for hue, saturation & contrast all are +4.One thing I am struggling with is the Image tone settings. Is there some rule of thumb as to which default settings to use and when to make adjustments to these defaults and how much?

Thanks again to everyone for the analysis!
2) If shooting JPGs in the daytime sunlight, I find the "bright" setting is useful, rather than ramping up the settings in natural. I tend to shoot (on a K7, but I suspect these are similar) this way and -1 the saturation.

The contrast here is quite high, and I do reduce that by -1 also. Otherwise I find the camera does a good job in daytime under these settings. If shooting Jpg, I do also turn on highlight correction.

There are no hard and fast rules though, and it is a matter of preference as to what "feel" you want to get from your images.
04-21-2010, 05:43 PM   #12
Senior Member




Join Date: Jul 2009
Location: Japan (Australian expat)
Posts: 166
QuoteOriginally posted by alokaga Quote
Can I have some clarifications on the following two points:

1) In case the whole picture is in the DOF range the word pepsi (Smaller letters and not the bigger ones only) on the rack should have come out clearly. What is the reason for that not coming out clearly.

2) The natural image tone settings for hue, saturation & contrast all are +4.One thing I am struggling with is the Image tone settings. Is there some rule of thumb as to which default settings to use and when to make adjustments to these defaults and how much?
On point (2), there are no custom settings on the K-x, so you need to modify one of the presets. In this case, you have used the "natural" preset, but then modified it to hue, saturation & contrast to +4 (as opposed to the original setting of 0)
This may explain why the the image in general looks overexposed: It's not completely overexposed, but the contrast setting of +4 will overexpose the highlights, which appear to have happened in this case.
Setting saturation to +4 will over blow bright colors, particularly the red & yellow on that stand, and the blues on the other signs.
Hue will change the color balance.

So in context, if the highlights and bright colors are over blown in those images, then the "blooming" effect on the images, will give detail which is less sharp. This would explain (1)


For example, here is your original at F9 (the one that shoudl be the sharpest)



Here's the same one, but I've backed off the contrast ad saturation. Now, although the highlights have already been "damaged" in original shot, notice that the yellow detail in the stand has improved:


The second image is not ideal, because the original was not handled correctly, but you get the idea.....
Back the setting off to "0", then adjust after that. Maybe +2 on contrast and saturation as a maximum, not +4.
04-21-2010, 08:32 PM   #13
New Member
cheers's Avatar

Join Date: Apr 2009
Posts: 9
the reds appear overcooked in the original photograph. but not the coke bottles. those appear to be about right. if anything they are a bit dark. so maybe the reds are just that bright.

the lighting in this scene is very challenging. you've got a bright white area on one side, a darker area to the other, and the center is a mess of light and dark areas. the camera's meter has no clue what's going on and has to guess quite a bit.

dnas's alterations have mostly improved the image, although the yellow rack now looks a bit sickly. as if it disagreed with what it had eaten. but there's only so much you can do when the original photo is all over. which is necessarily the case because the scene was all over. if the lighting were a bit more even it'd be a very good test for various picture styles as it is so colorful.

looks like thailand to me.
04-21-2010, 11:11 PM   #14
New Member




Join Date: Apr 2010
Location: Delhi
Photos: Albums
Posts: 22
Original Poster
Thanks dnas for your efforts on making changes....somehow the default setting I have on my k-x for natural is +4, I haven;t made any changes to these.....the bright settings are more near to 0 with contrast at +1

I had clicked these one because of it's colors and with an intention to see how the camera performs. I think will find other spots with a more even light around!

Thanks cheers for adding on! I agree pre changes it looks like the yellow chips rack had overeaten and post changes it did not like what it ate!! The pics have been taken in India.
04-22-2010, 02:05 PM   #15
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by alokaga Quote
1) In case the whole picture is in the DOF range the word pepsi (Smaller letters and not the bigger ones only) on the rack should have come out clearly. What is the reason for that not coming out clearly.
DOF is not an absolute thing. That is, there is no hard and fast dividing line between in focus and out of focus. The only thing that is ever *perfectly* in focus is the thing the camera actually focused on (and anything else on the same focus "plane"). Closer or further than that, things gradually get less well focused, until finally it passes this somewhat arbitrary point where a formula says it's out of focus enough for people to notice when viewing a typical print from a typical distance. Things that are still inside that limit should look reasonably in focus when viewing a typical print from a typical distance - but they'll definitely be a bit soft blowing it up to 100% on your computer screen and examining it from less than a foot away, as I presume you are doing here.

Plus, the only way to get DOF big enough to encompass the whole scene even according to the formula is to stop way way way down - and no lens is at it's sharpest when stopped down that far.

QuoteQuote:
2) The natural image tone settings for hue, saturation & contrast all are +4.One thing I am struggling with is the Image tone settings. Is there some rule of thumb as to which default settings to use and when to make adjustments to these defaults and how much?
Learn what the terms mean - playing with those settings in a PP program would help you get a handle on it - then decide for yourself when you want more versus less saturation, more versus less contrast, etc.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, change, dof, image, issue, mirror, pentax help, photography, pic, sec, settings, tone
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
catching sky detail with people detail Genshu Pentax DSLR Discussion 6 04-15-2010 06:40 PM
Saturation mask... K7er Digital Processing, Software, and Printing 2 03-17-2010 05:51 PM
what do you set the sharpness and saturation to? Deiberson Pentax DSLR Discussion 13 03-07-2010 07:11 AM
Color Saturation FishrOfGrizz Troubleshooting and Beginner Help 6 11-04-2009 03:36 PM
Super Saturation WillInTO Troubleshooting and Beginner Help 5 07-10-2009 06:33 AM



All times are GMT -7. The time now is 11:24 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top