Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-15-2013, 01:53 PM   #1
Pentaxian
Zafar Iqbal's Avatar

Join Date: Oct 2010
Photos: Gallery
Posts: 1,157
Bleached area - why?

I shot a bunch of photos using 21mm Limited.

The first 35-40% are perfectly fine but the rest have this thing going on at the bottom left corner.

The affected area is smaller in some and larger in others - but it's hard to tell for sure - overall it's pretty large.

I can't figure out why - I first noticed this during post-processing and the cam+lens shoots just fine now.

I tried simulating it by placing a finger close to the edge of the lens. The area affected is much smaller and I clearly see the tone of the finger. There is no coloring going on in any of the photos from the event.



Ideas?

06-15-2013, 03:59 PM   #2
Veteran Member




Join Date: Mar 2007
Location: Christchurch, New Zealand
Photos: Gallery
Posts: 433
QuoteOriginally posted by Zafar Iqbal Quote
I shot a bunch of photos using 21mm Limited.

The first 35-40% are perfectly fine but the rest have this thing going on at the bottom left corner.

The affected area is smaller in some and larger in others - but it's hard to tell for sure - overall it's pretty large.

I can't figure out why - I first noticed this during post-processing and the cam+lens shoots just fine now.

I tried simulating it by placing a finger close to the edge of the lens. The area affected is much smaller and I clearly see the tone of the finger. There is no coloring going on in any of the photos from the event.



Ideas?
Overall the image is reasonably exposed. What metering pattern were you using? Matrix, centre weighted or spot?

The grey background and other greys in the photo are probably key to the exposure. When a camera exposes it usually does this in a manner that the scene looks 18% grey, and your grey background looks to be about 18% grey. So correct exposure. The exposure for 18% grey has meant that the white table cloth is ALL white and overexposed.

What you need to do is to either change your exposure metering pattern, change your exposure using exposure compensation to under expose the white table cloth, or reframe the photo to avoid the white table cloth. You might also if you under expose for the table cloth need to add back some light on the person with some additional light like a small amount of flash.

Regards

Chris
06-15-2013, 04:07 PM   #3
Pentaxian
Zafar Iqbal's Avatar

Join Date: Oct 2010
Photos: Gallery
Posts: 1,157
Original Poster
Thanks for your reply, Chris.

I either didn't explain myself well enough or you missed the meaning.

Part of the shirt is lacking contrast. This is what I'm wondering about and this lack of contrast is consistent with other photos as well, and at the same corner.

I've used the 21mm many times before (and tested it afterwards) and can say it's not a lens thing.
06-15-2013, 06:23 PM   #4
Veteran Member




Join Date: Mar 2012
Location: Perrineville, NJ
Posts: 1,364
The only problem I see here is maybe a white balance issue due to the bounce flash "raining down" on the subject's right shoulder, while his neck and chest are shadowed, left to collect only warmer ambient light. If this is the case, maybe a partial CTO gel would help. Are the other photos that have a contrast problem, also shot indoors with flash?

06-15-2013, 07:01 PM   #5
Veteran Member




Join Date: May 2009
Location: Twin Cities, MN
Posts: 2,869
QuoteOriginally posted by Tanzer Quote
The only problem I see here is maybe a white balance issue due to the bounce flash "raining down" on the subject's right shoulder, while his neck and chest are shadowed, left to collect only warmer ambient light. If this is the case, maybe a partial CTO gel would help. Are the other photos that have a contrast problem, also shot indoors with flash?
could possibly be some condensation of you changed the camera from a dry cool bag to to a warm outdoor space? that isn't uncommon and can manifest itself in the form of lost contrast and lighter exposures. nothing to worry about, but something to be aware of in the future if you think this idea might have fit your shooting situation.
06-15-2013, 07:52 PM   #6
Pentaxian
Zafar Iqbal's Avatar

Join Date: Oct 2010
Photos: Gallery
Posts: 1,157
Original Poster
A different shot, and perhaps illustrates the problem clearer:



This is a shot from 15 mins earlier, without the problem:


It was a warm day and couldn't have been related to warm/cold fog. I also used 2 bodies and different lenses. I do not have this going on with any other lens. Also, I did not change environment between these shots.
06-15-2013, 08:10 PM   #7
Veteran Member




Join Date: Mar 2012
Location: Perrineville, NJ
Posts: 1,364
OK, I think I see the spot you are referring to, near the four knobs on the keyboard. But I don't know what is causing that.

Just to clarify, for others who may be more helpful -- when you mention that you used 2 bodies and different lenses, you mean that with all the various combinations, the problem was always associated with just one DA21, right?
06-15-2013, 08:40 PM   #8
Pentaxian
JinDesu's Avatar

Join Date: Jun 2011
Location: New York City
Photos: Gallery
Posts: 5,624
Did you look at the back element and see any hazing/fogging/whatever?

06-15-2013, 10:00 PM   #9
Site Supporter




Join Date: Oct 2010
Location: Melbourne
Photos: Gallery
Posts: 2,824
Hi

You saythere is a bleached area at the left bottom corner (...but the rest have this thing going on at the bottom left corner.) Is it just my eyes or monitor, but I can't see what you are referring to.

The FxIF shows you selected manual WB and I think you may have been in the wrong space. I doubt the gentleman's skin is quite this orange, an orange cast which is also noticeable in the rest of the picture. And the photo simply is not exposed as good as it otherwise could be. Take note of what seventhdr above has to say here. With correct exposure a lot can/will be taken care off in this regard. The washed out table cloth is unrecoverable. (Pardon the pun)

Also you didn't by any chance put any of those ghastly (perhaps even a cheap) UV filters up front ? The have no place in digital photography and are known to induce strange reflections on images. That is all I can think of.

Greetings

Edit: While writing this answer some more pictures appeared and they all have the same orange drift, so there is definitely an incorrect WB at play here.

Last edited by Schraubstock; 04-06-2014 at 03:28 AM.
06-15-2013, 10:02 PM   #10
Pentaxian
Zafar Iqbal's Avatar

Join Date: Oct 2010
Photos: Gallery
Posts: 1,157
Original Poster
Yes, it happened only using the 21mm Limited, which was used with one particular body.

The Piano photo is fine and the bokeh or whatever going on by the knobs is IMO something else. It looks different. In the other example, you can see lack of contrast under the table of the left side, while the right is much darker.

JinDesu: I checked after I discovered it in Lightroom. I did not see anything suspicious and when doing some test shots, the photos were fine.

I had the 21mm on the first body some days ago and I just checked those photos. They are all fine. I do not remember cleaning the lens since the event shooting. Could have happened, but I usually don't clean my lenses too often since there usually is no need for it.

As mentioned easlier, first bunch of photos were fine then suddenly the latter bunch have this foggy thing going on. the degree and size seems to vary, but that could an illusion (it's clearer to see against dark areas). The plants on the table also contain less contrast.

Another shot with the foggy thingy @ bottom left corner:
06-15-2013, 10:15 PM   #11
Pentaxian
Sagitta's Avatar

Join Date: Feb 2011
Location: Maine
Photos: Gallery
Posts: 2,912
Silly question, but did you leave the lens unguarded where someone could have walked by and gone "Oh, pretty!", picked up the camera, and in doing so put a big fat fingerprint on the lens?

It looks like its doing a soft focus effect, but only in one spot, which makes me think you had something physically on the lens itself.

If it was internal, you'd see something so I'm guessing its external, either on the front or rear element.
06-15-2013, 10:30 PM   #12
Site Supporter




Join Date: Oct 2010
Location: Melbourne
Photos: Gallery
Posts: 2,824
Hi

Some more photos appeared. I can now see a defined circular pattern. I still suspect a UV filter, no ? Or a hazy spot somewhere in one of the lens elements which can show up under certain conditions. Was a lens hood used ?

Also it is now clear that you were in the wrong WB space because all photos show the same orange drift. My corrections are not perfect,working with JPGs is not giving the best result. The are just a hint.

Greetings

Last edited by Schraubstock; 04-06-2014 at 03:28 AM.
06-15-2013, 10:40 PM   #13
Pentaxian
Zafar Iqbal's Avatar

Join Date: Oct 2010
Photos: Gallery
Posts: 1,157
Original Poster
Schraubstock: It's not exposure or WB related. Also, I don't use any filters. To me, the shirt is washed out towards the corner. The dark areas under the persons right arm contain less contrast than opposite side.

The spot on the photo you adjusted is different and much smaller. The washed out look I'm refering to is not colored.

Sagitta: No, I took it out from the bag and used it for the remained of the evening. I agree that it looks like soft-focus.

Another shot:


Edit: Yes, I used a lens hood.

Last edited by Zafar Iqbal; 06-15-2013 at 10:52 PM.
06-15-2013, 10:53 PM   #14
Site Supporter




Join Date: Oct 2010
Location: Melbourne
Photos: Gallery
Posts: 2,824
QuoteOriginally posted by Zafar Iqbal Quote
It's not exposure or WB related
Hi

I understand this is not WB related I have just included this as an added observation.

This sort of thing just does not happen if the lens is in good order, no filter was used, lens hood was on and the camera sensor is clean. Shine a torch through the lens and see what you can see. If there is some fault it will show up when you shine the torch through the lens in different angles.

Greetings
06-15-2013, 11:08 PM   #15
Pentaxian
Zafar Iqbal's Avatar

Join Date: Oct 2010
Photos: Gallery
Posts: 1,157
Original Poster
QuoteOriginally posted by Schraubstock Quote
I understand this is not WB related I have just included this as an added observation.
Thanks. I do have split toning going on and it might be a tad severe on that particular shot, but I'm overall OK with the looks.

I tried using a torch light and still can't see anything of suspicion

The lens has also been used since and I haven't experienced the same problem.

I'll try some shots later, with the flash mounted.
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!
finger, lens, pentax help, photos
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
LBA, why ohh why are you sucking my money away? VoiceOfReason Pentax SLR Lens Discussion 24 05-13-2012 09:34 AM
Why is the K7 so terrible? or rather why am i having such a problem with it? runslikeapenguin Pentax DSLR Discussion 60 05-01-2012 01:16 PM
Why and why not bannor75 General Talk 2 10-25-2011 08:34 AM
Do you use the in camera color settings? why or why not? SlickYamaha Troubleshooting and Beginner Help 13 08-13-2011 09:36 PM
Burning of the Koran ... ! Why? Why? Why? jpzk General Talk 128 09-14-2010 04:45 PM



All times are GMT -7. The time now is 02:50 PM. | See also: NikonForums.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