Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-25-2008, 11:53 AM   #31
Inactive Account




Join Date: Dec 2007
Location: South Carolina
Posts: 38
Original Poster
QuoteOriginally posted by mattdm Quote
Oh, hey, along those lines: do you have the "Release when Chrging" [sic] option set to "2 On" in the configuration menu?
Its set to 1 Off...

01-25-2008, 11:55 AM   #32
Veteran Member
mattdm's Avatar

Join Date: Feb 2007
Location: Boston, MA
Photos: Gallery
Posts: 2,964
QuoteOriginally posted by jjfdvm72 Quote
Its set to 1 Off...
Worth checking, at least.
01-25-2008, 12:04 PM   #33
Inactive Account




Join Date: Dec 2007
Location: South Carolina
Posts: 38
Original Poster
QuoteOriginally posted by BarneyCG Quote
Totally expected behaviour Program and Av modes will always select a shutter speed that is 1/focal length when the flash is up if you've not selected slow sync. If you have s.s on then it will expose for the ambient light. It is all in the manual.
So do you recommend I use either slow sync or otherwise avoid using pop up flash with the P or Av modes? Is it better to use the flash in slow sync usually?
01-25-2008, 12:11 PM   #34
Veteran Member
PentaxPoke's Avatar

Join Date: Jan 2008
Location: Oklahoma
Posts: 1,411
OK, I think we have a working theory here now. I took a closer look at the EXIF data, and the flash guide number data for the k10d (p176 of the manual.) Note that the maximum distance for the flash is the guide number / aperture.

Take picture 1067 for example (the lady and gentleman looking at her P&S camera). The aperture was 5.6 and the ISO is 200. For ISO 200, the k10d flash guide number is 15.6. So the maximum distance for the flash is 15.6/5.6 = 2.8 meters. I don't know if you think in feet or meters, but that means that your subject should have been no more than 8 ft away. From the looks of it, I think that they are farther away than that.

I'm sorry to say that this may be simply a "flash operator error" which is common. It is really hard to know how to set exposure for flash, particularly in a large room.

I have some more suggestions, but have a meeting now. Back in a "flash"

01-25-2008, 12:22 PM   #35
Inactive Account




Join Date: Dec 2007
Location: South Carolina
Posts: 38
Original Poster
I understand how the flash doesn't have enough power to reach the subject that far, but why wouldn't the camera change the ISO to 400 or 800 to achieve the proper exposure?
01-25-2008, 12:27 PM   #36
Veteran Member




Join Date: May 2007
Location: York Region Canada
Posts: 642
I don't have a lot of success with the pop up flash, the D200 is more reliable, but two things to look for.
1-Do you have flash compensation dialed in by mistake. I adjust this, and sometimes i forget to zero it.

2- Set iso to 400 and try P mode.

Dave
01-25-2008, 12:53 PM   #37
Veteran Member
PentaxPoke's Avatar

Join Date: Jan 2008
Location: Oklahoma
Posts: 1,411
QuoteOriginally posted by jjfdvm72 Quote
I understand how the flash doesn't have enough power to reach the subject that far, but why wouldn't the camera change the ISO to 400 or 800 to achieve the proper exposure?
Therein lies the difficulty with shooting flash in a large area (WITH ANY CAMERA)...The camera has no idea how far away your subject is with regards to the flash. The P-TTL (Through The Lens) flash metering will try to modulate the flash amplitude as it fires. If it senses underexposure, it will increase it's output. It can only go so high though, hence the guide number rating for the flash which gives you an indication of the maximum distance it can travel. The camera does not have time to adjust exposure when it is firing the flash, only the flash intensity/duration. Exposure is entirely determined either by you or the program line.

If you plan on doing alot of flash photography using the flash at the limits of its travel, you need to do some experimentation to learn how to use it. Remember, increasing ISO and aperture (shutter speed has no effect on this) will increase your effective flash range.

Might I suggest another thing to consider? If you are doing alot of indoor shooting of your kids, you really should look at a fast lens. That way you won't even need to use the flash most of the time. Since I purchased my Pentax FA 50/1.4 lens, (under $200) I have not even used flash anymore with the exception of some fill flash outdoors. This is a lens that every parent needs in thier bag. I'll bet that lens would have enabled you to take every one of those pictures you posted without flash. When you take the flash out of the equation, there is no guesswork. If your k10d doesn't give you any exposure warnings then chances are excellent that you will get a properly exposed picture (unless your subject is heavily backit or something). I also find that family pictures without flash are typically much warmer, interesting, and more "3 dimensional" because of the natural shadowing. I use that lens to take stop action shots of my kids during basketball in poorly lit gyms, dance recitals, school functions, etc. All WITHOUT flash. In fact I just realized that I don't have a single flash shot on my entire Flickr site, and most shots are indoors. Realize that at the wide open aperture setting, the 50/1.4 will take in over 6 times more light than the best your kit lens can do.

Last edited by PentaxPoke; 01-25-2008 at 01:09 PM.
01-25-2008, 01:22 PM   #38
Forum Member




Join Date: Nov 2006
Location: Livingston, Scotland
Posts: 52
QuoteOriginally posted by jjfdvm72 Quote
So do you recommend I use either slow sync or otherwise avoid using pop up flash with the P or Av modes? Is it better to use the flash in slow sync usually?
"Better" is subjective ... if you don't use slow sync flash mode the Auto and Av modes will be assuming that the flash is the main/only source of light and, as others have said, that there will be enough power in the flash (in a big room such as those soft play areas even a 540 may have problems) so it uses a shutter speed designed to prevent hand held camera shake effects ie 1/focal length. If you use slow sync it slows the shutter speed down ... on the GX-1S/DS/K1x0D range you can't use slow sync in Av mode so I have to use full manual or Tv BUT I'm not sure with the K10D since it has an explicit slow sync flash mode ... you'd need to check your manual.

I must admit I don't see why the program lines default to 1/focal length since in flash photography the flash freezes the motion rather than the shutter speed so hand held blur shouldn't be an issue, do the other brands flash operation (without slow sync) in auto modes work in the same fashion ?

01-25-2008, 01:24 PM   #39
Veteran Member
PentaxPoke's Avatar

Join Date: Jan 2008
Location: Oklahoma
Posts: 1,411
Sent you a PM jj.

OK I just put together a quick table for those that use the kit lens and must use k10d internal flash and have it reach as far as possible. Set the flash simply to the auto mode, and set exposure to Av with aperture to 3.5 (wide open). The maximum distance your flash will go is as follows (rounding):

ISO 100: 9 ft.
ISO 200: 13 ft.
ISO 400: 19 ft.
ISO 800: 27 ft.
ISO 1600: 37ft.

OK, now for the tricky part: Realize the kit lens has a variable minimum aperture (makes them cheaper to make). That means that unless you are zoomed wide out, you won't get the above numbers. If you are zoomed to the maximum (55mm) your min aperture is now 5.6, and the table looks like this:

ISO 100: 6 ft.
ISO 200: 8 ft.
ISO 400: 12 ft.
ISO 800: 16 ft.
ISO 1600: 23ft.

So a simple strategy of using Av mode and setting the aperture wide open, and an iso of 800, will allow the k10d to give you a nice flash exposure of your subject over the entire zoom range, as long as your subject is within 16 ft. Don't mess with slow sync until you really know what you are doing, since it adds another variable, and you may end up with blurred subjects.

Personally, I would get the 50/1.4 and forget about it...With the kit lens zoomed to 50mm the kit lens takes in 16 times LESS light than the 50/1.4! OK and if you buy the 50/1.4 and absolutely insist on using flash, here are your max distances:

ISO 100: 24 ft.
ISO 200: 33 ft.
ISO 400: 47 ft.
ISO 800: 66 ft.
ISO 1600: 94 ft.

See why there are so many 50/1.4 disciples?
Have I convinced you yet??? Less than 200 bucks, and you end up with the ultimate family camera! The only drawback is that you "zoom with your feet" but you will get shots no zoom will ever give you unless you spend thousands.

Last edited by PentaxPoke; 01-25-2008 at 02:13 PM.
01-25-2008, 04:40 PM   #40
edl
Veteran Member




Join Date: Dec 2007
Location: San Francisco
Posts: 457
PentaxPoke - you should get an award for helpful forum member of the day or something like that Nice post.

I agree, the 50/1.4 is great for indoor shooting. Flash - huh - why?
01-25-2008, 05:27 PM   #41
Veteran Member




Join Date: Feb 2007
Location: Ontario
Posts: 433
QuoteOriginally posted by jjfdvm72 Quote
I understand that it would read the foil as being bright, but wouldn't it still "average" it out to the midtones?
How it is treated is entirely dependent on the algorithm programmed for metering. Most metering algorithms weight to the centre as that's where the main subject usuall is found. In the seconf picture, the juice box is approximately in the centre of the image and it is properly exposed. In the top photo, the window and the juice box occupy a great deal of the centre of the image and, again, the juice box appears to be properly exposed. Have a look at the manual sections on spot metering (and the other metering modes) as well as the section on AE-L. (auto exposure lock). In situations like this, they will help you get more useful exposures. If you want to use automatic modes in situations like this, try popping the built-in flash up. In my experience, the Pentax metering algorithms are very good at calculating fill flash in these situations. Others have some good suggestions on things to check such as whter or not exposure compensation is on by mistake, ISO limit settings and the overall exposure setting. Frustrating as it seems, the additional capabilities of a K10 vs the P&S will lead to results such as these until you have experimented enough to master the tool.

Btw, there are ways to test the meter. A good camera repair facility will have such a setup. The less scientific way is to compare it against a known good meter.

Dave
01-25-2008, 06:36 PM   #42
Veteran Member
PentaxPoke's Avatar

Join Date: Jan 2008
Location: Oklahoma
Posts: 1,411
Thanks ed. That is kind of you to say. I can sympathise with the OP since we should be able to expect our DSLR to give us performance significantly better than a P&S. That is why many of us bought a DSLR to take pictures of our kids anyways!

I have been running some flash exposure tests and have found the following on my k10d:

Tests all run in Green mode and P mode.
Tests run with Program Mode set to MTF and Normal
Tests run with Pentax 18-250 zoom, and Pentax 50/1.4
All tests using Multizone metering
Tests run in Auto ISO with limits set to full 100-1600 as well as fixed values
Tests run in dimly lit room, to well lit rooms
Obviously flash was up for all tests.

I found the following: In all cases, the k10d wants to maintain a mid-range aperture such as 5.6 or 8. ISO will almost always go to 1600 or 800.
Guidelines for flash maximum distances at different ISO are confirmed. In all cases though, as long as I was within the maximum flash distance, flash exposure was bright and clear.

It is bothering me that JJ's k10d is not switching to higher iso's for any picture during flash assuming that auto is set, and limits are full.

Last edited by PentaxPoke; 01-25-2008 at 06:53 PM.
01-25-2008, 07:54 PM   #43
Inactive Account




Join Date: Dec 2007
Location: South Carolina
Posts: 38
Original Poster
It is bothering me that JJ's k10d is not switching to higher iso's for any picture during flash assuming that auto is set, and limits are full.[/QUOTE]


That's exactly what I thought! So even if I was too away from the subject or whether I used flash or not, why did the camera decide to use an ISO as low as 200 when I have it set to Auto 800-1600 (can't remember which). Wouldn't the camera first try to correct the exposure by raising the ISO before using the flash? Wonder how I could test that?

BTW, thanks for all the posters. Its kind of hard when you have questions like this and don't have a GOOD photo store or anybody else that uses the same camera. You guys seem to take time and deliberation when answering my questions, and for that I am thankful.
01-25-2008, 08:30 PM   #44
Forum Member




Join Date: Nov 2006
Location: Livingston, Scotland
Posts: 52
Ahhhh you pesky K10D owners with their auto ISO that works when you use flash
01-25-2008, 09:07 PM   #45
Veteran Member
PentaxPoke's Avatar

Join Date: Jan 2008
Location: Oklahoma
Posts: 1,411
QuoteOriginally posted by BarneyCG Quote
Ahhhh you pesky K10D owners with their auto ISO that works when you use flash
Does your camera not do that?

JJ, how about you try to replicate my test to see if you get similar results. Go to the largest room in your house, and maybe set the lighting low (to a point where you can see, but it wouldn't be that comfortable to read)

Run these settings:

P mode, normal and or MTF
Flash on and up
Auto ISO range full
Multi-segment metering

Push the shutter down halfway to get an exposure reading, and then push the OK button to see what the ISO is. Then write down the shutter speed, fstop, and ISO for us. Maybe even take a picture?

If this isn't working, maybe it is either a metering issue, or possibly a P-TTL problem with the camera. It should not be this hard to get a good flash pic with a k10d!
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, dslr, k10d, photography, pics, priority, underexpose
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Underexposed pics with new Sigma EF 530 DG Super Flash. What I'm I doing wrong? ismaelg Flashes, Lighting, and Studio 8 02-09-2011 01:46 PM
Underexposed photos from my K-x richardm Troubleshooting and Beginner Help 25 07-30-2010 10:58 AM
K10D and 540 - underexposed and always shoots at 1/30 sec KettererE Pentax Camera and Field Accessories 4 12-25-2009 10:35 PM
Underexposed without eye to viewfinder? WackySnapper Pentax DSLR Discussion 12 01-19-2009 01:07 AM
Dramatic or underexposed? Fox Three Post Your Photos! 10 12-06-2006 11:45 PM



All times are GMT -7. The time now is 01:41 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