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Old May 30, 2005, 4:46 AM   #1
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Hello steve,

I am using my nikon 7900 fromthe pastone month. I am very pleasedwith image quality and performance but the onlycase I am suffering badly is with low light shots.I am experiencinglot of focus problems in night potrait mode. most of the photos taken in night portait mode came out blurry and rarelythe good one. Could you please post the review of this camera with some tricks to over come the focus problemsassociated withnight potrait mode. Is it woth taking pics in auto shooting mode bytuning the settings like meetering, AF area mode, Auto focus mode, and exposure etc., if socould you please suggest the best stettings for taking the indoor potrait shots. I triedbut could not get good results. I am very new to digital photography. I could see many people saying about this problem, but no one is helping to overcome this problem. I would be very grateful for your help in this regard. I appreciate the help of any member of this forum.

Thanks

pal vg

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Old Jun 1, 2005, 1:21 AM   #2
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No help ???? c'mon guys!!!!!!!!!
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Old Jun 1, 2005, 9:09 AM   #3
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Blurry photos are a common problem with all cameras, film and digital. You must use the proper technique to capture the image, with some understanding of exposure.

Most blur is caused by shutter speeds that are too slow (motion blur from camera shake/subject movement) versus focus problems.

If you're using Night Portrait Flash mode, the camera is keeping the shutter open longer to allow exposure of the background, then firing the flash to illuminate the foreground.

If you have too much ambient light, you'll get motion blur and ghosting using this technique (because of the slower shutter speeds). You'll definitely need a tripod, even with a relatively still subject to keep from getting a blurry background. Depending on light, you may get ghosting/motion blur for your foreground subjects, too.

You will need to balance the need for a brighter background with the exposure of the foreground subjects with flash. A shutter speed too slow, with ambient light that is too bright will cause problems (because the subject can be exposed with light other than the flash).

You may want to post samples of what you are talking about. Chances are, it has nothing to do with the camera, only your technique. IOW, Night Portrait Flash mode requires special considerations. For most conditions, you'll want to use other modes instead.


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Old Jun 1, 2005, 3:43 PM   #4
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Nikon has good Tech Support. I would contact them with your problem and see what their answer is.

Go to NikonUSA.com>Digital Tech Support>Choose your product>FAQs>Contact Us.

I hope you will post your answer from Nikon so we all can benefit. I find it tricky to find the right settings for the Nikon compact cameras although I have the 7900 and I love it.
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Old Jun 4, 2005, 12:25 AM   #5
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my mate has this camera, he too has problems with some low light pictures, punctually of people. some are great and others just . . . well i would be edited if i said it here!
(day light pictures are great!)

he has had some luck turning it off then on, but again could just be luck.
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Old Jun 4, 2005, 10:37 AM   #6
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Guys, post some examples... I'll be glad to look at them, and give you an opinon of what is going wrong.

As I mentioned before, chances are, it's more likely your technique (you're trying to do something the camera is not designed to do).

For example, Night Portrait Flash Mode is not the way you normally take flash photos of moving subjects. This is a special mode designed for the camera to be used on a tripod so that cityscapes in the background are properly exposed (keeping the shutter opened longer to expose the background, then firing the flash at the end of the exposure to illuminate foreground subjects).

It requiresexposure knowledge/practice to use. Otherwise, if you have too much ambient light illuminating your foreground subject, you'll get ghosting/motion blur (and you'll also need to use a tripod with this feature, since shutter speeds will be too slow to prevent motion blur of the backgroundfrom camera shake in most conditions).

Using this mode assumes that your foreground subject ismuch darker than the background you're trying to expose (so that the foreground subject is not exposed properly *except* during the flash burst at the end of the exposure).

Using the standard flash modes, you'll need to make sure you're within the rated flash range. Most users getting poor flash photos are trying to use their cameras outside of their specifications.

The flash on the Coolpix 7900 is actually quite good compared to many compact models. It's rated at14.8 feet at it's wide angle lens position, dropping off as more zoom is used to11.5 feet at full zoom. This should be considered the maximum range using Auto ISO. Lower ISO speeds will reduce the range.

Note that more than twice as much light reaches the camera's sensor at the wide angle lens position (versus full zoom). By keeping the lens set to it's wide angle lens position, you enhance the camera's ability to focus better indoors, as well as increasing your Depth of Field. You're much better off using your feet for zoom in low light (and indoors is low light to a camera's lens).

Also, keep in mind that the camera must "throttle" the flash strength to keep from overexposing closer subjects. This means that therecan bea lot of difference between the foreground and background brightness. The opposite can also happen if you're photographing a further subject (closer subjects can be overexposed compared to the subject further away from the flash, since the flash burst must be longer to illuminate the subject you're focused on).

The human eyesees dramatically more dynamic range compared to any camera. So, the camera sees a much greater difference between brighter and darker portions of an image. This is the way cameras work guys.

If you want a well illuminated larger room, you'llwant a model with an external flash that can be bounced from ceilings/walls, etc., to more evenly illuminate a room (or you'll need to go with higher ISO speeds which increase noise levels, or slower shutter speeds which increase the potential for motion blur from ambient light exposure). A slave flash is another option (making sure it's "digital compatible" so that it fires on the second versus first flash, since most models use a barely noticeable "preflash" for metering).

Cameras have limitations, and no one camera is going to be perfect for all conditions. You have to learn to take advantage of their strengths and work around their limitations to get the best results out them.


P.S.

Don't be afraid to experiment. You don't have any developing/processing costs with Digital. ;-)

Change the settings to see what impact they have, taking the same photo with a variety of settings. Learn to look at the EXIF (a header in the image files that containsthe camera settings used for a photo). Many image editors can read this information.

A good free editor is irfanview (downloadable from http://www.irfanview.com ). Make sure to download the free plugins, too. You'll seethe camera settings used under Image, Information, EXIF after you open an image.

Then, look atthe settings used by the camera in different modes and conditions, paying attention to things likeshutter speed, aperture, focallength and ISO speed, tosee how different settings and lighting conditions impact things like motion blur,darker backgrounds versus brighter backgrounds,noise/grain, etc.

You can learn a lot about what to do (and what not to do), with a better understanding of your camera's behavior.


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Old Jun 13, 2005, 6:13 AM   #7
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Hope this helps 7900 users- -----thanks.--catall

http://forums.dpreview.com/forums/read.asp?forum=1007&message=13835778

7900 - Sorting Out Tradeoffs and Techniques


I recently bought a 7900 to try it out as a P&S carry-around camera. Thanks to all on this forum for the hugely informative discussions that made me aware of the strengths and limitations of the camera - I went into this with my eyes open. So here's my feedback on the discussions based on a few hundred images over the past few days. Most of my thoughts are in agreement with points that have been brought up in a number of different threads.

1. The 7900 does have some serious low light focusing issues, but they are not consistent and seem to relate to the contrast-based autofocus. And there are ways to get around this in some situations. Setting AF-Area mode to manual and essentially using a manual spot focus and tying the exposure point to it definitely helps, but still requires some visible contrast in the focus area. When there is a lot of inherent contrast in the scene it works fine: when I took a photo of a brightly coloured clown mobile in my son's room in almost complete darkness, it turned out fanatstic - but there is huge contrast in colour and brightness in the image.

There are various other things that can lead to blurring in low light - eg it is easy to forget that the lens has a narrow range of focal lengths in which it can focus while in macro mode (if it is out of that range, it will hunt and hunt). But occasionally, I just give up reframing and refocusing and try another shot.

2. I think that mid-range (10-20 m) shots in low light with only moderate contrast is the weakest point for the camera. For instance, I take a lot of photos under forest canopy, the light is alway low and contrast can be muted. After 30-50 tries, I have been unable to produce a really good photo in this situation - the macros work fine, but the overall forest shots are blurred. The flash isn't strong enough to extend that far and the focus is very inconsistent. Some of the blurr may be due to hand-holding in low light, though I've tried the BSS a fair bit. I'll retry the experiment with a tripod, but I'm trying to evaluate what the camera can do as a P&S - when I'm carrying it because I can't (or won't) carry a big camera, tripod ect. These kinds of photos are something I've done for years with my film SLR with lots of success, so it is possible.

3. The camera can produce some fantastic results in macro - this is a real strength. The lens is small enough it can actually get inside large flowers. I am pretty stunned by what it can produce. When things work, the photos are tack sharp, with great colour saturation, nice range of depth of field for controlling subjects, etc. I'll post some examples if I can figure out how. The small size of the lens and camera is a real advantage here in fitting into places that would have been hard with larger cameras.

4. It is really easy to carry around and have available anywhere - presumably it's intended purpose. Shot-to-shot speed is great, flash refresh is great. Ergonomics are very good - it's the only really small camera I looked at that feels good in the hand.

5. I am impressed with the range of creative control and customizing of exposure that can be done with the combination of exposure compensation and range of options for flash ISO, metering, etc. Though it takes a fair bit of thought to figure out what combination of work-arounds will trick the camera into doing what you want. I seem, so far, not to mind working through the menus and find them pretty intuitive. The live histogram on the compensation screen is nice and it seems a workable way to have it. The one place I REALLY miss true manual control is in focusing - for the above reasons, but the other small P&S don't really have a graceful option for that either.

6. One thing I am struck by is just how quickly the camera seems to require the flash as the light starts to reduce from full - except in full sun, it seems to want to use the flash. I've had the ISO mainly on auto and will try it for a bit at 100 or 200 and see if the noise bothers me.

So I'm left with things I REALLY like about this camera and some things that may make it not work for my needs. I think I really need a DSLR to do some of those things (or at least a more full function prosumer type non P&S) - and will probably get a DSLR in the next 6 mo to year. In the meantime, I'm trying to sort out whether the 7900 is good enough at enough things to be worth the $700 CDN (camera plus card plus CDN tax). I suspect and 8400 or G6 would be better at more things, but they're more money and won't be carried everywhere like the 7900.
I hope these thoughts are useful and would appreciate any feedback.

Ken


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Old Jun 13, 2005, 9:00 AM   #8
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catall wrote:
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Hope this helps 7900 users- -----thanks.--pal

7900 - Sorting Out Tradeoffs and Techniques

http://forums.dpreview.com/forums/re...ssage=13835778

I'll take a shot at some of your concerns... First of all, this is Steve's Digicams, not Dpreview, so I don't know why your posting links to another forum with the same information as you put in this post. Thispulls forum traffic away from this site, which is not fair to Steve.

Quote:
The 7900 does have some serious low light focusing issues, but they are not consistent and seem to relate to the contrast-based autofocus. And there are ways to get around this in some situations. Setting AF-Area mode to manual and essentially using a manual spot focus and tying the exposure point to it definitely helps, but still requires some visible contrast in the focus area. When there is a lot of inherent contrast in the scene it works fine: when I took a photo of a brightly coloured clown mobile in my son's room in almost complete darkness, it turned out fanatstic - but there is huge contrast in colour and brightness in the image.

Pay attention to whether or not you're getting Autofocus Lock to judge if a camera is able to focus in a given situation. It's possible to have perfectly sharp photos without a focus lock (because depth of field can be huge with a small sensored camera), and blurry photos with a focus lock. Very often, usersmistake motion blur for Autofocus problems. BTW. the center focus point is more sensitive on most cameras. I've seen many users, of many different cameras, change from multi-point to center pont only focus to help achieve lock in a greater variety of lighting conditions.

As a rule, I always half press the shutter button first, reframe after a focus lock, then press the shutter button the rest of the way down. If the subject does not have enough contrast, find something with enough contrast atapproximately the same distance, and use this technique (get a focus lock, then reframe and shoot).

I use the half press technique to see if I'm getting focus lock with all cameras I use, including SLR cameras.

Quote:
I think that mid-range (10-20 m) shots in low light with only moderate contrast is the weakest point for the camera. For instance, I take a lot of photos under forest canopy, the light is alway low and contrast can be muted. After 30-50 tries, I have been unable to produce a really good photo in this situation - the macros work fine, but the overall forest shots are blurred. The flash isn't strong enough to extend that far and the focus is very inconsistent. Some of the blurr may be due to hand-holding in low light, though I've tried the BSS a fair bit. I'll retry the experiment with a tripod, but I'm trying to evaluate what the camera can do as a P&S - when I'm carrying it because I can't (or won't) carry a big camera, tripod ect. These kinds of photos are something I've done for years with my film SLR with lots of success, so it is possible.
I've suggested posting some examples, twice. The reason I suggested this is so members could see what went wrong and offer some suggestions.

Do you know if you had focus lock? Did you look at the shutter speeds used for the photos?

The rule of thumb for hand held, non-flashphotos is that shutter speeds need to be 1/focal length or faster to reduce blur from camera shake. In other words, if you're shooting at a 35mm equivalent focal length of 40mm, you want shutter speeds of 1/40 second or faster. If you're shooting at a 35mm equivalent focal length of 100mm, you'll want shutter speeds of 1/100 second or faster.

This is only a "rule of thumb", since some users can hold a camera steadier than others, and some users may require even faster shutter speeds.

The EXIF (a header in the image files that contains camera settings used) is something I would look at when photos don't turn out as expected. If you don't have an image editor that can see this information, download irfanview from http://www.irfanview.com , and make sure to download the free plugins, too. You'll see the camera settings for any image you open under Image, Information, EXIF.

The shutter speeds the Auto Exposure Algorithms will be able to achieve (and still allow proper exposure) is dependent on the Lighting Conditions, Aperture and ISO Speed.

The lens on the 7900 is rated at f/2.8-4.9. This is typical for a compact camera. The vast majority of compact Digital Cameras have a lens brightness that is virtually identical to this.

This means that the sensor will see more than twice as much light at it's wide angle position versus full zoom position in lower light (and the Autoexposure Algorithms will be selecting the largest available aperture for the focal length used in low light anyway).

Not only does using zoom decrease the amount light reaching the sensor (requiring slower shutter speeds for proper exposure and making it harder for the camera to "see" for Autofocus purposes), but using zoom also requires fasterspeedsto prevent motion blur from camera shake (since more magnification amplifies the effect of camera movement).

If you are in low light, try not to use any more zoom than absolutely necessary, so that you don't need to increase ISO speed.

But, in many situations, you're going to need to increase ISO speed to get faster shutter speeds (to reduce blur) if you're not using a tripod.

To see how Lighting Conditions, Aperture and ISO speed impact the shutter speeds a camera can achieve, see this handy online exposure calculator. Film Speed with this calculator is the same as ISO speed with your camera.

http://www.robert-barrett.com/photo/...alculator.html

Quote:
One thing I am struck by is just how quickly the camera seems to require the flash as the light starts to reduce from full - except in full sun, it seems to want to use the flash. I've had the ISO mainly on auto and will try it for a bit at 100 or 200 and see if the noise bothers me.
See the above for how exposure works with cameras (and not just digital cameras).

If you don't have enough light for the ISO speed and aperture being selected (and the largest available aperturewill depend on how much zoom you're trying to use with the vast majority of compact digital cameras), then it's going to use the flash if you don't have it forced off.

Also, there are very good tools to reduce the appearance of noise when higher ISO speeds are needed. Two popular tools are Neat Image and Noiseware.

Quote:
I suspect and 8400 or G6 would be better at more things, but they're more money and won't be carried everywhere like the 7900.

The G6 has a lens that is twice as bright as the lens on the majority of compact Digital Cameras. It's rated at f/2.0 at it's wide angle position (and f/2.0 is twice as bright as f/2.8 ), only stopping down to f/3.0 at full zoom. The lens on the 8400 is rated at f/2.6-4.9. So, when using much zoom at all (and it's full zoom positon only has a 35mm equivalent focal length of 85mm), it's not going to be any brighter than the lens on most other cameras.

Any camera is gong to have limitations. If you learn it's behavior, and have a basic understanding of how exposure works, you can learn to take advantage of it's strengths, and work around it's limitations.

No camera is going to be perfect in all conditions.



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Old Jun 13, 2005, 10:53 AM   #9
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Dear JimC,

First of all, I would like to say sorry for posting links to from another forum, as I am unaware of the consequences. My intension was just to help 7900 users and take help from them and I will make sure that will not happen again.

Thank you very much for your excellent analysis and kind suggestions. I was taking hand heldshots in night scence modes that require slow shutter speeds, as I cannot take tripod to each and every time I go out in the night or attending parties. Your suggestions definately helps in this regard.

thanks
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Old Jun 13, 2005, 11:05 AM   #10
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catall wrote:
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First of all, I would like to say sorry for posting links to from another forum, as I am unaware of the consequences. My intension was just to help 7900 users and take help from them and I will make sure that will not happen again.
No problem. We don't have a rule against it. But, it's preferred to start discussions here, versus elsewhere. ;-)

Quote:
Thank you very much for your excellent analysis and kind suggestions. I was taking hand heldshots in night scence modes that require slow shutter speeds, as I cannot take tripod to each and every time I go out in the night or attending parties. Your suggestions definately helps in this regard.
I take a little pocket camera with me everywhere, and in low light, I often need to increase ISO speed so that shutter speeds are fast enough. In true night conditions, you'll need a tripod if you're not using a flash and/or you are outside of the flash range.

In a party scenario, I usually keep ISO speeds set relatively low (ISO 100 or 200), and use a flash. I also keep my camera's lens set to it's full wide angle position in these conditions (so that more light reaches the sensor, making AF easier, increasing flash range range).

Trying to use a non-DSLR model in low light conditions without a flash or tripod is going to cause problems with most compact cameras. If you can't use a flash (or your subject is outside of the flash range), you may need to increase ISO speed. Often, more noise is preferred to blur.

Even increasing ISO speed may not give you shutter speeds that are fast enough in many conditions. Any camera is going to have limitations.


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