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 Post subject: Underexposed with Flash?
PostPosted: May 24th, 2012, 2:24 pm 

Joined: July 26th, 2010, 12:26 pm
Posts: 193
Location: South Carolina
Seems that every picture I take with a flash is underexposed, obviously I am doing something wrong.


Equipment: Nikon D200, Nikon 105mm f/2.8 VR, SB-600 with one of those plastic diffusers.

Setting on flash: TTL, BL, FF, Zoom set on 85mm. Every now and then I will use the equipped diffuser set at 14mm.

Settings on D200: f/16 1/60 second, 1/250 sync, 1/60 shutter speed, TTL, modeling flash off. All comp set at 0. ISO 100


With these settings every photo is underexposed. The only time the exposure comes out somewhat right is when I am using overhead lighting, I am real close on very small animal and I have it set at f/11. Obviously I do not have something set right. I have seen lots of great photos here with the same 1/60-f/16 shot. Any help will be appreciated.

Thank You,
Derek


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 Post subject: Re: Underexposed with Flash?
PostPosted: May 24th, 2012, 6:19 pm 

Joined: June 7th, 2010, 5:46 am
Posts: 425
Location: Albuquerque, NM
OK, I hate to sound stupid, but I own a D200 and a couple sb600’s, what the heck is BL and FF? I’ve never had any problems with underexposure using TTL, but I consistently had problems when using the flash wireless. I just got in the habit of always dialing in plus one or two stops exposure compensation. Are you using the flash in the hot shoe or with a cord? Is it possible that it is simply not aimed correctly?


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 Post subject: Re: Underexposed with Flash?
PostPosted: May 24th, 2012, 7:06 pm 

Joined: July 26th, 2010, 12:26 pm
Posts: 193
Location: South Carolina
If you look in the upper left corner there is an icon for TTL, BL and FP. BL stands for balanced light and FP stands for high speed sync, not sure how they get that out of FP. When I scroll through mode my choices are TTL/FP, TTL/BL/FP, or Manual. I do not have the choice of just TTL.

I have used it in the hot shoe, on a cord and wirelessly. I get the same results all the time. If I do not aim the flash right the histogram shows far left, very uderexposed. The best I can get to correct exposure on histogram is about 1/4 way, 1/2 being properly exposed.

When I am shooting a larger animal, like adult kingsnake I have to step back a bit I am lucky to get the histogram to read 1/8 way through.

I do understand that you cant always go by histogram. I have actually got blown highlights when histogram was reading underexposed.


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 Post subject: Re: Underexposed with Flash?
PostPosted: May 24th, 2012, 7:30 pm 
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Joined: October 13th, 2010, 8:42 am
Posts: 403
Location: So. California
I don't own a Nikon, but is there a way to check your flash exposure compensation settings on the camera? It may be set too low, which would cause your under exposure problems.


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 Post subject: Re: Underexposed with Flash?
PostPosted: May 24th, 2012, 8:25 pm 

Joined: June 7th, 2010, 5:46 am
Posts: 425
Location: Albuquerque, NM
dthor68 wrote:
If you look in the upper left corner there is an icon for TTL, BL and FP. BL stands for balanced light and FP stands for high speed sync, not sure how they get that out of FP. When I scroll through mode my choices are TTL/FP, TTL/BL/FP, or Manual. I do not have the choice of just TTL.

I have used it in the hot shoe, on a cord and wirelessly. I get the same results all the time. If I do not aim the flash right the histogram shows far left, very uderexposed. The best I can get to correct exposure on histogram is about 1/4 way, 1/2 being properly exposed.

When I am shooting a larger animal, like adult kingsnake I have to step back a bit I am lucky to get the histogram to read 1/8 way through.

I do understand that you cant always go by histogram. I have actually got blown highlights when histogram was reading underexposed.



Interesting. I’m looking at my sb600 in the hotshoe and I only get the choice of ttl or ttl/bl, (and manual of course). I don’t see any fp. I’ve always just used ttl. This is on my d7000. Unfortunately I lent my d200 to a friend, so I don’t have it handy to check the flash on. Are you sure you cant get just ttl? As I understand it ttl/bl tries to balance the flash and ambient light , (if I’m trying to do this I prefer to set the camera shutter speed manually based on the available light exposure and then use the flash exposure compensation to get the amount of flash I want, typically about -1 stop), and if you are working in dim to dark conditions that could definitely foul your flash exposure up. Also I don’t see any advantage to high speed synch if you are shooting at 1/60 second, (I think that is what you meant. I assume 1/250 synch and 1/60 shutter speed refers to the settings in the camera menu that determine the maximum and minimum shutter speeds for flash in a and p modes). I would definitely not use the fp setting. Kevin also has a valid point. Make sure you do not have some minus flash exposure compensation dialed in.

I just thought of something else. Is fp mode something you have to set in the custom settings menu? If so, unset that puppy and set the flash mode to ttl. I apologize for not knowing this, but fp is not something I ever used, and as I said earlier I don’t have my d200 available to check now. Maybe somebody else will chime in on this.


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 Post subject: Re: Underexposed with Flash?
PostPosted: May 25th, 2012, 5:06 am 

Joined: July 26th, 2010, 12:26 pm
Posts: 193
Location: South Carolina
I figured out the FP setting. It is made in the D200 under sync speed. You get two choices on a 1/250 sync speed. One is Auto FP 1/250, the other just 1/250. I made the change and the FP icon was no longer there. However, it did not change the outcome. Something tells me that Auto FP only kicks in when your shutter speed exceeds the sync speed. Seems like it would be very useful for shooting birds with a flash, especially hummingbirds.

As I stated earlier, all compensation is at 0.

Bgorum, do you go by your histogram when using flash? Are your photos always properly exposed, meanig the curve smack dead in the center. From what you see of my setting, everything looks pretty normal, right? A flash is pretty much plug and play with settings, right. It is up to us, the photographers, to get the right light by diffusing, bouncing, multiple flashes, etc. I am just making sure I am not missing something in settings.


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 Post subject: Re: Underexposed with Flash?
PostPosted: May 25th, 2012, 4:47 pm 

Joined: June 7th, 2010, 5:46 am
Posts: 425
Location: Albuquerque, NM
dthor68 wrote:
I figured out the FP setting. It is made in the D200 under sync speed. You get two choices on a 1/250 sync speed. One is Auto FP 1/250, the other just 1/250. I made the change and the FP icon was no longer there. However, it did not change the outcome. Something tells me that Auto FP only kicks in when your shutter speed exceeds the sync speed. Seems like it would be very useful for shooting birds with a flash, especially hummingbirds.

As I stated earlier, all compensation is at 0.

Bgorum, do you go by your histogram when using flash? Are your photos always properly exposed, meanig the curve smack dead in the center. From what you see of my setting, everything looks pretty normal, right? A flash is pretty much plug and play with settings, right. It is up to us, the photographers, to get the right light by diffusing, bouncing, multiple flashes, etc. I am just making sure I am not missing something in settings.


Yeah, I use the histogram a lot when using either flash or available light. With my D200 and the flash attached with an SC-17 cord and mounted to a Wimberly bracket, (typical calling frog setup), my histogram was typically right in the middle for a middle toned subject where everything in the frame was roughly the same distance away. I only ever got underexposure with CLS, and I found that making sure the sensor on the flash was pointed towards the camera really helped with that issue. So you tried it on just ttl, not ttl/bl and its still underexposing? This is a wild shot, but have you tried cleaning the contacts on the flash foot and the hot shoe?


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 Post subject: Re: Underexposed with Flash?
PostPosted: May 25th, 2012, 7:09 pm 

Joined: July 26th, 2010, 12:26 pm
Posts: 193
Location: South Carolina
I will try to clean it. However, it acts the same on my D300. I can still get great shots seting D200/300 on slow. Of coarse I cant freeze a tongue or rattle doing that. I am getting the sb-700 soon and was hoping I could clear this mess up if it were user era, prior to purchase. Thanks for all your help. If you can think of anything else that may be helpful, please let me know.

Derek


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 Post subject: Re: Underexposed with Flash?
PostPosted: May 26th, 2012, 6:24 am 
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Joined: October 12th, 2011, 2:03 pm
Posts: 71
Location: Antelope Valley, CA
A couple of things to check out:
http://www.kenrockwell.com/nikon/d200/u ... om-bkt.htm
http://nikonclspracticalguide.blogspot. ... tl-bl.html

http://prairielightimages.com/2010/04/m ... otography/

"In the end, now that I have confirmed the problem, the solution is relatively simple: I just need to ensure that my flashes are set to around +2ev compensation as a starting point for flash assisted photography and adjust it from there according to how I want the final lighting to look."


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 Post subject: Re: Underexposed with Flash?
PostPosted: May 30th, 2012, 12:33 pm 

Joined: June 12th, 2010, 12:49 pm
Posts: 205
Location: Chicago
Are you sure the problem is just not enough light from the diffused sb600? F/16 @ iso100 with a good sized subject and 105mm lens seems like you need a good bit of light.


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 Post subject: Re: Underexposed with Flash?
PostPosted: May 31st, 2012, 8:35 am 
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Joined: October 12th, 2011, 2:03 pm
Posts: 71
Location: Antelope Valley, CA
matt ignoffo wrote:
Are you sure the problem is just not enough light from the diffused sb600? F/16 @ iso100 with a good sized subject and 105mm lens seems like you need a good bit of light.


I didn't even think to consider GN when I came up with my suggestions.

I calculated the GN of the SB 600, which is 98. Using ISO 100, and an Aperature of F/16, the flash (on manual power) would need to be 6.125 feet away from the subject, in order to get a proper exposure. Adding a Diffuser "usually" subtracts two stops of light.

Assuming one stop of light loss from the diffuser, your flash would need to be 4.45 feet from the subject.

Assuming two stops of light loss from the diffuser, your flash would need to be 3.0 feet from the subject.


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 Post subject: Re: Underexposed with Flash?
PostPosted: June 2nd, 2012, 3:50 am 
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Joined: June 7th, 2010, 10:14 pm
Posts: 2530
Location: San Antonio, TX
kit fox wrote:
matt ignoffo wrote:
Are you sure the problem is just not enough light from the diffused sb600? F/16 @ iso100 with a good sized subject and 105mm lens seems like you need a good bit of light.


I didn't even think to consider GN when I came up with my suggestions.


Bingo. That's the problem exactly. We often assume that just because a flash has a larger guide number that it should be able to light things up close at high f/stops. Do the math.

Since you can't make your flash more powerful, try these things...

1. Why are you shooting at ISO 100? For many sensors built by Sony (including those in Nikon cameras) have a native resolution of ISO 200 which means that their least noise is visible at ISO 200, not ISO 100. ISO 100 is no worse, but just costs you light. Most modern DSLRs, particularly those with CMOS sensors can take excellent noise free photos at ISOs up to 1600 or better.

2. Why are you shooting at f/16? Yes, it does give you more DOF, but do you really need the edge of the stuff behind the animal to be tack sharp? Really? There are reasons NOT to stop your lens all the way down. One is that your lenses are sharper at lower f/stops and the other is the loss of light. If you can get adequate DOF at f/11 or f/13, why go to f/16? In this shot of a captive Eryx jayakari, I stopped down to f/11 to make sure the head was sharp enough, but let the background be out of focus. I don't think having the sand or the coil behind the head in focus would add anything to the photo at all. In fact, I would argue it detracts by pulling your eye away from the subject.

Image

As herp and macro photographers, one of the first rules we are taught is "stop down as far as your lens will go". I think that is generally a mistake. Stop down as far as you need to and no further.

Of course, YMMV and we all know what they say about opinions, but try opening up to f/11 (or dare I say it!....f/8) and see if your flash will have enough power and you get enough DOF.


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 Post subject: Re: Underexposed with Flash?
PostPosted: June 6th, 2012, 7:31 am 

Joined: June 11th, 2010, 5:41 pm
Posts: 46
Location: Cambridge MA
your flash is likely trying to fill in for ambient light, which is obviously too low. If you are getting what appears to be a constant shutter speed of 1/60th of a second, then this is the problem--your camera wants more light, but the slowest your camera will allow is 1/60th to avoid motion blur.

Set your camera to manual and then set the shutter to the minimum shutter speed (the sync speed) it will allow (usually 1/200 or 1/250th of a second for manual shutters and faster for electronic shutters like a d70). You can set the aperture for whatever you want...it's unlikely you'll overexpose if the flash is being used as the primary source of light.

Using these setting with nikons CLS system (like an sb600) should nail the exposure every time. If it's a bit off, you can adjust with exposure compensation ON THE FLASH (don't use the cameras EC). You'll also need to dial up the flash exposure compensation if you're bouncing your flash or using a diffuser etc..


When there actually is plenty of light (a shutter speed of greater than 1/125 of a second would suffice without flash) then you can set your camera to A or S and Nikons CLS will adjust the flash to equal the ambient (fill) though this is usually still too bright and you'll have to dial in a fair bit of negative exposure compensation (again on flash).

Hope this helps...

Gabriel


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 Post subject: Re: Underexposed with Flash?
PostPosted: June 6th, 2012, 7:38 am 

Joined: June 11th, 2010, 5:41 pm
Posts: 46
Location: Cambridge MA
Also, if you do want to go below 1/60th of a second to allow for more ambient light in your photos, set your flash to slow-sync (usually on camera), but you'll need to either have your subject stay motionless or put your camera on a tripod, otherwise you'll get blur. Also, with these slower shutter speeds you'll need to decide between front curtain sync and rear curtain. Front curtain fires the flash immediately when the shutter is opened and is what is generally used when you're taking flash photos. If there is blur it will appear that it is in front of the subect (i.e., a person walking from left to write would be frozen on the left side of the image and blurred as they walk across). The opposite is true with rear-curtain--it fires at the end of the shutter. Here you will freeze your subject at the end of the photo and in the example used above, the person would be frozen on the right side of the image with a blurred trail behind them. This is what you see in many sports or action photos.

Good luck,
Gabriel.


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