D700 WB for fluorescent lighting

Brunswick · January 8, 2013

Hello Folks,
Does anyone have experience shooting under metal halide lighting in a basketball gym? I have a D700. In the manual it shows a chart of the different fluorescent lights that are under the fluorescent setting but not how to set the camera to them. If i roll the sub dial I get A1 thru A6 in one direction and B1 thru B6 in the other. There are more positions than choices listed in the book and the book does not index the chioces to anything. I have contacted nikon tech support but have had no response yet.
Anyone have any input on this?

ziggy53 · January 8, 2013

Set a "custom white balance" and use that. Page 148 of your user manual or on the following PDF.

http://www.nikonusa.com/pdf/manuals/dslr/D700_en.pdf

If you shoot in RAW, you can defer WB until processing the RAW files. Then you just develop a profile, and then apply that profile to all images exposed under the same conditions. It helps to shoot a white target at the event in order to help setting the white balance using the WB dropper (in ACR).

Ed911 · January 10, 2013

You can shoot a white card, or you can use something like an Expodisc, which is what I have and use. The Expodisc works very well under halogen, twisted CFL's, and other color / tonal variations. And, it's all done in camera, so no post processing later.

Here's the link to the Expodisc site: http://www.expoimaging.com/product-detail.php?cat_id=1&product_id=2&keywords=ExpoDisc_Neutral&gclid=CJvCuqLC3bQCFayPPAodSEAACA

Good luck.

Zerodog · January 10, 2013

I shoot under these conditions often. Custom WB is your best option. I really like my expodisk for this. You will find that these lights have a color pulse. I think it is red, green, yellow. Or at least that is what I perceive when editing. When shooting higher shutter speeds you will see this. To minimize this effect I shoot my WB setup shot at a very slow shutter speed. 1/20. This averages the effect to some degree. In the end, unless you shoot very slow speeds you will still see this color pulse. So in turn, RAW is the way to go for max adjustment in PP.

Matthew Saville · January 10, 2013

I bought an Expo Disc years ago, but found it was way too difficult to use in certain conditions where I could not access the exact lighting that was shining on my subject, (Stage etc.) ...nor was it practical for me to take readings and re-test every time the lighting changed.

Kelvin is your absolute best friend on the D700, and most any other Nikon for that matter. Just crank it and test it. Start at the bottom at 2500 and work your way up. Once you get it where you like it on that scale, if you still have some funky looking colors then go into the WB menu (I add this to the very top of my custom "My Menu") ...and dial it either in the up (green) or down (magenta) direction. This will be more than enough to give you exactly what you need. Heck, even shooting under nasty sodium-vapor lamps, I can still figure things out by this method.

The best part is, once you get it figured out then you're not locked into it like with a WB tool. You can still fine tune it any time you like, right there on your Kelvin scale.

One handy thing is to throw your camera in live view and dial your Kelvin in during live view. This is pretty dang awesome to see in real-time, it helps me nail WB in just a few seconds with 1-2 test clicks.

If the WB is truly puzzling, you don't necessarily need a $$$ WB tool like an Expo Disc, all you need is a blank image clicked when pointing your camera in the direction of your main light source. In a large gym or other arena, I simply rack focus to the near limit, so my image is completely blurred, and point my camera straight up. This gets me close enough usually, and then once again you can fine tune it in the up/down (green/magenta) or even left/right (cold/warm) direction in the "PRE" WB menu.

The last thing to watch out for is, when the lights have a low-frequency flicker. I can't tell if the bulbs you're talking about are like this, but for example:

These images were all taken at the same exact white balance, believe it or not. The bulbs are flickering at about 60 or 120 hz, and my shutter speed was 1/500 sec. In order to eliminate this effect, no white balance tricks can help. My only option is to simply lower my shutter speed to capture a longer cycle in the bulb's frequency.

Anyways, good luck!
=Matt=

Zerodog · January 10, 2013

This is the effect I was talking about. Not much to do about it but get your average WB close. This is why I like the slow shutter method with the disk. Matt is some sort of color guru or something. I am lazy. Slap the disk on walk to the middle of a matt sit on the ground and shoot straight up at the lights. This is not ideal, but if you are moving around it is the best option for something that is very close and tunable in PP.

Brunswick · January 10, 2013

Wow! Thanks everyone. You all have hit the nail right on the head. I am seeing the color change due to the hertz cycle. That is what has been driving me crazy. I could not figure out if it is isolated to one area of light in the gym or scoreboard reflections or what. I am shooting raw at 1/400th shutter speed to catch the action of the basketball players. Is there a slower shutter speed I dare go to that will still render focused shots? I am running at around 3200 ISO and sometimes as much as 6400 depending on my apeture. I have tried custom, kelvin, auto and flourescent white balance. I have a pop out gray card. The color can be on and then its off and I am sure it's because of the hertz cycle. Sometimes Green, sometimes magenta. And usually half screen like above. I have taken to looking at my rear display with a hoodman to help prevent the lights from influencing what I see there. I will try the slow shutter speed WB test shot next time. Otherwise, Am I just going to have to go with it and resign myself to some post WB correction? I was hoping not to, but I don't think that is going to be possible based on what you folks have told me.
Thank you, everyone, for your time and input!
Brunswick

Matthew Saville · January 11, 2013

Brunswick wrote: »

Wow! Thanks everyone. You all have hit the nail right on the head. I am seeing the color change due to the hertz cycle. That is what has been driving me crazy. I could not figure out if it is isolated to one area of light in the gym or scoreboard reflections or what. I am shooting raw at 1/400th shutter speed to catch the action of the basketball players. Is there a slower shutter speed I dare go to that will still render focused shots? I am running at around 3200 ISO and sometimes as much as 6400 depending on my apeture. I have tried custom, kelvin, auto and flourescent white balance. I have a pop out gray card. The color can be on and then its off and I am sure it's because of the hertz cycle. Sometimes Green, sometimes magenta. And usually half screen like above. I have taken to looking at my rear display with a hoodman to help prevent the lights from influencing what I see there. I will try the slow shutter speed WB test shot next time. Otherwise, Am I just going to have to go with it and resign myself to some post WB correction? I was hoping not to, but I don't think that is going to be possible based on what you folks have told me.
Thank you, everyone, for your time and input!
Brunswick

Usually, the only other option is incredible amounts of wireless flash. If you're the official photographer and you have free roam of everything, sometimes they let you set up wireless flashes in the rafters or around the edges. But that can be distracting and you probably don't have permission if you're just a regular photographer on site.

Just keep trying slower and slower shutter speeds, until it gets manageable but doesn't get too blurry. Usually 1/200 is workable, and 1/100 or 1/125 is not bad at all...

=Matt=

Zerodog · January 12, 2013

For me I like to shoot action sports with a minimum of 1/500 for this reason. You can fix noise, you can fix WB or weird color, you can not fix blurry pictures. Simple as that. When I am shooting event stuff I need a very high keeper rate. I bet I keep 80-90% People want to see themselves doing what they do. So every shot is important to me.

Matthew Saville · January 13, 2013

Zerodog wrote: »

For me I like to shoot action sports with a minimum of 1/500 for this reason. You can fix noise, you can fix WB or weird color, you can not fix blurry pictures. Simple as that. When I am shooting event stuff I need a very high keeper rate. I bet I keep 80-90% People want to see themselves doing what they do. So every shot is important to me.

I am going to bet that you have never shot under these types of lights when they are at their worst. A 1/500 sec shutter speed doesn't just give you WB "issues", it can completely ruin your photos.

When "tube" bulbs flicker, they don't just change color slightly, they actually dim and brighten by quite a few stops of light. You can end up completely under-exposed with a variance of thousands in Kelvin from one edge of the frame to the other.

=Matt=

Wayupthere · January 14, 2013

Zerodog wrote: »

You can fix noise, you can fix WB or weird color, you can not fix blurry pictures. Simple as that. When I am shooting event stuff I need a very high keeper rate.

Same here, I shot 2 of the 3 largest trade show conventions in the US last year. You get the 3 phase 480 volt..100ft high bay lighting. Plus every single booth has their own light setup. Flashing LED's, florescent, CF, 10 feet wide LED TV's showing vids. And sometimes all of the above at the same time!

Out of all of the shots for both events I never had a WB that PS couldn't fix easy.
Of course I did have many shots ruined by people walking into..and in front of me...I need a app for that.

Gary

Matthew Saville · January 14, 2013

Wayupthere wrote: »

Same here, I shot 2 of the 3 largest trade show conventions in the US last year. You get the 3 phase 480 volt..100ft high bay lighting. Plus every single booth has their own light setup. Flashing LED's, florescent, CF, 10 feet wide LED TV's showing vids. And sometimes all of the above at the same time!
Out of all of the shots for both events I never had a WB that PS couldn't fix easy.
Of course I did have many shots ruined by people walking into..and in front of me...I need a app for that.
Gary

If your images have never looked like the ones I posted, with extreme exposure and white balance differences across the image, then it is not simply because you magically avoided the problem in the same lighting conditions. You're simply not in the same lighting conditions as what I am talking about.

It is simple: There are many, many types of man-made lighting. A certain few types of "tube" fluorescent lighting has a Hz freqency of about 60 or 120. If your shutter speed goes too much than this, you're screwed. There is no way to work around this, other than to lower your shutter speed. Look at the images I posted, and tell me whether or not you could salvage them with post-production.

Stonehead · January 24, 2013

What a heartening post ! Well done.

Qarik · January 24, 2013

so the other thing to consider. if your under fluorescents and you don't notice this 60mhz kinds WB issues, then it could be that the light sources are running off different sets of transformers that have mixed or offset noise cycles so that you are seeing "average" light regardless. count yourself lucky

Zerodog · January 24, 2013

I have seen the huge color shift that Matt is showing. But in general you are shooting a subject not an entire arena. So you do not see the wild color temp gradients in a single shot. You do however capture the pulse. This is generally fixable in post. You are not trying to fix 2 or 3 different areas of WB.

Matthew Saville · January 24, 2013

Qarik wrote: »

so the other thing to consider. if your under fluorescents and you don't notice this 60mhz kinds WB issues, then it could be that the light sources are running off different sets of transformers that have mixed or offset noise cycles so that you are seeing "average" light regardless. count yourself lucky

Yes, they do that in some venues that have wised up to the severe limitation. Any professional or high-end arena will not have this problem. But in my particular situation for those sample images, it was just a warehouse converted into a gym. No bueno!

ZeroDog,

I understand what you're saying about how close-up photos will be easier to correct than wider angle photos, however indeed the frequency has nothing to do with your FOV and everything to do with your shutter's motion. And since the motion of the shutter is what causes this problem, you might still get frames that are un-acceptably dark or color-shifted.

=Matt=

Brunswick · February 5, 2013

Hello Everyone,
Wow again. I did not know I was sturring up such a hot topic. Sorry I have been MIA. I was out of the country photographing my neices destination wedding. I will be starting my basketball shoot on Feb 16. I have one more saturday to practice with them. I will let you know how it goes. Thanks again for all the input.

Matthew Saville · February 5, 2013

Brunswick wrote: »

Hello Everyone,
Wow again. I did not know I was sturring up such a hot topic. Sorry I have been MIA. I was out of the country photographing my neices destination wedding. I will be starting my basketball shoot on Feb 16. I have one more saturday to practice with them. I will let you know how it goes. Thanks again for all the input.

Are you going to be shooting in the same gym for all the games? Or various different gyms? You'll probably have some (most) gyms where the lighting is great and you can easily crank your shutter speed as high as you please, but a few gyms where the tube lights are perfectly in (bad) sync, and you'll have issues...

=Matt=

Zerodog · February 12, 2013

For sure you get junk in there. I like to shoot a burst of about 3 pics. In general, 1 will be really good color and the other 2 need more lovin in LR. But usually most are usable. But you will get ones that are randomly dark or so horribly colored you can not fix them. That is when you just convert to B&W

Brunswick · March 25, 2013

Hey folks,
Just following up on how it went. I ended up using flash the whole time. I bought a bolt power pack so my flash could keep up. It works really well. I liked that I could mount it to the bottom of my camera. The only problem is it is just a little too long when I put it on properly and it messed up my ability to hold the camera on the shutter end. I mount it sticking out beyond my camera body to the left, opposite the trigger and that seams to work good. But enough about that. I still struggled with color shifts but it was manageable. Pulled out magenta quite often. I took the images at ISO 3200, f4.5 to f5.6, mostly f5.6, and at a shutter speed around 1/500th. White balance was set for fluorescent. Custom balancing was worse so I stuck with fluorescent. The lights were Sodium Vapor and actually changed as the day progressed. The camera showed me that it does a better job at 1/640 shutter speed on the last week by accident. Its such a balancing act. It was amazing that they even let me use a flash in the first place so I tried to keep my flash from being too bright and blinding the players but the more it took over exposing the image the better the color was. Plus the faster shutter speed helped get a tighter focus. That was the other battle. I found a way to function but I did not ever reach a point where I felt like I had mastered a technique. I ended up taking the focus off of focus locking with track on and letting it continuously focus. That helped but I usually could not reposition the focus sensor quickly enough when transitioning to a wider angle to catch them all stretched out shooting. Often I ended up cutting off their hands or the photo frame ended between their hands and where the ball went. I tried the dynamic area focus but it jumped around way too much. I tried 21 sensors instead of 51 to see if that would slow it down a bit but I still I missed more shots than I got so I stuck with single sensor and just tried to plan ahead. I also set my Active D lighting to high, thinking it might help minimize shadows created by the flash. Can't really tell you if it helped or not because I did not try it both ways. I do know I had to add contrast back in to all the images in post processing and a lot of the shots don't have any flash shadow. I took on average 1000 images per week. Games went from 8 am in the morning till 8 pm at night, every Saturday for 8 weeks. In the afternoon they converted the court and had two games in progress at the same time. I only shot for 5 of the 8 weeks and that was enough. Had fun but I am glad it is over.
Thanks again for all the advice. I hope this information will help someone else in the future. Below is a link to a few sample shots. I don't know if links work from here or not. If they don't I will just pick a few and embed them.
Have a great day everyone!

http://photohog.smugmug.com/PRIVATE-GALLERIES/upward-for-Digital-Grin/28600814_d4NPz3

<?xml:namespace prefix = "o" ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

percentgrey · January 30, 2014

Expo Disc (using for exposure with zoom lens)

Hi. I recently watched tutorials on how to use the Expo disc. I saw your post and read several posts first. I do not yet see my question being answered. If it's alright, I'd like to ask you?

I learned in the tutorial, that I can use my expo disc just like I would an INCIDENT LIGHT METER to meter for exposure. After putting my camera in manual with the expo disc on top of the lens, I would adjust my settings until the meter is at zero and the spike in the histogram is in the center (grey).

Here is my question. Ready? I am using a 28-300mm variable f/3.5 to 5.6 aperture ZOOM lens. Imagine if I took my exposure reading while my zoom was out wide at 28mm and chose f/3.5 for my aperture. I guess the exposure would stay the way I set it if I keep my zoom lens at 28mm and do not extend it?

But what if I decide to walk further away from my subject? And then I zoom my lens out telephoto? My lens will close down on my automatically, won't it, to something like f/5.6? Would I have to keep my zoom lens steady at the same focal length that I took the expo disc exposure at?

The only thing I am thinking now, is that, perhaps I have to choose apertures 5.6 and higher to ensure that the zoom won't affect it because the aperture can stay set at F5.6 or F8 or F11 and I don't have to worry about the zoom?

Any thoughts would be very much appreciated.

Zerodog wrote: »

I shoot under these conditions often. Custom WB is your best option. I really like my expodisk for this. You will find that these lights have a color pulse. I think it is red, green, yellow. Or at least that is what I perceive when editing. When shooting higher shutter speeds you will see this. To minimize this effect I shoot my WB setup shot at a very slow shutter speed. 1/20. This averages the effect to some degree. In the end, unless you shoot very slow speeds you will still see this color pulse. So in turn, RAW is the way to go for max adjustment in PP.

Matthew Saville · January 31, 2014

percentgrey wrote: »

Hi. I recently watched tutorials on how to use the Expo disc. I saw your post and read several posts first. I do not yet see my question being answered. If it's alright, I'd like to ask you?

I learned in the tutorial, that I can use my expo disc just like I would an INCIDENT LIGHT METER to meter for exposure. After putting my camera in manual with the expo disc on top of the lens, I would adjust my settings until the meter is at zero and the spike in the histogram is in the center (grey).

Here is my question. Ready? I am using a 28-300mm variable f/3.5 to 5.6 aperture ZOOM lens. Imagine if I took my exposure reading while my zoom was out wide at 28mm and chose f/3.5 for my aperture. I guess the exposure would stay the way I set it if I keep my zoom lens at 28mm and do not extend it?

But what if I decide to walk further away from my subject? And then I zoom my lens out telephoto? My lens will close down on my automatically, won't it, to something like f/5.6? Would I have to keep my zoom lens steady at the same focal length that I took the expo disc exposure at?

The only thing I am thinking now, is that, perhaps I have to choose apertures 5.6 and higher to ensure that the zoom won't affect it because the aperture can stay set at F5.6 or F8 or F11 and I don't have to worry about the zoom?

Any thoughts would be very much appreciated.

In the indoor conditions that we've been talking about in this thread, hitting f/11 (or even f/5.6 for that matter) will not be ideal, unfortunately. The name of the game in these types of indoor conditions is often an f/2.8 zoom.

Having said that, let's say you're shooting outside with that zoom that is f/3.5-5.6.

If you use the Expo Disc to gauge your exposure, you would probably want to give yourself a middle-of-the-road aperture value to start from. F/4 maybe.

To be honest, from there I wouldn't too much about nailing your exposures perfectly on the first click. I would only use the Expo Disc to get within ~1 stop of "perfect", and then from there I would start clicking actual pictures and just looking at my real-world histogram.

Yes, if you zoom all the way in then your aperture will change by over a stop, thus affecting your exposure. HOWEVER, your composition and subject will be changing dramatically too, so you're probably better off just shooting like you normally would, keeping an eye on your in-camera exposure meter while you shoot, and adjusting if necessary based on your histogram and/or blinking highlight warning.

Keep in mind that to properly use an Expo Disc for gauging exposure AND white balance, the camera needs to be "turned around" so that it faces your light source, NOT your subject. This is a great way to meter for an overall light source that is falling on BOTH you and your subject the same way, however it utterly fails in certain conditions where the light that falls on your camera position is dramatically different from the light that falls on your subjects, especially if you cannot easily walk over to where your subjects are in order to take a reading. (Such as theater / stage performances, and church weddings, and many similar things...)

Good luck!
=Matt=

percentgrey · January 31, 2014

Expo disc (for exposure and white balance) using Zoom lens
I typed "expo disc" in the dgrin search box and this was the thread that I was directed to... so I have posted my questions here. The title of this thread matched the Nikon camera I use (D700) and the idea of WB or white balance and the posts mentioned the expo disc. So here we go...

Two photos are attached to this post (about the holiday moose toy sitting on the rocking chair).

The top picture: I used the expodisc for setting both a manual exposure and a manual white balance - while my f3.5-5.6 variable zoom lens was kept wide (at 28mm). Yes, I measured for the exposure while standing close to the toy and aiming my lens away and back to where I would be taking the picture from (to get the amount of and color temperature of the light falling on the toy). I set the aperture at 3.5 and then turned the shutter dial until the meter was at Zero, which meant that my shutter speed ended up being around 1/10th of a second (slow). I left my ISO in my Nikon D700 to choose whatever it wanted within a range of 200 to 6400 (it chose ISO 2800 for this picture). I know, it's a good thing that the toy and the rocker are not moving.

The bottom picture: I left my settings exactly as above and didn't change anything. The only thing that I did change was the zoom (focal length). I wanted to see what would happen to my settings if I went from wide to telephoto with the zoom lens? Would my settings change automatically? As expected, while I was extending my zoom (for telephoto) I could see my settings changing in the camera's viewfinder. I took the bottom picture at 92mm focal length (the holiday moose on the rocker). I could see in my viewfinder that the aperture became f5.3 and my ISO dropped to 6400. The only measurement that stayed the same was the shutter speed which stayed at 1/10th of a second. I didn't make any of these changes, the camera did.

My question is this. It seems like the exposure and white balance based off the using the expo disc while my lens is kept at a wide angle - are pretty good. Even when I didn't change those measurements, and then zoomed in telephoto, the camera seemed to change things on it's own (while I was in Manual mode) and both pictures look alright? Does this mean, that maybe the camera can figure out what to do, if I decide to zoom in?

I used to have an f2.8 70-200 lens for like 9 years and I relied on automatic everything (for sports etc.) but the fast lens is not available to me right now, so I can't use it (I miss it). For now, I am trying to get by with the f3.5-5.6 and I am trying to understand how manual settings are affected by zooming and changing the focal lengths.

I was hoping, that I would not have to know (beforehand, before I took any pictures) that I wanted to take a telephoto 92mm picture of this moose and therefor should take my expo disc settings for both exposure and white balance - while my lens is zoomed to 92mm? Should I have?

Maybe the camera (based on these two photos) somehow knows how to make the necessary changes on it's own (from wide to telephoto)? This would mean that I would not have to think about what focal lengths my zoom is at, when I set the camera up or when I take the actual photos? I did not set my camera up based on 92mm for this experiment. Anyone have some more thoughts on this?

Below, I have done another experiment, using a Kung Fu Panda toy (which is black and white) as my model, and this time, it is done outdoors in winter time. I used a Nikon D700 camera body with a 28mm - 300mm zoom variable f3.5-5.6 lens.

The first two photos (on the left) are a wide angle 28mm of the Panda, and a telephoto close to 100mm of the panda. I put the camera on automatic mode (P or program) for both the exposure and white balance. Wide angle automatic: f8, 1/250th, ISO 200. Telephoto automatic: f7.1, 1/200th, ISO 200.

The next two photos (in the middle) are a wide angle 28mm of the Panda, and a telephoto close to 100mm of the panda. I put the camera in manual mode (M or manual) for the exposure only and left the white balance on automatic (the camera picked that). I used the expo disc to set an exposure while my lens was wide. Maybe it will get a better reading because more light is available? I do not know the answer to that question that I just asked. Wide angle manual: f7.1, 1/160th, ISO 200. Telephoto manual: f7.1, 1/160th, ISO 200. I'm not sure, but is it because the aperture is narrower than f5.6 and there is plenty of light, that the aperture does not change when I zoomed in to do the telephoto picture? Maybe. Note: I've only used the expo disc for the exposure reading so far.

The last two photos (on the right) are again a wide angle and telephoto picture (similar to the above). I put the camera in manual mode (M or manual) and used the expo disc for BOTH the exposure and the white balance. Since I used an older version expodisc (when they sold an individual "portrait" disc) the colors are warmer looking in the last two photos. The exposure is the same (as in the middle two photos) and the only thing I changed, was going to manual white balance using the expo disc.

I am trying to figure out if I need to pay attention to my focal lengths (how much the zoom is retracted or extended) whenever I put the expo disc over my lens to take the measurements. So far, I have been basing my exposure and white balance off a wide angle 28mm measurement and then zooming in - however I want to take the actual picture of the panda - and letting the camera figure out any changes. The camera did not make any changes and kept the same settings, whether I was at wide or telephoto, when there was plenty of light outside (and there was no need to close down the lens)? At least, I think this is making some sense. You tell me?

This is the difference between AUTOMATIC and MANUAL (exposures and white balance). See below, the picture of Kung Fu panda. The top picture of Kung Fu Panda is what the camera picked on automatic. The bottom picture is what the camera did after I manually set an exposure and white balance using the expo disc.

No exposure compensation was used, but I feel like maybe the final photo could use a bit of a minus exposure to darken it tad. If I do a slight minus, it would probably give the final photo at the bottom more density. Perhaps I did not adjust the meter as accurately with the disc over it, since I'm just learning about the expo disc. Maybe I have to make sure that while the manual settings appear to be at zero - that no indicators are blinking in the viewfinder? Who knows.

I had thought to email expo disc about my question related to using a zoom lens. I watched all five of the video tutorials on their website which was helpful. It would be extremely helpful if one of the support techs could join this thread. If would also be helpful, if they could include another video as part of the tutorials on their website - about how to use a zoom lens (with the disc) for exposure and white balance.

lifeinfocus · January 31, 2014

percentgrey wrote: »

Two photos are attached to this post.

Anyone have some more thoughts on this?

Why not ask support at Expodisc to join in this conversation? I would be interested in their reply.

Phil

Matthew Saville · February 3, 2014

percentgrey wrote: »

I typed "expo disc" in the dgrin search box and this was the thread that I was directed to... so I have posted my questions here.

........

I had thought to email expo disc about my question related to using a zoom lens. I watched all five of the video tutorials on their website which was helpful. It would be extremely helpful if one of the support techs could join this thread. If would also be helpful, if they could include another video as part of the tutorials on their website - about how to use a zoom lens (with the disc) for exposure and white balance.

Hi Percentgrey,

Allow me to answer your questions. I'm not an Expo Disc tech, but I can tell you with certainty that although I was being vague before, you are indeed correct in your overall suspicion: Properly using the Expo Disc to gauge your exposure at different apertures would involve taking your measurement at the exact aperture you plan to shoot at.

It also sounds like you're using Auto-ISO, especially during your very first test. This will throw all "Manual-ness" of Manual exposure mode out the window, unfortunately. It will not only automatically adjust the ISO if you change your aperture, it will automatically adjust the ISO for ANY exposure, thus turning your Manual mode into basically a reversed P mode.

That's not to say that Auto-ISO isn't going to be useful, but it sounds to me like you'd really enjoy getting full manual control over everything, in which case Auto-ISO cannot give you that. All your hard work with the Expo Disc is going to be wasted, basically.

Unless I am mistaken, and you aren't in Auto-ISO for some of the other tests you performed.

By the way, a quick note about using the Expo Disc to measure color / exposure: When you place the camera at the subject's location and point the camera back, you actually don't want to point the lens / expo disc at your camera position, you want to point it directly at the most prominent light source that is falling on your subject. Unless of course that light source is coming from behind your subject and will be acting as a rim light, that is.

Anyways, moving on.

Basically, we should talk about how an aperture works here: the f/5.6 number is a fraction, or a division problem if you will, with f being the focal length. The result of this "division problem" are the measurement of the diameter of the iris of the aperture. So for example, let's say you have a constant f/2 lens just for the sake of easy division. 28mm/2 would give you a 14mm diameter aperture, while 300mm/2 would give you a 150mm aperture.

The question is, do the different diameter apertures of 150mm and 14mm allow different amounts of light through the lens? In other words, would a 300mm f/2 lens at f/2 give you a brighter exposure at the same ISO and shutter speed than a 28mm f/2 lens? I'll pass the torch on to someone else who has studied physics / optics a little more recently than I have; I don't remember and I dropped out of mechanical engineering anyways so don't listen to me

!

The bottom line is that one way or another, your lens is going to give you something different, so YES if you want to be perfect then you probably ought to re-take your reading at each focal length. Annoying? Yes. Necessary? Fortunately in my opinion, NO!

Why am I still going to advise against this level of "following procedure"? Because it's just not the fastest way to arrive at a perfect exposure every time. I hate to say it and I know it sounds simple or dare I say beginner, but you're still going to do better by just clicking a test photo and checking the back of your camera.

Indeed, my advice is once again that you ought to stop worrying this much about how to perfectly gauge your exposure with a variable aperture lens, on the very first click. Test exposures and the histogram are your best friend! Because as you just saw in your indoor VS outdoor test, the Expo Disc isn't perfect. It cannot take into account the reflectiveness (brightness) of a surface, such as a stuffed moose VS snow. It is an incident light meter, not a reflective one; and is thus much more suited to things like portraiture where you are usually concerning yourself with the same exact subject type every single time.

That, plus the variable aperture question, leads me to strongly encourage you to use the Expo Disc for WB more readily than for gauging exposure.

=Matt=

percentgrey · February 3, 2014

Yes, I would like to take control of the camera manually. I will have to stop my dependence on Auto ISO, since I got your point (both tests were leaving auto ISO "on") about how using Auto ISO would defeat setting the Aperture/Shutter manually.

If my zoom lens had notches on it (so I can make sure the barrel will hold steady at a certain marked mm for focal length) then this would help me to use it more like a fixed lens? My lens only has a lock for the 28mm wide angle so that the barrel doesn't slip out or extend while it's resting on me with a neck strap and I'm walking around with it etc. If they made zoom lenses so that you can lock the lens at different lengths, this would help me do my tests without barrel slippage.

They had a gallery on the expodisc website and I looked at every one (before and after pictures). When they had a model, they pointed the lens back at the shooting position. They did have another example of a football stadium (where you would point your lens at the dominant light source or bank of lights)

Who will take the torch and answer the question: "do the different diameter apertures of 150mm and 14mm allow different amounts of light through the lens?" Inquiring minds want to know (like me!).

The expo disc gives a spike in the center of the histogram to indicate a good exposure. If I could lock my lens on say, 72mm for basketball, and then take my readings for all my settings for aperture/shutter/and ISO... maybe........ my tests would work alright?

Because the first person to post a message also mentioned basketball, I feel a need to add one of my own basketball photos that I took for my local weekly newspaper (watermarked and copyrighted). How did I manage to get by and take a decent image of basketball with a slow lens? I used the same camera and lens used for my tests, that being: a D700 plus f3.5-5.6 28-300mm zoom. The exposure was set automatically by the camera (f5 aperture/250th second shutter/6400 ISO) and then added a SB-900 flash. One well timed photo with flash is worth it (even if it's daunting to think about having only one chance to take them jumping because of using a flash). I used the expodisc to manually set the white balance in this gym.

Below is Q&A (question and answers) from previous post to remind me of it:
>>Properly using the Expo Disc to gauge your exposure at different apertures would involve taking your measurement at the exact aperture you plan to shoot at.
>>It also sounds like you're using Auto-ISO...it will automatically adjust the ISO for ANY exposure, thus turning your Manual mode into basically a reversed P mode.
>>sounds to me like you'd really enjoy getting full manual control over everything, in which case Auto-ISO cannot give you that.
>>point it directly at the most prominent light source that is falling on your subject.
>>The question is, do the different diameter apertures of 150mm and 14mm allow different amounts of light through the lens? In other words, would a 300mm f/2 lens at f/2 give you a brighter exposure at the same ISO and shutter speed than a 28mm f/2 lens?
>>Test exposures and the histogram are your best friend!

D700 WB for fluorescent lighting

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