Light Cell ? - DPChallenge Forums

03/13/2006 01:16:44 PM · #1

Hello everyone,

In my quest of becoming a better photographer I bought this book the other day: Link to the book on Amazon (great book by the way!) and the author talks about a little device, a sort of Light Cell (sorry I got the book in French so it's only called "Cellule" so I roughly traduced it, I don't know the exact name). But do I need to buy a device that fulfills this purpose or can my digicam do it for me? (my camera : Fuji FinePix F700

Thanks a lot in advance for your help

Best regards

ignite

Canon EOS-500D Rebel T1i

Canon EF 50mm f/1.8 II

03/13/2006 01:43:05 PM · #2

Not really sure what you are asking, but I think you mean a light meter for measuring light and exposure. If that is the case, you will only have use for a light meter if your camera lets you set shutter speed and aperture. If your camera does not offer that function, a light meter at the moment will be useless, although it will come in handy when you upgrade to a better camera.

Canon EF 17-40mm f/4.0L USM

03/13/2006 03:21:14 PM · #3

Yeah, that's it: a Light Meter :)

It lets me choose Aperture and shutter speed yes, but I was wondering if maybe I already have it integrated with my cam. How can I be sure?

I know it tells me when there is risks of "moving" (like when shooting a person without flash in the night without using a tripod for exemple) so perhaps it has one integrated ... What do you think?

Thanks again

Best regards

soup

Canon EOS-30D

03/13/2006 03:39:19 PM · #4

the camera has a light meter integrated - it wouldn't function properly -w/o one. how well it works is another question.

set the camera on manual mode - so you can adjust shutter and aperture. there should some sort of guide telling you whether the photo will be too dark or too light, which will change with different settings of shutter and aperture.

Canon EF 17-40mm f/4.0L USM

03/13/2006 03:45:07 PM · #5

Oh now I know what is that little bar on the bottom of the screen with a "-" and a "+" at each extremity is for lol!

Thanks :)

Do you know where I could buy a Light Meter that would be quite good but not too expensive ?

ignite

Canon EOS-500D Rebel T1i

Canon EF 50mm f/1.8 II

03/13/2006 03:54:07 PM · #6

Well, I dont have a light meter. If I ever need one I just meter using my camera in auto and play around with those settings in manual mode. I've heard Sekonic are good.

soup

Canon EOS-30D

03/13/2006 04:06:50 PM · #7

i wouldn't worry about an external meter.
might cost more than your camera

03/13/2006 04:06:52 PM · #8

Ok thanks. I'll see on ebay if I can find some not too expensive.

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

03/14/2006 12:13:04 PM · #9

I will second what soup says here. At the point where you are in your photography with that camera, you are unlikely to find any serious value in buying the light meter.

It would do you much more good to save the money and pick up a DSLR instead (like a used 300D).

Light meters cost a fair bit of money and while they do help you with certain things, unless you have a studio with strobes, you are unlikely to find a need for one that can't be already filled by your camera.

External Light meters differ from Internal Light meters in that an external unit measures light that is coming from light sources BEFORE they hit the subject and internal light meters measure light AFTER it illuminates the subject. I feel that in the digital context, the AFTER is more important than the BEFORE in 95% of situations. I am not an expert of course, but I would be surprised if anyone stated otherwise.

Your biggest need for a light meter with a P&S camera is in balancing light within your frame. The Dynamic Range of a P&S camera is quite low. This means that the difference between the amount of light bouncing off of the bright things compared to the amount of light bouncing off of dark areas in your picture cannot be too much, or your camera will see it as either a value of 0 (with no detail) or 255 (commonly known as "blown out"... also without detail). When light reaches "blow out" levels, it also has the tendency to spill all over the place and ruins detail of neighboring parts of the picture.

In a digital camera, there's lots of detail to be seen near the 255 mark, but when you start to get into deeper shadow, the ratio of noise to actual light decreases. It's harder for the camera to tell if the energy stored in a photocell is from light gathered by the camera or if it's interference and dirty electrical 'noise' generated by the sensor. This means that in many cameras, shadowy areas can be very noisy and look bad.

In short, shadow areas with little information usually look bad, but this keeps to individual pixels. If you stay under the 255 mark, it will be bright, but it's easy to go over and if you do, the picture will look bad in that spot and it's possible for the badness to spread and bloom.

Both ends are fraught with badness and extremes should be avoided unless you are doing something intentionally.

Most people try to shoot closer to the bright side of things because there's always more real information there. If you take bright pictures and make them darker, the quality remains. If you take dark pictures and make them brighter, you end up amplifying a lot of garbage and the pictures can look noisy and bad.

You can easily check for this type of effect by doing some testing by yourself...

Find a picture you want to use as your test. Make sure it has fairly even lighting and coloring (light colored objects).

Put your camera into Av mode (aperture priority), set the ISO to what you use most often, and half-press the shutter. If possible, set your camera to Spot Metering. This will probably make a difference, although depending on the situation and the camera, it may not be a very big difference. When it comes up green, it will tell you a shutter speed (example 1/100). Now move the center spot around in your scene and try a couple of other spots. If it's very even throughout, you will probably get figures like 1/80, 1/100 and 1/125. These are all within one stop of each other. (One stop is a unit of measurement that you will probably already have encountered in your book. When the shutter speed doubles, it goes up a stop)

You have just metered the light within your frame and determined that at that ISO, with that aperture, those are the shutter speeds you need to get proper exposure. The numbers will probably be quite accurate. You have also determined that your entire scene is within one stop. This is a pretty flat picture to be honest, but take the picture anyhow.

In your final image, you will notice how even everything looks. There are no really glaringly white areas and there are no really shadowy, dark areas. Noise should be fairly even and detail should be as sharp as your focus allowed.

Now change the setting.

Find a setting with more variance in light. Maybe there is a center subject that is lit by a small lamp while the rest of the scene is quite dark with the main light turned off. Maybe you have closed the curtains.

Now keep the same settings and stay in Av mode, and half-press to meter your subject. Let's say that you get 1/60. The subject will be clear and visible, but the rest of your room will be dark and shadowy.

Now move your spot to a dark area of the picture. This is where you see a massive change in the look of your scene. Your camera will probably also "gain up" your EVF or LCD if you are using one and the shadowy areas that were dark before are suddenly visible (and probably pretty grainy looking). Your camera will probably show a red number for the shutter speed, and if there is a camera shake warning, it will probably now be active. A half-press later and you just came up with a red 1 second shutter speed. Automatic modes often don't allow for metering less than 1 second shutter speed. I don't think light meters do either. At this level of light, you are into a different kind of shooting altogether.

Now move your spot back to your subject. If you are like me, you live alone, so your subject is probably not a curvaceous young lady. More likely, it is a Woody doll or a Teddy bear.

We have moved back to 1/60 for our shutter speed. Great. Now move it off to the edge of your subject. Watch how there's a bit of a shadow there. Things change a bit, and after a half-press, your shutter speed switches to 1/30. You also notice that fully lit part of your bear is now quite a bit brighter, possibly a bit too bright. Don't worry.

Take the picture at 1/60 and again at 1/30.

In the picture at 1/60, you will notice that your subject is well-exposed with good detail. Your background is all black and quite clean looking, and if you look really closely, you will notice that the shadowy areas of your subject are somewhat or perhaps even fairly noisy.

This tells you that whatever you have in frame that is underexposed by 1 stop, you will have that amount of noise. At 5 or 6 stops difference, the camera simply doesn't see anything.

In the picture at 1/30, you have still probably got a pretty black background, but now you have a lot better detail and cleaner information in the shadowy areas of your subject. What else you may notice is that certain parts of your subject that are lighter in color and especially those parts that are more reflective now have a glary look about them with little color. You may even have some purple fringing here and those pinpoints of light that you didn't notice or feel were bad in the previous picture have now become distracting, harsh points of light with soft edges.

This tells you that when you overexpose by 1 stop, you get harsh highlights and washed out colors.

Finally, take the picture at 1/40 and 1/50. You can also learn from these pictures because now you can see the effects of under and over-exposing by 1/3 of a stop. At this point, you should be able to interpret the data by yourself.

This will teach you a great deal about the operation of your camera.

This example given is not necessarily accurate for real cameras though because each camera has it's own characteristics. It's up to you to do the tests yourself and see how your camera responds.

The example given was that of a camera with about 2-3 stops of Dynamic Range. This is pretty close to the actual figures on many real Point and Shoot cameras.

While a lot of these cameras have different ISO settings, these settings do not actually influence the Dynamic Range (except that at High ISO's, the DR could be significantly less, but that's a performance issue, not a technical issue).

What does affect dynamic range is pixel size. Generally, the bigger the pixels, the better the dynamic range. The dynamic range is the difference between the smallest amount of light that can be measured and the largest amount of light that can be measured.

A pixel could be likened to a bucket. So a bigger bucket can collect more water. But all buckets can collect no water. So having bigger buckets means that the difference between 0 and full is a wider range.

If you later took a DSLR (like the 300D for example) and did the same test, you would probably be surprised at the difference in performance within the same scene. On the picture taken at 1/30 of a second, you would notice that the color has NOT been washed out and there's still lots and lots of detail in the brighter areas. In fact, it doesn't really look blown out at all. It just looks brighter.

The dynamic range of the 300D is 2-3 TIMES that of a typical P&S camera. This means that you can now overexpose by a full stop and still have a really nice, bright image, with no loss of detail in the bright areas. Because you brought the image up a bit with the overexposure, two things will happen. Shadow areas will not have quite so much noise and you will still be able to have lots of good detail in bright areas.

Many photographers also work close to the bright side of things because it also has an effect on the details that are sometimes not wanted, such as skin imperfections. Try it out!

These are the primary lessons you need to learn about light metering and using your camera. Once you master these methods and learn these lessons in your own ways, you will then be in a much better position to determine if you really need a light meter or not.

thegrandwazoo

Nikon D750

03/14/2006 12:21:55 PM · #10

Originally posted by Smasher:

It is a great book. I have it and refer to it often. If you read all the book you will see that the author is saying that really for most of what he does a light meter is not necessary and goes so far to say that the in camera meter is more than enough for most every situation. So save your money and buy more books!

Message edited by author 2006-03-14 12:30:53.

03/15/2006 04:24:04 AM · #11

thegrandwazoo I just started the book but what are his other books? Do you know?

eschelar I can't read rigt now your post since i'm at work lol so I'll read it later when I can (thanks for all these infos by the way :)). But I read the beginning though and I must say that if I started looking for a light meter was to use with my digicam but mainly to use it with this cam I got for 8 dollars in a garage sale (and it works!): SEMFlex TLR

Best regards

Message edited by author 2006-03-15 06:01:47.

03/15/2006 11:16:02 AM · #12

Ok, that I didn't know. NICE find btw! WOO!

I wonder what kind of pictures you will be taking with it? A lot of MF shooters shoot only once they know.

My downstairs roommate (possibly) just sold his Bronica and what they used to do was use a Polaroid back to make instant proofs to check their lighting.

Instead of doing that, you could do something quite similar with your P&S camera. Bring it with you and do the metering with it. Make sure you check to see if the ISO settings on your P&S match the film. A lot of P&S cameras don't have accurate ISO numbers. If you can figure out how to get a reading for ISO 100, you should have all the information a light meter will give you (provided your camera has some manner of spot metering) and you can simply change the data as appropriate.

IE. Your P&S shows that at ISO 100, you can shoot a picture at 1/500, f/2.8 but you are using ASA 200 film. Well, double the sensitivity and you are suddenly shooting 1/1000. But you want to shoot at f/22... so then you have to change that now to 1/15.

Make sure you match focal lengths as this can affect the amount of light gathered.

These methods are really only effective for reading the light present in a scene, not for use with studio applications where you have strobes and the like.

This will also help you to measure out the overall range of light throughout your scene. You may find that Medium format slide film (or whatever you are using) is MUCH less forgiving than digital. You can still use your P&S as a tool to learn how to balance your scenes just about as well as a light meter. It will save you a few bucks too.

03/16/2006 08:37:56 AM · #13

Thanks for the tips ! Dunno why I didn't think of it earlier lol.

The thing is, my light meter in my P&S cam doesn't tell me what F/stop or Shutter Speed to use, it only lets me set everything and a little line at the bottom of the screen with a minus at the left and a plus a the right has a cursor that moves according to the exposition I guess. But I think the middle is a correct setting for the exposition yeah.

I got a Sekonic light meter with the cam but it doesn't work lol, too bad.

Also, the cam works, I took a few pics with my grand-father, I then got 6x6 photo (B&W), but it costs 5$ a photo lol ! So yeah I'd like to avoid getting them wrong :)

Best regards

03/16/2006 09:18:47 AM · #14

Woo. Fun stuff. One thing that can really help with keeping MF printing costs down is something called a contact print. MF shooters like to use something called a loupe (which itself can get a bit expensive) and examine the 1:1 prints off of film to see which ones they like enough to get printed. Contact sheets can be made quite cheaply (I've heard).

Ask around your local developers. Tell them you are a beginner and see their reaction. If they act snobby, you might want to look elsewhere. If they have a bad attitude towards you, they might be careless with making your prints. With chemical work, there's a lot of the developers skill that goes into making things happen right, so it's definitely worthwhile to keep them happy.

Do you have a "Display" button on your camera?

You should have the ability to see what the camera wants to take the picture at before it takes the picture. Sometimes my camera stops displaying this information, and I have to hit the display button while composing to get the information to pop up again.

At the very least, you can use your P&S like a Polaroid. Place it directly overtop where your MF cam is and take the pic. Examine it for highlights and whatnot. Check also to see if the things you want bright are actually bright enough. If you want, you can experiment with under and overexposing by a half stop or so. You can usually adjust aperture in 1/3 stop increments in your P&S. If you actually take the pic, you can get around the weakness of metering with your camera which can easily be fooled by scenes containing darker and lighter objects. Also, you can have information which you can compare later to the print to see what the differences are like between the P&S at f/5.6, 1/125, ISO 100 and the Film camera at f/5.6, 1/125 with ISO 100 film.

I'm sorry I am really inexperienced when it comes to Fuji F700's. I've never been much interested in the Fuji line of P&S cams. (That one HDR cam they had was kinda neat though)

All of the functions I am referring to here are available on my P&S as well as the Canon A80, A95 and my old S30. I can only hope they are on yours too.

While you are getting used to using these cameras, I would suggest two peices of equipment.

1. A medium strength tripod.... Your camera isn't too heavy, so a medium level tripod should be sufficient. I think there's a listing in another thread for something like an avona or something? It's like 60 bucks US and is a totally decent peice of kit. Maybe someone else can post that or you can search the forums...

At least for the beginning, a lot of your shots will probably be very deliberate and you will want a stable point of reference. Depending on your eye for focus, you may also be shooting narrower apertures.

2. A small notepad with lots of pages. Taking basic notes on each frame will help you a very great deal. Especially if you are actually saving some of your test images (generally a decent policy. A good third of my test images turn out better than the images I put effort into taking deliberately) to compare. This will increase your learning curve a great deal.

Don't forget that the sensitivity may be different, and the dynamic range of the two mediums is certainly different. You may choose to slightly overexpose the shot and find that there are loads of blown highlights in the digital, or you might find that they are only on the film. A lot to learn there.

As you learn more from shooting with your film camera, you will probably get a better and better eye for exposure settings and light levels. Most pro's or really experienced photog's that I know can tell you what to shoot just by looking at a scene.

This kind of ability will allow you to start using the proof system less and less and give you more freedom to start taking more casual shots, candid shots and shots of moving subjects.

03/16/2006 09:54:04 AM · #15

Originally posted by eschelar:

External Light meters differ from Internal Light meters in that an external unit measures light that is coming from light sources BEFORE they hit the subject and internal light meters measure light AFTER it illuminates the subject. I feel that in the digital context, the AFTER is more important than the BEFORE in 95% of situations. I am not an expert of course, but I would be surprised if anyone stated otherwise.

Surprise!!

Measuring the incident light (with a hand held meter) as opposed to the reflected light (in-camera meter) is neither more or less important. Each has their advantages and it's important to understand the difference.

If you measure the incident light and set your exposure according to that, you do not have to worry about your subject being dark or light, it will record correctly.

If you use a reflected meter, have a dark subject and follow your meter, you will overexpose the shot. If you do the same thing with a light subject, you will underexpose. This is where it's important to look at the scene and understand how to use exposure compensation to adjust the camera settings to get the correct exposure.

The big advantage of reflected light metering is that it can always be done from the camera position, whereas an incident metering needs to be done in the same light conditions as the subject. Metering near the subject is not an issue in a studio, but, there are often situations outside that environment where it's not practical.

03/16/2006 10:00:34 AM · #16

Originally posted by eschelar:

I always looked at the film itself and not the proofsheet. It's cheaper still to get film developed as "process only" and evaluate it on the light table. A bit harder to do with neg film, but certainly do-able. Proofsheets are nice to look at and show to clients.

Depending on where you are, you might consider a mail order pro-lab. I would suggest A & I in Hollywood. They are one of the best pro labs, bar none.

03/16/2006 10:19:50 AM · #17

Thanks for setting things straight Spaz!

03/17/2006 08:53:37 AM · #18

Thanks for all these infos!

eschelar, by Display button you mean the one that let's me switch On and Off the screen of my cam?

Nice tips you gave me there :), I'll try this out!

Spazmo99, I understand now what a external light meter is for, I'll try to find one not to expensively if I see I really need one.
Also, what do you mean looking at the film itself? You mean in your private darkroom? If yes I don't have one of these so I can only got the lab and get a contact print I guess.
Thanks for the link but I'm France so they probably don't exist here but I know a very good photo lab over here so I'll ask them.

What did you mean by getting the film developped as "Process Only"?

I was also thinking of getting a tripod since most the shots I want to take in manual need one otherwise they blurred.

Thanks again for your help guys :)

03/17/2006 08:56:04 AM · #19

Originally posted by Smasher:

Spazmo99, I understand now what a external light meter is for, I'll try to find one not to expensively if I see I really need one.
Also, what do you mean looking at the film itself? You mean in your private darkroom? If yes I don't have one of these so I can only got the lab and get a contact print I guess.
Thanks for the link but I'm France so they probably don't exist here but I know a very good photo lab over here so I'll ask them.

What did you mean by getting the film developped as "Process Only"?

"Process Only" means all they do is develop the film, no prints.

You look at the developed film with a loupe on a light table.

03/17/2006 10:12:24 AM · #20

I see! What the cheapest between doing that and the contact print?

03/17/2006 10:48:46 AM · #21

Originally posted by Smasher:

I see! What the cheapest between doing that and the contact print?

Process only is cheaper, because they still have to process the film, then make the contact sheet.

03/17/2006 11:04:21 AM · #22

Spaz, you rock, I'm glad you are still paying attention to this thread and helpin' out cos I'm a little out of my league :) Obviously :)

The Display button is indeed the same button as the one that you use to turn your LCD on and off. If used in shooting mode, you usually have to press it twice to actually switch the LCD off. This is because the first press SHOULD bring up shooting info on-screen, like shutter speed and aperture and the like.

A tripod would be something I would consider ESSENTIAL equipment... Particularly when you are moving into heavy learning territory like this.

The general policy for hand-holding vs stabilized (mounted) is that if your shutter speed falls BELOW 1/focal length (IE at 50mm focal length, 1/50 is the beginning of your danger zone), The average person is at risk of camera-shake induced blur. This gets worse if you have the camera away from the eye (for example, when composing a shot on ground glass). At 5 bucks a pop for pictures, I'd say camera blur is a big issue here and it's not really worth it to just "hold your breath".

I would look around for a cheap set of legs and grab something versatile and light like the Giottos 1001 head. It's strong enough to handle what you want and gives you some versatility to do other things later. It's also very cheap and very light. I'll try to find that tripod link in a minute.

Only thing to do is see if you can figure out the right way to operate the somewhat odd 3 knob system. I am guessing that 5 minutes playing with it should suffice.

There are also a couple of "rules of thumb" that you can find too. Bear_music mentioned a great one that on a bright sunny day, with an aperture of f/16, the shutter speed is equal to the reciprocal of the Film speed. SO with ISO 100, you shoot 1/100, ISO 200, you shoot 1/200... You can figure the rest out by simple math. Down a stop in aperture, double the shutter speed.

This is based on incidental light.

EDIT: Google dynatran AT828

I had a look before and it looks like a great deal. It really does everything a tripod should.

Message edited by author 2006-03-17 13:40:00.

03/18/2006 06:01:03 PM · #23

Thanks Spazmo99 :).

eschelar: What did you mean by the 3 knob system? For my old 50's cam?

I was thinking of getting this tripod? The one you recommend me seems great but expensive (I found a website that sold it for a 100 euros).

Thanks for the ISO technique :), I'll try it out with my P&S as soon as I have a sunny day here in Paris .... which is very rare sadly lol !

bandit

Samsung S23 Ultra

03/18/2006 06:17:21 PM · #24

Qu'est-ce? Well I think thats how you spell it ...