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03/13/2006 11:59:45 AM · #1 |
I just had to share my excitement with my new lense. I have a whole new apreciation for my 20D now that I have a wide angle lense for it. I must say it is much sharper than I anticipated.
-GreenGiant
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03/13/2006 12:42:49 PM · #2 |
that is a very nice lens - i have used one and as soon as i get some more money i'll have one of my own.
I think I need pocket wizard and a light meter first though...
here's a shot from last month with that lens on my rebel
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03/13/2006 01:50:12 PM · #3 |
| Thats great you wont regret getting it. Just curious why would you need a light meter for digital work? do you do delicate light work with portraits or something. I used to use one when I did film stuff but now I use the histogram is I need more info or shoot in RAW so I can fine tune it later if I need to. And what is a pocket wizard? |
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03/13/2006 02:46:39 PM · #4 |
As i advance in my photography and use flash, I find i need to measure the light on different parts of a scene - you want the BG brighter or darker than the subject? How much difference? Measure the subject, back off 2 stops, add fill flash and you get what you want the first time. You can take shots and look at the LCD and repeat as needed, but it's not as precise.
I am finding out afterwards that i didn't get what my mind saw, and am trying to learn how to fix that and a lightmeter seems to be the tol i need.
I also just got studio lights (a pair of paterson interfit stellars) and you need a way to measure each light's output to properly balance the lights so to keep the whole scene within 5 stops or so. the histogram is useless for this.
There are several ways to trigger a flash. On the hotshoe is one way, but for studio flash that aren't on the hotshoe you can do it optically (they fire when the see a flash fire), via cord (pc cord from camera to a flash unit) or wirelessly, via pocketwizard (or other companies units). For weddings where other folks are using flash and you have to move around, wireless triggering is the only option.
//www.pocketwizard.com/
//www.pocketwizard.com/HTML/plus.asp
This adds extra crap to carry at a wedding, and means moving my on-camera flash to a bracket, so I am not sure it's the ultimate solution for me, but for the studio and location work it'll work well.
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03/13/2006 06:07:51 PM · #5 |
I think it's more the shooter than the lens.
All the ultrawides are good lenses with minor differences in real world photos, in my view.
Those are nice shots.
Message edited by author 2006-03-13 18:08:56.
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03/14/2006 09:55:07 AM · #6 |
Hey prof, have you ever tried using your in-camera light meter? Place the AF spot on a part of the scene you want to meter with the camera in Av mode and watch the shutter speed change.
I had a chance to play with one briefly that my roommate had (cost him like 2000 bucks originally ZIPES!), but in the end, I couldn't see what it could do much better than my in-camera meter.
Also, don't forget that your Canon is usually a bit more sensitive in ISO than the equivalent film number, so you will have to learn to factor that in when using the light meter too... (I think Canon sensors are generally 1/8 stop more sensitive or something like this... I think dpreview often mentions this in their reviews, ISO=ISO 125 film or other brand sensors? Memory fails me) This is another plus for in-camera metering.
Of course I might be way off because the camera may not actually have spot metering, but I was pretty sure it did after using the Russian hack? |
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03/14/2006 10:34:09 AM · #7 |
Originally posted by eschelar:
Hey prof, have you ever tried using your in-camera light meter? Place the AF spot on a part of the scene you want to meter with the camera in Av mode and watch the shutter speed change.
I had a chance to play with one briefly that my roommate had (cost him like 2000 bucks originally ZIPES!), but in the end, I couldn't see what it could do much better than my in-camera meter.
Also, don't forget that your Canon is usually a bit more sensitive in ISO than the equivalent film number, so you will have to learn to factor that in when using the light meter too... (I think Canon sensors are generally 1/8 stop more sensitive or something like this... I think dpreview often mentions this in their reviews, ISO=ISO 125 film or other brand sensors? Memory fails me) This is another plus for in-camera metering.
Of course I might be way off because the camera may not actually have spot metering, but I was pretty sure it did after using the Russian hack? |
The SS will change if you meter a darker or lighter surface too.
The incident meters operate independent of this. They measure the light falling on a subject, not the light being reflected from it. This allows you to meter independent of your subject. You can use the in camera meter to emulate an incident meter by metering a gray card, but that's even more of a PITA.
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03/14/2006 10:55:01 AM · #8 |
True. But I think this is still in keeping with the general purpose of metering.
He wants to know what the difference of light is between his background and his subject is in the picture he will take. If you are shooting dark surfaces, they will appear dark. If you shoot a light surface, it will appear light.
I realize that there are things that a light meter can do that the in-camera one cannot, but I'm of the feeling that for what he needs to do with it, it's going to be faster and easier to use the in-camera than an external unit most of the time.
Light meters can also provide information much closer than full, or even third stops.
This can be very useful for really close fine-tuning, but in the digital medium, it's probably less important. |
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03/14/2006 11:13:44 AM · #9 |
Originally posted by eschelar:
True. But I think this is still in keeping with the general purpose of metering.
He wants to know what the difference of light is between his background and his subject is in the picture he will take. If you are shooting dark surfaces, they will appear dark. If you shoot a light surface, it will appear light.
I realize that there are things that a light meter can do that the in-camera one cannot, but I'm of the feeling that for what he needs to do with it, it's going to be faster and easier to use the in-camera than an external unit most of the time.
Light meters can also provide information much closer than full, or even third stops.
This can be very useful for really close fine-tuning, but in the digital medium, it's probably less important. |
In the studio, an incident meter is a lot more useful than the in-camera meter. It's indispensible if you're using flash.
Let's say you have some subject containing a variety of values and have your lights arranged in some suitable fashion. What's the correct exposure? With your incident meter, you just hold it by the subject, facing the camera, push the button, read the meter and you are DONE.
With the in camera meter, you have to select some portion of the subject, and get some reading. depending on what values of your subject you have in the metering area, the camera will use some algorithm to mash all of those together and come up with some average which is the exposure displayed. If the values in the subject are too dark, the camera will overexpose, too light and underexposure will be the result.
Now, if you are shooting a portrait or some other multiple light shot and need to control multiple lights to achieve a certain effect, you will have the same problems, only multiplied by the number of lights.
The problem is that the in camera meter assumes that the average value in the subject is the same as 18% grey. It works great most of the time, but for accuracy anytime, and for speed in the studio the hand held meter wins every time.
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03/14/2006 11:50:45 AM · #10 |
Canon doesn't do the spot meter thing for some reason - the 30D has it (!!!) and i cam getting one, so that will help alot as that's what i'm used to.
the rebel does evaluative in all modes except M, where it is center weighted. So if yo have a backlit subject and are in any mode other than M, you are guessing. In M it's center weighted so it's better, but not much.
RAW is consistently underexposed compared to JPG.
good luck measuring the contrast in a scene with your camera.
For studio to more than something boring or random, a meter is very helpful if not indespenible. I have stuff to sell on ebay then i'll have the cash for a sekonic L358 ($240 or so).
two lights, main is to camera left, fill on camera right. with a meter you can measure each, set the 1 or 1/2 stop difference and you're done and it's right. Using the camera you can take a shot, adjust the camer and / or one or both lights and try again, and again until you stumble across the right mix of ingredients.
For metering, perhaps i could put my camera in Tv mode and read the ap changes to get the info i want, and then change modes to get the shot i want...but if i'm willing to do all that, why not get a meter and do it right? My in camera meter shows max 4 stops but the sensor can record 5 to 7 (depending on who you believe) so I am really doing mental gymnastics to get all this figured out.
No take a backlit subject. You want to add fill flash to balance things out - how much? perhaps you can let teh camera figure this out, but I am trying to be a pro, and so a)i got to get it right, no excuses b)i don't have the time to fix it later in PS - it needs to be captured properly.
And if you are using strobes for this (like an outdoor senior session or wedding) you don't get eTTL and you'll look really non-professional taking 3 or 4 shots and adjusting the lights between each one. hit the flash with the meter, make one adjustment, and your done.
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03/14/2006 01:47:16 PM · #11 |
Ok, fair enough.
I do understand that multiple strobes will get you using your light meter a fair bit.
Also, with the undutchables firmware hack, I believe you get 8% spot metering which is apparently pretty good for the meantime.
I've got a friend with a 300D using this hack and he loves it. No problems.
He realizes that the warranty is up anyhow, so no point worrying about that.
Just wanted to give you another option, not trying to talk you out of buying something.
I also seem to think that you can use Flash Exposure Compensation mode to meter your flash setup. It won't allow you to meter individual flashes quite so easily though. |
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03/14/2006 02:08:29 PM · #12 |
An honest question here: How does the incident light of itself determine the exposure? I would have thought that the important part of the equation would be the reflected light, as, after all, it is that component that reaches the camera. Different levels of reflectance would render different amounts of light to the camera for the same incident light. I assume that I've got this completely wrong. Help me out here, please.
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03/14/2006 02:23:47 PM · #13 |
Originally posted by AJAger:
An honest question here: How does the incident light of itself determine the exposure? I would have thought that the important part of the equation would be the reflected light, as, after all, it is that component that reaches the camera. Different levels of reflectance would render different amounts of light to the camera for the same incident light. I assume that I've got this completely wrong. Help me out here, please. |
In theory, here's how it works:
A reflected light meter reads the light reaching the sensor plane and assumes the light is reflected off a zone 5 gray surface. It gives you camera settings to render what it "sees" as zone 5 (middle) gray. If you shoot a white wall, it will show up gray (underexposed). If you shoot a black wall it will show up gray (overexposed).
To some extent this is mitigated by "intelligent metering" in modern cameras, where the camera itself makes "decisions" based on the relative frequency of different values of light within the scene, but the fact remains that a camera doesn't know what it's pointed at and a light meter has to make assumptions about the reflectivity of the surfaces, so to speak. Look at it this way: you can light a black wall with a 500-watt flood and a white wall with a 100-watt flood, say, and the actual amount of light reaching the sensor might be identical (I haven't done the math but you get the idea), so how does the camera "know" if it's weak light on a bright surface or bright light on a dark surface?
An incident light meter measures the intensity of light illuminating a scene, and delivers an exposure that will render a zone 5 gray under that light correctly. So the whites will be brighter, the blacks will be darker, than in the white wall/black wall scenario using the reflected light meter. In theory, if you know the brightness of illumination of a scene, you know the "correct" exposure for that scene. This is where the old rule of thumb comes from; at any given ISO for a clear-sky, daylit scene, the correct exposure is f/16 at the reciprocal of the ISO: f/16 at 1/100, or 1/200. or 1/400, whichever represents the ISO used.
Experienced film photographers usually become so adept at judging natural light witht heir eyes that they don't even NEED meters; this was certainly the case in my architectural photography business, where I rarely used a light meter outdoors when shooting transparencies.
Incident light meters are remarkably accurate, and are the meter-of-choice for transparency work. You meter the light falling on the scene and then make an intelligent decision as to whether you want to over-or-under a tad as you set your camera.
Incident light meters a5re indispensible for serious studio work, if only because they allow you to meter the relative levels of fill and key light in a scene; set up your lights, then turn off all but the fill light and take a reading. Then turn off the fill, turn on the key, take another reading. Adjust the lights as needed so the desired ratio of fill-to-key is attained, and shoot away.
Many incident light meters also will function as strobe meters, so you can manually trigger strobes while holding the meter at the subject plane and adjust relative balance of strobes as described above.
Robt.
Message edited by author 2006-03-14 14:34:10. |
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03/14/2006 02:33:41 PM · #14 |
Originally posted by AJAger:
An honest question here: How does the incident light of itself determine the exposure? I would have thought that the important part of the equation would be the reflected light, as, after all, it is that component that reaches the camera. Different levels of reflectance would render different amounts of light to the camera for the same incident light. I assume that I've got this completely wrong. Help me out here, please. |
You're exactly right when you say that different levels of reflectance send different amounts of light to the camera. While the fraction of light reflected from a surface is determined by the reflectance, the AMOUNT of light reflected is the product of the reflectance and the incident light.
By using an incident meter, you know the amount of light falling on the subject. If you use that meter reading, it will place the values of any reflected light according to their reflectances.
If you measure reflected light, the measurement you get is dependent on the amount of light being reflected off of the surface being metered. If you have a scene that averages out to a middle value, you are probably ok. If you have a very dark scene, the camera, by default sets exposure to make that very dark scene an average one, resulting in overexposure. If the scene is very bright, the camera again, by default, tries to make that scene an average value, resulting in underexposure.
The jist of it is that the in-camera meter is dependent on the reflectance of the scene and the incident meter is independent of subject reflectance.
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03/14/2006 02:52:34 PM · #15 |
Originally posted by eschelar:
Ok, fair enough.
I do understand that multiple strobes will get you using your light meter a fair bit.
Also, with the undutchables firmware hack, I believe you get 8% spot metering which is apparently pretty good for the meantime.
I've got a friend with a 300D using this hack and he loves it. No problems.
He realizes that the warranty is up anyhow, so no point worrying about that.
Just wanted to give you another option, not trying to talk you out of buying something.
I also seem to think that you can use Flash Exposure Compensation mode to meter your flash setup. It won't allow you to meter individual flashes quite so easily though. |
Spot meter is like 3%, but the hack does nothing in that regard - i have had the hack for 10 months now. the hack details
FEC is great IF you are using eTTL with an onboard flash. Otherwise it makes no difference. Reason being, in eTTL the camera is doing the thinking, so you can alter that thinking. (camera turns on flash, measure light hitting the sensor in the camera, turns off flash) If the flash is set to manual it just pops off teh amount of light you have it set for. If if you have a flash with an auto mode (metz54, vivitar283, etc) then the flash is doing the thinking so adjusting FEC on the camera does nothing. (the flash measures the light returning to it, and based on the settings it reads fform the camera, it decides when to turn off the flash). Amount of light is determined by the amount of time the flash tube is on, not by actual brightness of it.
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