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Betsy_Finn
09-21-2006, 03:40 PM
Since the Light Ratio vs. Lighting Ratio question prompted so much discussion, let's start a new thread just for discussion of exam questions! I'll start us off by grabbing another sample question from the sheet. For reference, here is the link to the PDF of Sample Test Questions. (http://www.certifiedphotographer.com/files/public/SampleItems.pdf)

Since we're not going in order anyways, I've chosen number 2! :cool:


A particular filter used with black and white film calls for an exposure factor of 8X. Applying this factor to the intial exposure reading of 1/8 second at f/32 will require a new exposure of

a. 1/8 second at f/22
b. 1/8 second at f/16
c. 1/4 second at f/22
d. 1/4 second at f/16

David_A._Lottes
09-21-2006, 04:04 PM
I'll bite, I would say answer d. 1/4 @ f16. Why? 8X is four stops so slowing down to 1/4 gives you one stop, opening up to f16 gives you three more. 4 x 2 = 8.

Mark_Levesque
09-21-2006, 04:08 PM
I'll go with C. 8X is 3 stops. (1 stop is 2X, 2 stops is 4X, 3 stops is 8X), right?

Michael_Gan
09-21-2006, 04:25 PM
Both of you are half right. Mark is correct that 8x is 3 stops difference. But, C. is a 2 stop difference (f32 to f22 is one stop, 1/8 to 1/4 is 1 stop). D. is a combination of a 3 stop difference.


Michael

Joseph_Froeschle
09-21-2006, 04:33 PM
Yes, It's 3 stops answer "D" is correct.

David_A._Lottes
09-21-2006, 04:34 PM
Gotta love multiple choice! Even though my reasoning was wrong my answer was right. LOL! Thanks for straightening out my math Mark, I forgot to double each time I go up a stop, and thanks for clearing up the answer Michael. So 16-22-32 is three numbers but only two stops difference. Man I KNOW that, why did I think it was three! JEEEZ. This is great, I had no idea I was this rusty. Next question please!

Betsy_Finn
09-21-2006, 05:01 PM
Alright good work guys, D is correct according to the sample sheet as well. Next question!

If focusing on the same subject at the same distance, what will happen to the image size if a 300 mm (12 inch) telephoto lens is used on a 35 mm camera compared to a 300 mm (12 inch) lens used on a medium format camera?

(only 3 options)
a. there will be a larger image size with the 35 mm
b. there will be a smaller image size with the 35 mm
c. there will be no difference in the image size

Don_Chick
09-21-2006, 05:19 PM
Same thing that happens when you take your 300mm lens off your full frame DSLR and put it on a camera with an APS (smaller) sized sensor. The image is larger and you end up with a multiplication factor.

Joseph_Froeschle
09-21-2006, 05:29 PM
A 300mm lens will project the same image size regardless of what camera it's mounted on. The correct answer is "C". The difference is the crop of the sensor or film size.

Derek_Alvarez
09-21-2006, 05:40 PM
The image will be larger

standard MM for 35mm is 50mm and for medium it is 80mm

Mark_Levesque
09-21-2006, 05:48 PM
C. The image size will be the same. The size of the image relative to the size of the frame will be smaller.

David_A._Lottes
09-21-2006, 06:04 PM
I'm with Derek and Don. Your subject will appear closer on the 35mm viewfinder than it does on the medium format viewfinder.

Mark_Levesque
09-21-2006, 06:43 PM
I'm with Derek and Don. Your subject will appear closer on the 35mm viewfinder than it does on the medium format viewfinder.
That is true, but nonresponsive to the question. What happens to the image size, not the size of the image in the viewfinder. The image size itself remains the same. This is a bit of a tricky question, because as a practical matter, the effective image size does change in a predictable and useful to know way. And the tendency is to read the question with that in mind. But a 300mm image circle on a fixed subject at a fixed distance from the lens is the same size irrespective of what is located in the film plane.

David_A._Lottes
09-21-2006, 06:57 PM
Yup it is a tricky one.....Wonder what the answer is? I read it to mean if you create an image with one and then the other, print the neg full frame to 5x7, what will it look like. In that case the 35mm 5x7 will appear as though you were closer to your subject than the medium format 5x7.

Joseph_Froeschle
09-21-2006, 06:58 PM
Maybe this diagram will help explain what Mark said better.

KirkDarling
09-21-2006, 07:38 PM
Joseph is correct. I can lay a negative shot by my Elan right on the groundglass of my view camera, and if the lens focal lengths match, the images match.

David_A._Lottes
09-21-2006, 07:39 PM
Thanks Joseph
But the cropping does change, not because of the lens but because of the camera. I get what your saying and it may be the correct answer, but I wouldn't be surprised if they are asking about the differences in formats as much as they are the sameness of the lens. ;) It's a tricky one.

Betsy_Finn
09-21-2006, 07:58 PM
So, according to the cheat sheet ;) (gee that's nice to have -- it's making me sound extremely smart!!!)

The answer is C. There will be no difference in image size

Looks like this question is meant to capatalize on the confusion between image/subject and frame/cropping terms. The relative size will appear to change, but the actual size of the image is the same. The image/subject will be the same size if you overlaid the two negatives. Joseph's picture does a great job of illustrating this concept.


(hehe, hopfeully I summarized that right!)

Mark_Levesque
09-21-2006, 08:12 PM
:) I needed to redeem myself after the 1st answer. I wasn't paying careful attention when I answered that one. I saw that A was one stop and B was two stops, and david said D was 4 stops, so C had to be 3 stops. Except it wasn't. :o

David_A._Lottes
09-21-2006, 08:20 PM
Don't feel bad Mark. I'm batting 1000! ;)

Next question please.

(I'm bound to get one right.....maybe)

Joseph_Froeschle
09-21-2006, 08:20 PM
So then to continue this just a little further.
Question:

If we use the same focal length lens on several different format cameras why is there a difference in the depth of field?

We've just established that lenses of equal focal length will project the same image circle. Why then would the DOF be different?

Answers?

Derek_Alvarez
09-21-2006, 08:23 PM
Distance to the Film plane

Joseph_Froeschle
09-21-2006, 08:32 PM
Exactly, When we shoot with a smaller format we move back from our subject to aquire the same crop therby increasing the subject to film plane.

Betsy_Finn
09-21-2006, 08:45 PM
A photographer has been asked to photograph some diamond jewelry for a department store. Which of the following styles of lighting would be best to use?

a. back-lit
b. front-lit
c. overhead
d. non-directional


As a twist -- what would be a good example of when you should use the alternate types of lighting?

David_A._Lottes
09-21-2006, 08:51 PM
d. Non-directional. I think I may have gotten one right!!!! :D


Use for back lighting - Silhouettes
Use for front lighting - Crime scene photographs
Use for overhead lighting - Hair light in conjunction with other lighting.

Derek_Alvarez
09-21-2006, 08:53 PM
Wow that is an interesting question

I would say "d"

But I have a jewelry flier here and the lighting is different on each page

So I have no idea of the CORRECT way but if I was doing it I like the look of the side/back lit

Betsy_Finn
09-21-2006, 09:01 PM
Yup it's D. non-directional.

The question specifically asked about diamond jewelry (very tricky :eek: wording) ....and I did a quick search online, the top results didn't really vary in their lighting setups all too much.

I think I can explain the reasoning for non-directional as a choice.... If you are selling diamonds you want the clarity to be emphasized -- this will be most prominent with non-directional lighting, as the light will be able to hit all the different angles/cuts of the diamond.

You also don't want any facet of the diamond to appear muddy/dark/in shadow -- which will more likely occur with directional lighting. Even non-directional lighting should make sure the whole thing sparkles. After all, aren't diamonds supposed to be sparkly and shiny!! :p

David_A._Lottes
09-21-2006, 09:23 PM
NEXT question please! ;)

Betsy_Finn
09-21-2006, 09:34 PM
For the best results, where should the hair light be positioned?

over the subject's hair
below the subject's chin
to one side of the subject
at the center of the subject's nose

Mark_Turner
09-21-2006, 09:37 PM
You know some of these questions make me scartch my head. Sometimes it's the difficulty, and sometimes the absurdity.

Betsy_Finn
09-21-2006, 09:39 PM
hehe ....yup :)

David_A._Lottes
09-21-2006, 09:49 PM
a. Over the subjects hair

I can't believe no one commented on my example of how to use front lighting? "Crime Scene Photography". I thought that was pretty funny!

Betsy_Finn
09-21-2006, 10:03 PM
I can't believe no one commented on my example of how to use front lighting? "Crime Scene Photography". I thought that was pretty funny!
I was going to! :p but then I forgot :eek:

David_A._Lottes
09-21-2006, 10:06 PM
When I took the exam a hundred years ago there were questions about color wheels. Additive printing/subtractive printing etc. Anything like that still on the test?

Betsy_Finn
09-21-2006, 11:57 PM
yup...most definitely. The only "sample" question about color theory I'm giving out now! (oops, I lied. There's two....so we'll do one at a time).

When going clockwise around the color wheel with red on the top, the progression of colors is:
cyan, magenta, yellow, green, blue
green, blue, yellow, magenta, cyan
magenta, blue, cyan, green, yellow
yellow, green, cyan, blue, magenta

Mark_Levesque
09-22-2006, 12:28 AM
C. magenta, blue, cyan, green, yellow

Mark_Turner
09-22-2006, 01:16 AM
I agree. Really I do. (The message was too short.)

Joseph_Froeschle
09-22-2006, 01:39 AM
RGB
Red, Green, Blue
Between Red and Green is Yellow
Between Green and blue is Cyan
Between blue and red is magenta

so I'll go with answer "D".

Red, yellow, green, cyan, blue, magenta.

KirkDarling
09-22-2006, 02:14 AM
So, according to the cheat sheet ;) (gee that's nice to have -- it's making me sound extremely smart!!!)

The answer is C. There will be no difference in image size

Looks like this question is meant to capatalize on the confusion between image/subject and frame/cropping terms. The relative size will appear to change, but the actual size of the image is the same. The image/subject will be the same size if you overlaid the two negatives. Joseph's picture does a great job of illustrating this concept.


(hehe, hopfeully I summarized that right!)

That confusion only came into existance with the marketing of APS-C DSLRs. All this "crop factor" and "magnification" factor mumbo-jumbo. Old-school folk who used multiple formats didn't have a problem with it, especially those who used a view camera and a smaller format.

Betsy_Finn
09-22-2006, 02:20 AM
RGB
Red, Green, Blue
Between Red and Green is Yellow
Between Green and blue is Cyan
Between blue and red is magenta

so I'll go with answer "D".

Red, yellow, green, cyan, blue, magenta.
The correct answer is D.

Here's a picture to help clarify (it's from Photography 8e)

KirkDarling
09-22-2006, 02:23 AM
So then to continue this just a little further.
Question:

If we use the same focal length lens on several different format cameras why is there a difference in the depth of field?

We've just established that lenses of equal focal length will project the same image circle. Why then would the DOF be different?

Answers?

There is no difference in depth of field in the original image. The difference comes when you enlarge the different sized formats by different factors to reach the same final display size.

Using a subject at the same distance, put a 200mm lens in front of a piece of 35mm film or in front of a piece of 4x5 film--the optical distance between the optical center of the lens and the film in both cases will be 200mm. The image size will be the same. The size of blur circles as a point of light is distanced from the focal plane remains the same.

If you chop a 24x36mm piece out of the 4x5 negative and enlarge that piece to 8x10, it will have the same depth of field as the 35mm negative enlarged to 8x10.

But if you take the entire 4x5 sheet and give it a 2x enlargement to 8x10, it will actually have more depth of field than the 35mm negative given an 8x enlargement to 8x10. You can go here and run various numbers through for each format (keep all the factors the same, just change the film format) and see: http://www.dofmaster.com/dofjs.html

KirkDarling
09-22-2006, 02:32 AM
Exactly, When we shoot with a smaller format we move back from our subject to aquire the same crop therby increasing the subject to film plane.

Nope. You said: We've just established that lenses of equal focal length will project the same image circle. Why then would the DOF be different?

If you really meant "image size" (rather than "image circle" because lenses of the same focal length may very well project different sized image circles), then the depth of field will be the same for either format. You didn't say anything about moving the camera.

What we had just established was that if the focal length and the image size are the same (thus, the distance from the lens' optical center to the subject is the same), then on the image everything else is the same, including depth of field. We see a difference in depth of field only when we enlarge the image by different factors to reach the same final display size.

KirkDarling
09-22-2006, 02:35 AM
A photographer has been asked to photograph some diamond jewelry for a department store. Which of the following styles of lighting would be best to use?

a. back-lit
b. front-lit
c. overhead
d. non-directional


As a twist -- what would be a good example of when you should use the alternate types of lighting?

We discussed this before, and determined that none of the choices was optimum (snooting lights would produce the optimum sparkle and clarity), but the key wording here is "which of the following." "Non-Directional" is the lease offensive of those given.

KirkDarling
09-22-2006, 02:37 AM
yup...most definitely. The only "sample" question about color theory I'm giving out now! (oops, I lied. There's two....so we'll do one at a time).

The fact that there were two sample questions should make your antennae rise.

Betsy_Finn
09-22-2006, 02:48 AM
The fact that there were two sample questions should make your antennae rise.Very true. A chapter to study very carefully ;). Onto the next color question we go....

Which of the following is created when equal amounts of yellow, magenta and cyan filtration are combined over a single light source?

Blue
White
equal amounts of red, green and blue are reflected
equal amounts of red, green and blue are absorbed

Joseph_Froeschle
09-22-2006, 02:56 AM
Yes Kirk you are absolutley right I did not say anything about moving the camera position and I did mean image size.

However, from a pratical point we move farther away from a subject to obtain a similar crop in the camera when using the smaller format digital cameras as compared to cameras with larger sensors or film size. Or I guess we can also use wider angle lenses.

For instance a 200mm lens at f/8 on 35mm and subject distance of 20 feet yeilds a DOF of 1.42 feet.

Put that 200mm lens on an small format digital camera (fuji s3) and we would have to move the camera position back to about 30 feet to obtain a similar crop of our subject. This would increase the DOF to 2.15 feet.

I appologize if I wasn't clear about how I presented this.

KirkDarling
09-22-2006, 03:11 AM
Yes Kirk you are absolutley right I did not say anything about moving the camera position and I did mean image size.

However, from a pratical point we move farther away from a subject to obtain a similar crop in the camera when using the smaller format digital cameras as compared to cameras with larger sensors or film size. Or I guess we can also use wider angle lenses.

Until I bought my 5D, I was still using my Mamiya RZ 6x7 along with my 20D. I have always thought about focal lengths and formats in terms of "difference from normal."

The "normal" focal length for the RZ is 90mm. The "normal" for the 20D is 28mm (the normal focal length is the length of the diagonal of the format).

If I'm using a 180mm lens on the RZ for a portrait and decide to take a few identical shots with the 20D, I see that the 180mm is 2x the normal length for that camera, so I mount a lens that is 2x the normal length for the 20D--which would be about 60mm (actually, I zoom to about 60mm or the closest point possible).

I don't change my distance to subject, because that would also change the perspective.

Mark_Levesque
09-22-2006, 03:13 AM
I always get killed by the color ones. And the filtration ones.

I'll say c. equal amounts of red, green and blue are reflected

KirkDarling
09-22-2006, 03:18 AM
Looking back at your color wheel, each color filter absorbs/filters/removes the color opposite on the wheel. Thus, equal amounts of red, blue, and green are absorbed.

Pitfall: The "distractor" here is "white," because we learned in school that if you mix all the primary colors of light together, you get white. But with "filtration" we're not mixing color, we're subtracting color.

Joseph_Froeschle
09-22-2006, 03:30 AM
I was always taught that Cyan, Magenta, and Yellow are called the subtractive primaries. So I'm with Kirk on this one. Equal amounts of RGB are absorbed.

Mark_Levesque
09-22-2006, 03:31 AM
Naturally. That was my first answer, but since I always get the filter questions wrong, I changed it. Grrr. One of these days I'm gonna have get the London book.

Joseph_Froeschle
09-22-2006, 03:35 AM
The "normal" focal length for the RZ is 90mm. The "normal" for the 20D is 28mm (the normal focal length is the length of the diagonal of the format).

If I'm using a 180mm lens on the RZ for a portrait and decide to take a few identical shots with the 20D, I see that the 180mm is 2x the normal length for that camera, so I mount a lens that is 2x the normal length for the 20D--which would be about 60mm (actually, I zoom to about 60mm or the closest point possible).



I had completly forgot that the diagonal of the format is equal to the normal focal length. It's a good rule to know and remember.

Don_Chick
09-22-2006, 02:58 PM
Betsy,

Thanks for starting this thread.

It's been good to review this info and put it back in the front of the braincells!
This has been a very productive thread (imho).

Betsy_Finn
09-22-2006, 04:08 PM
Betsy,

Thanks for starting this thread.

It's been good to review this info and put it back in the front of the braincells!
This has been a very productive thread (imho).
No Problem! THanks to David for suggesting we start a thread :)

Are we ready for the next question or shall we wait a bit longer?

David_A._Lottes
09-22-2006, 04:34 PM
Next question please! :)

Betsy_Finn
09-22-2006, 04:55 PM
Ok, here we go:

Which of the following will be produced when a large white umbrella is used close to a subject?

minimal effects of flare
flat, low contrast results
crisp, sharp, richly saturated results
enhanced texture, color, and shadows

Mark_Turner
09-22-2006, 05:08 PM
B. Low Contrast, if in front.
D. Enhanced texture, color, and shadows, if to the side.

How large, I wonder?

Renee_Giugliano
10-01-2006, 01:52 AM
I think I know this one from my own personal mess-ups while trying to learn how to use studio lights...

I say:
B - Flat, low contrast results

Betsy_Finn
10-01-2006, 02:28 PM
B is correct.


:) Any discussion on this one or you guys ready to move on?

Don_Barnes
10-01-2006, 02:55 PM
Exactly, When we shoot with a smaller format we move back from our subject to aquire the same crop therby increasing the subject to film plane.

In your answer you stated that you move back from the subject. Moving back will change the depth of field. If you have a 70-200 make one shot at 70mm, then without changing exposure or moving the camera zoom to 200mm and take the same shot. Enlarge the 70mm shot to only include the area from the 200mm shot and you will find that they have the same depth of field.

Michael_Gan
10-01-2006, 04:47 PM
B is correct.


:) Any discussion on this one or you guys ready to move on?For those of you lucky enough to see Dean Collins, he would demonstrate why b. is the correct answer. The closer you bring the light source, the less you have specular highlights, thus lowering the contrast. Interestingly, the closer you have the light, the less glare you have on glasses!

Michael

KirkDarling
10-01-2006, 07:10 PM
Ok, here we go:

Which of the following will be produced when a large white umbrella is used close to a subject?

minimal effects of flare
flat, low contrast results


BTW, let me correct a mistake that was not made here.

You will sometimes hear someone say that you decrease contrast by moving the subject farther from the light source. A person who says that is confusing two concepts of "contrast"...but he's not wrong.

When discussing contrast and lighting, we are normally talking about the quality of the "shadow terminator," that is, the edge of the shadow. A sharp, acute, distinct, hard transition from highlight to shadow we say is "contrasty light," while a long transition, indistinct, smooth we say is "soft light." We know that when we make the light larger in relation to the subject (such as by moving the subject closer to the light), it broadens the transition from highlight to shadow, so we say it makes the light "softer."

However, "contrast" can also refer to the difference in the reflectance value between portions of the subject. A great difference in reflectance, such as the difference between absolute black and absolute white we say is a "great contrast," while between two close grays we'd say we have "low contrast." When we move the subject away from the light, we can actually decrease this difference between shadow and highlight because of the inverse square law.

Let's say we face a subject to our soft box and move it so that it's only one foot from the tip of her nose. The light is 12 inches from the tip of her nose, but it's 18 inches from the lobe of her ear--a difference of 50% farther. That difference means a correct exposure for her nose will underexpose her earlobe by a whole stop.

Pull the light away so that it's six feet from the subject's nose. It's now 72 inches from her nose, but 78 inches from her earlobes, a difference of less than 8%...which is negligible. So by moving the subject away from the light, we have decreased the difference between parts of the subject are closer or farther from the light.

How can we use this? Let's say we want to photograph a bridal couple. If we place them both very close to the window, but one is a bit closer to the window than the other, we may get a significant difference in exposure between them. If we move them both farther from the window, we can keep the same relative posing position--but now they are both at the same exposure level.

Valerie_Harte
10-17-2006, 07:35 PM
Ahhh Kirk don't confuse me- I had it.... LOL...

Seriously, thank you. I just read this entire thread and I really like the "how we use this information" pieces. It makes some of the official terminology stick better with me.

David_A._Lottes
10-17-2006, 08:08 PM
Well it looks like Betsy won't be posting any new questions now that she has passed the image submission and taken the exam. :p So......Anyone else want to "STUMP THE CHUMPS"! Post a question from the CPP sample exam and see how many different answers you get. Don't tell us what's correct until you think the it's about to come to blows. :D

Betsy_Finn
10-18-2006, 02:16 PM
Well it looks like Betsy won't be posting any new questions now that she has passed the image submission and taken the exam. :p So......Anyone else want to "STUMP THE CHUMPS"! Post a question from the CPP sample exam and see how many different answers you get. Don't tell us what's correct until you think the it's about to come to blows. :D
Honestly, I've been having troubles keeping on top of threads without my user CP!! :p

We're over halfway through the sample questions, I think. But, I'll post a new one :cool:



JPEG compression is the key to
enhancing images
expanding memory
adding more pixels to the file
keeping large images manageable

Cassandra_Sullivan
10-18-2006, 02:39 PM
JPEG compression is the key to

D: keeping large images manageable