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need help finding zoom calculators/ ratios
Zack Podell, Photographer, Assistant
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Marina Del Rey | CA | USA | Posted: 3:33 AM on 05.03.06 |
->> So I have been searching (to no avail, as of now) the web for a site that has calculations for zoom ratios (in focal lengths) for 1/3 inch CCD's.
Is there any resource out there that would tell me exactly what lens would be equivalent to a 3x zoom for 1/3 inch ccds?
Any help would be greatly appreciated.
Thanks in advance.
ZAP |
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Amir Gamzu, Photographer
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Ann Arbor | MI | USA | Posted: 9:09 AM on 05.03.06 |
->> Ok, hopefully someone will correct me if I'm wrong, but from my understanding;
zoom ratios are simply how much further it can 'zoom' in from the widest focal length, example would be
a lens that’s 100-300 will be a 3X zoom
a lens that’s 20 - 60 is also a 3X zoom
it has nothing to do with max or min focal length, only to do with magnification amount
Now, as I said I'm not 100% on this, but if you look around the market you only see this system of describing lenses at the consumer level (P&S digital and video), I have never heard that used on an SLR lens, medium or large format. |
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Zack Podell, Photographer, Assistant
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Marina Del Rey | CA | USA | Posted: 4:02 PM on 05.03.06 |
->> Sorry, I was using improper terminology...... how do I calculate focal length and magnification.
What I need is 1x, 2x, and 3x magnification of several ccds, namely the 1/3 inch CCD. Most of us know these in relation to 35mm, (like 50mm being pretty close to a 1x).
I had my head up my A** when I posted previously..... (I apologize) I never should have used the word "Zoom" I was thinking magnification...... and talking zoom.
Amir, you're pretty much right...... It was my brain fart that caused the misunderstanding.
Thanks in advance. |
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Zack Podell, Photographer, Assistant
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Marina Del Rey | CA | USA | Posted: 3:01 PM on 05.05.06 |
| ->> anyone???? |
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Thierry Gourjon, Photographer
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New York | NY | USA | Posted: 5:07 PM on 05.05.06 |
->> Zach,
I am a little confused by your question: The focal lenght of a "normal" lens is approximately equal to the diagonal measurement of the film format used, and a "normal" lens sees and records the subject much as the eye sees it (approx. 46 degree angle). Then,as you stated, 50mm is normal for a 35mm neg, 80 mm for 2 1/4 by 2 1/4, 150 mm for 4 by 5 inch and so on.
If I understand your question correctly, all you need is the diagonal measurement of the CCD. That will give you the normal focal lenght for that CCD and you can extrapolate from there.I am not sure where you would get those specs but if you can get them, wouldn't that solve your question and my headache?
T. |
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Tom Dahlin, Photographer
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St. Louis Park | MN | USA | Posted: 10:48 PM on 05.05.06 |
->> Zack,
This should help:
http://www.dpreview.com/news/0210/02100402sensorsizes.asp
One of the bibles for all things photo and optical is 'The Manual of Phtography, Photographic and Digital Imaging' by Ralph Jacobson et al. It has lots of technical data in it like you are looking for. Unfortunatly I can't easily copy and paste from it. But you might want to get a copy of you do much of this sort of thing.
Cheers
Tom |
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Vern Verna, Photographer
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Greenville | SC | United States | Posted: 11:23 PM on 05.07.06 |
->> zach, i am still not sure of ur question but i think u r asking what is say normal focal length for say a mark ii etc?
first off, i think i am correct on all the info but if not someone correct me as this is the way i understand it.
35mm film is 24x36mm so
a mark ii has a 1.3 mag factor so the sensor is 24/1.3 x 36/1.3 or 16x24 and thus a normal lens is calculated by the sqaure root of (the squared of the length plus the square of the width) so a 35mm film is square root of (24x24)+(36X36) or give or take the 46mm which we always equate to the 50mm lens.
so on a mark ii it is the sq. root of 16x16+24x24 or sq root of 832 or 29ish. u can also figure roughly taking 46mm/1.3 since it is the conversion factor.
the nikon r 1.6 if i remember right so take the 24x36 and divide each by 1.6 and do the math.
hope this helps and if not i try to clarify more |
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Baron Sekiya, Photographer
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Kailua-Kona | HI | USA | Posted: 5:20 AM on 05.08.06 |
->> Like others I'm not sure about the question you seek the answer to but if you have a Palm PDA I wrote a free application that gives a person an idea of what different sized sensors will seem like in the 35mm film world.
Here's the shortened link: http://tinyurl.com/f76ak
Dont' know if that will help, if you don't have a Palm PDA it won't. |
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Zack Podell, Photographer, Assistant
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Marina Del Rey | CA | USA | Posted: 2:58 PM on 05.08.06 |
->> Ok..... to hopefully end the confusion....
I needed to find a way to calculate the focal lengths for 1/3 inch CCDs, among others.
Tom's post helps alot, since I could not find measurements for the various sensors.... And I needed to figure out what a 3x maginfication on that sensor would be.
Any more help/ resources would be appreciated. |
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