Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-12-2010, 02:41 PM   #1
Veteran Member
jaieger's Avatar

Join Date: Jul 2010
Photos: Gallery | Albums
Posts: 586
Question on Magnification Ratios

Hi all, just wanted to get a confusion cleared up about the magnification ratios..What do they mean, exactly? If a lens has a max magnification ratio of 1:1, or 1:2:7, or 1:3x10^8, what does that mean? Also, why are macro lenses only considered macro (in the purest sense) at a 1:1 ratio? In my mind, a 1:1 ratio means the subject (let's say, an ant) would appear in the picture at a 1:1 ratio of how it appears in real life, ie., 3-4 cm or something on an 8x12 print or 5x7 print or whatever.

07-12-2010, 02:52 PM   #2
Pentaxian




Join Date: Feb 2009
Location: Alameda, CA
Posts: 3,194
QuoteOriginally posted by jaieger Quote
In my mind, a 1:1 ratio means the subject (let's say, an ant) would appear in the picture at a 1:1 ratio of how it appears in real life, ie., 3-4 cm or something on an 8x12 print or 5x7 print or whatever.
Almost correct.

Using your words: a 1:1 ratio means the subject (let's say, an ant) would appear on the camera's sensor at a 1:1 ratio of how it appears in real life.

The width of the APS-C sensor in a Pentax DSLR is about 24 mm. Here is a photo of 1:1 (note the ruler in the background):




So 1:2 ratio means the subject appears half as large on the camera's sensor as it it in real life.
07-12-2010, 03:04 PM   #3
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,312
correct SOldBear, Ideally people would always relate to the image projected only by the lens, but unfortunately people get this idea to , for example talk about the focal length factor of the cropped sensor. That really screws things up, as opposed to discussing field of view, which is correct.

one thing to point out however is that when discussing shutter speed to stop image blurr, and depth of field, both of these issues are a function of print size, because you are more likely to notice the lack of sharpness the bigger something is printed.
07-12-2010, 03:21 PM   #4
Veteran Member
jaieger's Avatar

Join Date: Jul 2010
Photos: Gallery | Albums
Posts: 586
Original Poster
Hmm, okay. And what about the ratios that have 3 numbers, what does that mean?

07-12-2010, 03:34 PM   #5
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,312
An example of three ratios would be helpful
07-12-2010, 03:40 PM   #6
Veteran Member
jaieger's Avatar

Join Date: Jul 2010
Photos: Gallery | Albums
Posts: 586
Original Poster
I don't know exactly where I've seen them, but I know it's not uncommon, cause I have seen it multiple times...magnification ratios stated as 1:2:7 or 1:2:4, etc.
07-12-2010, 03:46 PM   #7
Pentaxian




Join Date: Feb 2009
Location: Alameda, CA
Posts: 3,194
QuoteOriginally posted by jaieger Quote
I don't know exactly where I've seen them, but I know it's not uncommon, cause I have seen it multiple times...magnification ratios stated as 1:2:7 or 1:2:4, etc.
I think they are 1:2.7 or 1:2.4.

Same thing applies: The size in real life is 2.7 (or 2.4) times as large as the size on sensor.
07-12-2010, 09:30 PM   #8
DAZ
Veteran Member
DAZ's Avatar

Join Date: Sep 2006
Location: Everett, WA USA
Photos: Gallery
Posts: 699
One more thing to point out. This ratio is usually when the object is closest point to the lens that it can focus on i.e. minimum focal distends. So if you have 2 lenses that are 100mm both will give the same FOV but if 1 can focus to 3 feet and give a 1:1 and the other only 6 feet then it maybe 1:2.
DAZ

07-13-2010, 09:45 AM   #9
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
Magnification ratios are never given as 1:2:4. It's possible you've seen something like 1:2,4 if the number was provided by someone in a country that uses commas instead of periods for decimal points (eg, much of Europe, I believe).

As for why 1:1 is considered "true" macro, it's just a convenient round number to use. it's not like there is some magic line that makes 1:1 that much better than 1:1.2. Kind of like in baseball a hitter is considered good if he hits .300, but it's not liek that's relly that much better than if he hits .291.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, macro, magnification, pentax help, photography, print, ratio
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Aperture and Light Ratios D4rknezz Photographic Technique 5 06-18-2010 12:37 PM
Please help with Lighting and Ratios.... D4rknezz Photographic Technique 7 06-14-2010 03:09 PM
Magcro Magnification Ratio Question GregK8 Pentax SLR Lens Discussion 18 03-16-2010 10:17 PM
AF-540 flash ratios jedcrocker Flashes, Lighting, and Studio 0 01-25-2010 07:29 PM
Macro Magnification ccallana Pentax SLR Lens Discussion 3 04-20-2007 03:03 PM



All times are GMT -7. The time now is 05:01 AM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top