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Photography Question 
America B
 

Is There a Big Difference Between f/1.4 & 1.8??


I am wanting to purchase a 50mm lens and wonder if I will see a big difference between f/1.4 and f/1.8... My use for this lens would be shots of children using available light. Thanks.


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7/9/2003 12:09:18 PM

 
Maynard  McKillen   Dear America:
It's not vital to know this, but perhaps helpful - which brand of camera do you have?


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7/9/2003 8:54:08 PM

 
America B   I have a Canon D60 & also a Canon 10D, I would interchange the lens between the two. Thank you in advance for your help and opinion.


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7/9/2003 9:01:46 PM

 
Maynard  McKillen   Dear America:
Perhaps you've noticed a slight difference in price between the two? It may reflect the fact that the EF50mm f/1.4 is a bit more challenging to manufacture well, and is likely made in smaller quantities than the EF50mm f1.8.
The EF50mm f/1.4, with its slightly larger maximum f/stop, is slightly better at shooting in available-light-only situations than the EF50mm f/1.8, given that you use each lens at its' maximum aperture. By letting in slightly more light at maxumum aperture, you will sometimes be allowed to shoot at a slightly higher shutter speed with the f/1.4 lens than you would with an f1.8 at its maximum aperture. This can make it slightly easier to get a sharp photo when you handhold the camera and when your subjects are less than completely still.
The slightly larger maximum aperture on the f/1.4 will produce a slightly brighter image on the focusing screen, too, making it slightly easier to compose your photo in low light.
Do you know anyone who will loan you one or both lenses? Can you rent one locally? Other contributors may have leads on the technical specs of each lens, or reviews and testimonials.


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7/9/2003 10:01:31 PM

 
America B   Quite a price difference is the reason I was inquiring. It seems to me that I would be happy with the f/1.8 as I am getting by with f/3.5 now. My only reason for wanting a lense with a larger aperture is to gain shutter speed with photographing my children. Unfortunately, I live in SD(woohoo!!) so nothing local. I thank you very much for your halp on this matter, Maynard. Take care, America.


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7/9/2003 10:14:35 PM

 
Jeff S. Kennedy   I'm getting ready to buy a 50mm and I'm going for the f1.4. It never hurts to have more speed. I am going to use it on my 10D for a portrait lens (it will be equivalent to an 80mm f1.4) and I like to shoot portraits wide open to keep the DOF as short as possible. The f1.4 will be great for that. There's a comparison on Photo.net between the two lenses that you might find interesting.


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7/11/2003 9:51:57 AM

 
America B   Thanks, Jeff, for the info. I will definetely check out the comparison on Photo.net. I'm cheap, what can I say, there is like a $200 difference between the 2 and that's a lot of money to me so that's why I inquired. I think I may just hold out for the 1.4 per your recommendation. Thanks again, America.


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7/11/2003 10:19:08 AM

 
Jeff S. Kennedy   You should note that I shoot for money so I will almost always go for speed. If you just shoot for a hobby the 1.8 may be all you need. When I bought my 85mm I had a choice between the f1.8 and f1.4 and opted for the f1.8 because of the huge price discrepency. And the quality of the f1.8 is excellent. But it will be really nice to have an even faster lens in my arsenal in the 50mm f1.4.


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7/11/2003 10:33:43 AM

 
America B   Thanks Jeff.


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7/11/2003 11:49:50 AM

 
Artur    Hi, I have both lenses and both cameras and will not use 1.8 any more after I try 1.4. It is much sharper lens and at wide aperture has beautiful selective focus effect.


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7/15/2003 7:16:39 AM

 
John A. Lind
BetterPhoto Member Since: 9/27/2001
  To directly answer your question, the difference between f/1.8 and f/1.4 in pure aperture is 2/3rds of an f-stop. Full f-stops are the following sequence:
f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32

In terms of the amount of light admitted by the lenses when their apertures are wide open, an f/1.8 lens admits about 63% of the light admitted by f/1.4 lens. By comparison, an f/2 lens admits exactly half the light.

From a practical exposure standpoint 2/3rds of an f-stop isn't much. While it's enough to make a noticeable difference for slide film exposure, it's just barely noticeable for negative film exposure (depends on the film latitude). It won't make an enormous difference in low light; usually it's ability to get something not the best and marginal versus dead on. It can allow bumping up the shutter speed to stop motion or mitigate shake, but again you would have to be just barely too slow with the f/1.8 for the f/1.4 to make a difference. In addition, shooting a 50mm f/1.4 wide open at distances of 20 feet or less has a very shallow depth of field. Doing so is often a deliberate compromise to to get a proper exposure.

IMO, the two much more practical differences with the f/1.4 lens are:
(a) Gaining the noticeably brighter viewfinder that Maynard mentions; it enables faster and more accurate focusing in low light
(b) Having noticeably improved optical qualities that Artur mentions.

Some portion of the higher cost for the f/1.4 lens is the "bigger glass" which is a little more expensive to make, but the greater portion of the higher cost is for its better optical qualities. The market segment for the f/1.4 is more demanding of the optics and has higher expectations for overall optical performance.

-- John


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7/15/2003 11:50:31 AM

 
Doug Vann   I had a Canon 50mm f1.8 lens which I sold when I got a much more expensive Canon L lens. However the 1.8 lens gave excellent pictures even for enlarging. It is possibly the best bargain in the Canon lens lineup. If you don't abuse it you should get great pictures and long life however don't drop this lens as I have heard it won't take it.


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7/15/2003 3:20:29 PM

 
Hank Greenfield   All very good advice.
Lets look at the situation from a slightly different angle.
I am assumiong you are using a flim camera.
Check the accuracy of the rated ISO of your film. According to ANSI spec, any manufacturer is able to market any film that is within half a stop of its rated ISO. This means that an ISO 400 film will be anywhere between 200 and 600 effective speed.
When we buy a few rols at a time at the local store, we are not paying attention to emulsion numbers. Different emulsions of the same film can take the allowed half stop spread and actually exhibit up to a full stop difference.
Speaking of manufacturing variability - just how close to the rated f1.4 or f1.8 do you think that lense is?
Lenses are manufactured in batches too (so are antibiotics, don't get me started).
There are quit a few good books out that will tell you just how to test a film emulsion to determine just what the speed is and just where the color balance and contrast index falls.
Professional film is better.
You will need a referance strip. McBeth makes one that has been the industry standard for 30 + years. Its worth the money and will be a lot cheaper then getting the larger lense.
Good luck and keep asking questions.

Hank Greenfield


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7/16/2003 7:43:47 AM

 
Jeff S. Kennedy   I'm not exactly clear on the relevance of Hank's post but as long as he made it I will make a correction to it. 1/2 stop under ISO400 would be 300 (320) not 200. 200 is a full stop. A minor point.


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7/16/2003 10:59:01 AM

 
America B   First, I would like to thank everybody very much for taking the time to help me out! All the info is much appreciated, however maybe I should have been more clear on my question. I I only use digital, no film. And basically was wondering if I would be happy or not with the Canon 50mm f/1.8 or if I should spend the xtra $200 and go with the f/1.4. My outlook is one that my fastest lens right now is one that opens to f/3.5 so the f/1.8 would be a world of difference. THis lens would be used strictly for photographing my children in available lighting conditions. Thanks again for everybodys help, I think that I may just try out the 1.8. Thanks all!


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7/16/2003 11:34:39 AM

 
Jeff S. Kennedy   I think that's probably the best plan. I doubt you could go wrong with either lens. And since the 1.8 is pretty cheap it wouldn't hurt to go with that first. One of the reasons I'm going for the 1.4 that I didn't mention above is that since digital has inherently more DOF I want a lens with as wide an aperture as possible.


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7/16/2003 12:31:52 PM

 
Hank Greenfield   Me again,

I was wrong and I stand corrected. Half a stop range from ISO 400 would be 300 to 500, not the 200 to 600 I mentioned.
I think this is a large gap when you are considering paying $200 extra for a fraction of an f stop. The point is that whichever lense you choose, if you are using commercial film behind it, the film will have more "noise" in the system then the lense can correct. Whatever advantage you think you are gaining by spending the extra money could be lost by the variability of the film.


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7/17/2003 8:50:57 AM

 
Jeff S. Kennedy   LOL! Actually Hank you were half right before and now you're half right again. 1/2 stop below ISO 400 is 300 and 1/2 stop over 400 is 600. Not to be anal just don't want anyone getting confused. ;-)))


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7/17/2003 11:52:38 AM

 
America B   Jeff & Hank...You guys are soooo funny! I'm glad I don't shoot film cuz I'd be real confused! Take care, America.


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7/17/2003 12:30:05 PM

 
Jon Close
BetterPhoto Member Since: 5/18/2000
  (a) While the EF 50 f/1.4 USM is more expensive due to larger, more difficult to manufacture high-refraction glass elements, and slightly better optics than the EF 50 f/1.8 II, it has other appealing features besides being 2/3-stop faster. It has USM (UltraSonic Motor) autofocus for very fast/silent autofocus. It is also much better to use in manual focus than the f/1.8. The f/1.8 has a tiny and very loose manual focus ring and no focus distance scale, while the f/1.4 has a wider, damped focus ring and also features full-time manual focus - can manually override the af without switching the AF/M switch. It has somewhat more sturdy build and the mount is metal instead of plastic.

(b) 1/2 stop in ISO is a factor of ~1.41, so 1/2 slower than 400 is 280, not 300, and 1/2 faster is 560, not 500. Not that it matters as a practical matter as film is generally rated by the manufacturer in 1/3 stop intervals, as is the ISO setting on most cameras: 25, 30, 40, 50, 64, 80, 100, 125, 160, 200, 250, 320, 400, 500, 640, 800, 1000, 1250, 1600, 2000, 2500, 3200, 4000, 5000, 6400.


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8/26/2003 5:36:13 AM

 
John P. Sandstedt
BetterPhoto Member Since: 8/8/2001
Contact John
John's Gallery
  18 answers/comments on your question. But, is anyone thinking clearly here?

Most winning pictures are taken at f/5.6 to f/11. Most pros have given up writing down the exposures they take because they are using autofocus cameras, so we don't really know what lens opening was used.

It's hard to imagine you'll be taking a lot of pictures that "require" f/1.4 but, if you do, you probably should consider using flash, too.

I have a read a lot of lens reviews in the last 30 years. Most suggest, or state specifically, that at the widest opening the results are NOT as good as when one uses something slightly smaller. In other words, f/2.8 might just get you a better, sharper picture after all.

The difference in cost between an f/1.4 and an f/1.8 lens will buy a lot of film, media cards, printing ink and paper, maybe a new printer.

But, I'm a conservative who doesn't believe in the need for a digital camera. So, I'd opt for more film.


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8/27/2003 3:10:05 PM

 
Wayne Attridge   Just an opinion. I have a 1.8 50mm and a 1.4 50mm. I find the pictures a little sharper with the 1.4 even at a smaller aperture.


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8/28/2003 3:31:29 AM

 
Maynard  McKillen   Little did she know that, without intending to, America had spawned the question that would not die! It lives on still, stalking the innocent, preying upon the unwary, lurking in the shadows. There it is now! Somebody wrestle it to the ground! Hand me that wooden stake...


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8/29/2003 8:03:02 PM

 
John A. Lind
BetterPhoto Member Since: 9/27/2001
  Maynard:
This one has a l_o_n_g way to go before it catches up with the thread about the International Library of Photography: 50+ and still climbing! You might be able to deal with this one using only a wooden stake. The ILP thread will require circus tent stakes plus all of the Lone Ranger's silver bullets, and burial in a bed of garlic under the shadow of a crucifix . . . and that's still no guarantee it won't resurrect itself on some Friday the 13th in the future.

-- John


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8/29/2003 9:38:37 PM

 
Wayne Attridge   Now that it's been said, the game is on . We shall not let it die. If an f1.8 lens was good enough why would manufacturers bother with a 1.4 or a 1.2?


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8/29/2003 10:48:51 PM

 
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