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10-20-2008, 05:53 AM   #1
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Noticable difference between 1.4 and 1.8?

I had the 50 1.4 at one point but traded it in when I got the 31ltd 1.8 thinking that if I was only to have a few lenses, the 31mm would probably cover me for 50mm situations. Now I'm wondering, with regards to the low light birthday picture type photo's that are blurred, would there be a significant difference between 1.4 and 1.8?
Thoughts are appreciated.

10-20-2008, 06:09 AM   #2
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a blurred picture is a blurred picture in my book
10-20-2008, 06:12 AM   #3
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What difference are you referring to? The ability to blur out of focus areas or gather light?

1.4 is great but keep in mind that shooting so has a very shallow DOF so it's easier to shots that are out of focus.
10-20-2008, 06:51 AM   #4
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DOF wise, the 31/1.8 would have a deeper one than the 50, due to both focal length and aperture.

The difference between 1.8 and 1.4 is 2/3 stop:
F-number - Wikipedia, the free encyclopedia

So all things being equal, you COULD increase shutter speed by 2/3 stop using the 1.4 lens. However focal length vs shutter speed and DOF are the trade offs.

10-20-2008, 07:05 AM   #5
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So in real terms an 2/3 stop difference means you need 1.67 x the amount of light to capture the same scene. f stops are exponential, so a lens that is 1 stop slower needs 2 x the amount of light and a lens 3 stops slower needs 8 x the amount of light (eg f1.4 vs f4) to get the same shutter speed.

So you will be shooting at slow speeds and increasing the chance of blur. Also to the 2 specific lenses here, the FA50mm f1.4 will focus faster than the FA31mm f1.8. They are just different lenses this way. The 31mm is a bit slower and much more suited for a scene where you can take more time. Fast action is not it's strength although the lens does just about everything else well or exceptional. I suspect the design has a fast speed not so much for light gathering rather but for image control which are very different. The fast aperture is to control the DOF and render the 3D types of images this lens is famous for.

The 31mm is an artist's lens not an action lens.
10-20-2008, 07:13 AM   #6
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Buy a flash already, bounce it off the sealing. The pictures are MILES better and i mean MILES better than trying to squeeze out an image with really shallow DOF. At 1.4 the DOF is too narrow IMHO, certainly for non-artsy people photos.

I bought the 360 flash and even this el-cheapo means I get better results with the kit lens than the 50/1.4.
10-20-2008, 07:24 AM   #7
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QuoteOriginally posted by Alfisti Quote
Buy a flash already, bounce it off the sealing. The pictures are MILES better and i mean MILES better than trying to squeeze out an image with really shallow DOF. At 1.4 the DOF is too narrow IMHO, certainly for non-artsy people photos.

I bought the 360 flash and even this el-cheapo means I get better results with the kit lens than the 50/1.4.
We have a winner
10-20-2008, 08:24 AM   #8
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beaumont,
The difference in focal lenght will mean that you will be much closer to the subject with the 31mm when composing the same shot. This will result in comparable DOF withe 50mm at a greater distance. the 31mm will be at least 2/3rds of a stop slower of course. The 50mm may be to long to allow shooting groups indoors. I would go with the 31mm and bounce flash as mentioned in earlier post. Myself, I would use either my 24mm or 20mm indoors to get as many people in focus as possible.

Dave


QuoteOriginally posted by beaumont Quote
I had the 50 1.4 at one point but traded it in when I got the 31ltd 1.8 thinking that if I was only to have a few lenses, the 31mm would probably cover me for 50mm situations. Now I'm wondering, with regards to the low light birthday picture type photo's that are blurred, would there be a significant difference between 1.4 and 1.8?
Thoughts are appreciated.


10-20-2008, 09:42 AM   #9
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QuoteOriginally posted by Alfisti Quote
At 1.4 the DOF is too narrow IMHO, certainly for non-artsy people photos.
Well. I'm not sure about the "artsy people photo" statement, but I agree that DOF at 1.4 is pretty narrow for most people shots. Not for the creative aspect, but - as soccerjoe5 pointed out - because it is easy to miss your shots. 70% of my shots at F1.4 are crap, but only because I'm a crappy photographer. But still, if you shoot in low light and do NOT want to use a flash (for whatever reason), 1.4 is a significant difference from 1.8.
10-20-2008, 02:06 PM   #10
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I've had no issues with missed focus using auto-focus with the FA 50mm f/1.4 in low light, shooting subjects at 2-5m. Wide open, of course.
10-20-2008, 02:15 PM   #11
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QuoteOriginally posted by Miserere Quote
I've had no issues with missed focus using auto-focus with the FA 50mm f/1.4 in low light, shooting subjects at 2-5m. Wide open, of course.
hmm, than I'm either overcritical concerning crappy shots or I really suck.
10-20-2008, 09:34 PM   #12
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QuoteOriginally posted by soccerjoe5 Quote
What difference are you referring to? The ability to blur out of focus areas or gather light?

1.4 is great but keep in mind that shooting so has a very shallow DOF so it's easier to shots that are out of focus.
Thanks for all of the feedback everyone. It's not the bokeh that I'm wondering about, nor about the difference between 31mm and 50mm. I'm mainly wondering if the 1.4 to 1.8difference is significant in low light, non-flash scenarios?
thx
10-20-2008, 11:57 PM   #13
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QuoteOriginally posted by beaumont Quote
Thanks for all of the feedback everyone. It's not the bokeh that I'm wondering about, nor about the difference between 31mm and 50mm. I'm mainly wondering if the 1.4 to 1.8difference is significant in low light, non-flash scenarios?
thx
As Nesster mentioned, you may get 2/3 of a stop better speed with 1.4, won't change much motion blur wise. FWIW, I keep my 31 these days for low, natural lighting party shots. The bit you lose in speed, you gain in depth of field and the focal range is generally easier to shoot indoor. Its a good lens for doing what your asking, probably better than the 50 overall.


Kelly.
10-21-2008, 04:47 AM   #14
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QuoteOriginally posted by thePiRaTE!! Quote
As Nesster mentioned, you may get 2/3 of a stop better speed with 1.4, won't change much motion blur wise. FWIW, I keep my 31 these days for low, natural lighting party shots. The bit you lose in speed, you gain in depth of field and the focal range is generally easier to shoot indoor. Its a good lens for doing what your asking, probably better than the 50 overall.


Kelly.
Certainly didn't mean to discount Nesster (or anyone else's response). I'm not at the level where I understand the "2/3 of a stop" impact though. Re the lowlight natural lighting party shots, that is often what I use the 31 for, and I was wondering if I was missing out by not having the 1.4. Sounds like the answer is "no"?
thx all...
10-21-2008, 06:15 AM   #15
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QuoteOriginally posted by beaumont Quote
Re the lowlight natural lighting party shots, that is often what I use the 31 for, and I was wondering if I was missing out by not having the 1.4. Sounds like the answer is "no"?
thx all...
I may be repeating myself, but IMO 1.4 makes a difference. Of course it's not a dramatic one, but for lowlight natural lighting shots, I'm glad for any gain of light I can get, even if it's just a little bit.....
So I think the real problem is to decide whether this gain of light is worth loosing the 31 convenience for indoor shots.
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