Does anyone have real world comparisons of these 2 lenses side by side wide open? Yes I have looked at the charts, but I'd like to see images if anyone has them. Especially how much more light 1.2 lets in vs 1.8 in a real world comparison. Thanks.
Does anyone have real world comparisons of these 2 lenses side by side wide open? Yes I have looked at the charts, but I'd like to see images if anyone has them. Especially how much more light 1.2 lets in vs 1.8 in a real world comparison. Thanks.
What do you mean exactly Cozen?
The lens is theoretically about 1.25? stop faster. Perhaps a little bit more. If you'd make a correctly exposed image with the 85mm 1.8 I assume that if you take the same image with the 85mm 1.2 you'd get a 1.25-stop over-exposed version?
But I can't image you want that kind of photo...or do you?
I could do something like that if you want, by photographing with my 50mm 1.4 on 1.4 and 2.2? It's about the same difference in exposure.
Or perhaps I'm misinterpreting your question?
Let me know, Jan
I can understand wanting real world pictures to compare how images from the two lenses, but...
Originally Posted by Cozen
Pictures won't show you that, will they? Unless it was a carefully controlled test (and not what I would call "real world")... are you looking for something done in manual mode to see how much darker the f/1.8 looks?
Really, you just need to know that F/1.2 lets in about 225% as much light as f/1.8. That is, your shutter speed will be 2 1/4 times as fast to get the same exposure.
(Assuming it is really f/1.2 vs f/1.8. Maybe they're a little off to make it exactly one stop difference, or 200% and twice as fast... I don't know about that)
That's why I put a questionmark behind my 1.25 stop-calculation [:P] Didn't have a clue it would be that much....I figured: 1.4 would be a half-stop darker than 1.2 and a 2/3 stop lighter than 1.8, sum it up and I ended with my 1.25-stop guess. But I guess proper math won't let me sum it up like that??[:#]
http://the-digital-picture.com/Pictures/Picture.aspx?Picture=2006-04-29_19-21-38
http://the-digital-picture.com/Pictures/Picture.aspx?Picture=2004-04-17_11-09-19
Honestly, if you're looking for an 85 prime, you probably have a reason to get one. If so, that reason should lead you to the right lens. If not, your wallet should lead you to the right lens. They really are two totally different animals. If you don't know what you want/need, get the 85/1.8. It'll work very well for everything you ask it to do.
We're a Canon/Profoto family: five cameras, sixteen lenses, fifteen Profoto lights, too many modifiers.
Your reasoning seems sound to me, except that I think 1/2 + 2/3 is 1 1/6, not 1 1/4
Anyhow, we came up with almost the same answer. 1 1/4 stop is about 238% more light.
Your reasoning seems sound to me, except that I think 1/2 + 2/3 is 1 1/6, not 1 1/4
Anyhow, we came up with almost the same answer. 1 1/4 stop is about 238% more light.
Ah yea crap you saw my faulty calculation...even a junior would have done a better job than me on that one [A]
Your reasoning seems sound to me, except that I think 1/2 + 2/3 is 1 1/6, not 1 1/4
Anyhow, we came up with almost the same answer. 1 1/4 stop is about 238% more light.
Ah yea crap you saw my faulty calculation...even a junior would have done a better job than me on that one [A]
Can it really be 2.25x faster? Probably you came up with 225% by calculating the areas of the respective iris diaphragms (i.e.πr². However, practically speaking shutter speed is set in minimum 1/3-stop increments, so I'd think f/1.2 vs. f/1.8 would simply be a full stop - meaning double the shutter speed for the 'same' exposure.
You're right - technically the exposure would be a little different(barring some physical correction in the lens/aperture relationship in the lens design). I wonder how it really works, and if the same scene metered with the 85mm f/1.8 @ f1.8 vs. the 85mm f/1.2L @ f/1.8 would give the same shutter speed, and if stopping the 85mm f/1.2L down from f/1.2 to f/1.8 for the same scene would halve the shutter speed? I suspect the answer to the both questions is yes. If 85mm f/1.2L really does let in 2.25x as much light, and the metered exposure is just one full stop different, then a shot at 85mm f/1.2 may be slightly overexposed? Then again, someone shooting with an 85mm f/1.2L would probably tweak the RAW image anyway?
But this is all a big (though fun) digression from the OP's question.
Cozen, there's a real-world difference of one stop between the lenses wide open - meaning, you can get a shot in half as much ambient light (for the same ISO and shutter speed). Wide open, the f/1.2 lens has ~30% thinner DoF than the 85mm (note the implication for low-light shots, as well - you get more light, but less of the subject in focus). The 85mm f/1.2L is a little sharper at f/1.8 than the 85mm f/1.8 @ f/1.8. Saturation and contrast are a little better with the L lens. The 'costs' you pay for that 2.25x amount of light and thinner DoF are: 2.5x the weight, slower AF, and 5x the cost.
Focused on one given spot with my 85 1.2 @ 1.2 = 1/125. Then bumped up to 1.8 = 1/60.
I'll let the brains figure out the decimals. I know it something over 1 stop. Obviously the 85 1.8 may expose differently.
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