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At what aperture is a canon f1.8 55mm sharpest?

post #1 of 28
Thread Starter 
I am fairly new to photography and now have my first 50mm lens for my Canon D1000.
I would also be interested to know about the 50mm for the nikon as well for my freinds camera.

I have been reading in the Kelby photo books and came across this: (The Digital Photography Book, book 1)
"Another trick the pros use is, when possible, shoot at your lens' sharpest aperture. For most
lenses, that is about two full stops smaller than wide open (so the f-stop number you use will
go higher by two stops). For example, if you had an f/2.8 lens, the sharpest apertures for
that lens would be f/5.6 and f/8 (two full stops down from 2.8). Of course, you can't always
choose these apertures, but if you're in a situation where you can (and we'll talk about this
later in the book), then shooting two stops down from wide open will usually give you the
sharpest image your lens can deliver. Now, that being said, this isn't true for all lenses, and if
that's not the case with your lens, you'll find your lens' sweet spot (its sharpest aperture) in
short order if you keep an eye out for which aperture your sharpest images seem to come
from."

Has anyone found this to be true, or is this the first time that you have heard of this?
I don't assume that sensor size would have any bearing on this, but i am asking just in case.

I will be testing this for my self in the near future, but has someone already found this to be true on this lens, and if so what aperture is it f/3?
post #2 of 28
It's not necessarily a universal truth as there are many pro lenses that are sharp wide open as well. That being said, usually even the least expensive consumer lens is sharp at f/5.6 and f/8. I don't own Canon equipment, but the Nikon 50mm f/1.4 and f/1.8 are typically sharper around f/2.8 and above. The same is probably true of your 55mm.
Mark V "Cylon"
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Mark V "Cylon"
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post #3 of 28
376


On a 350D.


392

On a 5DII.




I regularly use it at f/9-f/11 on film, and the occasional wide open shot.
post #4 of 28
Thread Starter 
I am not sure if i am reading the graph properly.

Is it when the center and border graphs are closer to equal that the picture is the sharpest, thus telling you what aperture to use for a sharper picture?
post #5 of 28
No, it's simpler than that. The higher the bar, the higher the resolving power in that area of the frame.
post #6 of 28
Thread Starter 
Quote:
Originally Posted by sub50hz View Post

No, it's simpler than that. The higher the bar, the higher the resolving power in that area of the frame.

Thanks, that does make more sense. I had to look up "resolving power".
I have not used a microscope in 20 years and i am new to photography.

resolving power
n
1. (Physics / General Physics) Also called resolution Physics
a. the ability of a microscope, telescope, or other optical instrument to produce separate images of closely placed objects
b. the ability of a spectrometer to separate two adjacent peaks in a spectrum
2. (Miscellaneous Technologies / Photography) Photog the ability of an emulsion to show up fine detail in an image
post #7 of 28
Personally, I don't worry too much about critical sharpness unless I plan on making bigger prints, where it will be more noticeable. Getting the shot is way more important than going over the image at 100% magnification with a fine-toothed comb looking for softness.
post #8 of 28
Do yourself a favor and start out by finding a pair of scissors. Next, hack that Kelby book up into about 10 nice size pieces. Next, acquire a lighter and some sort of accelerant (Lighter fluid or gasoline). Pour this over the 10 nice size pieces of that Kelby book and then take the lighter you acquired earlier and place it onto the accelerant.

Seriously, though .. Forget what is the "sharpest" aperture out. If you focus your shot properly, any aperture will do and if you know how to shoot wide open, your photos will be sharp.

If you're shooting landscape, sure, consider using F/8.0 -- Otherwise, who'd even bother going over F/2.0 - F/2.8? I mean, you might as-well go buy a P&S if you're shooting at F/8.0 and there is plenty of light around. No kidding.
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post #9 of 28
Quote:
Originally Posted by sub50hz View Post

Again, what are you talking about? You're quite obviously trolling, or just plain ignorant. For a guy who supposedly gets flown around the world because of his elite wedding photography, I haven't seen you post anything noteworthy -- for that matter, you never replied to my earlier request of a website/flickr/portfolio.

Condescending to the OP, how? I'm simply saying that I don't like Scott Kelby. Maybe condescending to Scott Kelby. Not to the OP, though.

And knowing how to shoot wide open is pretty straight forward -- AF lock doesn't always "land" on the area you'd hope. Knowing how to manually focus forwards or backwards and correct the focus that comes with shooting wide open usually results in fantastically sharp images on good quality lenses or even "bad" quality ones. Knowing how to tell when it is focused properly and not is what I meant. And what physical limitations? There are none if you know how to use it properly and use it for it's intended use.

And no, not trolling at all. In fact, it seems you're the one trolling. Why are you replying to me? I answered the OP's question, I wasn't talking to you.

And you're welcome to a Flickr / Portfolio / Website -- I'm yet to see you request it and to be honest, can't understand why you'd want it in the first place -- I'm not asking you for your opinion on my work, so seeing my work holds little to no weight for you. Unless you're getting married, of course. In which case, give me a PM and I'll happily link my professional life to that of my online life in private.
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post #10 of 28
Quote:
Originally Posted by Kariz-Matik View Post

I'm not asking you for your opinion on my work, so seeing my work holds little to no weight for you.

When you push your opinions and "information" with such authority and claim to be the real deal, you seem pretty suspect without providing anything that can, you know, validate anything you're claiming.
Quote:
Unless you're getting married, of course. In which case, give me a PM and I'll happily link my professional life to that of my online life in private.

Based on your attitude here, I can say with all confidence that you are absolutely the last person on the planet I would hire to do any sort of work for me. You could be the most renowned shooter ever to live offering me services for free, but your snide demeanor and elitist attitude are ridiculous. Especially since it's usually towards someone who is new to photography, or very inexperienced.
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