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02-20-2011, 01:55 PM   #31
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Thanks so much for all the tips in here as well, they're very useful. I lost my tripod the other day and I wanted to take moon photos last night. I ended up resting the camera on the windowsill but I'm pretty sure they all blurred. Anyway, I did find that I was able to shoot at wide open and it captured so much more detail than I've been able to with my zoom lens. It was great

02-20-2011, 03:35 PM   #32
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QuoteOriginally posted by NicoleAu Quote
I lost my tripod the other day and I wanted to take moon photos last night. I ended up resting the camera on the windowsill
Here's an I-lost-my-tripod trick: Beanbags. Or sandbags. Put such on a windowsill or wall-top or car-top or wherever. Diddle with bags and camera until camera is pointing in the right direction. VOILA! Even if I haven't lost my tripod, I'll sometimes put bean- or sand-bags atop a long lens to stabilize it. Especially my massive Rubinar 1000/10 mirror. It needs all the stability it can get. Excitement is not an option.
02-20-2011, 04:12 PM   #33
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Now there's an idea! I ended up using a pillow, without too much success lol. Where do I find those?
02-20-2011, 04:47 PM   #34
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U shaped neck pillows filled with barley husks (or whatever they use) work well; they hang nicely on a railing, over a sill, your car window, etc.

Plus you can use it as a pillow!

02-20-2011, 06:32 PM   #35
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yay gotta love things that have 2 uses! Can sleep with it on the train on my way home from shooting in the city lol.
02-20-2011, 10:34 PM   #36
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Oh and another question. Why can I set exposure with an M lens from the exposure button and i sets the correct shutter speed for my K-x, but when I try and do that with my FA lens, it doesn't work?
02-21-2011, 07:02 AM   #37
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Not sure what you're asking Nic, but if you mean the use of the green button, it should work to be an 'auto exposure' button for all A, F, FA, DA and DFA lenses and their equivalents. It's theoretically not supposed to 'work' for M lenses since there's no way for the camera to communicate aperture settings with the M lens, so it needs 'stopping down' by the DoF preview function before choosing the right shutter speed for the exposure with the M lens. If this wasn't well explained (likely), please refer to your camera manual as it gives examples of the use of both the green button and the DoF preview switch.
02-21-2011, 07:21 AM   #38
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I see what you mean. When using M mode with an A, FA, F, and DA lens you don't do stop down metering hence you do not need to press the green button to get the right exposure values. Whereas with an M series lens you must press it. Well, I'm assuming the reason why is that they want you to use the Av, Tv, and Sv modes instead.

I am assuming that you are annoyed that in M mode with these newer lenses you have to rotate the aperture and shutter speed till you get the right exposure for the scene. but when using the M series lenses it's just click and there it is.

Which in many cases is exactly what Av mode is for on these newer lenses. You select the aperture and meter it in M mode. In Av mode you select the aperture via the body instead of the ring and the camera adjusts the shutter speed immediately.

I hope that's what you are asking.

02-21-2011, 02:33 PM   #39
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I meant the exposure button, not the green one Ash. When I press it with my M lens on, it sets the shutter speed for perfect exposure. But I can't do that with my FA lens. I had an awful time trying to expose correctly for the late afternoon sun reflecting off the water on Sunday

Yes epqwerty, that's correct.
02-21-2011, 03:20 PM   #40
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QuoteOriginally posted by NicoleAu Quote


.....What I was wondering if anyone could tell me, is why they make f1.4 lens if they're virtually unusable wide open? IE too soft for portraiture etc. .......
I'm not sure if this is even possible
02-21-2011, 07:55 PM   #41
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QuoteOriginally posted by Wheatfield Quote
I'm not sure if this is even possible
What's not possible? An explanation?

BTW IMHO 50/1.4's aren't unusable, and zillions of other shooters seem to agree. No, a 50/1.4 (or that ilk) isn't used wide-open when maximum detail is desired. For that, stop it down. It's used so, to get otherwise unobtainable shots. It can take practice, and maybe Catch-In-Focus and/or a KatzEye-type focusing screen, and an attitude.

Why make them? Demand. There are shots a f/1.4 or f/1.2 or f/0.95 lens can get, that other glass just can't. Shooting in low light, or high-speed subjects. Using razor-thin DOF to surgically separate a subject from their surroundings, or for certain spatial effects. That kind of stuff.
02-21-2011, 09:35 PM - 1 Like   #42
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OK, some lens basics are in order. Most everyone has been skirting the sweet spot of the issue, so here goes.

In general, a lens has it greatest sharpness when stopped down 2-3 stops from its widest opening. This is due to the lens using more of the center area of the glass. Unfortunately, as you increase the f-stop, you start getting light diffraction, or scattering. This starts at apertures above f11 and is caused by the light having to go through the small aperture opening. As it passed through, there is a slight scattering on the other (camera) side thereby creating less resolution, i.e. sharpness.

If you have an f1.4 lens, then the lens is sharpest at about f2.8 (we'll be generous and use the two stop rule). You are getting a lot of light in at f2.8 which means the lens is sharp for low light applications. As you continue to stop down, you will still have good sharpness down to f11 (a 4 stop range). If you have an f4 lens, then it is sharpest at f8 and starts loosing sharpness at f11, a 2 stop range. And with an f5.6 lens, you only get one stop of really good sharpness, f11!

And keep in mind how sharpness is determined, and depth of field has nothing to do with it. It comes down to image resolution. This is measured with resolution targets (you can get them on ebay, search "lens test chart" or from Rochester Institute of Technology) on a perfectly flat surface with the lens perfectly parallel to the target. For a good lesson on using them with digital cameras, and alternatives, check out this link: Radial Resolution Target

We like to test sharpness of the imaging system, but now with digital sensors, and the grid patterns formed by the pixels, this becomes harder. Even so, in the days of film, judging the sharpness of the lens was also subject to how good the film was! Ideally, sharpness of the lens should be judged without respect to the imaging system, but we have to be practical here!

Regards,

Last edited by BigDave; 02-21-2011 at 09:39 PM. Reason: additions
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