Tack Sharp Confusion

[Blazin]

So, I've been trying to get the basics down.. and have been reading and shooting to get my skills up.

I have found a source of confusion someone validate my thinking:

Sunny 16 -

Let's say I'm shooting f/16 ISO 200 Shutter: 1/250 in Full sun

Great exposure. In Theory.

Tack Sharp? well This depends on the focal length of the lens?

Say, this were being shot on at a focal length of 400mm.. now we got some softness coming into play..

To adjust, set shutter speed to 1/500, 1 stop to f/11 and now we have the same exposure; however, we now have regained some sharpness since we compensated for our lens' focal length?

Someone correct me if I'm wrong here.. somtimes it is just hard to tell on the Camera LCD if I'm 'sharp' or not and if my thinking is already in the right spot.. then I'll be more confident in my shooting experiments.

[Sorarse]

I think you may be confusing softness with camera shake.

Your thinking is correct that by increasing the shutter speed you will help to eliminate camera shake when using a long focal lens. However, if the lens is not of the best quality, and is inherently soft, increasing the shutter speed will make no difference.

[Bosscat]

.. somtimes it is just hard to tell on the Camera LCD if I'm 'sharp' or not

Despite what many will tell you, you cannot tell if an image is sharp on the LCD.

[elysium]

Reminder, majority of lenses tend to be at their peak/sharpest around the f/8 mark.

[Blazin]

I think you may be confusing softness with camera shake.

Your thinking is correct that by increasing the shutter speed you will help to eliminate camera shake when using a long focal lens. However, if the lens is not of the best quality, and is inherently soft, increasing the shutter speed will make no difference.

Yea I guess I misunderstood that, the reason you would like a minimum shutter speed of at least the reciprocal of your focal length is to reduce the chance of camera shake..

[KarlosDaJackal]

The rules still works if you bump the iso

So at 300mm you want a faster shutter speed than 300 mm so change from

ISO100 - 1/100 - f/16 to
ISO400 - 1/400 - f/16 same exposure and sharpness (hopefully if no reciprocity failure occurs)

[Blazin]

The rules still works if you bump the iso

So at 300mm you want a faster shutter speed than 300 mm so change from

ISO100 - 1/100 - f/16 to
ISO400 - 1/400 - f/16 same exposure and sharpness (hopefully if no reciprocity failure occurs)

I understand this, and theoretically ISO400 is well within the issues of noise these days, my thoughts were best best best quality with the gear you got.

ISO 100, 2-3 stops down from wide, Shutter the reciprocal of focal length, assuming bright sun.

So with an 85 f/1.8

ISO100, f/4, 1/2000 -- 0 camera shake, exposure should be good, little to no noise, fast enough for stop motion, tack sharp.

I'm basically advancing Sunny 16 to Tack/Peak Sharpness for my lenses.

[poloman]

You will always run into compromising situations. I think the idea is to do the best you can. If you use an aperture of f4, your image will only be tack sharp within your depth of field. This is often desirable. Depth of field will increase as aperture is decreased (larger number). Your focusing method can be critical too. Is your subject moving? Skill in panning can create some great effects.

[KarlosDaJackal]

Your thinking and adjustments seem to be in line with what I'd expect, barring reciprocity failures, but why sunny16 and why "tack" sharp?????

Sunny 16 is a guide not a rule, and its a guide about exposure not sharpness. Bright daylight varies around the world. Your 400d has a meter with 3 different modes, that are far more reliable than sunny16 and work in the dark also. For that meter to stop working the whole camera would probably stop working also, so no pictures anyway. So sunny16 is not that much use to you as far as exposure is concerned, its a poor 2nd to the camera meter.

If sharpness is your concern you already know your aperture is going to be between 5.6 and 8, and your shutter is going to be anything above the focal length of the lens. Thats your sharpness choice made.

That only leaves you with ISO to play with to get close to a decent exposure. Good luck on a dark day. Your cameras metre will tell you how close you are to "correct" when you adjust the iso to match your desired aperture/shutter.

But really a decent lens will not be that much softer wide open than it will be stopped down. Is it worth sacrificing creative control for slightly more sharpness, I'd say in 95% of situations its not based on the fact my fast lenses are usually used wide open and sharp at that speed. I would not buy a f/1.8 lens to shoot at f/8, because an f/4 lens at f/8 would look just as good.

A sharp shot @f/2.8 with some bokeh or background movement usually tells a much better story than a marginally sharper shot @f/8 with a busy background and no movement.

[Blazin]

Your thinking and adjustments seem to be in line with what I'd expect, barring reciprocity failures, but why sunny16 and why "tack" sharp?????

Sunny 16 is a guide not a rule, and its a guide about exposure not sharpness. Bright daylight varies around the world. Your 400d has a meter with 3 different modes, that are far more reliable than sunny16 and work in the dark also. For that meter to stop working the whole camera would probably stop working also, so no pictures anyway. So sunny16 is not that much use to you as far as exposure is concerned, its a poor 2nd to the camera meter.

If sharpness is your concern you already know your aperture is going to be between 5.6 and 8, and your shutter is going to be anything above the focal length of the lens. Thats your sharpness choice made.

That only leaves you with ISO to play with to get close to a decent exposure. Good luck on a dark day. Your cameras metre will tell you how close you are to "correct" when you adjust the iso to match your desired aperture/shutter.

But really a decent lens will not be that much softer wide open than it will be stopped down. Is it worth sacrificing creative control for slightly more sharpness, I'd say in 95% of situations its not based on the fact my fast lenses are usually used wide open and sharp at that speed. I would not buy a f/1.8 lens to shoot at f/8, because an f/4 lens at f/8 would look just as good.

A sharp shot @f/2.8 with some bokeh or background movement usually tells a much better story than a marginally sharper shot @f/8 with a busy background and no movement.


Thanks for slapping my nonsense in the face.. now that I read this it all boils down to what I've been doing.. shoot first, ask questions later.

I really haven't had any issues with OOF, Exposure, Sharpness to complain about.. and I generally try to pick a good DOF relative to the subject matter..

I think I'm just over thinking this stuff.. oh well I'll be taking a little trip to the city saturday to make some great captures