Optimum Resolution

[pgavalis]

<p>Please bear with me on this. I haven't found an answer on Google so I am going to try this here.</p>

<p>When taking a photo, are there converse or similar settings to obtain the same image resolution? For instance, leaving DOF out of it, is an image taken at ISO100-1/100thsec-f4 similar in resolution to a photo taken at ISO100-f8-1sec? I'm just using imaginary numbers here but does anybody understand what I am asking? Does a longer shutter allow more information into the image, making it a "better" image? Or does it allow for the intro of more artifacts making it lesser desired image? </p>

<p>This again, may have to do with my math skills or maybe I'm just talking nonsense. But I am very curious because it seems to me that with a longer shutter one could capture 'more' of the image and a faster shutter seems like a "cheap/lazy" alternative? </p>

<p>This was probably covered in Photography 101 but I have no fear when it comes to asking questions! This has been bugging me for a few years now and I need to know! I am not trying to start a debate here, if that's even possible with this question. Nor am I trying to get into which camera is best, lens, etc... Strictly trying to get to the basic elements of the question. Or maybe it is completely subjective?...just talking out loud here.</p>

[steven_clark]

<p>I think it may be the opposite: photons are photons, so at the same sensitivity (lens performance aside) an equivalent exposure using a wider aperture is at least as good in terms of sensor image quality as one with longer exposure. And since there are types of noise that only appear in long exposures the shorter exposure might, in theory, have a little less noise. As long as you don't have the camera cast into cement block or something shake and vibration of the camera can be an issue. Also, shake and vibration of the subject is an issue, even when you aren't taking pictures of people, wind is a thing. Both of these can smear information across multiple pixels reducing your resolution.</p>

<p>That said, most lenses don't perform their best wide open. And the narrow depth-of-field of a wide open lens can limit sharpness if the subject isn't paper thin and all in the field of sharp focus.</p>

<p>So I guess the advice might be: f/8 and be there, and take a tripod if you can.</p>

[SCL]

<p>Sharpness is often defined as what we perceive in a combination of contrast and resolution (ability to distinguish individual closely placed parallel lines from each other - for instance). Both resolution and contrast are dependent on lens design and do vary with aperture. MTF charts for lenses often convey some of these relationships as one moves from the central point of focus to the edge of the sensor/film plane. The relationships are pretty complex but can be described in mathematical terms. I hope this sort of answers your question.</p>

[Jochen_S]

<p>I believe it might depend. - There is surely something like long exposure noise created by digital sensors. Some digital cameras do post-exposure denoising that hogs them up for a while. On film things might matter less, you only have to compensate exposure a bit if measured shutter speeds get longer. https://en.wikipedia.org/wiki/Reciprocity_%28photography%29<br>

Like Stephen I'd worry most about the lens used spitting into my soup. A lot of lenses get sharper stopped down about 2 stops. And depending on the pixel size on your sensor you have to worry about diffraction sooner or later. So any given lens should have its own optimum aperture on a given sensor and it might be up to you to figure out at which f-stop. or if the sensor resolution is low enough in which f-stop range. <br>

A case where a long shutter speed might be really helpful is when you have a gallery or similar with people wandering around. if you make your shutter speed long enough they can march through your image without blocking a view. Same is done photographing waterfalls from a tripod, but usually wind ruffling hair moving leaves & grass is unwanted.<br>

Expanding Steven's hint about vibrations: the entire world seems basically swinging. If you mount a camera on a tripod you face mirror slap and usually less avoidable: shutter slap. Your tripod is supposed to dampen these somehow... On the other hand: there are earth quakes and architectural vibrations that set your tripod mounted camera into motion too. example: its impossible to do holgraphic images with just tripods and such placed inside a building. the shaking of the floor caused by somebody walking on it will ruin them . (my physics teacher tried and the school was solidly built. Wind, acoustic noise, traffic on nearby roads, everything might introduce further unwanted and sharpness killing vibrations into your tripod.<br>

So fastest shutter speeds, usually achieved by relying on quickly discharging strobes might be your best bet to gain ultimate sharpness.</p>

[pgavalis]

<p>Thanks guys. It was more of a lingering thought I had, rather than a specific problem or immediate issue, but I see your points. Thanks again!</p>

[wayne_campbell]

<p>Most Pentax DSLRs have that 2 sec. delayed shutter release feature that gets the mirror slap and other vibration over with before the shutter opens and closes. If tripod-mounted, this means the best possible camera steadiness.</p>

[bebu_lamar]

<p>You do not have the same exposure. ISO 100, f/8, 1 sec gives 4 and 2/3 stops more exposure than ISO 100, f/4, 1/100 sec. </p>

[celasun]

<p>Even though today's sensors are a lot better than the earlier ones, they are still a source of noise (as electronic devices). So; everything equal (they are hardly ever!), I expect more noise with longer exposures. Not sure about noise itself but noise removal techniques can decrease resolution. </p>

[jeff_drew4]

<p>for us old dogs, Group f/64 philosophy produced a special segment of incredible, sharp pictures. One can spend a small fortune in time and wealth pursuing razor sharp quality. Lens quality and light are important. Inevitably, the whole technique & process for an image is additive. Practice & play!</p>