Optimum shooting distance

[JimmyCat]

Is there such a thing as optimum shooting distance for a given sensor, lens, focal length and aperture e.g. if photographing an object 75mm high at a distance to subject of 30 metres using a focal length of 300mm, is it reasonable to expect a sharp image when cropped to fill an image size suitable for AP given appropriate shutter speed (fast) and use of a tripod/monopod.

Am I expecting too much of a camera/lens system to produce acceptably sharp images with the above parameters? I realise there are probably a lot of other variables such as glass quality but I am continually amazed at the high quality of the images appearing here but there is no distance to subject info disclosed?

[ameerat42]

OK, like a smallish bird in your neighbour's high tree. You will be reproducing an approx 0.75mm image in your camera.
That's a small fraction of the (APSC) sensor height.

Lots of conditions are at play. Glass, light, camera capabilities (others I haven't thought about). And on top of that, it's remains hard to say.
Having recently done a bulk of just that at some wetlands, I can say that you will get an identifiable image - IF ALL GOES WELL.

Birders especially (of which I am NOT one) go to a lot of trouble to get what they do. A few should answer you with more detail than this.
Am.

[ricktas]

Sharpness is a quality that is not really a byproduct of distance. However longer distances and light quality between sensor and subject can affect quality.

Consider this. An object is 50 metres away. It could be raining, it could be foggy, it could be smokey, there could be a freshly ploughed paddock nearby so lots of dust in the air. So yes distance can affect the sharpness, due to the environment at the time. Some of these conditions may not be visible to the naked eye, but they will still affect sharpness.

However, in general sharpness is a product of the quality and calibration of the lens used, along with the camera/sensor, and focusing systems. If the lens is not as sharp as it could be, or the sensor is an older model (take a Canon 300D from years ago), or the focusing system is not accurate then sharpness will be compromised.

Most kit type lenses are reasonable quality, but will not compete with the quality of a good professional level lens. Also lenses can be bumped etc and not be as accurate as they should be. You can get your camera/lens combination calibrated together to ensure sharpness and focus accuracy is optimal. Some cameras allow micro adjustments of the autofocus to set a lens to ensure focus accuracy and thus sharpness is improved as well.

Also ALL digital photos need to be sharpened in editing software due to the inherent softness that a digital sensor has based on its basic design. http://www.ausphotography.net.au/forum/showthread.php?8579-Why-all-Digital-images-need-SHARPENING

lens calibration tools: http://www.ausphotography.net.au/forum/showthread.php?96874-Lens-Calibration-Tools
micro adjusting: http://www.ausphotography.net.au/forum/showthread.php?41426-Autofocus-micro-adjust

[oliviadavid]

very informative post.

[swifty]

Just to add to the confusion, some lenses do indeed perform better at various distances. It all depends on how it is tuned by the designers.
The now old Nikon 200-400 f4 is said to be stellar at closer distances but not particularly good at distance which the new 180-400 f4 lens is supposed to have addressed.
Similarly, the Micro-Nikkor 105mm f2.8 VR doesn't rate as well in many review sites due to testing methodology and need for consistency between the many lenses that they test. However, it is stellar at macro distances so when used appropriately as a macro lens it is indeed very good. But as a general 105mm lens, then not so much.
The 58mm f1.4G does the opposite and is actually quite soft (maybe not the right word but more hazy?) at minimum focus distance but sharpens up quickly with distance. It is actually very good at infinity.

I know this isn't exactly what you're asking but there are a lot of factors that affects 'sharpness' and sometimes focus distance is one of them.

[NikonNellie]

I do quite a bit of bird photography and there are a few factors which determine the quality of sharpness in my images.
1) I have two lenses for birding -the Sigma 150-500 and the Nikkor 200-500. Most of the time I shoot at a focal distance of 500mm with both lenses. I definitely get better images with the Nikkor as it has a much better quality of glass.
2) The closer I can get to a subject (and not exceeding the minimal focal distance for the lens), the more detail I can get in the feathers. So yes, distance of camera to subject can make a big difference. I always take my images handheld but if I was to use a tripod, the images would be sharper even more. I find the tripod too restricting (even with a ball head) to take images of BIF.
3) I get much better results in detail on a bright sunny day than on a dull cloudy day. However I prefer to shoot on a dull day as I don't have to deal with harsh shadows. I always have to use a higher ISO on a dull day which then brings more noise into the image. So light is a definite factor in the quality of my images.

[Tannin]

Rule-of-thumb: fill the frame with the subject (but leave a little space for minor cropping afterwards). If you can't fill the frame, at least fill half of it. At a pinch, a quarter will often do.

30 metres from a 75mm subject is never going to produce much of a result with a 1200mm lens (say a 600/4 with a 2x teleconverter), never mind 300mm.

With birds, you really do need to get quite close. For small birds, I often have to use a close-up ring because of the minimum focus distance of long primes (typically around 4.5 metres), but you'd be OK with a 300mm lens. Most 300s will focus down to 1 or 2 metres, which is fine.

[Mark L]

....
2) ...... I always take my images handheld but if I was to use a tripod, the images would be sharper even more. I find the tripod too restricting (even with a ball head) to take images of BIF.
....


I have no problem getting BIF using a monopod. You need a tilt head and please consider.
For other bird photos the stability offered by a mnopod lets you use a lower shutter speed and means you are not holding the weight of the lens as you wait for the bird to do what you want it to do.

[Tannin]

^ Better yet, use a gimbal head on a tripod.