Help a novice: sharp or unsharp images? Should I return my X-T30?

Started 5 months ago | Discussions
Bill Ferris
Bill Ferris Veteran Member • Posts: 6,752
Re: Help a novice: sharp or unsharp images? Should I return my X-T30?

giovirovi wrote:

Hi everybody,

I am a novice to photography and I am facing an issue: my new X-T30 seems very often to deliver blurry/not so sharp images. I have all the basic knowledge regarding focus, autofocus, exposition triangle, etc. If someone more expert than me could give me an opinion I really would like to post some images with the respective info to understand if it's a real issue.

Thank you.

If you're making soft photos with your camera, I recommend first addressing possible issues with settings or technique.

A reliable general rule is that a shutter speed of 1/focal length is the slowest that will reliably deliver handheld images without motion blur. There are exceptions. If you photograph sports or other fast action using a 400mm lens, you may need to use a shutter speed of 1/1000 to 1/2500 to adequately freeze motion. That acknowledged, if shooting handheld to make a portrait or landscape, a shutter speed of 1/focal length or faster should do the trick. If the lens has OIS, you should be able to use much slower shutter speeds to make a sharp photo of a static scene.

For most of the photography I do with my X-T20, I use a single, small autofocus point and position it directly over where in the scene I want focus to be. When making a portrait, I position the focus point over a subject's eye. When shooting landscapes, cityscapes, or architecture, I position the focus point over the dominant element anchoring the composition. Careful placement of the primary AF point over the subject of the scene is essential to making a sharp photograph.

Finally, your handholding technique is very important. Earlier, I mentioned that lens OIS opens the possibility of using slow shutter speeds to make sharp photos of static scenes. That starts with keeping two hands on the camera; the right hand on the body and the left supporting the lens. I'll lean against a wall or column for additional support. If using a really slow shutter speed, I'll sit, brace my elbows on a solid surface, and regulate my breathing to eliminate any unsteadiness.

If you address those three things - shutter speed, autofocus mode, and handhold technique - you'll be well on your way to making nice, crisp photos. If you are regularly out in low light situations such as shooting landscapes at sunrise and sunset, I heartily recommend using a tripod for the most stable platform possible.

Good luck to you.

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Bill Ferris Photography
Flagstaff, AZ
http://www.billferris.photoshelter.com

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photonut2008
photonut2008 Veteran Member • Posts: 6,174
Re: Smartphone depth of field

Mark Scott Abeln wrote:

If you want to match the depth of field of a typical smartphone, you'll have to set your aperture to something between f/8 or f/11.

Technically, to match DOF you need to divide the focal length of the smartphone's lens by the f/stop and then divide the focal length used on the larger format by that number to determine the equivalent f/stop. For example, an iPhone with a 4.25mm f/1.8 lens is equivalent to the OP using a 17mm lens at f/7.4 (17mm divided by 2.36mm aperture) or 26mm at f/11 (26mm divided by 2.36mm) -- which is pretty darned close to what you wrote (so +1).

Then, you'll have a large depth of field and more of your scene will be sharp. But you may want to add some more sharpening at the larger f/stop settings.

Yes, same as is being done by the iPhone.

Your camera likely has moderate-to-low sharpening set as default, and you may have to increase it to counteract diffraction softening which may become apparent when using f/8 and larger. Basically, the degree of diffraction softening is proportional to the f/stop, so f/16 will have double the softening as does f/8.

+1

Your problem is very common with people who first get a large-sensor camera. You have deep scenes with lots of detail both near and far, and the only stuff that is sharply rendered is a tiny, maybe unnoticeable, part of the image.

But experienced photographers will use a shallow depth of field—like using your lens at f/2—for good benefit, where they want to strongly separate their subject from the background. But this requires a distinct subject and distinct background, without a lot of stuff in-between or in front of the subject. The classic use of shallow depth of field is portraiture, where a person is in the foreground and the background is distant, without anything else visible in the image: the subject will be clearly sharp, and the rest of the image will be blurred.

I sometimes like gentle blurring and will for instance make a conscious choice between using f/8 and f/11 even though the foreground is in-focus with both and the background is out-of-focus with both -- which again, you said below.

It helps if you choose a subject that is rather flat, or if you shoot it head-on, so that there isn't much depth to the subject, and you use a camera position that avoids showing too much ground or extraneous items. Of course, out-of-focus blur can be used creatively, such as framing an in-focus subject with nearby out-of-focus flowers or vegetation.

+1

I can only give you +1, but I would rate your post a +3.

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Gerry Winterbourne Forum Pro • Posts: 18,801
Re: Lens testing

jrtrent wrote:

Gerry Winterbourne wrote:

jrtrent wrote:

"The centre is slightly soft wide open at f/2, with the peak performance achieved in the f/2.8-f/11 range. Diffraction sets in at f/16. The edges are soft from f/2-f/2.8, sharpening up at f/4, with f/5.6-f/11 the optimum settings." https://www.photographyblog.com/reviews/fujifilm_xc_35mm_f2_review/sharpness_1

That's a weird way of putting things. Diffraction doesn't "cut in" - it's always present for all lenses. As with all lenses its effects start to be noticeable round about f/4-5.6, and on APSA-C the effects are quite severe by f/11. f/16 is hardly ever useful on APS-C except for macro work.

That's interesting. Here's a quote from Bob Atkins that I've long thought was accurate:

"If you want to keep your images sharp, don't use f32 with an APS-C DSLR. The effects of diffraction are clearly visible at f32 and significantly degrade the image. Use f22 only if you have no choice. Optimal sharpness depends on the lens. For a lens with significant aberrations (e.g. a consumer zoom at maximum focal length and minimum focus distance), stopping down to f16 may give optimum results. For a lens with less aberrations (e.g. a consumer zoom used at infinity focus), optimum performance is around f11, though both f8 and f16 are very similar. For a really good lens like the EF 300/4L, with well corrected aberrations, performance may peak at f5.6, but be good from f4 to f11. f16 is acceptable, but f22 and smaller apertures should be avoided."

All lenses suffer aberrations, which are caused by the curvature of the glass. This is steeper at the outer zone of a lens so aberrations are greater when a lens is wide open. The result is that virtually all lenses are softer wide open than stopped down. If this were the only factor then we could just keep stopping down forever to get sharper sand sharper photos.

However, diffraction is an effect caused by the edge of an aperture: as all lenses have apertures, all lenses suffer from diffraction. Although this is an inexact description, it's easy to conceptualise the idea that small apertures have a higher edge-to-middle ratio so diffraction gets worse as the aperture reduces.

The result is that unless a lens is really well corrected it will start soft wide open, improve on first stopping down as aberrations have less effect but then get softer again as the effect of diffraction steadily increases. The point where the two adverse effects balance, giving best resolution, is the "sweet spot" of the lens.

The better corrected the lower f-number is the sweet spot; a really good prime lens might be at f/4 or (occasionally) lower; decent lenses tend to be around f/5.6, while cheaper "kit" lenses and similar might be f/8 or f/11.

All the above is true but it doesn't matter in the slightest if the picture you get is sharp enough. That, of course, is to a large extent a matter of personal taste. However, as a broad generalisation (which is borne out by questions here asking "why are my pictures soft") the point at which the effects of diffraction starts to be noticeable in making images soft is about f/16 on FF and one f-number smaller for each reduction in sensor size (f/11on APS-C, f/8 on M43 etc). To be safe I usually advise one f-number less if that's possible.

This, however, is an older article now, and he used an 8 mp camera. From the calculator at Cambridge in Colour I see that diffraction limits change with increasing resolution. My 6 mp DSLR is not diffraction limited at f/11, but the OP's 26 mp Fuji is already diffraction limited at f/8.

Diffraction "limit" isn't, in my experience, a helpful term. Relative softening is a gradual effect; there's never a fixed point at which things suddenly dissolve into loss of detail. Things like local contrast, the size of individual things in the frame, even comparison with other parts of the picture affect how we decide what's sharp enough.

How does this translate to comparative results? For example, I just don't get the depth of field I want most of the time at f/5.6, so I'm going to stop down to f/8 and even f/11 on occasion. Does the fact that I'm not diffraction limited at those apertures with my old camera mean its output is going to look better than if I used those same apertures with the OP's kit, or will the newer camera still produce better output at those apertures despite being diffraction limited?

DOF is never san absolute range of distances. All the standard DOF calculators use a set of assumptions about lots of things like size of picture looked at, distance from it, acuity of the viewer's eyes and so on. They ignore diffraction Its effect is relatively unimportant for FF, which is what was the smallest common size when the calculations were developed; but as diffraction softening increases the size of the blur circle - which is effectively the circle of confusion plus other effects - than stop down too far and instead of increasing DOF you can reduce it.

I rarely use a longer FL than 35mm on APS-C. My most used lens has its sweet spot sat f/5.6. When I put 35mm f/5.6 into a DOF calculator36'. for 1.5 crop I get hyperfocal distance = 36'. So if I focus there my DOF runs from 18' to infinity, which covers most situations. I use 43mm on FF, which by pure coincidence gives the same hyperfocal distance. I rarely use hyperfocal focusing in practice but with those lenses (or shorter) I virtually never need to go beyond f/8 for sufficient DOF.

As you see, the loss of resolution at f/8 on my 35mm lens is small - less than the ~15% that is often cited as the "just noticeable difference". Even f/11, though it is heading that way, is mathematically tolerable.

Edit: I'll add that the lens test I quoted used an X-A7 camera body with a 24.2 mp sensor. If we end up getting more government money, an X-T200 with that XC 35mm F2 sounds tempting. PC Mag's review (using an X-T200) also suggested that the smaller apertures are quite usable:

"It's a lens that, on today's cameras, delivers nearly as much resolution wide open as it does when stopped down, notching an excellent 2,735 lines at f/2 and settling in at a slightly better 2,800 at smaller f-stops. It hits 2,900 lines, close to outstanding, at f/8, and drops off just a little bit at f/11 (2,775 lines). The weakest resolution is at f/16, but images are still in the good range (2,440 lines). You needn't fret about distortion—there's none—nor worry about a heavy vignette." https://www.pcmag.com/reviews/fujifilm-fujinon-xc-35mm-f2

Yes; that's consistent with the OP's results. But remember that many these days view their photos on screens that are a lot bigger than the 8x10" that is assumed in DOF calculations. Other than macro (where - see above - the size of objects is relatively large in the frame) I'd stick to the smaller f-numbers to be safe.

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Gerry
________________________________________________________________________
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_________________________________________________________________________
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OP giovirovi New Member • Posts: 14
Re: Help a novice: sharp or unsharp images? Should I return my X-T30?

Bill Ferris wrote:

giovirovi wrote:

Hi everybody,

I am a novice to photography and I am facing an issue: my new X-T30 seems very often to deliver blurry/not so sharp images. I have all the basic knowledge regarding focus, autofocus, exposition triangle, etc. If someone more expert than me could give me an opinion I really would like to post some images with the respective info to understand if it's a real issue.

Thank you.

If you're making soft photos with your camera, I recommend first addressing possible issues with settings or technique.

A reliable general rule is that a shutter speed of 1/focal length is the slowest that will reliably deliver handheld images without motion blur. There are exceptions. If you photograph sports or other fast action using a 400mm lens, you may need to use a shutter speed of 1/1000 to 1/2500 to adequately freeze motion. That acknowledged, if shooting handheld to make a portrait or landscape, a shutter speed of 1/focal length or faster should do the trick. If the lens has OIS, you should be able to use much slower shutter speeds to make a sharp photo of a static scene.

For most of the photography I do with my X-T20, I use a single, small autofocus point and position it directly over where in the scene I want focus to be. When making a portrait, I position the focus point over a subject's eye. When shooting landscapes, cityscapes, or architecture, I position the focus point over the dominant element anchoring the composition. Careful placement of the primary AF point over the subject of the scene is essential to making a sharp photograph.

Finally, your handholding technique is very important. Earlier, I mentioned that lens OIS opens the possibility of using slow shutter speeds to make sharp photos of static scenes. That starts with keeping two hands on the camera; the right hand on the body and the left supporting the lens. I'll lean against a wall or column for additional support. If using a really slow shutter speed, I'll sit, brace my elbows on a solid surface, and regulate my breathing to eliminate any unsteadiness.

If you address those three things - shutter speed, autofocus mode, and handhold technique - you'll be well on your way to making nice, crisp photos. If you are regularly out in low light situations such as shooting landscapes at sunrise and sunset, I heartily recommend using a tripod for the most stable platform possible.

Good luck to you.

Thank you very much for all the suggestions. It is really helpful to receive tips from experienced people. I am honest when I say that I have absolute zero idea on how to use the autofocus on my X-T30 and I often get very confused.

mujana Veteran Member • Posts: 7,461
Re: Help a novice: sharp or unsharp images? Should I return my X-T30?
1

giovirovi wrote:

Bill Ferris wrote:

giovirovi wrote:

Hi everybody,

I am a novice to photography and I am facing an issue: my new X-T30 seems very often to deliver blurry/not so sharp images. I have all the basic knowledge regarding focus, autofocus, exposition triangle, etc. If someone more expert than me could give me an opinion I really would like to post some images with the respective info to understand if it's a real issue.

Thank you.

If you're making soft photos with your camera, I recommend first addressing possible issues with settings or technique.

A reliable general rule is that a shutter speed of 1/focal length is the slowest that will reliably deliver handheld images without motion blur. There are exceptions. If you photograph sports or other fast action using a 400mm lens, you may need to use a shutter speed of 1/1000 to 1/2500 to adequately freeze motion. That acknowledged, if shooting handheld to make a portrait or landscape, a shutter speed of 1/focal length or faster should do the trick. If the lens has OIS, you should be able to use much slower shutter speeds to make a sharp photo of a static scene.

For most of the photography I do with my X-T20, I use a single, small autofocus point and position it directly over where in the scene I want focus to be. When making a portrait, I position the focus point over a subject's eye. When shooting landscapes, cityscapes, or architecture, I position the focus point over the dominant element anchoring the composition. Careful placement of the primary AF point over the subject of the scene is essential to making a sharp photograph.

Finally, your handholding technique is very important. Earlier, I mentioned that lens OIS opens the possibility of using slow shutter speeds to make sharp photos of static scenes. That starts with keeping two hands on the camera; the right hand on the body and the left supporting the lens. I'll lean against a wall or column for additional support. If using a really slow shutter speed, I'll sit, brace my elbows on a solid surface, and regulate my breathing to eliminate any unsteadiness.

If you address those three things - shutter speed, autofocus mode, and handhold technique - you'll be well on your way to making nice, crisp photos. If you are regularly out in low light situations such as shooting landscapes at sunrise and sunset, I heartily recommend using a tripod for the most stable platform possible.

Good luck to you.

Thank you very much for all the suggestions. It is really helpful to receive tips from experienced people. I am honest when I say that I have absolute zero idea on how to use the autofocus on my X-T30 and I often get very confused.

Don' t worry...you learn and enjoy photography even more.

Happy shooting!

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WryCuda Forum Pro • Posts: 10,804
Re: Lens testing

D Cox wrote:

photonut2008 wrote:

ChelseaPhotographer wrote:

An APS-C camera can only resolve so much,

Care to elaborate on that? I was doing the math the other day and came up with about 340 MP to fully resolve f/4 on a DX sensor versus 181 MP to fully resolve f/5.6 on an FX sensor, that is what would be required before a theoretically perfect lens would be diffraction limited.

An APS-C sensor is most likely to have 4000 x 6000 pixels, so it can resolve only 2000 line-pairs per image height. It probably has a colour mosaic, which will almost halve that.

Only if you don’t understand the technology.

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WryCuda Forum Pro • Posts: 10,804
Testing times

Mark Scott Abeln wrote:

It helps if you choose a subject that is rather flat, or if you shoot it head-on, so that there isn't much depth to the subject, and you use a camera position that avoids showing too much ground or extraneous items.

That’s why I recommend using resolution charts to test lenses.

A little time spent setting up a suitable target avoids endless hours puzzling over images of brick walls, twigs etc. and battling with supposed AF errors.

However, an occasional random shot can provide encouragement...

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