F/18 is just not sharp enough

[Mike Buckley]

Thanks, Dan!

Mike--If you are going to be doing studio work, any reputable macro lens should be sharp.

It's not just sharpness that I will be evaluating. I'll also be evaluating the relative ease of using this 60mm macro lens lacking an automatic aperture versus using the 90mm Tamron macro with Kenko extension tubes. Part of the reason for wanting first-hand testing is that the 2:1 macro lens is so little known that there's not much practical information readily available about it. The other part is that macro shooting seems to this macro novice to be so different from the kind of shooting I normally do that I wouldn't feel comfortable making a long-term purchase decision based only on theoretical likelihoods.

the amount of magnification from any length of extension is inversely proportional to focal length.

I haven't been able to wrap my mind around that enough to understand what it really means, so I would appreciate it if you would please provide a numerical example.

[george013]

It's always a question for me when examining a picture how to distinguish between the optical and the pp part. What we see is the result of both. Diffraction belongs to the optical part.

The crop of Brian is about 1/4 lineair of the image. To fill my screen or a print, it has to be enlarged 4 times more. That has consequences not only for motion blur but also for sharpness based on the coc. I don't think anybody is working with this but it should be known.

When I've time I'll make my own tests.

George

[Mike Buckley]

I mentioned that Brian's crop is probably no more than 10% of the original file. I've now taken the time to measure the crop and full image sizes and realize that the cropped image is actually only about 8% of the full-size image.

[george013]

I mentioned that Brian's crop is probably no more than 10% of the original file. I've now taken the time to measure the crop and full image sizes and realize that the cropped image is actually only about 8% of the full-size image.

I mean lineair figures.

George

[DanK]

Thanks, Dan!
It's not just sharpness that I will be evaluating. I'll also be evaluating the relative ease of using this 2:1 macro lens lacking an automatic aperture versus using the 90mm Tamron macro with Kenko extension tubes. Part of the reason for wanting first-hand testing is that the 2:1 macro lens is so little known that there's not much practical information readily available about it. The other part is that macro shooting seems to this macro novice to be so different from the kind of shooting I normally do that I wouldn't feel comfortable making a long-term purchase decision based only on theoretical likelihoods.

I haven't been able to wrap my mind around that enough to understand what it really means, so I would appreciate it if you would please provide a numerical example.

Mike,

I haven't tried a macro lens without an automatic aperture. I was considering getting the Laowa 15mm macro for wildflowers, but it got bumped from the priority list. My guess is that studio macro is the situation where automatic aperture would matter least, as you would have time after focusing to shut down the aperture, but that is only a guess.

Re magnification: the normal equations don't work at macro distances, in part because the effective focal length is often quite different from the nominal, but here is a very rough rule of thumb. As a starting point, assuming the lens can reach 1:1 without extension, assume that the maximum magnification will be somewhat greater than (FL+EL)/FL. So, for example, a full 68mm of Kenko tubes on a 90mm lens would come out to a maximum magnification somewhat greater than (90+68)/90=1.76:1. I think if you tested it, you would end up with something closer to 2:1. From this you can see that the shorter the focal length, the greater the magnification.

Dan

[Mike Buckley]

Rather than hijack Brian's thread more than I already have, please see this thread about macro lens questions.

[JBW]

Rather than hijack Brian's thread more than I already have, please see this thread about macro lens questions.

you haven't hijacked anything. I am learning a lot. I have just shot a series of shots from F/ 2.8 to 32. My camera/lens limits. I used as controlled an environment as possible. I'll post the results ASAP.

[JBW]

As I suspected Brian there was more to this than the aperture used, it's a hefty crop and has been played with



I would disagree with this Brian and associate it with the saying 'a good workman never blames his tools' ! Your kit does not have a sweet spot that is narrow but a sweet spot that then tails off gradually and the results along the way are dependent upon a number of influencing different variables.

It also doesn't do much good to shoot an elephant with an air rifle

These four shots were taken in as controlled an environment as possible. After adjusting the F I would move other settings to maintain 0.-7 exposure. They were all shot at near prime focus.

Admittedly I'm no pro. However F/32 is really soft and F/2.8 is really shallow to my eyes.

settings, the green is the in focus area



Export settings



F/14


F/2.8


F/18


F/32


I don't know much so if there are ways to get a sharp F/32 out of my gear please teach me how cause I love Grahams matches.

[Mike Buckley]

It also doesn't do much good to shoot an elephant with an air rifle

That depends on your goal. It might work fine if you're trying to blow a spec of dust out of its eye.

I love Grahams matches.

Me too, but I have no idea why he buys them in such short lengths and stores them individually amid the plants.

[Stagecoach]

These four shots were taken in as controlled an environment as possible. After adjusting the F I would move other settings to maintain 0.-7 exposure. They were all shot at near prime focus.

Ok, but by 'moving other settings to maintain -0.7' I am assume this was only shutter speed? The f/14 one is coloured somewhat different not sure why, but does not really affect the results.

In analysing these shots for 'sharpness' Brian the method I use is to find one item, a fine scratch in this example, on the image shot at the widest aperture and compare it at all other smaller apertures. In theory it would not be affected by DoF as you stop down.

Admittedly I'm no pro. However F/32 is really soft and F/2.8 is really shallow to my eyes.

The example results show exactly what we would expect, and I would go as far as saying demonstrate how decent that camera/lens combo is.

f/2.8 has a very shallow DoF as we would expect but also note how sharp it still is. It does not exhibit the softening so often mentioned when many lenses are wide open, but a bit useless as far as DoF goes for macro

f/32 (minimum aperture the same as my minimum aperture of f/32 which Nikon indicate as effective f/57) is softer as we would expect. The only way you are going to get that image to appear 'sharper' (assuming there was absolutely no camera/subject movement during the exposure) is to improve it in PP or restrict it's viewing size. But for real world photography I suspect maximum aperture (error, should read minimum aperture) on a macro lens is only used for tests

I don't know much so if there are ways to get a sharp F/32 out of my gear please teach me how cause I love Grahams matches.

Sharpness is subjective and depends upon many things, colour, contrast and image size viewed are a few that alter peoples perception of what is or is not sharp to them. My other half looked at your f/32 image and thought it was excellent

[Mike Buckley]

The example results show exactly what we would expect, and I would go as far as saying demonstrate how decent that camera/lens combo is.

Thanks for confirming that. I was thinking the same thing but have so little experience with a macro lens that I didn't feel qualified to offer an opinion.

[JBW]

Ok, but by 'moving other settings to maintain -0.7' I am assume this was only shutter speed? The f/14 one is coloured somewhat different not sure why, but does not really affect the results.

The example results show exactly what we would expect, and I would go as far as saying demonstrate how decent that camera/lens combo is.

Seems to me I was right and wrong. Right that F/18 isn't sharp enough. Wrong because for some shots it will be the perfect sharpness.

Bottom line, my skills aren't near as good as my equipment.

[Mike Buckley]

Right that F/18 isn't sharp enough. Wrong because for some shots it will be the perfect sharpness.

It seems to me that you're confusing terminology when it comes to differentiating between sharpness and depth of field. As an example, using f/18 on the same subject but at different distances between camera and subject will yield the same sharpness but different depth of fields. When moving the camera farther away from the subject, the depth of field will increase, which will also result in a larger area of the subject being displayed sharply.

my skills aren't near as good as my equipment.

Perhaps you should revisit your photos made just a few months ago to fully appreciate how dramatically your skills have improved in such a short period of time.

[Black Pearl]

I notice from the screen shot that your shutter speed was 3.2 seconds. With such a massive crop any - or should that be ANY - very, very, very slight instability in your camera set-up will be magnified dramatically.

[george013]

I notice from the screen shot that your shutter speed was 3.2 seconds. With such a massive crop any - or should that be ANY - very, very, very slight instability in your camera set-up will be magnified dramatically.

When trying to view the exif of that last window shot, my exifviewer freezes. Not with the others.

Brian,
Beside that strange behavior on my exif viewer I don't know what you did with the light/exposure.
f14 30s
f2.8 0.125s
f18 5s

George

[JBW]

When trying to view the exif of that last window shot, my exifviewer freezes. Not with the others.

Brian,
Beside that strange behavior on my exif viewer I don't know what you did with the light/exposure.
f14 30s
f2.8 0.125s
f18 5s

George

I used light exposure and actual light brightness to keep my exposure constant.

[george013]

I used light exposure and actual light brightness to keep my exposure constant.

I don't know what you mean with that. When I calculate it back to EV you'll see

f14    30s       EV 2.67 ?
f2.8   0.125s    EV6
f18    5s        EV6
f32    8         EV7

I used an exposure calculator for that, the first I found. If you do such an experiment it would be easier to use a range like 32,16,8,4,2.

If you look at the picture f2.8, the widest aperture, you see unsharpness in the upper left and lower right corner. Probably the result of the lens not beeing orthogonal to the subject. Which I hope is flat. Like Graham mentioned look for the sharpest place in that picture. For me somewhere below the middle and compare only that part with the other images. Compare them by opening them in separate windows,zoom in at 100% and compare them by switching windows. You'll have to find your own way in this.
The sharpest point in the f2.8 picture is getting less sharp. If everything is the same, then diffraction is left.
This is the optical part. To sharpen that will be the pp part, where Graham used USM, which means UnSharp Mask.

One more tip. If you're doing such a research, don't pp the images. Just out off the camera so the processing will be as equal as possible. Maybe even use jpg.
You could use the A-mode too. That would have been easier.

And don't forget your camera shows the nominal f-number, where Nikon shows the effective f-number. I'm not sure if that happens in the lens or the camera. I don't know if you know the difference. If not just say so.

George

[Stagecoach]

I don't know what you mean with that. When I calculate it back to EV you'll see

f14    30s       EV 2.67 ?
f2.8   0.125s    EV6
f18    5s        EV6
f32    8         EV7

I used an exposure calculator for that, the first I found. If you do such an experiment it would be easier to use a range like 32,16,8,4,2.

There is likely little point looking at wider apertures than what we are going to use in real world macro photography and that's going to be from around f/8 to f/11 upwards to try and find the minimum aperture we can get away with at the sizes we want to post or possibly print at.

If you look at the picture f2.8, the widest aperture, you see unsharpness in the upper left and lower right corner. Probably the result of the lens not beeing orthogonal to the subject. Which I hope is flat.

It is an area of watch cover, A new learning series: Pocket Watch

Compare them by opening them in separate windows,zoom in at 100% and compare them by switching windows.

One more tip. If you're doing such a research, don't pp the images. Just out off the camera so the processing will be as equal as possible.

The main purpose I would (did) undertake a similar test as Brian has just done is to learn how my specific lens is affected by diffraction, and how and if it can be compensated for acceptably to me, at the sizes I want to display my image at (for Brian I recall that's 1600 px wide). The reasoning for doing the test/research is to determine acceptable apparent sharpness of the 'final' displayed image.

For this reason comparing by pixel peeping images at 100% and undertaking no PP is simply going to tell you one is better or worse than the other. This type of data is available in text books, but as we know this often does not correlate to real world photography image producing situations.