What "Tack Sharp" means?

[anita]

Hello guys.

Long time, no seen.
I have a little question if you're kind to help me. What is exactly the term "tack sharp"? How can be measured. I
'm looking at photos and to me something is missing. Can u tell me pls pls pls what is the limit of the sharpness because i can't get it right!

If you look at this link http://www.juzaphoto.com/hr.php?t=215022&r=79944&l=it. Do you think this photo is tack sharp? Is it normal to be like this (can't this be more sharp?) :'(. I don't know what to think more, maybe my lens has a problem, or this is the maximum sharpness that can exist withoug pp. VERY VERY difficult for a begginner.

Thanks a lot guys and a good day!

[Soozie B]

Hi Ana,

I took the liberty of looking this up for you: A tack sharp image is one that is sharp even when viewed at its largest size.

Hope this helps

[ajohnw]

The link just brings up a registration page of some sort. Hope that isn't the reason for the post.

[Dave Humphries]

Hello guys.

Long time, no seen.
I have a little question if you're kind to help me. What is exactly the term "tack sharp"? How can be measured. I
'm looking at photos and to me something is missing. Can u tell me pls pls pls what is the limit of the sharpness because i can't get it right!

If you look at this link http://www.juzaphoto.com/hr.php?t=215022&r=79944&l=it. Do you think this photo is tack sharp? Is it normal to be like this (can't this be more sharp?) :'(. I don't know what to think more, maybe my lens has a problem, or this is the maximum sharpness that can exist withoug pp. VERY VERY difficult for a begginner.

Thanks a lot guys and a good day!

Hi Ana,

This is a term that may mean more to people of english background than other cultures. To give a little background, a tack is a small nail which WAS used typically to hold down carpets in Britain, I have no idea whether other European or American carpet fitters ever used them. They are (and yes, I have drawn blood while using them), very sharp, which was due to their manufacturing process of slicing metal up, then sticking the head on.

In photographic parlance, it just means 'as sharp as can be' - in other words (as you already know), the image sharpness is very good, with fine detail clearly resolved (under the right conditions).

The link you posted didn't mean anything to me, not just due to my not being able to read the language, it seemed to be to a generic page about a camera, rather than displaying an image.

The thing about sharpness is it depends not only on the lens and camera being used, but on many other factors too; how much it was cropped, how the image is being viewed, at what resolution, whether in print or on screen and what post processing (PP) was used to optimise the image for that viewing method. Certainly a photo PP'd for one use will not be suitable for another and the viewer's perception of image sharpness can be improved.

You can look at review sites that publish graphs of lens performance to answer questions of lens A vs lens B.
After that, if printing, you would aim for a final ppi of say > 150 ppi. If for web display, SO MUCH depends upon how much you downsize (to no more than 1000px tall and or 1600px wide) before applying essential final sharpening and saving/uploading.

Hope that helps, but do ask for clarification if I have only made things worse

[anita]

The link just brings up a registration page of some sort. Hope that isn't the reason for the post.

Yes, i just figure it out now. The problem is that this photo is on this site. It's not my photo, any suggestion how to make it visible for you?

[anita]

test upload

[anita]

This is the sample photo

[rpcrowe]

As Dave Humphries aptly stated, "tack sharp" is a slang term which means "very" sharp". (BTW: we use carpet tacks in the USA and also use "thumb tacks" to attach items to a cork buletin board.) There is not specific measurement of sharpness which allows the use of "tack sharp" as a term. It is up to the individual photographer to decide if he or she considers the image "very sharp". What is "tack sharp" to one photographer is not "tack sharp" to another. Just as one image is "beautiful" to one photographer and may not be "beautiful" to others.

[anita]

Short version: I look at a photo(that is not mine) and i say THIS IS 100% sharp. WOW how many details and clarity.
I take a photo with my lens, and i don't get that WOW, i feel that smth is missing. A 0.00000000000000000000001 to be perfect. What is it not perfect? Is it me? Is it the lens? I took a photo with a lens that cost 1000 $ and after 1 year i can't find a photo to say WOW, although i've read many many reviews regarding this lens. I take 10 photos with a lens that costs 100 $ and i see a 90% WOW, for the first time i remained impressed, not at maximum, but i see that WOW. I don't know how to achieve it, BUT I KNOW THAT I CAN RECOGNISE IT!

Long version:
You didn't understand the essential, my mistake. I'm not interested in the TERM. I'm intersted more in what it really means, or what represents it. Let's call MAXIMUM sharpness or correct sharpness. When you are taking a portrait photo, focus on the eyes and realize when u get back home that are a little blurry(not moved, but maybe could have been better). How do you know that your focus is correct?!? I know that there are some factors(dof,focal length, subject distance, shutter speed, aperture,etc.), it's just i don't have a comparison ... a standard. What is the maximum sharpness a camera can obtain? What if i obtain the maximum,minus a little and i want full? Or tried another lens, and remaind WOW looking on the sharpness of that lens. How can you say that your lens is at its full sharpness or is a user error?

BETTER EXPLAINED: It's like you look through your viewfinder that it;s has that wheel +/- and that it's set "1 stop" under your dioptry. After u set it right (add that "1 stop" you see it perfectly clear!)

[FrankMi]

Hi Ana, here is a link to an e-book on how to get images that are photographically 'Tack Sharp'. At this link you can get a free sample of the contents of the e-book. I purchased this book some time ago and found it to be well worth reading more than once. http://www.flatbooks.com/tack-sharp-...nailing-focus/

Hope this helps you as much as it did me!

[Dave Humphries]

Hi Ana,

Rather than try to see what others have done, I think the best solution is to let us see what you have shot.

Can you upload a picture and put the link in the post in this thread please? (Don't be shy, we all started somewhere)

I can see you were having problems with the other picture, there are four ways to do show images here at CiC, with step-by-step instructions here;
HELP THREAD: How can I post images here?

TinyPic is easiest and will allow you to upload a picture up to 1600 pixels on the longest edge.

If you do not use any software to;
a) downsize and
b) sharpen
an image before uploading and web viewing, this will result in them appearing a bit soft online (although not as bad as a whole dioptre of vewfinder adjustment).

Post #6 in that thread goes into a process of how to do that.

Another option is you send me an FZ100 RAW picture you think is your best and we both PP it and see what the differences are - then I say what I did to (hopefully) have got it looking good, or what the problems were that meant I couldn't.

Good luck,

[rpcrowe]

Lighting and air quality has a lot to do with apparent image sharpness. There is a local vista which I pass just about every day and which, one of these days I will shoot.

Some days the air is so clear and crisp that I feel like I could touch the mountains in the background. This could result in an image which really appears sharp.

Other days, the air clarity is not very good. Haze or smog obscures the mountains and the resultant image would not seem sharp.

Of course, I could attach a polarizing filter which would reduce the impact of the haze/smog somewhat. The CPL can, if the sun is at the correct angle, reduce or even eliminate much the reflection off the particulates in the air and tends to "penetrate" smog or haze". I could also work with vibrance, contrast, saturation and sharpness in my editing program.

However, having the luxury of passing this scene many hundreds of times during any given year, I would choose to shoot on a day when the air is clear.

I suspect that if I picked the "right" day fo the shoot, I could obtain an image with a lesser quality lens that would "look" sharper than one I shot on a hazy or smoggy day with one of my top line lenses.

[anita]

If u believe me i believe you. The great shot is composed always by small details + LUCK, Richard.

[ajohnw]

One of the usual problem with sharpness is that the camera generates a huge image as far as a PC screen is concerned. On my monitor for instance it's probably about 3ft by 4ft off a 12mp sensor. This is inevitably reduced in size for the web and presented in jpg format. That process has 2 effects. The none obvious one is that it may not possible to show all of the detail shown in the larger shot at the smaller size. Often that one can be forgotten but it does sometimes crop up. The other one nearly always crops up. Detail in the reduced size image looses it;s impact due to interpolation to the smaller size and compression effects. That one is easily cured by use of an unsharp mask. It's just case of adjusting the amount to suit the photo. At some point it will make a noticeable difference. A little more than that is usually best. To much might make grass or small features in the shot look rather strange so it's a case of watching what happens to the whole shot. If you ever want to use a crop from a whole frame strange interpolation and incompletely resolved detail crops up here as well so the unsharp mask is usually needed for best results. The process can make noise more apparent, particularly in darker areas

There are a couple of other simple adjustments. Brightness and contrast. Increasing contrast usually needs brightness increasing as well. Too much again will produce odd results. Then there is saturation. These 3 inter react some what.

If you have all of these adjustments available there will probably be another called curves. If you lift the lower left of the straight line it shows it will brighten up dark areas often revealing more detail. The top end adjusts bright areas and the whole curve represents the brightness range of the photo. Another way of looking at it is that the lower left indicates the black point and the top right the white point. Anything in the picture that is below the black point will be shown as black. Opposite at the white end. It's fairly easy to get to grips with and the curve can be bent to any old shape. To much introduces strange colour changes.

I would suggest just working on camera jpg's to start off with. Raw conversion needs similar controls and it's best to be familiar with what they do first. No doubt many will disagree but I learnt that way due to taking many shots with compacts and I still often use camera jpg's. Why not if they need little adjustment and not surprisingly camera manufacturers put a lot of effort into getting jpg's right what ever is in front of the camera.

The need for the curves control is very very apparent on compacts as they compress the light range at dark end of things. The same thing happens at the bright end as well. Curiously dslr'e do too. That's how they achieve very high dynamic ranges. The true linear really representative dynamic range may be as little as 5 stops. That is another factor to consider when taking what you might call exhibition shots. To much exposure in the compressed dynamic range may not result in a good shot and is likely to need more processing. On the other hand many "great" shots avoid it or minimise it's effects.

One other reason for unsharp photo's can be af systems. They may decide to just focus on the front surface of objects at times or sail straight through the bit you want to be in focus. That's what the viewfinder and manual focus are for. Using the cameras rear screen if it has one for the same thing isn't so simple unfortunately.

John

[xpatUSA]

Long version:
You didn't understand the essential, my mistake. I'm not interested in the TERM. I'm intersted more in what it really means, or what represents it. Let's call MAXIMUM sharpness or correct sharpness. When you are taking a portrait photo, focus on the eyes and realize when u get back home that are a little blurry(not moved, but maybe could have been better).

Hello Anita,

As a watch photographer, sharpness is a bit of a Grail for me. Firstly, I never use AF if I want the sharpest possible, not that my view-finder is the world's best and neither are my myopic diabetes-afflicted eyes. Manual focusing eliminates any incorrect AF decisions that the camera might make. However, my SD10 does beep when it thinks the focus is correct - even in manual, helps me get in the ball-park.

Lot of questions there:

How do you know that your focus is correct?
When you can't make it any better by adjusting the focus ring on the lens. Simple as that. However, this does not automatically give you a tack-sharp image :-(

What is the maximum sharpness a camera can obtain?
Difficult to answer, because "sharpness" is nowhere satisfactorily defined - it is only a subjective property of an image. For my own purposes, the best possible edge is what I look for, consistent with the aperture setting I am using (more depth-of-field = less sharpness, sorta). You may be surprised to know that more resolution (MPs) = less sharpness, too. I shoot watches in LO res (0.87 MP) with a (binned) 18.24 pixel pitch.

What if i obtain the maximum, minus a little and i want full?
First you figure out why you didn't get "the maximum" then take corrective action - said he, stating the obvious!

Or tried another lens, and remained WOW looking on the sharpness of that lens?
I don't understand the question - it's too vague.

How can you say that your lens is at its full sharpness? ["or is a user error" - ignored]
You shoot in Aperture Priority the ISO test target at a range of apertures and maximum JPEG size and quality. No in-camera sharpening and none in post-processing either. In this case AF would be OK to use and don't move the camera or change the lighting. Range from f/11 down to the lowest setting. Choose the "sharpest" and that tells you the sharpest setting for your lens, the so-called "sweet spot".

Some well-meant advice: You would probably get better answers by de-hyping your questions (MAXIMUM, WOW, max, full, etc) and being a little more specific.

[jcuknz]

Hello Anita,

As a watch photographer, sharpness is a bit of a Grail for me. Firstly, I never use AF if I want the sharpest possible, not that my view-finder is the world's best and neither are my myopic diabetes-afflicted eyes. Manual focusing eliminates any incorrect AF decisions that the camera might make. However, my SD10 does beep when it thinks the focus is correct - even in manual, helps me get in the ball-park.

.

A somebody who never uses manual focusing I would raise the point of the area used to find focus. Early on with my bridge cameras I considered manual focusing to be comparing mush with mush even with 230,000 pixel EVF/LCD. On getting my Pany G3 I discovered they had incorporated the ability to make a very small target area which meant I could use this to be highly selective as to which point I wanted to be the point of focus ... similar to how I used to focus with my SLRs and I guess today's DSLR users work though without the aids that were common with SLRs.

Good as AF may be I think it is merely a tool to be used by the photographer rather than left to its own devices, after all it cannot think and assess the subject matter like a human can.

This is getting off the OP's original question, sorry , but here I think there is an unhealthy preoccupation with sharpness and a couple of times that I can think of I have sharpened an image too much to have it accepted as top or honors image in a competition. Because some very expensive lens can do it does that mean it should be a requirement for all? A tail wagging the dog situation I suggest.

[Dave Humphries]

Hi Ana,

As per PM, I got the RAW files you zipped to me last night, thanks.



On the two portraits, I don't see the problem is in the capture - they look "Tack sharp" to me when pixel peeping at 100%.

Everyone, please bear in mind that this is the first time I have used Canon's DPP Viewer Module, but I think I am drawing valid conclusions here.

The images I show here are crops from the area we might have wanted to be sharp, so in the case of the two portraits, this was the eyes.

IMG_0519
From the EXIF; Canon 5D Mk.2 EF 50mm, f/1.8 lens, 1/500s, f/2.8, iso100
Picture style (Standard) applied by DPP; Sharpness 3, Contrast 0, Saturation 0, ColourTone 0.
This jpg screen grab is 1300 x 860px, view in Lytebox, at full size (and no browser zoom) to assess sharpness.



There is no red Fous point shown on this, so I guess you focused manually - and you seem to have got that spot on.


IMG_0838
From the EXIF; Canon 5D Mk.2 EF 24-70mm, f/2.8 lens, at 70mm, 1/160s, f/5.6, iso100
Picture style (Standard: User Defined 1) applied by DPP; Sharpness 5, Contrast 2, Saturation 0, ColourTone 1.
This jpg screen grab is 1300 x 860px, view in Lytebox, at full size (and no browser zoom) to assess sharpness.



There is a red box Focus point on the eye here - this also seems sharp to me.


IMG_0799
From the EXIF; Canon 5D Mk.2 EF 24-70mm, f/2.8 lens, at 35mm, 1/800s, f/8, iso320
Picture style (Monochrome) applied by DPP; Sharpness 3, Contrast 0, Filter effect 0, Toning effect 0.
This jpg screen grab is 850 x 860px, view in Lytebox, at full size (and no browser zoom) to assess sharpness.



There is no red Fous point shown on this one, so I guess you focused manually again - the sharpest area is the pavement a few feet in front of you, at this distance and with the aperture selected, it is demonstrably giving insufficient Depth of Field for the background to be sharp. The shot is also blown in some background areas on the left and that will also degrade sharpness of those subjects.

Here are the three again with the DPP highlight alert on; showing blown areas;




All were shot Manual mode, WB also set manually to what seems appropriate for the lighting.
Metering evaluative, sRGB colurspace.

In summary, I don't know what competance level you are, but I certainly don't see any 'beginner' errors with either of the portraits (although one is over exposed) - you worked manual and made reasonable choices; ones that haven't impacted unduly sharpness in my (somewhat inexperienced) view.

The mono shot is different though, the focus was clearly in the wrong place, or, if DoF tables were used to attempt an overall front to back sharp image, this hasn't worked for some reason - I haven't double checked what should be expected for that focal length and aperture on a DoF table because the Canon EXIF data doesn't seem to contain the focus distance.

I could PP one of the portraits for online viewing, but I don't think it is going to help that much unless we see one you have done to compare. The most telling thing for sharpness is the 100% crops, as above.

I hope this helps,

[anita]

All i am intersted now it's the SHARPNESS of this pictures, not the composition, not the blown highlights .Anyway thank you a lot for your time and help. I need to see if the images are "tack sharp" and mine "tack sharp" is a sharp recognised by all others(you say about a woman that she's beautiful, but other 9 are not so convinced, in change if 8 men tell she's beautiful than "your beautiful" = "their beautiful" => that woman is beautiful). So:
1. Regarding portraits it's ok the sharpness, i can start shooting knowing what to look for when i check the sharpness of photos, right?
2. Regarding "landscape" it's still problematic, i'm sure that i've used the f/13 setting and HFD calculated:
2.1. pointing at smth that i assume is the distance - because on distance scale is written 1.5 feet | 3 feet | etc - try to imagine where 1,71 feet is :-? when i focus manual or autofocus;
2.2. recompose the scene, placing the camera parallel to the ground(assuming that the camera doesn't calculate the DOF remembering what was the angle when i focus and take into consideration the distance, or am i wrong?)
THE RESULT? Same story as the photo presented above.
Going over f/13 i've read that it's not such a good idea...(don't remember well the reason).

Thank you for your analyze.

[anita]

How do you know that your focus is correct?
When you can't make it any better by adjusting the focus ring on the lens. Simple as that. However, this does not automatically give you a tack-sharp image :-(

. I think you didn't understand the question here. If i choose MF and point to an object a little and take the photo you will look at the picture and say "You didn't focus right! Try again!". I move the ring more this time. "Nope, it's better than the last time, but still isn't correct". I move the focus ring again and again... UNTIL when?!? because for me was focused at 8 on a scale of 10. FOr you, the correct one was the 10. So, for this i want other's opinion. How do i know that i obtain the "maximum correct focus"?

What if i obtain the maximum, minus a little and i want full?
First you figure out why you didn't get "the maximum" then take corrective action - said he, stating the obvious!

To get "the maximum" i have to know what MAXIMUM means?!? You have to pick the apples when they are RED. The maximum here is red, you recognise this aspect and know that when are orange is not enogh, you have to wait longer(rotate the focus ring more), get it?

Or tried another lens, and remained WOW looking on the sharpness of that lens?

I take a photo with 50mm 1.8 and same photo with 24-70 2.8 at 50mm focal length and observ that 50mm 1.8 has a BETTER SHARPNESS, sooooooo i've recognized with naked eye that MAXIMUM sharpness. I even remained "WOW", how much detail, wow this means "tack sharp", WOW. (isn't this one reason when buying lenses? the sharpness of the lens. What do that ppl see when afirming that?)

How can you say that your lens is at its full sharpness? ["or is a user error" - ignored]
You shoot in Aperture Priority the ISO test target at a range of apertures and maximum JPEG size and quality. No in-camera sharpening and none in post-processing either. In this case AF would be OK to use and don't move the camera or change the lighting. Range from f/11 down to the lowest setting. Choose the "sharpest" and that tells you the sharpest setting for your lens, the so-called "sweet spot".

Again here, you didn't understand my question. My mistake. You have a lens that from its specifications has a 10 focus scale. You make photos a year or so, and smby having the same lens sees your photos and say: "Your lens is not as sharp as mine". Could i've known this thing without a comparison or a specialist eye? Take that lens to service and they say, your lens had smth, focused at 8 instead of 10, but we've fixed it. Now focuses at 10. I didn't express myself right.

LOOk, for a beginner it's not so easy to understand what is going wrong. When he mistakes or when the camera/lens has a problem. If you are(not you) a person that pushes a button and says the photo is super ok, but a pro tells it could have been way way much better, well, i'm not. I want to know what is the "maximum" focus/color/exposure i can obtain in-camera and if it is smth not perfect it's not my fault. So for me the only thing is the COMPARISON. Make photos with 2 different lens, one takes photos with sharpness that impresses me, the other one seems that it stops at 8.5 instead of 10. It's sad that the better lens costs 10x less than the EXPensive one.

[anita]

Good as AF may be I think it is merely a tool to be used by the photographer rather than left to its own devices, after all it cannot think and assess the subject matter like a human can.

I am human and i know i have limitations. I also think that in some aspects a machine is better then me. It's confusing with MF. WHy? If you AF on a subject, the machine searches for the optimal contrast if i'm not wrong, let's call it "Limit X". If you move to MF and keep half way the button and rotate the focus ring until the led flashes, What is the differnce? In my opinion you've rotated manually until you've reached that SAME "Limit X".? why dhould u bother to rotate manually when the machine does the same thing + faster? I'm not 100% convinced about this, because in Macro foto i've heard that MF rulllz. But there maybe the magnification of objects, how you see them is different than the usual lens.
Second. Go to a wedding and MF 5000 photos(if u can, congrats). And let me know why AF photos are so good, or put it another way howmany of the best photos are AF and how many MF? (ingeneral)