How Sharp is Sharp?

[Aidan Briggs]

I was curious as to what you all considered is tack sharp. I have heard the rumors about the 100-400 being soft, and as that is the only telephoto I have ever used, I would like to compare it to a 500, 600 or 800mm lens. I have had a good experience with the 100-400, but I am not sure if my images would be considered tack sharp, because I have never seen the results from the supposedly superior lenses.

Here is an unsharpened 100% crop of a recent image of mine taken with the 100-400. Would you consider this tack-sharp? Here is the full sized image: http://birdphotographers.net/forums/showthread.php?t=46864

I would appreciate 100% crops from some of the others lenses that I mentioned.

Thanks in advance.

[Alfred Forns]

Aidan an image straight out of the camera without sharpening is not a good way of comparing sharpness (from a raw image)

We have had discussions regarding the sharpness of the 100-400 right here and have been interesting. Just to give you an idea there was a comment from one bird moderator as to the lens not being sharp, I sent him a PM after reading the thread and got a PM back he never has used it ..... The lens is sharp and there is nothing wrong with the AF being sluggish etc. Is is it as sharp as say the 400 straight or the AF as fast as the 400 straight, I'm sure it is not but don't sell the lens short.

I find this focal length very useful and rely on it at times. Will try to dig up samples for other lenses for you.

[Joerg Rockenberger]

Great question, Aidan! I've meant to ask the same with regard to folks posting 100% crops of 7D images to show the AF accuracy - or lack thereof. It's obvious that there is a wide range of what is considered tack sharp. JR

[Aidan Briggs]

Aidan an image straight out of the camera without sharpening is not a good way of comparing sharpness (from a raw image)

We have had discussions regarding the sharpness of the 100-400 right here and have been interesting. Just to give you an idea there was a comment from one bird moderator as to the lens not being sharp, I sent him a PM after reading the thread and got a PM back he never has used it ..... The lens is sharp and there is nothing wrong with the AF being sluggish etc. Is is it as sharp as say the 400 straight or the AF as fast as the 400 straight, I'm sure it is not but don't sell the lens short.

I find this focal length very useful and rely on it at times. Will try to dig up samples for other lenses for you.

Thanks Al, I consider it to be a very good lens, and from my experience with the lens I would have to agree with your assessment.

What would be a better way of comparing sharpness? Would you consider the above sample tack-sharp for being straight out of camera?

Thanks

[John Chardine]

Hey Aiden- this is an interesting topic. Al is right, all images out of the camera (except from my 5D!) look a little soft at 100%. However, in a series of images taken in rapid succession with my 50D and say the 500/4 or the 400/5.6, I notice that one or two are usually really sharp out of the camera. A lot of the variation has to do with micro-movement of the lens or the subject, air quality and focus. I owned the 100-400 and got some excellent results from it (just look at what Daniel Cadieux does with his). Every lens is a bit different and most benefit from a little stopping down. At 400mm the 100-400 works really well at f6.3 and smaller. It doesn't like filters in my experience so I would recommend not using one.

I'll look for a few from the 500/4 and 400/5.6 and post at 100%.

[Aidan Briggs]

Thanks John, and John.

JR: I agree with you, part of the reason I posted this was because I was curious about the IQ of the 7D crops

Here is a sharpened version if it makes it any easier.

[Jan Wegener]

I would consider your image as sharp. Tack sharp I'd call something like this.

This is a 100% crop of a Raw straight out of lightroom without any sharpening. However, not every shot looks like this, many are softer. Your image I'd call average sharpness. Something you could still work with nicely :)

http://www.vogelfotografien.de/Test/222.jpg

[Aidan Briggs]

Thank you Jan, that is the first real answer to my question. What lens was this made with?

[Dave Phillips]

Aidan, I have found that sharpness....the real sharp ones are more dependent
on stability during the shot more than any other "single" factor. On a beanbag
or tripod, results are always better than when handheld(for me).
Next IMO comes an accurate exposure, it's all about the light.

Good luck in your quest, but don't be overly concerned. Just polish technique
and have fun

here is a 50D sample with 400mm f/5.6 on a beanbag from car window

[Ákos Lumnitzer]

A sample at 100% taken with a 300 f/4L and 2x, manual focus only on 30D. Straight out of camera. While my 2x is great with a 500mm lens, the 300mm is hit and miss. Needs good light, but as you can see, I reckon the above picture is more than acceptable. :)

[Doug Brown]

Hi Aiden. You bring up an interesting subject. It's hard to gauge sharpness at 100%, particularly as pixel density increases. The 7D has 18 megapixels, which is a boat load of pixels IMO. But I've been posting some 100% crops because there are a lot of people who give 100% crops a lot of weight when evaluating image sharpness. The flip side, as you illustrate here, is that it's very hard to assess sharpness when you size your images for web presentation. You can definitely tell if an image is soft, but critical sharpness is a whole different ballgame. Images that aren't critically sharp at 100% may look quite sharp when sized for BPN.

Ultimately for me a lens is sharp if it produces sharp output after post-processing at my desired output size; sometimes that's 1024 pixels wide for BPN, and sometimes that's considerably wider for 13x19 prints.

[Desmond Chan]

Aidan an image straight out of the camera without sharpening is not a good way of comparing sharpness (from a raw image)


It's hard to gauge sharpness at 100%, particularly as pixel density increases.


I would like to ask why raw file zoomed in 100% should not be used to gauge sharpness. Correct me if I'm wrong, my understanding is that Aidan wants to see if his 100-400 is tack sharp, or at least sharp enough. If Aidan is able to shoot with his camera different lenses under the same condition, then the resulting raw files should be a valid way to compare the sharpness of one lens with another since there is no sharpening or anything added to the files.

Now if we are talking about whether the final photograph, i.e., the final product of the process, then it could be a different story since we know that there will be at least some processing done to that raw file to turn it into the final image as seen on the web, a print, etc., steps that could make a not so focused/sharp image look focused/sharp. So I would think judging a lens sharpness by a processed image could give us misleading result but judging it by a raw file should give us some idea if one lens is sharper than the other.

No?

[Ed Erkes]

I'm glad to see some photographers appreciating the quality and versatility of the Canon 100-400. I'm a Nikon user and have obviously never used the lens, but I've seen some exceptional prints from this lens. This lens has for some reason been much maligned on other forums (one photographer "expert" even stated the image quality of the Canon 100-400 compared to the 400 f5.6 was laughable).

[Ed Cordes]

This is an interesting discussion. I have used a 100-400 for about 4 years now and, frankly like it a lot. It is my work horse lens due to its versatility. I also feel the lens is maligned by many (some of whom never have used the lens) unnecessarily. Check out the following link. http://www.birdphotographers.net/forums/showthread.php?t=44746

I made this image with a 100-400 hand held. It is about a 60% crop. I know that some will say the image benefits from web presentation, but I can attest that the print at 8 1/2 X 11 is still excellent.

I do agree with those who said that exposure, air quality and steadiness are very important. I think many will rely on IS to make up for poor technique. That said, is my 500 sharper than the 100-400? Yes. I get many more consistently very sharp images from it. However it is a $6,000 prime that weighs 8 1/2 pounds. Is the versatility and light weight of the 100-400 allowing me to produce images my 500 will not due to its constraints? yes.

So, to answer your question, sharp enough is what is necessary to make the final output excellent.

Edit - I have sent the lens in 2 X for cleaning and recalibration. After an Africa trip there was lot of dust inside. This past Spring I sent it in again for general cleaning and calibration due to the amount of use it gets. So, my copy is a sharp lens as I ask for exact spec calibration.

[Doug Brown]

Here's a 100% crop from the 7D with a 500 f/4 lens. Lightroom processing only; no sharpening or NR. IMO this is a sharp RAW file. I would characterize Aiden's image as having reasonable but not great sharpness. Of course evaluating the sharpness of a lens requires an understanding of how to get the best results with that lens. In the case of the 100-400, I believe it needs to be stopped down to f/7.1 or f/8 to realize its maximum sharpness. Not so with the 400 f/5.6, which looks great wide open.

[Aidan Briggs]

Thanks all for the replies and images. From these samples, I would have to say that the 100-400 is a good, versatile lens that delivers acceptable, but not great sharpness wide open. Someday I'll own a 500...

I would also like to see Desmond's question answered, the RAW image seems like a good way to compare IMO.

[William Malacarne]

I don't think you can compare a RAW file between different brand or even same brand and different models of cameras. If it uses a Bayer type sensor then it has an Anti-aliasing filter. I think these will all be different for different cameras and they do effect sharpness.

Bill

[Roger Clark]

Aidan,

I'll try and add to what has already been said.

First, if you test the same lens on different cameras, you'll get different results, even if focus was perfect on each camera. This is largely/partly due the differences in the blur filter used in each camera. As pixel size decreases it is more of a challenge for the lens to produce pixel to pixel contrast. For example, the blur filter in the 5DII is not as aggressive as it is in the 1DII, so sharpness appears different.

To view an image, it is usually converted, whether in camera jpeg or raw converter. Each applies an algorithm that is likely different, so comparisons can vary widely.

The only way to know what is sharp from a specific camera and raw converter/in-camera jpeg is to have a reference sharp lens. For example, if you have a fixed focal length lens that is very sharp, say a 180 mm macro, set up a newspaper on a flat wall and photograph it at f/8 at a given distance, say 30 feet measured from the center of the lens. Then put on you 100-400 at 400 mm and move out by the factor 400 mm / reference focal length (e.g. 400 mm / 180 mm) = 2.22, so move out 30*2.22 = 66.6 feet (adjust the test so you can resolve the text). Then compare results using the same processing. Use mirror lock up and a solid tripod.

Another why is to compare the same subject with what other people obtain. A reference everyone can image all over the world is the Moon. Here are some links to images taken with a 500 mm f/4 L IS (links to the full resolution image are also on the page):
http://www.clarkvision.com/galleries/gallery.astrophoto-1/web/moon.rnclark.handheld.c10.25.2007.jz3f6583f-8s-800.html

http://www.clarkvision.com/galleries/gallery.astrophoto-1/web/moon-JZ3F3658-60-c-5x-700.html

Now to the 100-400. Yes, there has been controversy. In at least some cases it appears that filters may be causing the softness. Here is an example filter showing this effect:
http://www.clarkvision.com/photoinfo/evaluating_filter_quality

The above is an unfinished page; next I'll add images from the 100-400 with and without good/bad filters to show the difference. (I've been very busy at work with the water on the moon discovery so haven't had time to work on this.)

I have the 100-400 L IS, 300 f/4 L IS, 300 f/2.8 L IS, 500 f/4 L IS (and other lenses) and my 100-400 is not as sharp as the other lenses at 400 mm. It produces good 8x10s, but is not up to par above that compared to my other telephotos. You can also see these effects on Canon's MTF charts.

My main problem with the 100-400 is that is is not a sealed lens, so when you zoom, air and dust is being pumped into the lens and the camera body which can then get on the sensor. My choice when traveling light is the 300 f/2.8 and if lighter, the 300 f/4.

Roger

[Gail Spitler]

Here is a report on tests of a set of Canon 400mm & equivalents done by EJPeiker. Both the tests and the results are interesting in terms of the discussion above.

http://www.ejphoto.com/400mm_shoot_out_page.htm

Cheers
Gail

[Charles Glatzer]

I have been described as being overtly anal when it comes to image sharpness. I go to the point of buying 3 lenses, testing each and returning the other two. Whether it is the AF tolerance, lens elements and/or alignment, coatings, etc I know not, but one will always outperform the others. It is difficult to tell if an image is truly sharp, as Clark mentions there are many contributing factors.

When you see and know what a really sharp image looks like, it becomes disheartening that many of the images produced lack in comparison, myself included. Rest assured there is a definitive recognizable difference in the end result. These not-quite images are quite acceptable to many, and I can tell you most do not know the difference till shown otherwise. I see it on every workshop, a hundred times a year, and it has to do with proper technique, as well as the equipment in hand. If most images are slightly off the mark the problem must be approached systematically to determine the cause and effect. When I critique a photographers portfolio of images I most often have to address sharpness, albeit delicately.

FYI- I had a 100-400 that produced stellar images from about 130-380mm.

Warmest Regards to all,

Chas

[Daniel Cadieux]

Aidan, the sample image you posted looks sharp enough and very acceptable. The eye and immediate area around it seem softer, but that is a DOF issue (note the very sharp feathers in LRC). I love the 100-400, a very underated lens IMO, and you couldn't pry it out of my hands if you tried...having said this, the long primes really are impressive in sharpness and AF (I only have limited borrowed use with those as I don't own any) and I must admit they had me drooling for one.

P.S. I don't use any filter on mine, and never had the chance to use a TC so I can't comment on that. The said primes take a TC quite well so that is another potential plus if you ever go that route.

[Gail Spitler]

Oooops forgot the URL for the report I mentioned above

http://www.ejphoto.com/400mm_shoot_out_page.htm

Cheers
Gail

[Aidan Briggs]

Thanks everyone for the replies. That is some interesting stuff you brought to the table Roger.

Daniel, the big primes have me drooling too :) I have noticed with the 100-400 that there sometimes the sharpest focus isn't exactly where the focus point is, in my plover image above the focus point was exactly on the eye, but the sharpest areas are below and above it... Have you ever had something happen like that?

[Daniel Cadieux]

Aidan, I haven't particularly noticed that with my lens. In the full-size image you link to the eye isn't centered in the frame...perhaps you focussed and re-composed, therefore slightly nudging the eye out of DOF range just enough to make this small difference. I use the focus/recompose technique and therefore whenever possible I like to use f/7.1 - f/8 apertures to give me enough DOF to cover for this.

[Charles Glatzer]

:) I have noticed with the 100-400 that there sometimes the sharpest focus isn't exactly where the focus point is, in my plover image above the focus point was exactly on the eye, but the sharpest areas are below and above it... Have you ever had something happen like that?


The lens or camera could be slightly front or back focused. AF mico-adjustment on the new bodies is designed to allow the user correct for this error.

Chas

[Joerg Rockenberger]

I have been described as being overtly anal when it comes to image sharpness.

Well, how does an anally sharp 100% crop then look like? JR :D

[Charles Glatzer]

Aidan, the sample image you posted looks sharp enough and very acceptable.

Therein lies the problem when a viewer states an image looks sharp, what is acceptable to one may not be so to another. Different lines in the sand if you will. To me an image is simply sharp or is not sharp, no gray area. But, like I stated above...I am a stickler for sharpness. It is why I have been through no less than six Mark III bodies, and finally after much chagrin with the powers that be I now have in hand two brand new bodies that I can state are definitively sharp.

Respectfully,

Chas

[Dave Phillips]

The lens or camera could be slightly front or back focused. AF mico-adjustment on the new bodies is designed to allow the user correct for this error.
Chas


It "could" also be that most modern DSLR AF is set/guaranteed to be within one DOF.
If DOF at a given aperture is .5" then AF can occur anywhere within that .5".

I think I have found this to be true....and somewhat of an explanation regarding Aidan's
comment about varying areas of sharpness off the focus point

[Joerg Rockenberger]

Therein lies the problem when a viewer states an image looks sharp, what is acceptable to one may not be so to another. Different lines in the sand if you will. To me an image is simply sharp or is not sharp, no gray area. But, like I stated above...I am a stickler for sharpness.

Well, again, can you please put a stake in the ground (sand?) and post a 100% crop illustrating your sharpness standards in evaluating an image! I adore your images but your prose is a bit vague and not really helpful. And I don't necessarily disagree with your philosophy re sharpness - please just make it more accessible and relevant for Common Joe's and your peers.

And no, I don't have any beef with you (or anyone else) but I am just trying to learn.

JR

[Charles Glatzer]

Well, again, can you please put a stake in the ground (sand?) and post a 100% crop illustrating your sharpness standards in evaluating an image! I adore your images but your prose is a bit vague and not really helpful. And I don't necessarily disagree with your philosophy re sharpness - please just make it more accessible and relevant for Common Joe's and your peers.

And no, I don't have any beef with you (or anyone else) but I am just trying to learn.

JR

John,

This is an image that I consider sharp when viewed full size out of the camera. The variables of trying to do this type of comparison on the web are many, such as the different compression software used to reduce the file size for posting, different camera sensors and pixel ...., anti alising filter strengths, etc. Not enough controls to make this very relevant, but I have done so at your request.

1Ds Mark III, 500mm, ISO 800, 1/640 @ F/6.3 handheld from zodiac. As it appears out of camera.

FYI- I will post the image in the wildlife forum tomorrow. http://www.birdphotographers.net/forums/showthread.php?t=47445

Best,

Chas

[Joerg Rockenberger]

Thanks Charles. Much appreciated. It is helpful even though you think it is mute because of the lack of a controlled comparison. Keep in mind though that you might be worrying about and considering second-level effects on IQ whereas mere mortals like me are still wondering how to go from zero to first... :D So, knowing what others can achieve and what one should aim for is helpful.

JR

[Charles Glatzer]

Thanks Charles. Much appreciated. It is helpful even though you think it is mute because of the lack of a controlled comparison. Keep in mind though that you might be worrying about and considering second-level effects on IQ whereas mere mortals like me are still wondering how to go from zero to first... :D So, knowing what others can achieve and what one should aim for is helpful.

JR

Point taken.. glad to help.

Chas

[Ed Erkes]

To me an image is simply sharp or is not sharp, no gray area.

Respectfully,

Chas

I have to respectfully and strongly disagree with Chas on this statement. In fact it really doesn't make any sense to me at all. There are a lot of factors that affect the apparent and real sharpness of an image. Lens quality, ISO used, soft or hard light, direction of lighting, use of flash, etc. A close-up image taken with a macro lens will be sharper than one taken with a zoom and 2-element close-up diopter--but both images are acceptably sharp and can make very nice large prints. Two photographers could take a photo of the same subject with same lens, same aperture, in low light at ISO 800, and, depending upon the camera used (say a Nikon D300 and a Nikon D3)--one might obtain a significantly sharper image than the other--but both images again could be acceptably sharp. Chas, are you saying all your keepers are equally sharp? If they aren't equally sharp, then you are definitely dealing with gray areas.

[Charles Glatzer]

I have to respectfully and strongly disagree with Chas on this statement. In fact it really doesn't make any sense to me at all. There are a lot of factors that affect the apparent and real sharpness of an image. Lens quality, ISO used, soft or hard light, direction of lighting, use of flash, etc. A close-up image taken with a macro lens will be sharper than one taken with a zoom and 2-element close-up diopter--but both images are acceptably sharp and can make very nice large prints. Two photographers could take a photo of the same subject with same lens, same aperture, in low light at ISO 800, and, depending upon the camera used (say a Nikon D300 and a Nikon D3)--one might obtain a significantly sharper image than the other--but both images again could be acceptably sharp. Chas, are you saying all your keepers are equally sharp? If they aren't equally sharp, then you are definitely dealing with gray areas.


Ed,

Of course apparent image sharpness will vary with the tools in hand, atmospheric conditions, lighting, viewing source, etc. I am saying there is a difference in an image being the sharpest in can be with equipment in hand and under the conditions taken, and one that may be acceptably sharp. The difference is notable, such as when a sequence is taken and the individual images compared. What each of us is willing to accept is subjective.

Additionally, it is why I stated posting images for comparative analysis is not relevant when we cannot control all the variables.

Best,

Chas

[Milan V]

Hi!

Aidan photo is definetelly not sharp for me, Jan photo is tack sharp, Dave is close, Akon is close to sharp, the same of Doug.

Best!
Milan

[John Chardine]

It is well to remember that reviewing an image at 100% on a computer screen is extremely unforgiving, and something we never had with film, not even with a loupe. Although there are differences in the apparent sharpness of the images posted here, most of this could be due to the camera and sensor, as indicated by Roger. Out of the camera my FF 5D produces stunningly sharp images compared to my 50D.

I would wager that all the images here would print up to show on a computer screen very nicely!