Sharp or not? I can't tell for sure.

Terrence

I'm driving myself a bit mad trying to figure out if my images are sharp or not and if I have any focusing problems (worried about me, not the camera). I primarly shoot wildlife, birds in particular and I really want to improve the sharpness and clarity of my images.

Please take a look at the following images I made today. Links to the originals are below each image. When I zoom in to 100% or more, I don't think these images are as sharp as the should be. Am I right or am I asking too much from my equipment?

Setup

• Canon Rebel XT
• Canon 100-400L
• Bogen 3021 tripod, very solid
• Arca Swiss B1 ball head
• Wimberly Sidekick
• Physical position was about 4' to 6' from the subject

Post-processing

• Exposure, highlight and shadow tweaks in ACR
• 75% to 80% crop
• No sharpening, curves or levels
• Save as max quality JPEG from ACR

I normally shoot at either ISO 200 or 400 so I can get faster shutter speeds at dawn and dusk. In this case I shot at ISO 100 to try and keep the noise as low as possible so I could focus on focus and sharpness. The subjects were quite calm, so I don't thing their movement caused a problem.


ISO 100, 1/30 @ f/5.6, 400mm
Original (HUGE): http://terrencej.smugmug.com/photos/130533200-O.jpg


ISO 100, 1/80 @ f/5.6, 275mm
Original (HUGE): http://terrencej.smugmug.com/photos/130533254-O.jpg

LiquidAir

My guess is you are about as sharp as the 100-400L is going to get wide open. Try some shots stopped down to f/8 or f/11 and see if they get sharper. Another thing you might try is DxO Optics. It has a special shapening algoritirhm tuned for your camera/lens combination and it does a nice job of compensating for lens softness.

http://www.dxo.com/intl/photo/dxo_optics_pro/cameras_lenses

wxwax

LiquidAir wrote:

My guess is you are about as sharp as the 100-400L is going to get wide open. Try some shots stopped down to f/8 or f/11 and see if they get sharper.

Sounds right. Wouldn't mind hearing from other 100-400 owners.

pathfinder

Shutter speeds of 1/30th to 1/80th are not ideal for really sharp images, but I do not readily see movement artifact. The images are a little soft, but the 100-400 is famous for not being razor sharp at 400mm.

You said your images had not been sharpened either, and that will make a big difference in how they appear.

I downloaded your images and set a white and a black point and then sharpened them with USM in the Lightness channel in LAB at 500, 1.4, 22 and then 25, 50, 3 Now they look like this.......

With the sparrow, the Depth of Field is VERY shallow, really only the eyes are within the DOF, that is part of the reason it looked soft. The shallow DOF is typical of long lenses used on near subjects also






Is this more like you expected? Most images from DSLRs need significant sharpening to look their very best . These are amounts I typically use on many of my bird images, so do not feel that this is an unusual amount of sharpening. While the 100-400 does not get rave reviews for being sharp, on an APS sensor camera, you are loosing the soft corners of the image circle and only the better central part of the image. I think your lens is fine.

Terrence

Thanks for the advice and the re-worked examples. I'll try more shooting at f/8 (f/11 is the other reportedly sharpest aperture on this lens). I think I was most surprised that f/5.6 has such shallow DOF. I know it should be shallow, even more so on a tele, but I let that slip out of my memory banks.

Khaos

Four to Six feet is really close for a 400. I don't think I can shoot within 10 feet on my 400 5.6 L, which if you want sharp without breaking the bank and a great BIF lens this is the one for you.

I always sharpen on my telephoto shots and also use LAB. Pathfinder did a great job.

The telephoto has a learning curve. I think it's a fun one, becuase once you master it, you will be one happy camper with the results.

Jeff Geoghan

Khaos wrote:

Four to Six feet is really close for a 400. I don't think I can shoot within 10 feet on my 400 5.6 L, which if you want sharp without breaking the bank and a great BIF lens this is the one for you.

I always sharpen on my telephoto shots and also use LAB. Pathfinder did a great job.

The telephoto has a learning curve. I think it's a fun one, becuase once you master it, you will be one happy camper with the results.

OK, I know that USM is unsharp mask in PS but what is LAB? I'm interested in practicing the technique that pathfinder used...

Terrence

Jeff Geoghan wrote:

OK, I know that USM is unsharp mask in PS but what is LAB? I'm interested in practicing the technique that pathfinder used...

I'm no expert, but I am pretty sure LAB refers to changing the image from RGB to LAB color, which gives you separate color channels. Then you apply changes to the Luminance channel. What changes, I'm not exactly sure.

I reccomend a post in the Finishing School forum asking the question. You'll get a lot of good answers there.

LiquidAir

Terrence wrote:

I'm no expert, but I am pretty sure LAB refers to changing the image from RGB to LAB color, which gives you separate color channels. Then you apply changes to the Luminance channel. What changes, I'm not exactly sure.

I reccomend a post in the Finishing School forum asking the question. You'll get a lot of good answers there.

Sharpening the L channel prevents and color shifts in the sharpening halos.

pathfinder

Terrence wrote:

I'm no expert, but I am pretty sure LAB refers to changing the image from RGB to LAB color, which gives you separate color channels. Then you apply changes to the Luminance channel. What changes, I'm not exactly sure.

I reccomend a post in the Finishing School forum asking the question. You'll get a lot of good answers there.

Sorry for the confusion I contributed to.

The L channel in the Lab color space is found by clicking Image>Mode>LAB in the dialogue boxes.

The first thing I do when I am ready to sharpen, is type ctrl-J. This creates a duplicate layer in the Layers Palette. Make sure the top layer is active ( or click on it to make it the active layer ).

Next I convert the Image to LAB, by typing Image>Mode>LAB as described above.

Next I type ctrl-1 ( or Apple-1 on a MAC:D) to display the Lightness Channel which is a grayscale appearing image that displays the Luminance values from 0-100 in LAB.

You are correct - sharpening here is preferable to sharpening in RGB because you get much less change in color and less haloes as well.

I ALWAYS do this step on a duplicate layer that I have created by typing ctrl-J first. That way I can oversharpen signficantly and then adjust the sharpening by using the Opacity Slider of the Layers Palette to my taste. CTRL-~ lets me see the image in color image again, rather than the greyscale image of the lighness Channel.

The other advantage of sharpening in a layer, is that I can click on the little box that looks like a TV Set - a square box with a circle in it. Clicking on this brings up the Layer mask box in the upper layer in the Layers Palette.

Clicking this open box brings up the Layers dialogue box that allows you to paint with black or white. Using a black brush in Normal Blending mode, lets me paint away any sharpening in areas that I do not want sharpening, or the noise that sharpening can introduce to areas like sky, that do not need sharpening in the first place.

The are multiple threads here on dgrin about sharpening - try searching for sharpening and rutt and you will find a goldmine. Read the discussion of Sharpening with a Stiletto here on dgrin and you will find even more.

Jeff Geoghan

pathfinder wrote:

Sorry for the confusion I contributed to.

The L channel in the Lab color space is found by clicking Image>Mode>LAB in the dialogue boxes.

The first thing I do when I am ready to sharpen, is type ctrl-J. This creates a duplicate layer in the Layers Palette. Make sure the top layer is active ( or click on it to make it the active layer ).

Next I convert the Image to LAB, by typing Image>Mode>LAB as described above.

Next I type ctrl-1 ( or Apple-1 on a MAC:D) to display the Lightness Channel which is a grayscale appearing image that displays the Luminance values from 0-100 in LAB.

You are correct - sharpening here is preferable to sharpening in RGB because you get much less change in color and less haloes as well.

I ALWAYS do this step on a duplicate layer that I have created by typing ctrl-J first. That way I can oversharpen signficantly and then adjust the sharpening by using the Opacity Slider of the Layers Palette to my taste. CTRL-~ lets me see the image in color image again, rather than the greyscale image of the lighness Channel.

The other advantage of sharpening in a layer, is that I can click on the little box that looks like a TV Set - a square box with a circle in it. Clicking on this brings up the Layer mask box in the upper layer in the Layers Palette.

Clicking this open box brings up the Layers dialogue box that allows you to paint with black or white. Using a black brush in Normal Blending mode, lets me paint away any sharpening in areas that I do not want sharpening, or the noise that sharpening can introduce to areas like sky, that do not need sharpening in the first place.

The are multiple threads here on dgrin about sharpening - try searching for sharpening and rutt and you will find a goldmine. Read the discussion of Sharpening with a Stiletto here on dgrin and you will find even more.

Thanks! More research to commence immediately...