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Author Topic: Depth Of Field Question?  (Read 26815 times)

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« on: February 15, 2014, 02:25 »
0
Hello,

I am still very new to photography, when I look at some stock photos that are isolations, I notice that they are in complete focus. My mentor, has sugested using helicon focus, however I keep feeling like there must be a lens that can capture an object in complete focus? As of right now I have been taking multiple photos going across an object and ending up having to merge 25-50 photos in photoshop to get a picture completely in focus and its taking many hours to do that. I am using a 5D Mark2 with a 100mm lens.

Any suggestions?

Thanks!


« Reply #1 on: February 15, 2014, 04:25 »
0
Depending on what you are trying to focus, a lens or camera with tilt movements is the normal traditional way of taking close up images with total focus. The tilt (or swing) either of the lens or the back allows you to play with the plane of focus.

There is a useful thread here at photo.net.

ETA: actually that thread is rather irritatingly argumentative. Maybe someone else has a better link re tilt (swing).
« Last Edit: February 15, 2014, 05:26 by bunhill »

Beppe Grillo

« Reply #2 on: February 15, 2014, 05:54 »
0
Depending on what you are trying to focus, a lens or camera with tilt movements is the normal traditional way of taking close up images with total focus. The tilt (or swing) either of the lens or the back allows you to play with the plane of focus.

There is a useful thread here at photo.net.

ETA: actually that thread is rather irritatingly argumentative. Maybe someone else has a better link re tilt (swing).


Very strange that they don't tell the name of this (old) principle: Scheimpflug

http://en.wikipedia.org/wiki/Scheimpflug_principle
Exploring tilt and swing of a view camera with 35mm DSLR


If you already have a Sinar camera you can use this accessory to mount your dslr
http://www.sinar.ch/en/category/products/cameras/p-slr/



With a normal dslr I use Helicon Focus, and generally, with an f/11 aperture, I don't need more than 6 - 8 images to get a whole focused result.
« Last Edit: February 15, 2014, 06:12 by Beppe Grillo »

« Reply #3 on: February 15, 2014, 09:23 »
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I use Photoshop and the stacking technique.  Canon eos-1Ds, 100mm lens. f.22. Usually 4-6 shots.

If it is a simple shot of a screwdriver, at an angle, it is easily accomplished with Photoshop's automated process. The problem with stacking, comes when the foreground of the image falls directly in front of the back part of the image. There will be a blurring of that line, and no program can automatically correct it. Has to be done manually in post processing. Here's an example of that problem that was corrected in post processing.

« Last Edit: February 15, 2014, 09:28 by rimglow »

mlwinphoto

« Reply #4 on: February 15, 2014, 10:53 »
0
A T/S lens will help you adjust the plane of the camera's focus and allow you to get it more parallel to the subject plane.  If you are shooting a flat subject that may be all that is needed to get the image with one shot. However, depending on the depth of your subject you may still need to use a focus stacking technique to get everything sharp.

I don't use a T/S lens but do rely heavily on Helicon when I want the entire subject sharp.  The shallower your DOF the more images needed in the stack.  I typically shoot between 25-50 images per in most of my work; using f11 the closer I am to the subject and the longer the focal length of lens I am using, the shallower the DOF and therefore the more images are needed in the stack.

BTW, I also use focus stacking when shooting certain subjects with selective focus in mind.  For example, if I'm in close to a single flower and want just the pistil and stamens sharp and the fore-and background petals soft I'll shoot a stack series that includes just those parts of the flower that I want sharp (assuming a single shot wouldn't do it, which it often wont when you're in real close).

I use f8-11 (Nikkor macro lenses) when creating stacks.  Some advocate f 16-22 but I find diffraction rears its ugly head in that range and interferes with image quality....all depends on what you want.

« Reply #5 on: February 15, 2014, 11:02 »
+1
Dependant on the size of your subject, there are different ways:
1..The expensive one: A tilt shift lens
2..The troublesome one: Stacking
3..The easy one: Step back and use F16.


BTW?? can photoshop stack? and where is that?

Nice clear photo, rimglow.

stacked of 3-4 photos f 16
« Last Edit: February 15, 2014, 11:05 by JPSDK »

« Reply #6 on: February 15, 2014, 11:41 »
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Photoshop can stack - something about automate > photomerge. I find it doesn't always do a very good job of choosing which parts to keep and which to toss though, so some manual editing of the stack might be necessary. I am far from an expert at this. I think Rimglow might be the master.

« Reply #7 on: February 15, 2014, 11:43 »
+4
3..The easy one: Step back and use F16.

This.  I've never stacked anything when doing isolations.  Frankly, I feel a little DOF blur gives the image life, otherwise an all in focus cut out just looks flat.

On the other hand, I don't do macros of bugs or flowers, and I know people dig having those in focus across the range.

« Reply #8 on: February 15, 2014, 14:00 »
+1
In PS Bridge Menu go to      Tools = Photoshop = Load files into PS layers (or just load images into PS in sequence)
 
once in photoshop highlight all layers then go to

Edit=autoalign,  choose type , I used auto,  this takes a few minutes, 

Edit- auto blend = stack images,   (get a cup of coffee),    look closely and be prepared to repair on complicated images.

I once aligned 18 images with this method  23" x 162" a  2.034 gb tiff.  I found out jpeg has 30k width/height pixel limit.  Be prepared for PS to get squirrley with big jobs.
« Last Edit: February 15, 2014, 14:14 by old crow »

« Reply #9 on: February 15, 2014, 15:15 »
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I understand the benefit of stacked focus for extreme macros where the DoF can be so thin that you can't get an entire insect eye in focus, but in general is there any evidence that having everything in focus from front to back increases sales potential? In many cases I think it would risk creating an image without an obvious subject or where the subject is overwhelmed by unimportant information.

You can get tilt-shift lenses for DSLRs or you can use an adapter with a medium format lens (such as one of the Pentacon Six/Kiev camera lenses).

mlwinphoto

« Reply #10 on: February 15, 2014, 16:17 »
+1
I understand the benefit of stacked focus for extreme macros where the DoF can be so thin that you can't get an entire insect eye in focus, but in general is there any evidence that having everything in focus from front to back increases sales potential? In many cases I think it would risk creating an image without an obvious subject or where the subject is overwhelmed by unimportant information.

Depends entirely on the subject and your personal vision/composition.  For example, I often use focus stacking when shooting peeling tree bark; if I'm in close enough I can't get everything sharp with one shot and having some of the bark in focus and some out doesn't look very appealing, to me at least.
I've also used stacking in landscape work where I'm inches away from the foreground flowers and want the distant mountain sharp as well.  Stopping down all the way doesn't always get everything sharp enough particularly if you are not using an ultra wideangle lens.
There are many ways of handling a particular subject.....focus stacking just gives you some added options.

« Reply #11 on: February 15, 2014, 17:18 »
+4
I understand the benefit of stacked focus for extreme macros where the DoF can be so thin that you can't get an entire insect eye in focus, but in general is there any evidence that having everything in focus from front to back increases sales potential? In many cases I think it would risk creating an image without an obvious subject or where the subject is overwhelmed by unimportant information.

As a buyer, it is infuriating to find a great piece of food to drop into a grouping, only to find out the depth of field is so shallow in won't match the group you are trying to drop it into. If you provide the buyer with a full focus image, then the buyer is free to blur whatever part of that image they want, to match another photo.

You can fake depth of field on a sharp image, buy selective blur,  but you can't fake sharp focus that never was there.

« Reply #12 on: February 15, 2014, 17:41 »
0
I understand the benefit of stacked focus for extreme macros where the DoF can be so thin that you can't get an entire insect eye in focus, but in general is there any evidence that having everything in focus from front to back increases sales potential? In many cases I think it would risk creating an image without an obvious subject or where the subject is overwhelmed by unimportant information.

As a buyer, it is infuriating to find a great piece of food to drop into a grouping, only to find out the depth of field is so shallow in won't match the group you are trying to drop it into. If you provide the buyer with a full focus image, then the buyer is free to blur whatever part of that image they want, to match another photo.

You can fake depth of field on a sharp image, buy selective blur,  but you can't fake sharp focus that never was there.

Thanks for that info.

« Reply #13 on: February 15, 2014, 17:56 »
0
Dependant on the size of your subject, there are different ways:
1..The expensive one: A tilt shift lens
2..The troublesome one: Stacking
3..The easy one: Step back and use F16.


BTW?? can photoshop stack? and where is that?

Nice clear photo, rimglow.

stacked of 3-4 photos f 16



I have tried F 16 and the depth of field is almost the same as when I am shooting at F 8 which is where I typically shoot. So your knife picture for example if I focus on the tip the majority of the knife is going to be blurred, If I come in 1/3 from the point then the tip and the back handle part of the knife will be blurred. If I back away from the knife and shoot, it will be more in focus but then its not going to fill the frame and be much smaller which in turn limits the size of the isolated photo when cropping for composition. This of course would be with a 100mm, so if I tired a different mm lens would I have better success? What mm did you use on the knife?

« Reply #14 on: February 15, 2014, 18:02 »
0
I checked excif:
a 16, 5 frames at 85 mm.
original image size 4000 x 6000

Thanks old crow. I just tried. It works.
« Last Edit: February 15, 2014, 18:10 by JPSDK »

« Reply #15 on: February 15, 2014, 18:41 »
0
""Thanks old crow. I just tried. It works.""

Glad I could help. 

p.s.   That cockroach of yours has become a mascotte ! ! !

« Reply #16 on: February 15, 2014, 18:55 »
0
""Thanks old crow. I just tried. It works.""

Glad I could help. 

p.s.   That cockroach of yours has become a mascotte ! ! !

The one over at istock?

OM

« Reply #17 on: February 15, 2014, 21:01 »
0
If you're a Nikon user, there's a less expensive alternative to the T/S or PC-E lenses. Get a PB4 T/S bellows on feebay ($200). Get a 120mm-135mm lens from an enlarger or (what I use) a Tominon 135mm f4.5 lens from a Polaroid MP4 copy camera (cost me nothing as I bought the MP4 with other lenses as a job lot and sold a load of the stuff I didn't want for a profit).
The Nikon mount on the bellows rotates for vertical or horizontal shots and you have lens panel tilt/ shift and therefore a Scheimpflug plane of 'sharpness'.
A little slow in use compared to the T/S lenses but nevertheless effective as long as you remember to shield the old (and non-multicoated) lens against off-axis light. Probably useless for insects though!

« Reply #18 on: February 16, 2014, 01:20 »
0
So conclusion is therefore that unless you are using a tilt shift lens, all other lens types will have the same depth of field?

« Reply #19 on: February 16, 2014, 03:46 »
+2
There, the "part of the universe" rule set in.
Meaning, the lesser part of the universe you photograph, the lesser the dof.

And then there are teles... They dont really fit into the rule.

« Reply #20 on: February 16, 2014, 04:10 »
0
So conclusion is therefore that unless you are using a tilt shift lens, all other lens types will have the same depth of field?

Even the t/s lens has the same DoF. The difference with  it is that you are tilting the DoF over to lie on top of the subject.  Once you do that, things above and below the subject (that were in focus without the tilt) become out of focus.
Imagine DoF as a sheet of glass: With an ordinary lens the glass is like that in a window - always parallel to the camera. If you tilt the lens, then the glass (DoF) tilts, too, but it doesn't actually get any thicker than it was.

The thickness of the glass is decided by the aperture, not the tilt.

« Reply #21 on: February 16, 2014, 04:12 »
0
So conclusion is therefore that unless you are using a tilt shift lens, all other lens types will have the same depth of field?


It's physics.

DOF calculator

There are 4 factors: sensor size, f/stop, focal length and subject distance. The closer you are the less DOF and the less that reducing the aperture will make any difference.

« Reply #22 on: February 17, 2014, 13:02 »
0
So conclusion is therefore that unless you are using a tilt shift lens, all other lens types will have the same depth of field?


It's physics.

DOF calculator

There are 4 factors: sensor size, f/stop, focal length and subject distance. The closer you are the less DOF and the less that reducing the aperture will make any difference.


So I should back off the subject some, which would mean I would not fill the frame but would have to crop and would also lose some size for those extra large sales. I guess I worry that the stock sites will be less happy with the photo if its smaller in size for resale.

What about adding some tube extensions - lens extensions?

« Reply #23 on: February 17, 2014, 13:34 »
0
Unless it's an extreme closeup 5-6 images at f/11 - f/13 should give a decent coverage and stacking in Helicon Focus is pretty fast.  Except when you have the problem pointed out by rimglow - then it is a pain to correct manually.  In my experience HF does a better job than PS, but I only have CS4 and maybe the newer versions are better.

« Reply #24 on: February 17, 2014, 13:38 »
0
So conclusion is therefore that unless you are using a tilt shift lens, all other lens types will have the same depth of field?


It's physics.

DOF calculator

There are 4 factors: sensor size, f/stop, focal length and subject distance. The closer you are the less DOF and the less that reducing the aperture will make any difference.


So I should back off the subject some, which would mean I would not fill the frame but would have to crop and would also lose some size for those extra large sales. I guess I worry that the stock sites will be less happy with the photo if its smaller in size for resale.

What about adding some tube extensions - lens extensions?


Extension tubes will effectively increase your f/stop (calculated as f:aperture). The effect of this would be to increase depth of field. However extension tubes also reduce the focusing distance. The effective of which is to decrease depth of field.

Long story short is that extension tubes increase magnification. Increasing magnification reduces depth of field.

Uncle Pete

« Reply #25 on: February 19, 2014, 11:22 »
0
There, the "part of the universe" rule set in.
Meaning, the lesser part of the universe you photograph, the lesser the dof.

And then there are teles... They dont really fit into the rule.

Good way to put it.

Almost off topic?

Can anyone recommend a free stacking program? Or if I have CS3 do I already have one. What about Elements and multiple layers. I've never even looked into it, but wonder about even a small stack, say 4-5 images, to get better depth of field, it might be interesting.

I think I need to learn more technique in this area. Not going to buy a TS-E.

Looking for entry level, starting out and then work ahead from that.

« Reply #26 on: February 19, 2014, 12:01 »
0
I messed around w/ Zerene stacker or something like that (free stack program) it is more oriented towards macro w/ many layers, but worked. I see it is only a 30 day trial now.

I have heard that basically no matter what combination of lenses and distances, if you fill the frame w/ the object you will have a similar depth of field - so for a ball, wide angle up close will be about the same as telephoto from far away (with some differences because of the depth of the object that you actually see) and filling the frame would be similar for a basketball as for a bb. Things that help make the depth of field larger are a smaller sensor (essentially cropping) and a smaller aperture.

« Reply #27 on: February 19, 2014, 22:59 »
0
As for stacking programs I use ZM combine. Its free, a bit oldfashioned and creates splendid pictures.
I also have Helicon focus, that is not free, it is much more advanced and can control the camera and calculate the number of frames.

But I do not use it, its too complicated and ZM combine is good enough. That is because I have stacked so many times that I have a good feeling for how many frames and what distance to photograph from.
« Last Edit: February 19, 2014, 23:03 by JPSDK »


 

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