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Focus and Shadow

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  • Member since
    January, 2015
  • From: Katy, TX
Focus and Shadow
Posted by Aggieman on Tuesday, April 18, 2017 8:34 AM

I fancy myself an amateur (very amateur) photographer with some decent equipment.  I have a Canon Rebel XSi with the standard 18-55mm lens as well as a 70-300mm telephoto and a 85mm macro lens.  I also use a Canon Speedlite 430EX II external flash.

I typically use a tripod but often, because of space limitations, don't feel I can get the camera close enough to my subjects so I will take hand-held photos with the lens just an inch or two away from the subject.  I usually use the 18-55m lens to take pictures of the aircraft that I build.

Current settings on my camera are f-stop 1/80 and ISO 800, I don't think I alter these settings very frequently.

So here are a few recent photos to demonstrate the issue that I am noticing in my photographs.

On this Jug, the tail end is out of focus.  Is this because I have placed the lens to close that it is focusing on the nearest portion of the aircraft? Is there anything I can do to yield a bit more focus to the entire subject?

On this George, more of the same focus issue as with the Thunderbolt, but also it seems a bit dark under the wing.

On this Dinah, I was about an inch away and the camera was actually lower than the aircraft, yet there does not seem to be much light getting under there.  I have been looking at an LED ring flash and light (saw the orthodontist use one of these on extreme close-ups of my daughter's teeth), so I am curious if anyone has any experience using one of these?

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Tuesday, April 18, 2017 9:55 AM

There is an old rule of thumb in macro photography.  For taking advantage of your available depth of field, place the plane of best focus 1/3 of the way between the closest point on the object and the furthest.  On that first image, it looks like you focused on the closest point.

Having said that, the depth of field seems sparse for an f/80.  Did you mean f/8.0?  I find f/8 not really high enough- I generally shoot around f/22 to f/32.

Don Stauffer in Minnesota

  • Member since
    January, 2015
  • From: Katy, TX
Posted by Aggieman on Tuesday, April 18, 2017 3:08 PM

Looks like I am mis-reading the settings as they appear on the screen.  It is set at 1/80 but there is another setting that appears when I depress the "take the picture" button (for lack of knowing what it's actually called) - F4.0

So way less than what you suggest. 

I have played around a bit this afternoon with some test shots.  The screen displays 6" F22, then 8", 10", 13", 15", 20", 25", and 30", all at F25.  I am way out of my depth here as to understanding what these settings really mean, but am not averse to taking a bunch of pictures at different settings to see how things turn out.

  • Member since
    January, 2006
Posted by Paul Budzik on Tuesday, April 18, 2017 11:12 PM

Sounds like you have the camera set on aperture priority ..."AV" and ISO on some fixed number.  What you're seeing are the shutter speed numbers 8 = 1/8 of a second ... 30 = 1/30th of a second and so on.  In AV mode ... the camera selects the shutter speed for correct exposure.  If ISO setting was on AUTO, I doubt you would see such slow shutter speeds unless the 800 you mention is the max ISO for your camera ... 1/60 is about as slow as you want to go for reliable hand held shooting.

Judging from your sample images, what you're describing as your technique as well as the quetions you're asking, I think you would do well to watch my videos ... in the thread right below this one ... I'm trying to keep them simple enough that most anyone would maybe pick something up.

Paul

  • Member since
    January, 2015
  • From: Katy, TX
Posted by Aggieman on Wednesday, April 19, 2017 7:41 AM

Thanks for the information Paul.  I will take a look at your videos when I get a chance later today.

  • Member since
    April, 2016
Posted by GlennH on Friday, April 28, 2017 11:13 AM

Closeups. I remember hand making a parallax frame for my first camera with a coat hanger. Focus and DOF are always going to be an issue, worsening the closer you get. As you stop down past a certain limit you begin adding new diffraction issues.

This may seem counter to what you are trying to do but you may want to give it a shot. The higher the resolution you have at your disposal the better it may work. Move your camera/tripod BACK a few feet. You will get more DOF at that same aperature than you would a foot away. Now crop it.

A number Army Viet Nam scans from hundreds yet to be done:

https://www.flickr.com/photos/southwestdreams/albums/72157621855914355

Have had the great fortune to be on every side of the howitzers.

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Saturday, April 29, 2017 10:40 AM

There is an equation for figuring the f/# where the blur circle for out of focus equals diameter of diffraction blur.  However, take this with a grain of salt.  The shape of the two blur circles (spot profile) is different.  Diffraction blur lowers contrast somewhat over large areas of frame, whereas the defocus blur circle looks more like- out of focus. The result is that you can use a higher f/# than indicated by that equation.  Look at some of Ansel Adam's landscapes.  He always used very high f/#s.

If you are using a digital camera it doesn't cost anything to experiment.  Try some high f/#s- you may be surprised at how high an f/# you can go to before being bit by diffraction.

 

Don Stauffer in Minnesota

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