Explanation?

Needa

Senior Member
Challenge Team
Anyone have an explanation why there is no clean cut off?


_71D4942.jpg


Easy enough to fix move back from the door frame, but why no clean cut off. Reflection off the white frame?
 

Lawrence

Senior Member
Because your aperture is set at f4.5 giving a fairly narrow depth of field.

Part of the foreground (door frame) as well as the background is out of focus
 

BackdoorArts

Senior Member
Same reason none of the lines in the background are clean. Out of focus areas will never have clean edges. You don't need to move back, just increase your aperture so that there's more in focus. Use the Preview button on the camera to temporarily close the blades and you can see whether or not your chosen aperture gives you the effect you want.
 

Needa

Senior Member
Challenge Team
Maybe clean line is a bad description. The area in question is the light strip down the middle of the cat.
 

Whiskeyman

Senior Member
Maybe clean line is a bad description. The area in question is the light strip down the middle of the cat.


The answer is the same as before: depth of field limits. In addition, the obstruction is likely lighted unevenly, or has different shading, from near to far. (Possibly a piece of weatherstripping?) In addition, the far portion, that nearest the cat, is closer to being in focus than the rest of the obstruction, which is closer to the camera sensor.

I'm assuming that if you take a photo of the cat without the obstruction there is no line present.

WM
 

skene

Senior Member
The easier way to understand how depth of field works. If you will, open your eyes as wide as you can, how much can you see in focus? Not much when you look around wide open you can only focus on a particular area. Now do the reverse and squint and how much more can you focus on when you are not straining your eyes. The aperture on a lens works in the same way.

When you set the lens at wide open apertures it can focus on an item and the rest are out of focus. Then vice versa with stopping down the aperture the higher the numerical numbers the more the aperture closes down (squinting).


inv_fullxfull.750167872_bsxkdi6n.jpg

https://www.etsy.com/seller-handbook/article/mastering-depth-of-field-techniques-for/22793892943
 

Blacktop

Senior Member
The answer is the same as before: depth of field limits. In addition, the obstruction is likely lighted unevenly, or has different shading, from near to far. (Possibly a piece of weatherstripping?) In addition, the far portion, that nearest the cat, is closer to being in focus than the rest of the obstruction, which is closer to the camera sensor.

I'm assuming that if you take a photo of the cat without the obstruction there is no line present.

WM

You can see the cat through the part of the out of focus area, so it can't be anything solid in front of the cat. You can see where the doorframe ends and that part of the cat is hidden .
 

Needa

Senior Member
Challenge Team
You can see the cat through the part of the out of focus area, so it can't be anything solid in front of the cat. You can see where the doorframe ends and that part of the cat is hidden .

You would think but the door frame is a hard edge with nothing translucent or transparent, door is open. It is related to depth of field but have never seen it create a band that you can see the subject before. Originally though it was because the door frame was too close for that lens to focus the frame. But was able to recreate the band with a different lens that can focus the frame at that distance. Even at F16 you can see the band.
_71D4966.jpg
 
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skene

Senior Member
You would think but the door frame is a hard edge with nothing translucent or transparent, door is open. It is related to depth of field but have never seen it create a band that you can see the subject before. Originally though it was because the door frame was too close for that lens to focus the frame. But was able to recreate the band with a different lens that can focus the frame at that distance. Even at F16 you can see the band.
View attachment 214914

The way you may want to look at it is if you were to try this out.
Put a finger upright infront of your face, you can clearly see as an optical illusion that you can visually see through your fingers.
Then pull your finger away from your face as your eyes focus on it, you start to see the solid object. The door frame is out of focus and subject isolation is on the cat.
 

aroy

Senior Member
That band is diffraction of light around the hard edge which is very near the lens. You will not get the band if you move a bit back.
 
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