Newbie question: Higher aperture setting = more "blue" in photos (?)

[chrisv2]

Total newbie question here. I did search but could not find any pointers on this (which worries me a little).

I've been playing with the settings on my Sony Nex (c3) and one thing I wanted to try was "infinite focus" by setting the aperture at a high number. It seems that whenever I go to a higher F number than what the auto-setting on the camera selects for the scene I am shooting, the picture picks up a noticeable increase in "blue". Histogram confirms this.

Is there something wrong with my camera or is there something about changing the aperture that affects the color values of the picture? And...if the latter...how do you correct it?

thanks...

 

[Big Mike]

When your aperture gets smaller and smaller, you will likely run into problems caused by diffraction. Normally, you will see a loss of sharpness, but color abnormalities are not unexpected.

I'd suggest finding a DOF calculator (web sites or smart phone apps). That would allow you to calculate your DOF based on your focal length, aperture, sensor size and distance to point of focus. You may find that you can get to 'infinite focus' at a larger aperture (lower F number) than you might have thought....which would allow you to avoid the issues caused by diffraction.

 

[Hikaribushi]

When your aperture gets smaller and smaller, you will likely run into problems caused by diffraction. Normally, you will see a loss of sharpness, but color abnormalities are not unexpected.

I think this may explain why I've encountered a lack of sharpness/focus in many of the recent photos I took. My goal was to increase the depth of field so I shot a lot of my photos with as small an aperture as possible while maintaining a "correct exposure".

 

[Big Mike]

When your aperture gets smaller and smaller, you will likely run into problems caused by diffraction. Normally, you will see a loss of sharpness, but color abnormalities are not unexpected.

I think this may explain why I've encountered a lack of sharpness/focus in many of the recent photos I took. My goal was to increase the depth of field so I shot a lot of my photos with as small an aperture as possible while maintaining a "correct exposure".

I used to do that as well, but then I learned to use a DOF calculator and the technique of hyperfocal focusing. Now I will figure out what aperture I need to get the DOF that I want, rather than just defaulting to F22.

Also, I've watched a tutorial about getting shots where you need a really deep DOF (landscape with foreground, middleground and background). Rather than use a really small aperture for the DOF, and live with the diffraction, you can bracket your focus point and combine the shots in Photoshop. You end up with the DOF that you want, but will the sharpness that comes from using an optimum aperture like F8.

 

[Hikaribushi]

Thank you Big Mike!

 

[rokvi]

Try this one.

 

[chrisv2]

Thanks Mike and team for suggestions. If I could ask you for a little more help, here are three pictures which show what I am dealing with. I know I am making a dumb beginner mistake but I can't put my finger on it.

First picture is camera on full auto. It selected f/11 and shutter 1/100 @ ISO-200 (the lowest ISO this camera will go to). To my untrained eye this is an acceptable picture.

Second picture is camera set on aperture priority. I selected f/3.5 and camera selected shutter 1/640. ISO-200. This picture looks awful.

Third picture is camera set on aperture priority. I selected f/22 and camera selected shutter 1/10. ISO-200. Another picture I won't be sending in to any contests ;-)

So I am really confused - the instant I go to aperture priority, even at a lower f-stop -- I get this awful blue wash-out. Why?

 

[fjrabon]

Thanks Mike and team for suggestions. If I could ask you for a little more help, here are three pictures which show what I am dealing with. I know I am making a dumb beginner mistake but I can't put my finger on it.

First picture is camera on full auto. It selected f/11 and shutter 1/100 @ ISO-200 (the lowest ISO this camera will go to). To my untrained eye this is an acceptable picture.

Second picture is camera set on aperture priority. I selected f/3.5 and camera selected shutter 1/640. ISO-200. This picture looks awful.

Third picture is camera set on aperture priority. I selected f/22 and camera selected shutter 1/10. ISO-200. Another picture I won't be sending in to any contests ;-)

So I am really confused - the instant I go to aperture priority, even at a lower f-stop -- I get this awful blue wash-out. Why?

It looks like somehow that whenever you change your camera to aperture priority it is also changing the white balance settings. The first looks like auto white balance the second and third look like some wildly in appropriately cold setting like maybe tungsten or god knows what.

 

[chrisv2]

:blushing: wow I think that's it! In one of my prior threads here I was trying to figure out how to take nifty product photos for my web business. I had to create a 'custom' white balance using the spot-target-thingy feature in the camera to pick a white to use as a reference. That setting got left 'on' since then! I bet on full-auto the camera ignores it, then the instant I go away from full-auto it is picking up that custom white balance.

I will check it out - thank you! I'm a computer engineer by normal trade and let me tell you I have a new respect for photographers...no kidding.

 

[swiftparkour94]

Make sure auto white balance is not selected. If the problem persists than you may have a defective/bugged camera (I'd only assume). I've never had this problem before with my T3i

 

[Big Mike]

Yes, that is clearly a WB issue, not aperture or anything else.

When you use the green (fully auto) mode, the camera defaults to auto WB. (it also defaults to multi point AF, Matrix/Evaluative metering etc.). So those photos turned out OK. But when you switch out of fully auto, the camera goes back to whatever WB setting you choose. That is your problem here.

As for a solution...never EVER, use your camera's fully auto mode. If you want a brain-free mode, use P.

Also, shoot in RAW, rather than JPEG. That way, you can change the WB setting on the computer afterward.

 

[TCampbell]

When you're on "full" auto, many cameras wont allow you to customize any settings -- so your custom white-balance setting may have been ignored. When you came off "full" auto and went to a semi-auto setting, it will allow you to over-ride and was likely going with your custom white balance setting.

You'll want to switch the camera to "daylight" white balance (or whatever white balance mode is appropriate for your lighting) or if you stay in custom white balance mode you'll need to update your white balance.

 

[chrisv2]

thanks guys, advice taken and memorized.