Question: What causes lines?

RyanS

I've only been shooting a few months so my apologies in advance if I am asking dumb questions. What causes the strange lines on the arms in this shot? What would I call them besides "strange lines?" I know it probably has something to do with the wide aperture (f/1.8). I was trying to get a really creamy background so the sun, clouds, and and houses would melt in to abstract colors and shapes. I was also trying to get a very shallow DOF to get everything pretty much past her nose/eyes out of focus. I like how this turned out overall, with a few complaints beyond the lines. I've only got a 50 1.8, so the facial features seem a bit out of proportion to me. It is what it is. And her face was kinda dirty, kids, whatcha gonna do? I also didn't quite get the framing I wanted. 60 seconds later and the sun dipped below the houses, this is the very last sliver of light of the day. I got about 8 shots in this series, and this seemed the best one.

Would this have been a better shot with a little deeper DOF? Maybe backed off a little?

reyvee61

I'm sure someone here has the technical reason for this but I think it's the transition from the bokeh (shallow dof) to the in focus part of the image. I see this often when shooting at f/1.4 or f/1.8
Are you using the fifty on an APS-C sensor?
I think the back-light only accentuates the effect around her arms even more....

anonymouscuban

It looks like you may have punched the contrast up in post. I see this happen all the time when I up the contrast on shots like this. What I do is add a mask and remove the contrast effect on the BG and portions of the photo that take on these "lines". The photo actually looks better because you really don't want too much contrast on portions of the photo that are out of focus. You want those areas to be creamy with smooth transitions.

Yaflyyadie

I might under expose the background 1/2 to 3/4 stop and fill flash about 1/2 power (OR) fill with a white reflector made of white foam square, cardboard, corrugated aluminum foil on top of cardboard etc.
It could help a bit.!!!!!!!!!!!!!!!

VayCayMom

Looks Chromatic fringe, that is not the correct term, but close. It can be found in areas with high contrast. Comes in several colors. If you go to YOUTUBE there are tutorials for fixing it in post processing, look for "purple fringe removal".

briandelion

Yes, it's referred to as CA: chromatic aberration. If you use Photoshop there is a filter that gets rid of it fairly easily. Don't know about Lightroom. Nice mood in your capture by the way.

Bryce Wilson

Lightroom does have a minor CA filter, but it's pretty useless up against the purple/cyan/yellow CA varieties.

If shot in RAW and you use a Photoshop CS version, the Lens Correction filter available when you open your DNG file does a nice job at removing the colored CA. If shot in JPG, the Hue/Saturation Adjustment does an ok job on reducing the color of the lines. Pick the the color you wan't to eliminate with the eye dropper and then reduce the saturation with the slider bar.

Nice image.

DavidTO

Bryce Wilson wrote: »

Lightroom does have a minor CA filter, but it's pretty useless up against the purple/cyan/yellow CA varieties.

?

LR has fully adjustable CA settings.

zoomer

No sure what lines you are talking about there is some motion blur....looks kind of like lines and there is some chunky noise...caused by taking the picture to dark and bringing the exposure up a lot in post.

Alex_

This chromatic fringing can be controlled by closing your aperture, but naturally you also lose the creamy depth-of-field. It's a common trait in most lenses to some degree, but especially evident in the f1.4/1.8 units. Shooting at f5.6 will help but obviously you'll lose light. So it's a creative trade off which can be helped in post a little bit with the suggestions above.

Great shot regardless!

Bryce Wilson

DavidTO wrote: »

?

LR has fully adjustable CA settings.

Well, I sure haven't been able to get it (Lightroom) to work on the CA colors very well, at least not as well as the CS3 filter. Maybe I'm going about it all wrong in Lightroom. Pointers?

Hackbone

I think it might be a bleed over from overexposure. Try photographing a house lit up in Christmas lights. If you use a small f stop you get pin point lights. Change to a larger f stop even though your expsoure might be dead on you get bleed over and the "lines".

Your trying to do alot of opposites at the same time. You have to pick one not both. On the lens you used your depth of field was just a few inches and the rest blurs and also causes the lines.

DavidTO

Bryce Wilson wrote: »

Well, I sure haven't been able to get it (Lightroom) to work on the CA colors very well, at least not as well as the CS3 filter. Maybe I'm going about it all wrong in Lightroom. Pointers?

Here's a bit from the corner of a shot I took with the Canon 15mm fisheye. As you can see there is some CA.



Moving the Red/Cyan slider in the CA panel removes it:

anonymouscuban

What David posted is CA. What the OP posted, IMO, is not CA. Again, I think this is either an artifact from bumping contrast too much in post or from adjusting exposure of an underexposed photo as Zoomer pointed out.

DavidTO

anonymouscuban wrote: »

What David posted is CA. What the OP posted, IMO, is not CA. Again, I think this is either an artifact from bumping contrast too much in post or from adjusting exposure of an underexposed photo as Zoomer pointed out.

zoomer

I can see them better now on my home monitor. Yeah that is caused from bringing up a dark exposure. The same type of lines that show up in a dark sky when you lighten it up.

wave01

Hi IMHO its is not CA on the left side to me looks like motion blur the right side is better but at 1.8 dof is very shallow. It would be interesting to see the original picture.

reyvee61

I'm with Charles on the original image posted...makes sense to me

RyanS

Due to my own nubness I ended up with a higher iso at 400, didn't even think to double check it at the time. At f/1.8, all that light made the camera pick a very fast shutter speed of 1/4000. The shot was overexposed. I'm thinking Charles gets the gold star for pointing out the issue. Of course, I probably made one or two other mistakes as well. Thank you all for your feedback.

zoomer

Don't do that again..........just kidding. We all blow stuff out all the time.

DavidTO

As Schmoo often says, every day is check your ISO day.

Qarik

looks like just bokeh to me. It shows up more around the neck and arms where they are strongy back lit because as the light scatters from the edges it acts as point source to an extent