D750 aberration using studio strobes

D

dr. frets

New member
I make and sell electric bass guitars and do my own photography for our website. I am upgrading from a D700 to a D750. When shooting my instruments on the new D750 using two studio strobes with softboxes, I am getting an aberration on the strings, causing a rope like effect. Most visible on the two largest strings on the left. Reminds me of old school fishing line. Anyone know what causes this and if there is anything I can do to get rid of it.
700_vs_750_-_2.jpg
 
Last edited:
P

pforsell

Senior Member
dr. frets said:
Sorry for the typo, I meant "rope like"...sort of a stripe you can see on the two largest strings on the left.
Click to expand...

Can you post a sample image? Would like to see it. It could be something with the lights, a reflection, flare, glare, shadow, but my guess is it is moire.

EDIT: now I suddenly see the sample image. Looks 100 % like moire to me. That happens when some small repeating grid-like pattern (string surface) is overlaid on another grid (sensor) and the grid spacings do not perfectly align. And in the real world they never do.

The reason is that the lens outresolves the sensor, and the sensor has no anti alias filter. You could deliberately misfocus your lens by a little bit, that would take care of it.

You could also try post processing software to first get rid of the color moire and after that use some light blurring to get rid of the luminance aliasing.

Also by shooting from a bit further away and subsequently cropping the image would very likely get rid of the moire.
 
Last edited:
Horoscope Fish

Horoscope Fish

Senior Member
dr. frets said:
Sorry for the typo, I meant "rope like"...sort of a stripe you can see on the two largest strings on the left.
Click to expand...
I see what you're talking about the effect reminds me of rappelling rope, but I'm not sure how to correct it.

I'm wondering if this could be some kind of reflection on the strings themselves causing a kind of moire?
 
P

pforsell

Senior Member
dr. frets said:
The image is in the original post....I think Moire is the correct word....yet I do not get it on the D700.
Click to expand...

D700 has an anti alias filter that is there to prevent moire.

Made a long edit in my post above with suggestions to mitigate the moire issue.
 
Last edited:
Horoscope Fish

Horoscope Fish

Senior Member
dr. frets said:
I make and sell electric bass guitars and do my own photography for our website. I am upgrading from a D700 to a D750. When shooting my instruments on the new D750 using two studio strobes with softboxes, I am getting an aberration on the strings, causing a rope like effect. Most visible on the two largest strings on the left. Reminds me of old school fishing line. Anyone know what causes this and if there is anything I can do to get rid of it.
Click to expand...
Can you confirm a moons not hitting your eye, like a big pizza-pie? 'Cause that's amore.
Does the world seem to shine like you've had too much wine? 'Cause that's amore...

*crickets chirp*







...
I uh... I'll show myself to the door.
 
Marcel

Marcel

Happily retired
Staff member
Super Mod
I've seen instances where I got this effect but as soon as I changed the size of the image it disappeared. Do you see it at all image sizes on your computer screen? Even at 100%? I know that some people locally apply a bit of a gaussian blur to the affected areas to get rid of this moiré, but I guess on a guitar string it could be a bit of work.

Have you sold the D700 yet? Maybe you just found out that for you use less pixels could be better. Specially if most of you images end up on a web page.

Hope this helps a bit...

And welcome to Nikonites.
 
S

spb_stan

Senior Member
Moire pattern can be eliminated in Adobe Lightroom very easy. Using the brush tool to create a mask of the impacted area and then center all the adjustment sliders, then use the Moire slider to eliminate it.

The problem does not involve your lighting, it is simply the frequency of a repeating pattern being too close to the pixel pitch, what the optical low pass filter is supposed to compensate for but you have the unlucky combination of high res sensor and tiny repeating pattern in the strings. patterns that are closer or coarser would not have it.
 
Last edited:
P

pforsell

Senior Member
spb_stan said:
Moire pattern can be eliminated in Adobe Lightroom very easy. Using the brush tool to create a mask of the impacted area and then center all the adjustment sliders, then use the Moire slider to eliminate it.
Click to expand...

Very easy is a bit overstatement. Moire is false detail caused by aliasing. LR can desaturate the color fringing but it cannot get rid of the jaggies and beat pattern itself. All in all it is not removable in LR or anything else since the real detail in the scene never made it into the picture. It can be blurred though, but it is always better to prevent it, either by using an antialising filter ot by shooting from further away, or misfocusing the lens deliberately. Of these the best is AA filter.
 
D

Don Kuykendall_RIP

RIP :(
pforsell said:
Very easy is a bit overstatement. Moire is false detail caused by aliasing. LR can desaturate the color fringing but it cannot get rid of the jaggies and beat pattern itself. All in all it is not removable in LR or anything else since the real detail in the scene never made it into the picture. It can be blurred though, but it is always better to prevent it, either by using an antialising filter ot by shooting from further away, or misfocusing the lens deliberately. Of these the best is AA filter.
Click to expand...

The D750 has the AA filter unless you have had it removed.
 
B

Blacktop

Senior Member
It just looks like fading wood grain on the fretboard. Seems more pronounced under the E and A strings. I don't think it's shadows. (Unless I'm not understanding the question)
 
S

spb_stan

Senior Member
When I wrote a Reader's Digest version I was simply referring to every time I have had an image impacted, ACR or LR was able to salvage the image. It happens more often with the finer pixel pitch of my D800. He should try it in ACR if he has has the NEF file.
 
P

pforsell

Senior Member
spb_stan said:
When I wrote a Reader's Digest version I was simply referring to every time I have had an image impacted, ACR or LR was able to salvage the image. It happens more often with the finer pixel pitch of my D800. He should try it in ACR if he has has the NEF file.
Click to expand...

I agree, and often the removal of the color fringes is enough to conceal the moire effect, especially with fabrics. In urban landscapes fixing it might be harder with repeating patterns like fences or faraway rows of windows, which turn into a mushy rainbow, or that dreaded jagged colored labyrinth.

But yes, I concur with your observation.
 
Last edited:
Top