Aliasing VS Moiré

I shoot architectural projects with a GFX 50R and Canon shift and a Pentax 645 35mm lenses mounted on the HCam DRS. On some occasions I get Moiré patterns which I remove in Camera Raw. Lately, I've been wondering if I am getting some false colors in carpet or other fabrics like the back of a chair etc...anything with patterns in addition to the moiré.

My question is if I upgraded to a 100 MP body like the GFX 100S or the 100II would these artifacts still appear? If so, which would you recommend keeping in mind that I don't care about auto focus, or IBS?

I'm attaching 2 versions of the same image both before and after using an adjustment brush in camera raw to remove moiré.

Suggestions or comments?

Peter

Peter Brentlinger said:

I shoot architectural projects with a GFX 50R and Canon shift and a Pentax 645 35mm lenses mounted on the HCam DRS. On some occasions I get Moiré patterns which I remove in Camera Raw. Lately, I've been wondering if I am getting some false colors in carpet or other fabrics like the back of a chair etc...anything with patterns in addition to the moiré.

My question is if I upgraded to a 100 MP body like the GFX 100S or the 100II would these artifacts still appear? If so, which would you recommend keeping in mind that I don't care about auto focus, or IBS?

I'm attaching 2 versions of the same image both before and after using an adjustment brush in camera raw to remove moiré.

Suggestions or comments?

Peter

Click to expand...

Moire that is not visible to the eye is caused by aliasing. However, not all aliasing results in moire. The 100 MP 33x44 MF sensors are less likely to exhibit aliasing than the 50 MP ones. However, at some apertures you can still get moire aliasing with the 100 MP sensors.

The EXIF field is not right. What f-stop did you use? You can mitigate aliasing by stopping down.

--
https://blog.kasson.com

Hi,

Color Moiré is just a form of aliasing. My explanation is that aliases occur in different positions for red, green and blue pixels.

The GFX 50 models have undersize pixel aperture combined with relatively large pixel pitch, that combo increses sharpness but has high aliasing.

The GFX 100 models have smaller pixel pitch and have gapless micro lenses. That reduces aliasing.

Stopping down to say f/16 on the GFX 50 and f/11 on the GFX 100 will reduce aliasing quite a bit.




Calculations assuming a perfect lens with perfect focusing. Green is 'good signal' and red is what causes aliasing. Left side GFX 50 and right side is GFX 100.

The figure above assumes perfect technique and perfect lenses.

Best regards

Erik

--
Erik Kaffehr
Website: http://echophoto.dnsalias.net
Magic tends to disappear in controlled experiments…
Gallery: http://echophoto.smugmug.com
Articles: http://echophoto.dnsalias.net/ekr/index.php/photoarticles

Thanks for the comments. The aperture was not recorded because I used the Canon 24 TSE II on the hCam adapter. They were shot at F11, which since I can't control the aperture without connecting to a Canon body is always at f11. I'll try F16 on a few shots and see if that helps with the moiré, without negatively affecting sharpness too much.

Peter Brentlinger said:

Thanks for the comments. The aperture was not recorded because I used the Canon 24 TSE II on the hCam adapter. They were shot at F11, which since I can't control the aperture without connecting to a Canon body is always at f11. I'll try F16 on a few shots and see if that helps with the moiré, without negatively affecting sharpness too much.

Click to expand...

On the GFX 100x, f/11 will eliminate almost all aliasing.

JimKasson said:

Peter Brentlinger said:

Thanks for the comments. The aperture was not recorded because I used the Canon 24 TSE II on the hCam adapter. They were shot at F11, which since I can't control the aperture without connecting to a Canon body is always at f11. I'll try F16 on a few shots and see if that helps with the moiré, without negatively affecting sharpness too much.

Click to expand...

On the GFX 100x, f/11 will eliminate almost all aliasing.

Click to expand...

I’ve had success addressing aliasing artifacts in Lightroom using the moire reduction tool, painting it over the area of aliasing, and slowly raising the intensity of the effect until the aliasing disappears.

Part of the reasons I'm asking about the 100 MP bodies is because I'm trying to justify upgrading from the 50R. I'm able to manage the moiré/aliasing issues OK, but it would be nice to not have to. What about any increase in dynamic range between the 50R and a 100 MP body, is it significant? I'm wondering if there would be a noticeable difference when for example shooting interiors with bright windows or maintaining highlight detail in light fixtures when shooting a room that is not that bright overall. Twilight exteriors also come to mind as another scenario where having more dynamic range would be helpful.

Yes, I use that same technique in camera raw and it does a good enough job. It can just be time consuming.

Peter Brentlinger said:

Part of the reasons I'm asking about the 100 MP bodies is because I'm trying to justify upgrading from the 50R. I'm able to manage the moiré/aliasing issues OK, but it would be nice to not have to. What about any increase in dynamic range between the 50R and a 100 MP body, is it significant? I'm wondering if there would be a noticeable difference when for example shooting interiors with bright windows or maintaining highlight detail in light fixtures when shooting a room that is not that bright overall. Twilight exteriors also come to mind as another scenario where having more dynamic range would be helpful.

Click to expand...

DR delta at base ISO not that different.

Good to know. I guess I thought that the 100 MP sensors would have noticeably more DR. Thanks for the link Jim!

Peter Brentlinger said:

Yes, I use that same technique in camera raw and it does a good enough job. It can just be time consuming.

Click to expand...

The moiré tool in Lightroom just blurs the color information.

Best regards

Erik

Peter Brentlinger said:

Good to know. I guess I thought that the 100 MP sensors would have noticeably more DR. Thanks for the link Jim!

Click to expand...

The main DR difference is at higher ISOs after dual conversion gain kicks in. 50MP sensors do not have dual conversion gain.

Peter Brentlinger said:

Good to know. I guess I thought that the 100 MP sensors would have noticeably more DR. Thanks for the link Jim!

Click to expand...

I think that DR is both misunderstood and over rated. DR is simply the full well capacity FWC) of the pixel, divided by the readout noise.

With digital sensors, FWC per sensor surface is fairly constant over time, but readout noise is much reduced.

But, most of the noise we see is shot noise, and that depends only on the utilized well capacity. The only way we can utilize DR is to reduce exposure to protect highlights. That increases shot noise.

Having a sensor with good DR, we can push extreme shadows more, but high DR wouldn't help with mid tones.

The best solution may often be to combine a 'normal' exposure with one exposure that protects highlights and combine them as HDR.

But, HDR and other multi shot techniques will not work if there is significant subject motion.

Best regards

Erik

Erik Kaffehr said:

Peter Brentlinger said:

Good to know. I guess I thought that the 100 MP sensors would have noticeably more DR. Thanks for the link Jim!

Click to expand...

I think that DR is both misunderstood and over rated. DR is simply the full well capacity FWC) of the pixel, divided by the readout noise.

With digital sensors, FWC per sensor surface is fairly constant over time, but readout noise is much reduced.

But, most of the noise we see is shot noise, and that depends only on the utilized well capacity. The only way we can utilize DR is to reduce exposure to protect highlights. That increases shot noise.

Having a sensor with good DR, we can push extreme shadows more, but high DR wouldn't help with mid tones.

The best solution may often be to combine a 'normal' exposure with one exposure that protects highlights and combine them as HDR.

But, HDR and other multi shot techniques will not work if there is significant subject motion.

Best regards

Erik

Click to expand...

Using HDR means that one has to manage 2 or more shots in post (somehow mark the photos that belong together). Fuji has the right idea: they create one raw file that contains all HDR raw shots. Unfortunately, Adobe does not recognize it and cannot apply HDR merge on such file, you have to “manually” unpack the file.

Peter Brentlinger said:

Thanks for the comments. The aperture was not recorded because I used the Canon 24 TSE II on the hCam adapter. They were shot at F11, which since I can't control the aperture without connecting to a Canon body is always at f11. I'll try F16 on a few shots and see if that helps with the moiré, without negatively affecting sharpness too much.

Click to expand...

Obviously I'm not familiar with your workflow but I couldn't imagine not being able to control aperture. This would frustrate me more than the few minutes I spend in post dealing with moiré. Are you using the HCam because you need the use of an additional Y-axis?

Adam Kingston said:

Peter Brentlinger said:

Thanks for the comments. The aperture was not recorded because I used the Canon 24 TSE II on the hCam adapter. They were shot at F11, which since I can't control the aperture without connecting to a Canon body is always at f11. I'll try F16 on a few shots and see if that helps with the moiré, without negatively affecting sharpness too much.

Click to expand...

Obviously I'm not familiar with your workflow but I couldn't imagine not being able to control aperture. This would frustrate me more than the few minutes I spend in post dealing with moiré. Are you using the HCam because you need the use of an additional Y-axis?

Click to expand...

The HCam allows for movements with a lot of lenses, using the Canon EF mount, but it does not have electronic controls for the lenses. I think that Peter uses the HCam also with the Pentax 645 35 mm lens, I would wonder which of them.

I use both the Canon 24/3.5 TSE LII and the Pentax 645 35/3.5 A.

Neither lens is what I would regard as very good, at least regarding my samples, but I have seen aliasing on the Canon 24/3.5 TSE LII on my Sony A7rII, so I would expect aliasing on the GFX 50 models, but not on GFX 100, which is more like my Sony A7rIV. GFX 100 uses a larger version of the sensor used in the Sony A7rIV, so aliasing should be the same.

Best regards

Erik

Yes, if you switch to the 100MP sensor you'll see a reduction but not complete elimination of aliasing artifacts/moiré. You likely won't need to stop down as far to reduce aliasing with the camera rather than in post, depending on the lens you're using and other variables e.g. the nature of the scene, environmental factors etc. I found f13 often does the job.

I don't correct much of the aliasing I come across in the 50MP files because my clients have never noticed it. I deal with the very obvious stuff, but in terms of my workflow it doesn't seem burdensome and I rarely see it.

If you're already upgrading to the 100MP sensor then this is a bonus. The downside associated with that switch is the potential for PDAF stripes, which I've found are not correctable for the most part, but turn up about as often as un-correctable aliasing. Which is to say, very rarely. And IMO the weaknesses of the TS-E 24mm are more apparent with the 100MP sensor and are more important than aliasing.

Maybe it's worth noting that most of my clients have specifically asked me to stop sending huge files because they have no use for them, which means that in terms of the benefits of the 100MP sensor I'm left with the potential to crop (which I don't do) and having more scope to make minor geometric adjustments in post (which I try to make sure I don't have to do).

So to sum up, I'd have been perfectly happy continuing working with the 50S II but the 100S is doing the job and I've saved a few minutes here and there in post.

Here's the only example I have across several thousand frames of what I'd call un-correctable moiré from the 50MP sensor, and it wasn't client work in any case:


Moiré in the windows - some kind of patterned window blind material I believe


Moiré still evident toward the left edge of the frame even after working on it in post using a couple different approaches

Edit: I'd have stopped down and traded noise for less moiré had I known, but one of the reasons I'm not keen on EVFs is that they render moiré where it won't show in the file. The JPEG review does the opposite and often obscures it, even if you're saving a high-quality JPEG alongside the RAW.

Peter Brentlinger said:

I shoot architectural projects with a GFX 50R and Canon shift and a Pentax 645 35mm lenses mounted on the HCam DRS. On some occasions I get Moiré patterns which I remove in Camera Raw. Lately, I've been wondering if I am getting some false colors in carpet or other fabrics like the back of a chair etc...anything with patterns in addition to the moiré.

My question is if I upgraded to a 100 MP body like the GFX 100S or the 100II would these artifacts still appear? If so, which would you recommend keeping in mind that I don't care about auto focus, or IBS?

I'm attaching 2 versions of the same image both before and after using an adjustment brush in camera raw to remove moiré.

Suggestions or comments?

Peter

Click to expand...

Mads Bjerke has found that using Adobe's new AI based 'denoise' is quite sufficient at suppressing color moiré and does that without obvious side effects. Worth trying!

Best regards

Erik

--
Erik Kaffehr
Website: http://echophoto.dnsalias.net
Magic tends to disappear in controlled experiments…
Gallery: http://echophoto.smugmug.com
Articles: http://echophoto.dnsalias.net/ekr/index.php/photoarticles

Erik Kaffehr said:

Adam Kingston said:

Peter Brentlinger said:

Thanks for the comments. The aperture was not recorded because I used the Canon 24 TSE II on the hCam adapter. They were shot at F11, which since I can't control the aperture without connecting to a Canon body is always at f11. I'll try F16 on a few shots and see if that helps with the moiré, without negatively affecting sharpness too much.

Click to expand...

Obviously I'm not familiar with your workflow but I couldn't imagine not being able to control aperture. This would frustrate me more than the few minutes I spend in post dealing with moiré. Are you using the HCam because you need the use of an additional Y-axis?

Click to expand...

The HCam allows for movements with a lot of lenses, using the Canon EF mount, but it does not have electronic controls for the lenses. I think that Peter uses the HCam also with the Pentax 645 35 mm lens, I would wonder which of them.

I use both the Canon 24/3.5 TSE LII and the Pentax 645 35/3.5 A.

Neither lens is what I would regard as very good, at least regarding my samples, but I have seen aliasing on the Canon 24/3.5 TSE LII on my Sony A7rII, so I would expect aliasing on the GFX 50 models, but not on GFX 100, which is more like my Sony A7rIV. GFX 100 uses a larger version of the sensor used in the Sony A7rIV, so aliasing should be the same.

Best regards

Erik

Click to expand...

Not sure about the Pentax as I haven't used it with a digital body but the TS-E 24 definitely aliases unless stopped down quite far, and as you suggest is also generally quite weak on this system. My priority in this scenario would either be better lenses or going the tech camera route rather than worrying about megapixels/aliasing.

Edit: it should be said that the TS-E 24mm is a superb lens on a full frame body.