Author Topic: OLPF filter for Chronos cameras to reduce Aliasing/Moire?  (Read 6353 times)

B.H.V

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OLPF filter for Chronos cameras to reduce Aliasing/Moire?
« on: November 19, 2023, 09:50:36 AM »
I've been doing tests the last few years using external Caprock anti-moire filters to help reduce aliasing/moire in the Chronos 1.4. The problem is that which strength filter to use varies greatly on focal length and aperture which isn't suitable for zoom lenses as you need to change the filter strength each time. Most of the time for run and gun, I just base it off focal length and it does fine. The shot below was using a Navitar 75 1.3 at an fstop of 2.8. It's hard to test side by side as I don't have a separate Chronos camera, but it does help a lot in reducing aliasing/moire/false color in certain shots (mostly contrasty overly bright scenes, or things with very fine detail ie, trees, grass, feathers). However, while it does reduce these artifacts, it also blurs the image a bit which is why I use some upscaling/post sharpening in post. If I were to just upscale and post sharpen without using the filters, it will just oversharpen the moire/aliasing as well. The problem with using external OLPF filters in front of the lenses instead of the sensor is that you need to change it every time you switch focal lengths or lenses. If you use too strong a filter on a telephoto focal length, it blurs it too much and if you use too weak a filter on the wider focal lengths, it won't have any effect on moire/aliasing reduction.

Judging off the sample shots on the new Chronos 4K12, it looks like the new sensor design doesn't have these aliasing/moire artifacts as much, but it might be too early to tell. My question to Krontech is if they're eventually going to make a custom OLPF for the older cameras and the new ones? Some of the Chronos videos I’ve seen from users look way oversharpened laced with artifacts. I believe adding an OLPF will increase IQ for 1.4 and 2.1 owners and allow them to be more flexible with post sharpening giving more natural results.

Click on thumbnail below to see the video.

« Last Edit: November 19, 2023, 05:31:01 PM by B.H.V »

B.H.V

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Re: OLPF filter for Chronos cameras to reduce Aliasing/Moire?
« Reply #1 on: December 01, 2023, 06:30:00 PM »
Btw, this is an example of the aliasing I'm seeing. Look at the 15:20 mark with the lettering on helmet. That's one of the situations where the aliasing pops up. Only way I can reduce it is by using anti-aliasing filters on top of the lens with my 1.4 but again it's not ideal.

https://www.youtube.com/watch?v=zFOOY8MjChc&t=564s

B.H.V

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Re: OLPF filter for Chronos cameras to reduce Aliasing/Moire?
« Reply #2 on: December 07, 2023, 10:01:42 AM »
^^Looks like CHAT GPT has entered the chat! lol

moonlight

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Re: OLPF filter for Chronos cameras to reduce Aliasing/Moire?
« Reply #3 on: December 08, 2023, 06:19:09 AM »
I feel your pain with the filter juggling act. Been messing with external filters on my setup too. It's a hassle swapping them out for different focal lengths, right? Your shots look solid, though. I've been eyeing the Chronos 4K12 myself, but you're right.

B.H.V

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Re: OLPF filter for Chronos cameras to reduce Aliasing/Moire?
« Reply #4 on: December 08, 2023, 08:43:27 AM »
I feel your pain with the filter juggling act. Been messing with external filters on my setup too. It's a hassle swapping them out for different focal lengths, right? Your shots look solid, though. I've been eyeing the Chronos 4K12 myself, but you're right.

Nice Moonlight! Are you using Caprock filters? I want to try out the Q12 because the squarish sensor would pair very well with my anamorphic gear. It looks like tho it isn't as popular as only one Q12 has sold so far from what I've seen on the order page. Also, I found that VEAI upscaling doesn't do so well with unreadable fine texts and makes it alias more. I hope VEAI will create a model to keep the texts as is even if it's not readable. I try to avoid having fine print lettering in my shots.
« Last Edit: December 08, 2023, 12:12:47 PM by B.H.V »