More noise on SX60 compared to SX520 - General Chat - CHDK Forum
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More noise on SX60 compared to SX520

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Offline Garrett

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More noise on SX60 compared to SX520
« on: 29 / August / 2022, 12:23:19 »
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Hi!
Recently I bought an used SX60HS to make some night shots. But I found out that it seems to be performing much worse compared to SX520HS. I'm really disappointed, because it is a little bit newer, has better processor, but photos are kinda worse.
I'm not sure what I'm doing wrong, so I decided to create this topic. Hopefully, someone will be able to help me.
The settings of the shots are the same.
ISO: 3200
Exposure time: 60 seconds (Thanks, CHDK!)
Mode: Tv
Focal length: shortest possible.
White balance: auto
Image quality: highest possible.
I attached two samples of the shots, cropped at 100% zoom.
So, the photo from SX60 has less stars visible, seems to be more pixelated, and the sky seems to be further away from black.
Please advise.
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Offline Caefix

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Re: More noise on SX60 compared to SX520
« Reply #1 on: 29 / August / 2022, 13:40:40 »
There are ~3000 colors more counted in SX60´s Exif...  :blink:
https://chdk.setepontos.com/index.php?topic=12926.msg129324#msg129324
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Offline Garrett

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Re: More noise on SX60 compared to SX520
« Reply #2 on: 29 / August / 2022, 14:05:25 »
Caefix, thank you.
The topic is about SX50, but it gives an idea.
Looks like it won't be possible to fix...
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Offline reyalp

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Re: More noise on SX60 compared to SX520
« Reply #3 on: 30 / August / 2022, 02:09:09 »
Quote from: Garrett on 29 / August / 2022, 12:23:19
Hi!
Recently I bought an used SX60HS to make some night shots. But I found out that it seems to be performing much worse compared to SX520HS. I'm really disappointed, because it is a little bit newer, has better processor, but photos are kinda worse.
I'm not sure what I'm doing wrong, so I decided to create this topic. Hopefully, someone will be able to help me.
The settings of the shots are the same.
ISO: 3200
Exposure time: 60 seconds (Thanks, CHDK!)
Mode: Tv
Focal length: shortest possible.
White balance: auto
Image quality: highest possible.
I attached two samples of the shots, cropped at 100% zoom.
So, the photo from SX60 has less stars visible, seems to be more pixelated, and the sky seems to be further away from black.
Please advise.
It looks to me like the noise reduction is quite different between the two images. It might be interesting to compare the DNGs. In general, you can probably get better astrophotography results working from DNG, but more effort may be required in the workflow. A direct comparison would also be easier if they were at the same focal length.

As far as the difference between the two cameras, I'm not surprised the SX60 isn't a big improvement over the SX520. Digic 6 is *faster* but the sensors are similar if not the same, and the optics should not be hugely different.

FWIW, you may also want to consider stacking shorter exposures (possibly at lower ISO), preferably using raw or raw converted to a format that preserves full precision like 16 bit tiff.  Of course, this again requires more work on the workflow.
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Offline blackhole

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Re: More noise on SX60 compared to SX520
« Reply #4 on: 30 / August / 2022, 03:41:22 »
Quote from: Garrett on 29 / August / 2022, 12:23:19
So, the photo from SX60 has less stars visible, seems to be more pixelated, and the sky seems to be further away from black.
Please advise.
Judging by the diffraction spikes, the image on the sx60 was probably made at a smaller aperture. The spikes are visible only at smaller apertures, which means a higher AV value, and the focus must be very well adjusted, as it looks in the picture. If you did not manually set the AV value in the chdk menu, the firmware itself chose the AV according to the focal length and ISO value.The logic of the firmware is, longer focal length=smaller aperture. This can explain the appearance of spikes and the lower number of stars in the image.
The sky and the universe are actually not totally black, so it looks fine. On the Internet, you can find a large number of tutorials on how to correctly adjust the black point on the histogram, for astrophotography.
As reyalp wrote, it would be interesting to compare DNGs.
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Offline Garrett

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Re: More noise on SX60 compared to SX520
« Reply #5 on: 04 / September / 2022, 16:22:32 »
reyalp, blackhole, thank you for your replies.
I apologize for delay. I was waiting for some good weather to make some new photos, with DNG enabled, but unfortunately we had a very cloudy week. Tonight some clouds disappeared, so I taken a few images.
I put them onto Google Drive: https://drive.google.com/drive/folders/1CEjEpypc-7hMfgwfeOjhDD3WjAz5-XCi?usp=sharing
I wasn't able to turn on DNG for SX60, so instead I used the built-in RAW. Please let me know if it is OK, or maybe I should retry that somehow.

Also I tried to make some photos with the lens cap on, just in case if it is some kind of noise, but they seem to be quite black.
And yes, I do know how to set up the histogram. I just find it disturbing that a newer, more expensive camera with better processor shoots images that require more actions to get them viewable. But also it might be my mistake, so I'd appreciate if you tell me what might be wrong.
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Offline philmoz

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Re: More noise on SX60 compared to SX520
« Reply #6 on: 04 / September / 2022, 18:27:42 »
To me the SX60 JPEG image is better than the SX520 JPEG (in the latest uploaded Star images).


I think the JPEG differences come down to in-camera noise reduction being applied to high ISO images.


The SX520 noise reduction is eating the faintest stars and producing ugly looking artefacts in the darker areas (could also be JPEG compression artefacts). The faint clouds are also nearly destroyed in the SX520 image.


The SX60 image looks cleaner and seems to retain more detail to my eye.


The SX60 image appears a lot sharper to me - whether this is due to the focus being slight off on the SX520 or the different lenses is hard to say.


At 3200 ISO both cameras suffer badly from image noise. You should really compare images at much lower ISO.
You will need to do a lot of processing on the RAW images to get usable results at this ISO from these small sensors.

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Offline blackhole

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Re: More noise on SX60 compared to SX520
« Reply #7 on: 05 / September / 2022, 04:07:36 »
The same for me, the picture taken with the SX60 looks much better. The noise is much more acceptable.
I would reduce the aperture because the lens suffers from negative comatic aberration. The stars have small tails facing the edges of the image, but this is the same as chromatic aberration, almost normal for lenses on PS cameras.
ISO 3200 is far from a usable value for such cameras.
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Offline Garrett

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Re: More noise on SX60 compared to SX520
« Reply #8 on: 05 / September / 2022, 07:09:10 »
Well, this time somehow SX60 managed to get more detail available, but that is a rare coincidence (check the images in the first message of the topic).
Still, the biggest trouble for me is that weird color (as one of my friends said "like you're looking through swampy water").
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