ISO25600 from GX7

Due to my oversight, I used to think that GX7 can do highest ISO3200 only because I use e-shutter most of the time.

A couple of months ago, having been inspired by a member here and started to build up a C mode particularly for high ISO on GX85. The setting is:

• A mode,
• Burst=M,
• Manual ISO=25600,
• Standard Photo Style having NR=-5 (to retain most fine detail).

I took a burst shooting between 10~15 frames, imported to PhotoShop and stacked them using Median. The result is quite promising. When I try to set the same to GX7, I faced max ISO3200 only (my mistake) and so not worth to occupy a C mode.

A few days ago, worked with GX7 for something else and in m-shutter, I found ISO25600 could be used. Do the similar thing as GX85 and the result looks quite interesting.

The following is one of the 11 original OOC jpgs from GX7 at ISO25600. It has nothing to write home about it but I wish the dark knife sleeves/covers, the fine detail of knife handle, the blue and black color thigh protector, the wooden box, the dark background etc showed the serious noises of various kinds...

After stacking of 11 images plus a mild sharpening:

Cropped images of the above for easy reference:

The original might show more difference.

Just wish to share it with other GX users.

P.S. Teaching from Adobe on PS to do stacking:  https://helpx.adobe.com/photoshop/using/image-stacks.html

A really good improvement on the noise, Albert! I must remember to do stacking when at high ISO. Thank you!

Maggie

Wish it could be useful to you.

Happy shooting.

Thanks, those crops are very easy to compare!

I assume the OOC (non-stacked) images are shot with NR -5? It would be interesting to see how the stacking compares to NR 0 or NR +5 (and/or raw). The reason I am writing this is that the stacked images do not seem to have more detail, just less noise.

pannumon wrote:

Thanks, those crops are very easy to compare!

I assume the OOC (non-stacked) images are shot with NR -5? It would be interesting to see how the stacking compares to NR 0 or NR +5 (and/or raw). The reason I am writing this is that the stacked images do not seem to have more detail, just less noise.

Good point.

Originally I thought if the OOC image has less in-camera NR, I can have more detail to work with.

Shall try it later.

There's a very clear improvement, but I have a question:

Is there any advantage of doing the stacking, over using a lower ISO with longer exposure? In my mind they both ultimately seem to do the same thing (gather more light over time) and have similar requirements (needing to keep the camera and scene still).

I can imagine the ability to align frames when doing a stack could provide a sharper result in case of small camera movement? Or are there other advantages?

Here's a link to an article written in 2013 on the PetaPixel on stacking photos.

https://petapixel.com/2013/05/29/a-look-at-reducing-noise-in-photographs-using-median-blending/

For those who may not be aware, there is a variation on this process of shooting burst to obtain multiple frames, stacking in PS, auto align, convert to Smart Object, and then select Median averaging mode.

If you hand hold, as opposed to using a tripod, you can add a step that sets the size of the images in the stack to 200%. This step is performed before converting the images in the stack to Smart Object, so just know that it can increase the time it takes to convert the images to Smart Objects significantly. Be patient, it's worth it.

The result is something that one writer termed "Superresolution", and was even profiled here on Dpreview.

The process makes use of the small camera shifts that come into play when hand-holding, using it to create a result somewhat similar to pixel shifting that has appeared in cameras such as the Panasonic G9, Sony A7RIII, etc. Except that unlike those modes, it not only works when hand holding, it needs the (hopefully small) movements to create the additional detail that makes this process so beneficial.

And it reduces the noise at the same time!

So if you'd like file sizes and resolutions that exceed what the m43 sensors are capable of on their own, try this technique. I've run several trials, both with a Panasonic G85 and a Sony A7RIII, and it really works.

If it's a worthwhile image, shoot more than one series of bursts. Out of something like a dozen trials, I've had one or two series that came out soft, probably due to excessive movement of the camera during the burst capture.

Here's the Dpreview link; note that the article also links the earlier article by Ian Norman on Petapixel.

https://www.dpreview.com/articles/0727694641/here-s-how-to-pixel-shift-with-any-camera

Here's a link to my album on Flickr that contains a small assortment of images using this technique, both with the Sony & the Panasonic m43 cameras. These are downloadable, so you can compare them on your own computer screen. Please be sure to read the notes that accompany the individual images.

https://www.flickr.com/gp/blueshound/gy0995

Some of the images are resized for 4K display, but there are one or two at full "super resolution".

Brian

Lozrus wrote:

There's a very clear improvement, but I have a question:

Is there any advantage of doing the stacking, over using a lower ISO with longer exposure? In my mind they both ultimately seem to do the same thing (gather more light over time) and have similar requirements (needing to keep the camera and scene still).

I can imagine the ability to align frames when doing a stack could provide a sharper result in case of small camera movement? Or are there other advantages?

It allows me to shoot handheld in relatively dark environment.

Although stabilization (limited to either 3~3.5 stops on lens OIS or max 1 stop on IBIS of GX7, better on GX85) helps to use slower shutter speed, there is a limit on the slowest shutter speed for a steady image and when it is dark, higher ISO is still required.

The beauty of stacking can get clean image, which might come out even better than OOC at base ISO. It also permits using relatively faster shutter speed making handheld shooting much easier in the dark.

Yes, steady shots could result sharper stacking result. Tripod is the best but it is against my original intention on using stacking.

Thank you for the link.

Indeed I had read it, together with other articles, before set up the environment in my cameras.

It might be nothing but wish I might take this opportunity to see would some members coming up with other ideas that could be set and save to our cameras to expand its feature/application.

Thank you for heading up. Never think of it yet and will try it. If it works, could be a fantastic application.

Thank you again.

alcelc wrote:

Lozrus wrote:

There's a very clear improvement, but I have a question:

Is there any advantage of doing the stacking, over using a lower ISO with longer exposure? In my mind they both ultimately seem to do the same thing (gather more light over time) and have similar requirements (needing to keep the camera and scene still).

I can imagine the ability to align frames when doing a stack could provide a sharper result in case of small camera movement? Or are there other advantages?

It allows me to shoot handheld in relatively dark environment.

Although stabilization (limited to either 3~3.5 stops on lens OIS or max 1 stop on IBIS of GX7, better on GX85) helps to use slower shutter speed, there is a limit on the slowest shutter speed for a steady image and when it is dark, higher ISO is still required.

The beauty of stacking can get clean image, which might come out even better than OOC at base ISO. It also permits using relatively faster shutter speed making handheld shooting much easier in the dark.

Yes, steady shots could result sharper stacking result. Tripod is the best but it is against my original intention on using stacking.

It's a useful technique. Some Olympus cameras offer a "Handheld Starlight" mode which takes 8 shots and then stacks them in camera for a similar effect.

Chris

Cheshire-Chris wrote:

alcelc wrote:

Lozrus wrote:

There's a very clear improvement, but I have a question:

Is there any advantage of doing the stacking, over using a lower ISO with longer exposure? In my mind they both ultimately seem to do the same thing (gather more light over time) and have similar requirements (needing to keep the camera and scene still).

I can imagine the ability to align frames when doing a stack could provide a sharper result in case of small camera movement? Or are there other advantages?

It allows me to shoot handheld in relatively dark environment.

Although stabilization (limited to either 3~3.5 stops on lens OIS or max 1 stop on IBIS of GX7, better on GX85) helps to use slower shutter speed, there is a limit on the slowest shutter speed for a steady image and when it is dark, higher ISO is still required.

The beauty of stacking can get clean image, which might come out even better than OOC at base ISO. It also permits using relatively faster shutter speed making handheld shooting much easier in the dark.

Yes, steady shots could result sharper stacking result. Tripod is the best but it is against my original intention on using stacking.

It's a useful technique. Some Olympus cameras offer a "Handheld Starlight" mode which takes 8 shots and then stacks them in camera for a similar effect.

Chris

Yes, there is also similar modes, e.g., iHandheld Night Landescape(?), for Pany but not available to GX7. These are also pre set scenery modes that the camera will decide when to use, or the shooter has small control .

The discussed operation can have more control by the shooter, and can be used anytime. I can also take any number of shots that I think fit. Indeed although I set ISO25600 to the C mode, I can change to use any ISO depending on the situation.

The disadvantage: can only see result after PP instead of immediately from the camera.

As said, just attempted to see how C mode can be used and upon it, to see any other application could be suggested by the community. Sort of brain storming exercise?

Thank you for your comment.

alcelc wrote:

The beauty of stacking can get clean image, which might come out even better than OOC at base ISO. It also permits using relatively faster shutter speed making handheld shooting much easier in the dark.

Thanks, so kind of as I guessed, that the ability to align frames individually effectively provides better stabilisation than IBIS/OIS. I guess that I was underestimating how good current software is at aligning the frames. Cool, I'll definitely have to have a play.

As promised, had carried out a test using ISO25600, Standard Photo Style having NR set to -5, 0 and +5, took 12 images for each of the setting under M-Burst, and used Median stacking plus some minor sharpening in Photoshop.

The original OOC jpg scene (NR=-5):

Cropped and compare the original of the 3 NR settings as below:

After stacking the cropped result as below:

Conclusion:

Looking at the originals, NR-5 and NR=0 produced similar amount of detail and NR-5 of course is the noisiest. NR+5 had fine detail be erased despite it is the cleanest. So, it seems that NR0 be the ideal setting for OOC jpg.

The stacking results are quite close to each other and it seems that NR0 produced the best result (enough detail, similar noise condition to -5), closely followed by NR-5, and NR+5 be the worst of the pack (relatively noiser).

So, I think I shall change my C perset to NR=0 as NR-5 did not give me any obvious advantage.

The following are the stacking results:

NR-5, Median stacking by 12 OOC jpgs

NR0, Median Stacking by 12 OOC jpgs

NR+5, Median stacking by 12 OOC jpgs

Good idea. Is there any benefit shooting in RAW mode? Is it best to apply noise reduction on each photo before stacking or just stack the photos without noise correction then apply any noise reduction if required post stacking?

Very impressed with the improvement in IQ. Thank you for sharing this.

Thank you for your advice.

There was a suggestion to expend the original images to 200% before stacking and it can get something similar to Hi Res mode... Still exploring on the idea...

This is just hoping to gather more opinion/inspiration from members on how we can expand this old model, or the M43 more than the 2 manufacturers design for us to use...

Thank you again.

SC489 wrote:

Good idea. Is there any benefit shooting in RAW mode? Is it best to apply noise reduction on each photo before stacking or just stack the photos without noise correction then apply any noise reduction if required post stacking?

I think so but not sure how good software can handle the ISO25600 raw from GX7 such a relatively old camera.

I also concern that if the raw development software over does NR that might smear fine detail, such that might not produce a result as good as stacking from OOC jpg.

It has demonstrated in my second batch of testing according to member's suggestion using images from NR-5, NR0 and NR+5. It seems that despite NR-5 got noisiest OOC jpg to work with, the stacking result is as good as those NR0. Both (NR-5 and NR0 have similar detail). The stacked result from images of NR+5 (noise been erased, but also less detail) showed similar noise condition as the other 2, but have some detail lost.

Thank you for your head up.