Help with P to P charts for astro/low light performance

[Lettermanian]

Bit of a long post but I'd appreciate some help with reading/understanding Bill Claff's Photons to Photos charts on sensor performance, specifically within certain ISO ranges as they apply to astro and low-light landscape photography. I recently sold my X-T3 and Tamron 17-70 lens, wanting to move to a smaller, lighter setup, and hoping to get a Star Adventurer mini for astro tracking. I have held an X-T5 in-store and really liked it; it's smaller and lighter than the X-T3. I don't need the 40mp though. The rumoured X-T50 is of interest to me, but I am also looking at an X-T30ii, in order to save the new camera premium. I've had an X-T10 and 20 in the past, so ergonomically I know what I'm in for. The T30ii has Classic Neg to satisfy my ooc jpeg preferences, and its interval shooting has Exposure Smoothing for more automated adjustments while shooting changing light for timelapses.

I was looking at the measurements on the following charts (screenshots), but not being a technical wizard, I'd like to ask the more knowledgeable members if I'm understanding them correctly. I compared the Fuji cameras of interest to me, as well as some cameras from other brands, APS-C and full-frame (I've had the Nikon Z5, Z6ii and Panasonic S5 briefly in the past), and even some micro four-thirds, as they have some in-camera low-light and long exposure features no one else has. I'm not necessarily looking to change systems but for the sake of comparison I wanted to include them.

*It's important to note I'm mainly concerned with ISO's from 800 to 6400, the range I would use most in low light and astro.

The following three charts involve Fuji cameras. From these the X-T30ii seems like it performs a bit better than the other cameras, notably the X-T5. Would that be a correct conclusion? If so, are the differences negligible, or worth considering?

Dynamic range vs ISO:







DR shadow improvement (= recovery?) vs ISO. The X-T5 mostly matches the T30 when using ES, which I'd probably use anyway when shooting intervals, However, in layman's terms, does this mean shadows/dark areas in the image will be "cleaner" in the cameras with the better readings?





Read noise; I assume the lower readings of the X-T30 are better:







X-T30 DR/ISO vs Nikon Z APS-C and m43:







Shadow improvement T30 vs Z and m43. Impressive Olympus performance?







X-T30 vs full-frame. The T30 seems to be right in line with the Nikon Z5 at the ISO's I'm concerned with:







Shadow improvement T30 vs FF. The T30 holds the middle ground here:







Anyway, it seems to me that the T30(ii) really has decent performance overall if I'm wanting it for astro and low-light landscapes, probably very similar to my X-T3. Or am I way off and not interpreting these correctly?



--
The grass isn't always greener, unless you shoot Velvia.

 

[Bill Ferris]

I think you've done well with the comparison. When it comes to read noise, I generally use the "Input-referred read noise" chart: https://photonstophotos.net/Charts/RN_e.htm#FujiFilm X-T3_14,FujiFilm X-T30_14,FujiFilm X-T5_14

The three cameras you're comparing are all within 1/3 stop of each other so, while there are measurable differences, I wouldn't count on those differences being discernible on a screen when processing RAFs.

A comparison tool you can use to look at photos made with all three of the same subject in the same light is the DPR studio scene. At ISO 3200, they compare well with each other. I've added an X-T20 and a Sony A6500 to the mix just to give you some variety: https://www.dpreview.com/reviews/im...t=1&x=0.1458070798487799&y=0.5653440532947387

Have you visited the folks in the "Astrophotography Talk" forum? There may be a few who've used X-T series bodies for night sky work and would be willing to share their thoughts.

Depending on the kind of night sky photography you want to do, I suspect the keys to success will be the quality of the sky available to you, composition, the sturdiness and stability of the mount, tracking, and image processing technique. It's a demaning genre but the satisfaction when you get a great image is just about second to none.

Good luck to you.

--
Bill Ferris Photography
Flagstaff, AZ

 

[biza43]

I have used XT2, XT3, XT4, and now XT5 for night astro photography. Mostly taking multiple shots for stacking as star trails, or stacking several shots for MW. My settings for star trails are lens near wide open (currently using TTArtisans 10mm f/2), 30sec, ISO1600, and LENR off. I also take a couple of dark frames, and I use Sequator.

For MW stacks the settings are similar, except 15 sec.

I am happy with the Fuji results (used Canon and Sony in the past, FF), and would not obsess over it.











--
www.paulobizarro.com

PauloBizarroPHOTOBLOG – Some of my photography

 

[Lettermanian]

I think you've done well with the comparison. When it comes to read noise, I generally use the "Input-referred read noise" chart: https://photonstophotos.net/Charts/RN_e.htm#FujiFilm X-T3_14,FujiFilm X-T30_14,FujiFilm X-T5_14

The three cameras you're comparing are all within 1/3 stop of each other so, while there are measurable differences, I wouldn't count on those differences being discernible on a screen when processing RAFs.

That's good to know, I honestly shoot jpegs most of the time with customized film sims, and have only engaged lightly with processing RAFs for astro, so I know this is an area in which I will need more practise. I rarely look at charts so I appreciate the insight into my interpretation of them.

A comparison tool you can use to look at photos made with all three of the same subject in the same light is the DPR studio scene. At ISO 3200, they compare well with each other. I've added an X-T20 and a Sony A6500 to the mix just to give you some variety: https://www.dpreview.com/reviews/im...t=1&x=0.1458070798487799&y=0.5653440532947387

Thanks for that, I input several cameras, and it seems to my eyes that the X-T30(ii) sensor gen does quite well. The 40mp sensor seems noisier indeed at the ISO's I'm looking at, but as you indicate above, in processing the differences may be minimal at best. I have to decide if I want to pay the higher mp premium when in truth I've been quite satisfied with the 26mp sensor.

Have you visited the folks in the "Astrophotography Talk" forum? There may be a few who've used X-T series bodies for night sky work and would be willing to share their thoughts.

I dip into that forum from time to time, but there's a Fujfilm Astrophotography group on FB that I frequent. There are excellent images from a variety of cameras on display. One member in particular has some stunning images taken with the X-T5 and makes a compelling case for that camera/sensor.

Depending on the kind of night sky photography you want to do, I suspect the keys to success will be the quality of the sky available to you, composition, the sturdiness and stability of the mount, tracking, and image processing technique. It's a demaning genre but the satisfaction when you get a great image is just about second to none.

Good luck to you.

Thank you, part of the challenge is wanting a do-it-all camera because, well, the budget just does not allow for all the best equipment. As a hobbyist, I enjoy shooting timelapses, so I definitely at minimum want a camera with exposure smoothing (not in my former X-T3). I'm a fan of getting as much of my finished imagery out-of-camera as opposed to long processing sessions in front of a computer. An X-T30ii purchase would also allow the purchase of a star tracker (the Star Adventurer Mini or 2i), whereas an X-T5 purchase would not allow that at this time. Decisions, decisions...

 

[William the X-T5 guy]

Thank you, part of the challenge is wanting a do-it-all camera because, well, the budget just does not allow for all the best equipment. As a hobbyist, I enjoy shooting timelapses, so I definitely at minimum want a camera with exposure smoothing (not in my former X-T3). I'm a fan of getting as much of my finished imagery out-of-camera as opposed to long processing sessions in front of a computer. An X-T30ii purchase would also allow the purchase of a star tracker (the Star Adventurer Mini or 2i), whereas an X-T5 purchase would not allow that at this time. Decisions, decisions...

Thanks for putting me on to that tracker. I'm trying to teach myself night sky photography and have thought about looking into one.

That one allows 4 minutes with a 100mm lens. Does format size affect that calculation?

Anyway I went back and had a look at some of my attempts from ago and found that my K1 will track with an 85mm lens for about 30 seconds, so that would give me three more stops to play with.

That's significant enough to be interesting.

 

[Lettermanian]

Thank you, part of the challenge is wanting a do-it-all camera because, well, the budget just does not allow for all the best equipment. As a hobbyist, I enjoy shooting timelapses, so I definitely at minimum want a camera with exposure smoothing (not in my former X-T3). I'm a fan of getting as much of my finished imagery out-of-camera as opposed to long processing sessions in front of a computer. An X-T30ii purchase would also allow the purchase of a star tracker (the Star Adventurer Mini or 2i), whereas an X-T5 purchase would not allow that at this time. Decisions, decisions...

Thanks for putting me on to that tracker. I'm trying to teach myself night sky photography and have thought about looking into one.

To date I have not done any more "serious" astro work other than wide Milky Way/starfield shots on a tripod, along with timelapses, but from my research the two Skywatcher Star adventurer models seem to be best for beginners.

That one allows 4 minutes with a 100mm lens. Does format size affect that calculation?

I would assume so since the image is magnified 1.5X, but I don't think it's a matter of a simple calculation. There are many differing opinions on the application of exposure time rules for astro, so my guess is that you'll have to research the best one to follow. The question you asked can also be found in the Astrophotography forum:

https://www.dpreview.com/forums/thread/4743857

If you're on FB, there is a group dedicated to the Skywatcher SA's as well, called the Skywatcher StarAdventurer and Allview Group. Another group useful for Fuji shooters is Astrophotography with Fujifilm.

Anyway I went back and had a look at some of my attempts from ago and found that my K1 will track with an 85mm lens for about 30 seconds, so that would give me three more stops to play with.

That's significant enough to be interesting.

Yes, I wish other brands could replicate Pentax' Astrotracer tech, even though it has its limits.

 

[William the X-T5 guy]

Anyway I went back and had a look at some of my attempts from ago and found that my K1 will track with an 85mm lens for about 30 seconds, so that would give me three more stops to play with.

That's significant enough to be interesting.

Yes, I wish other brands could replicate Pentax' Astrotracer tech, even though it has its limits.

They just added a version of it that doesn't require GPS. I guess they take a short pre exposure to see which way things are moving and then take the real picture. This takes away the need to calibrate the GPS, stay away from anything with metal in it and obviates any potential errors caused by the GPs or compass not being as well calibrated as they could be..

I haven't tried the new emulation yet.

The sensor path is only a few millimeters, so exposures are limited, especially with longer lenses, but I've seen some very decent images shot with the Astro tracer and 400mm lenses on the K1.