Tips for focusing at infinity - Night Sky - Hasselblad X1D

[MomentsForZen]

Hi there. I have been trying to photograph the night sky with a Hasselblad X1D. There generally appears to be insufficient light for auto-focus to be successful. It is difficult to manually focus on the stars, which are normally the only visible features.

At this point, I am missing my 500 series camera and lenses with their hard stop for infinity (except for the 250mm superachromat)! This is a rare feeling because the X1D is very good.

I would be very thankful for any tips that would help me to achieve good focus on the stars (i.e., infinity). ... MomentsForZen (Richard)

 

[tcdeveau]

I just find the brightest star in the frame, set the focus point to that star, and then manually focus. Usually I'm at the lens' max aperture (wide open) and around ISO 6400.

One trick for focusing is put the ISO the highest it will go, which will give you a noisy but brighter field, focus, and then kick the ISO back down to whatever ISO you want to shoot.

 

[mostlylost]

Hi there. I have been trying to photograph the night sky with a Hasselblad X1D. There generally appears to be insufficient light for auto-focus to be successful. It is difficult to manually focus on the stars, which are normally the only visible features.

At this point, I am missing my 500 series camera and lenses with their hard stop for infinity (except for the 250mm superachromat)! This is a rare feeling because the X1D is very good.

I would be very thankful for any tips that would help me to achieve good focus on the stars (i.e., infinity). ... MomentsForZen (Richard)

While I have not tried the X1D lenses, prime lenses designed for the V system bodies have a hard infinity stop. Unlike many late model Japanese zoom lenses, assuming the lens and body focusing is correctly adjusted you would just crank it all the way to infinity. If that doesn't result in correct infinity focusing something may require adjustment. Could that possibly be your case?

 

[Ed Hurst]

My experience (not with this camera, but with a Pentax 645Z) is that relying on infinity focus stops/markings on lenses is not good enough in this situation. There is too much 'tolerance' error even in shorter lenses (and it's not just a case of camera adjustment, since each lens is different in this respect). Assuming the goal of a particular shot is to focus on the stars, my technique is to use live view - point the camera at a particularly bright star, zoom live view to maximum, and then focus carefully. Stars are often invisible on screen until close to being in focus, so it requires a little patience.

Of course, with some pictures, I am focusing on an element in the foreground scene and allowing the sky to be a background element. So this advice only applies to situations where the stars are what you want in sharpest focus.

When I used to do astro using a Nikon D800E, I found the live view didn't allow this technique and then all I could do was shoot a series of test pictures (making small and progressive focus adjustments - trial & error). The images could be inspected and zoomed right in to get close. Both laborious and less precise. But, if the X1D's live view doesn't allow for the technique described above, you could always fall back on this.

I certainly wouldn't rely on throwing the lens to infinity. With modern high resolution sensors and lenses used wide open, the errors are all too visible...

YMMV - good luck, and please let us know how you get on

 

[MomentsForZen]

I just find the brightest star in the frame, set the focus point to that star, and then manually focus. Usually I'm at the lens' max aperture (wide open) and around ISO 6400.

One trick for focusing is put the ISO the highest it will go, which will give you a noisy but brighter field, focus, and then kick the ISO back down to whatever ISO you want to shoot.

Thank-you @tcdeveau for your suggestion. I used a modification of your approach to obtain the image below from our apartment balcony. A convenient location, but a fair amount of light pollution. Still, a reasonable result, a little trailing of the stars, but nicely in focus! (N.B., This a 10% sub-sample.)

There weren’t any really bright stars in the frame. Instead I swung around to Jupiter and used this bright object to set the focus at infinity. I then carefully composed the shot, retaining the focus setting.

With focus peaking turned on, using a high ISO resulted in a digital snowstorm of pixels with the peaking color. I found it better to actually use a lower ISO so that I could more clearly see just the “real” signal from Jupiter. It was then easy to manually focus on Jupiter.

... MomentsForZen (Richard)

Incidentally, we are looking from the Southern Hemisphere at the Milky Way - It features the constellations of Scorpius and Sagittarius (hosting Saturn) and the Galactic Center / Core.

Hasselblad X1D camera
Hasselblad XCD 30 mm lens
15 frames @ ISO 1600, 16 seconds, f/3.5
Aligned and stacked with Starry Landscape Stacker.
Basic lighting adjustments in Lightroom and Photoshop.

 

[MomentsForZen]

While I have not tried the X1D lenses, prime lenses designed for the V system bodies have a hard infinity stop. Unlike many late model Japanese zoom lenses, assuming the lens and body focusing is correctly adjusted you would just crank it all the way to infinity. If that doesn't result in correct infinity focusing something may require adjustment. Could that possibly be your case?

Hello @mostlylost.

Unfortunately, the X1D body and its XCD lenses don’t operate the same as the CF lenses for the V /500 series bodies.

The X series focus mechanism is a “by wire” system, meaning that you effectively turn the ring one way to focus closer, and turn the other way to focus further away. There isn’t a distance scale as such.

The camera/lens system that you describe (my previous setup) is so much simpler in the darkness, because as you said, provided the infinity stop is well calibrated as it is with the Hasselblad lenses, you simply rotate the ring completely in one direction.

... MomentsForZen (Richard)

 

[MomentsForZen]

My experience (not with this camera, but with a Pentax 645Z) is that relying on infinity focus stops/markings on lenses is not good enough in this situation. There is too much 'tolerance' error even in shorter lenses (and it's not just a case of camera adjustment, since each lens is different in this respect). Assuming the goal of a particular shot is to focus on the stars, my technique is to use live view - point the camera at a particularly bright star, zoom live view to maximum, and then focus carefully. Stars are often invisible on screen until close to being in focus, so it requires a little patience.

Of course, with some pictures, I am focusing on an element in the foreground scene and allowing the sky to be a background element. So this advice only applies to situations where the stars are what you want in sharpest focus.

When I used to do astro using a Nikon D800E, I found the live view didn't allow this technique and then all I could do was shoot a series of test pictures (making small and progressive focus adjustments - trial & error). The images could be inspected and zoomed right in to get close. Both laborious and less precise. But, if the X1D's live view doesn't allow for the technique described above, you could always fall back on this.

I certainly wouldn't rely on throwing the lens to infinity. With modern high resolution sensors and lenses used wide open, the errors are all too visible...

YMMV - good luck, and please let us know how you get on

Hello @EdHurst.

Thanks for the caution - not to rely on the infinity hard stop.

Your trial and error method will be possible, but as you said, laborious (tedious).

I had some success with a method involving focus adjustment on a convenient bright star (or planet). Please see the image in an earlier post to this thread.

... MomentsForZen (Richard)

 

[tcdeveau]

Thank-you @tcdeveau for your suggestion. I used a modification of your approach to obtain the image below from our apartment balcony. A convenient location, but a fair amount of light pollution. Still, a reasonable result, a little trailing of the stars, but nicely in focus! (N.B., This a 10% sub-sample.)

There weren’t any really bright stars in the frame. Instead I swung around to Jupiter and used this bright object to set the focus at infinity. I then carefully composed the shot, retaining the focus setting.

With focus peaking turned on, using a high ISO resulted in a digital snowstorm of pixels with the peaking color. I found it better to actually use a lower ISO so that I could more clearly see just the “real” signal from Jupiter. It was then easy to manually focus on Jupiter.

... MomentsForZen (Richard)

Incidentally, we are looking from the Southern Hemisphere at the Milky Way - It features the constellations of Scorpius and Sagittarius (hosting Saturn) and the Galactic Center / Core.

Hasselblad X1D camera
Hasselblad XCD 30 mm lens
15 frames @ ISO 1600, 16 seconds, f/3.5
Aligned and stacked with Starry Landscape Stacker.
Basic lighting adjustments in Lightroom and Photoshop.

Very nice! I wish I saw stars like that from my balcony Glad you're finding a technique that works for you.

As mentioned, most modern non fly-by-wire lenses do not have a hard stop at infinity and other mirrorless systems with fly-by-wire, like sony, have an electronic DOF field scale but there is some play at infinity. With MF cameras having CMOS now and moveable focus points with magnification in live view, I've found that technique or modification thereof with live view, focus magnification, and manual focus to be the easiest and most reliable for me. I've used the technique Ed uses before too, it just requires a little bit of patience as he mentioned.

I really need to get out and do more astro work....and need that 21mm XCD to come out
-Todd

 

[Godfrey]

Q: Does the X1D not have any kind of distance readout on the LCD or EVF?

 

[MomentsForZen]

I really need to get out and do more astro work....and need that 21mm XCD to come out
-Todd

Yes, bring on that 21mm XCD lens. The difference in composition from the 30mm will be significant and change the look that we can obtain.

I hope that you can get out and enjoy some clear skies real soon.

... MomentsForZen (Richard)

 

[MomentsForZen]

Q: Does the X1D not have any kind of distance readout on the LCD or EVF?

Hello @Godfrey.

Not to my knowledge. I hope that someone will correct me and tell me where this information is hiding.

... MomentsForZen (Richard)