Bracketing question on Z8

[John Di Leo]

I will be shooting the upcoming eclipse. During totality lots of different exposures are called for to capture different parts of the sun's corona.

I will probably use bracketing for that.

I will be shooting through a small scope that has a fixed aperture of f/12 (1200mm).

My choices are changing exposures manually, looking at the camera instead of the eclipse—not preferred— or do a 7-8 frame bracket changing probably 0.7EV with each shot, I haven't worked out those details yet.

I will be at a higher shutter speed just before totality than what I will use during totality.

Is it possible to program the camera or the bracketing so that the changes in exposure only go in one direction,to only increase exposure rather than a + and - arrangement, ie only +?

I could do a bracket centered on a middle ground exposure and let the camera do the plus minus, but logistically it may be simpler during the hectic 4 minutes of totality to set the exposure and let the camera progressively increase exposure.

Thanks in advance

 

[ilkka_nissila]

On 3/9/2024 at 6:02 PM, John Di Leo said:

I will be shooting the upcoming eclipse. During totality lots of different exposures are called for to capture different parts of the sun's corona.

I will probably use bracketing for that.

I will be shooting through a small scope that has a fixed aperture of f/12 (1200mm).

My choices are changing exposures manually, looking at the camera instead of the eclipse—not preferred— or do a 7-8 frame bracket changing probably 0.7EV with each shot, I haven't worked out those details yet.

I will be at a higher shutter speed just before totality than what I will use during totality.

Is it possible to program the camera or the bracketing so that the changes in exposure only go in one direction,to only increase exposure rather than a + and - arrangement, ie only +?

I could do a bracket centered on a middle ground exposure and let the camera do the plus minus, but logistically it may be simpler during the hectic 4 minutes of totality to set the exposure and let the camera progressively increase exposure.

Thanks in advance

 

Not at all an expert on the topic but will check anyway: Do you have a filter to protect the camera during the photography? 

https://www.nikonusa.com/en/learn-and-explore/a/tips-and-techniques/how-to-photograph-a-solar-eclipse.html

 

Nikon suggests to take a sequence of shots at a broad range of shutter speeds of the midday sun and then base the exposure settings for the eclipse on the results of those test shots. During totality you take the filter off and I would guess one then should use automatic exposure to get to correct exposures during that phase. 

 

[mike_halliwell]

3 hours ago, ilkka_nissila said:

During totality you take the filter off and I would guess one then should use automatic exposure to get to correct exposures during that phase

I think that might be the time for wild exposure bracketing!

Spot, Centre Weighted, Matrix?? 

ETTR might be in order, and shoot RAW!

Sadly, no total solar eclipse in the UK until 2090..... I think I might (will!) be pushing up daisies by then 😞

 

[John Di Leo]

There are many sources for exposure recs, but typically one would shoot a number of different exposures to capture more and more, or less of the corona. You might shoot everything from 1/4, or slower, to 1/250sec  more or less. Typically an ISO of 100 is used to minimize noise.  Changing the shutter manually would require looking at the camera to change the shutter speed, that time would be spent NOT looking at the eclipse. It is widely rec'd to take time and actually look at the eclipse because it is beyond magnificent to view. That is why I would look to automate the process of exposures during totality, all of 288 seconds if we see it where we are planning to. I suppose I could set the shutter for 1/60 and bracket with 7 or 9 frames and then get 3 over and 3 under, but I was curious to know if one could set a sequence to start at one shutter speed and only get faster or slower. Sounds like no, can't do that.

@Ilkka. yes, big time filters specially made for looking at the sun through a telescope visually, so a camera sensor would be fine. Solar filters go way beyond NDs and are made by astronomy optical houses. I am using 2 Thousand Oaks solar filters, one on the z8 and one on the d810.  The filters stay on until nearly "second contact" (or C2) and that is when the moon completely covers the sun. At that time it is safe to look directly at the eclipse. Third contact, C3, is when the moon starts to leave the sun and the filter must be back on at that point, as well as eclipse glasses. Fourth contact, C4, is when no part of the moon any longer covers any part of the sun and the eclipse is over.

This will be my 6th and every time it is VERY hectic during totality, so minimizing fooling around with settings is of paramount importance. This is a somewhat longer one being almost 4.5 minutes. Everything has to go like clockwork, there are no do-overs

 

 

[mike_halliwell]

6 hours ago, John Di Leo said:

This will be my 6th

Eclipse Junkie ? 🤣

I caught the 1999 Total in NW France with a Nikon FM2, a Sigma 600mm f8 CAT lens and some AstroSolar film. Got some OK results.

Must fish them out of the archive and scan them properly.

As you say, the exposure for when any amount of the sun's disc is visible should be pretty fixed and wouldn't vary enough to merit bracketing.

But totality is indeed a different kettle-of-fish. However 4.1/2 mins is a long time AND the WYSIWYG EVF is priceless along with the Histogram function.

Do you have a solar tracker? 

I have a vague memory of 1mm on the sensor (film!) for every 100mm of lens, is that about right?

I remember it being hectic too....I used a rubber band to keep the Solar Film in place and it pinged off mid exposure😱

However, the film didn't move 👍

I'd be interested just how far out the coronal filaments go, so I can see why you're after increasing exposures in this way. I guess it's 'enough' when the histo 'molehill' leaves the LHS of the scale? Black is no-longer black.  HDR stack maybe?

Edited March 12 by mike_halliwell

[ilkka_nissila]

If you have several minutes of totality and your camera takes full size raw shots at 20 fps I don't know how there could be a situation where there is not enough time to get some correctly exposed frames. Personally I don't want to take any risk with my eyes and would not take off protective glasses even during totality as such experiences are not worth it for me to get a view of the event - I really need my eyes, and know people who have done solar photography and diminished eyesight as a result. Anyway I cannot see how several minutes would not be enough to get some correctly exposed frames. I am not saying it's not good to do one's research - it is, prepare as well as you can.

 

To the original question, no, there does not appear to be a way to bracket in one direction only. I would do the following: set up the manual exposure for the partial eclipse based on trial shots with the normal bright sun in the frame and the filter on. Maybe shoot with slight bracketing sequences. When the totality comes and the shots go dark, then switch to automatic exposure (aperture priority) and run broad brackets. This way you don't have to change the manual exposure settings by a large amount between the different phases; by switching between M and A modes the camera will do that for you and once totality ends you can go back to M and the camera will remember the original settings. Switching between large contrasts (normal viewing of the partial eclipse with filter on and the totality without filter) in manual mode would take some time cycling across 1/3 stops. The Zf has the nice option of easy access to full stops on the shutter dial and I've really come to like it (1/3 stops are available on request from the main command dial). This is a faster way to make large exposure changes, but I would still do it by using M and A and M modes, in that order. What the FW 2.0 of the Z8 added is larger set of increment options:

• Increments of 1.3, 1.7, 2.3, and 2.7 EV have been added to options available when ¹⁄₃ step is selected for Custom Setting b2 [EV steps for exposure cntrl].
• Increments of 1.5 and 2.5 EV have been added to options available when ¹⁄₂ step is selected for Custom Setting b2 [EV steps for exposure cntrl].
• Bracketing programs with increments of 2.0 EV or more offer a maximum of 5 shots.

I would imagine some of those options would work for you, setting the camera to bracketing burst and CH to do the brackets quickly and continuously.

Edited March 12 by ilkka_nissila

[John Di Leo]

@Ilkka

I am not going to take any chances with my eyes (or my sensors), but solar glasses during totality would, without debate, cause a complete and utter blackout. You would NOT be able to see totality—or anything, at all. Totality is the only safe time during the eclipse to remove the glasses and filter. Totality is the star of the show. The ambient light during totality is that of deep twilight. Thanks for the info there is not a way to do what I propose. I'll use in camera bracketing, or manual, or maybe both. 4.5 minutes goes VERY quickly. It is a very exciting time, often beautifully emotional, during totality and fiddling with a camera is challenging because of the spectacle overhead. You want this as smooth as possible to minimize disruption. There are no do overs.

@mike_halliwell@ilkka_nissila

There is no right exposure during totality as long as not totally black or totally white. Multiple exposures are taken to show different things often over 6 stops in increments. The shortest exposures will show the solar prominences — flames at the sun's limb sometimes 10s of thousands of miles long, an orange red color usually and filimentary in structure. As the exposures get longer, more and more of the sun's corona becomes visible as its light drowns out the light from the prominences. Depending on exposure the corona, which has the form of streamers and is beautiful, will be more or less visible. Solar coronas can extend out multiple solar radii, like 5 or more. I don't think there is anything else in photography that is similar to shoot.

The main thing is focus, f stop is usually fixed, iso is fixed, so the shutter changes to vary exposure. Anyone can do it poorly, but doing it well is a challenge

I don't think the histogram will be helpful at all, it's not a landscape but rather a black hole, the moon, surrounded by the eerie white light of the corona, surrounded by the dark of the sky, bright stars and planets are visible. As exposure decreases, blacks will get blacker, less corona, and as it increases, whites will get whiter, more corona...nature of the beast. Some people try to capture shadow detail of the moon, but doing so will burn out the corona. However, a composite can be made from that to show both coronal detail and moon detail. Those pics are rare.

The z8 will be mounted to a not very good (but owned!) 1200mm telescope and it will be on a clock drive. The d810 will be probably on my 24-70/2.8 on interval shooting, or maybe a 35/1.8? and taking a picture every 5 minutes for a composite of the eclipse. I did that for the annular eclipse last October and made a composite (attached).

For this I will be shooting manual the whole time—unless I bracket. There is no reason or visual advantage in bracketing the partial phases; get a good setting and stick with it until totality. The filter comes off and the sequence is shot. In the past what I have done is just change the shutter manually, run it up to my end exposure and then shoot back down to the original, so full stops. Doing 1/3 stops probably won't show that big of a difference, and would result in more time on the camera rather than enjoying the sight—probably the last one in my lifetime.

Seeing a total solar eclipse is a unique experience, leaving you wanting more, and should be on everyone's bucket list. Yes, I am a junkie. 😎

Thanks for the support and discussion! Clear skies.

 

[John Di Leo]

just a bit more. Attached are two screen shots from Lightroom showing a z8 shot through the 1200 of a partial phase during the Oct 2023 annular eclipse along with the histogram. the three shots show the difference in frame coverage of the solar disk between 1200 and 32mm.

 

[mike_halliwell]

Humm, if that's the 'correct' histogram at ISO 1000 on the Z8, you're leaving about 4 stops of dynamic range on the table.

You should have about 11 EVs of DR at ISO 1000

Love the composite shot. Awesome !

[John Di Leo]

That could be because even with the solar filter the sun is still very bright compared to the sunspots—two smudges near the center and to the LL—and the background sky.

If I drag the right edge of the histogram to the right, to fill the hist window, all shadow detail of those sunspots are lost. I'm open to suggestions.

[mike_halliwell]

I was meaning using the Histogram at taking time, not processing time. 😉

Deliberate underexposure is severely reducing the info you are capturing in-camera.

As long as the peak (s) remain between the 'ends', you never lose data.

9 hours ago, John Di Leo said:

If I drag the right edge of the histogram to the right, to fill the hist window, all shadow detail of those sunspots are lost.

That's where you can drag the middle pointer to get the best midtone info.

This is what happens when you use the full DR of your original posted JPEG pic, never mind the actual scene, bit overprocessed but you get the idea.

 

[John Di Leo]

So, just drag from the middle of the histogram to the right or left?

I'm on the road now and can't play w it. 

[John Di Leo]

re read your response,

Ok, I get it. Thanks

[mike_halliwell]

How did it go?