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Solar imaging question: camera lens sharper than refractor?

30 replies to this topic

#1 GuitsBoy

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Posted 23 March 2024 - 08:09 AM

Hi all -

 

I've been taking my first few test shots in perperation for april 8.   I plan on bringing two nighttime imaging rigs with me:

 

AT72EDii (430mm f/6) w/ Orion glass solar filter, imx571 OSC on an iExos-100 mount
Takumar 200mm or Canon 300mm kit lens, modded Canon 77D, 100,000ND filter on my 3D printed go-to star tracker

 

Right now I'm testing both options with the same DSLR.   One thing I've noticed over and over is that the two camera lenses appear to be much sharper than the 72mm refractor.   I find it very difficult to focus the sunspots clearly with the telescope.   Though the camera lenses result in a much smaller image scale, the lenses are much sharper.      Is this due to the slower focal ratio of the lense?   Ive been stopping the lenses down to about f/11, whereas the refrator is wide open at f/6.   Would I benefit from using an aperture mask on the refractor?  My exposure is in the 1/500" to 1/640" on both rigs, and testing was done at the same time so its doubtful the atmospheric distortion changed much.

 

Honestly, I would have thought the glass in the refractor was better than the stock kit zoom lens, but my test shots dont support this.  Any suggestions on why this is, and how I can improve it?

Thank you for any thoughts on this...



#2 MalVeauX

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Posted 23 March 2024 - 08:32 AM

Hi,

 

Lenses are refractors. They are just refractors for camera bodies with a specific mount and sometimes with internal focus mechanisms. They're more complex than a simple doublet through (camera lenses) because they are virtually all very fast focal-ratio so they need extra elements to essentially flat field it and eliminate coma while keeping color correction good.

 

Atmospheric seeing absolutely changes, every moment. And most of the time you are just comparing seeing moments in tests like these. Poor seeing means difficult focus, being out of focus in poor seeing is a quadratic amount of blur.

 

Your lenses operating at F11 have heavily reduced aperture, so yes, they will appear "sharper" because they don't resolve the seeing as the actual angular resolution of the system falls dramatically and its now a very low res system and will look fine virtually all the time, but lack resolution. That 200mm F4 Takumar for example at F11 has an aperture of 18.18mm, that's 3/4th of an inch, instead of its native full aperture which is 50mm (2 inch). So yes, you're comparing a 18.18mm aperture to a 72mm aperture which has much more resolution and will start to easily resolve poor seeing conditions as blur.

 

Improvement will come from better seeing conditions which is time of day specific to your area. Mid-day at Zenith is not it likely. Morning sunrise and sunset are commonly when its better for most areas. But your area is unique to your area, so you have to determine when those times are.

 

Very best,


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#3 GuitsBoy

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Posted 23 March 2024 - 09:00 AM

Thanks for your response.    I'm not sure I understand what you mean by reduced resolution due to stopping the aperture down?   It's still more than enough to fill the camera's sensor.   I also appreciate what youre saying about constantly chasing seeing.  Ive taken around a hundred test shots to compare, and the refractor is consistently more blurred.  But if stopping down a camera lens reduces the effects of atmospheric seeing, why wouldn't I want to do the same with the larger refractor?  I do understand that a smaller aperture will require a longer exposure or faster iso speed to compensate.

 

This is in preparation for the eclipse, so I am at the whim or whatever conditions are present during the time of the event.  And that's making the rather big assumption I can even see the sun!  What would you suggest in terms of optimising the equipment I have?   Is it a matter of finding a balance point between reducing focal ratio, before longer exposures become a bigger problem?

 

Thank you again



#4 gstrumol

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Posted 23 March 2024 - 09:10 AM

Perhaps two other factors are playing a role here. First, you note that though the camera lenses result in a much smaller image scale, the lenses are much sharper. Take a look at these 2 images of Jupiter:

 

AB.jpg

 

It certainly looks like the image on the right is sharper than the one on the left, no? But they are the same image (they, it, is mine). I just shrunk the left one down to get the right one. Scale can make things appear to be sharper when the object is adjusted in size.

 

Second, you noted that you were using the Orion glass solar filter. Garbage. In the scale of quality WL imaging we have:

 

basic glass filters < glass (polymer) filters << Baader solar film filters < Herschel wedge, with the difference between the last two being minuscule.  I don't know what ND5 filter you are using on the DSLR (Hoya ND5?) but the difference you see could easily be attributed to the difference in the filters being used.


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#5 MalVeauX

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Posted 23 March 2024 - 09:25 AM

Hi,

 

Aperture is the diameter size of the physical opening into the optic. This diameter size determines resolution potential. Larger apertures (physically larger diameter openings) have more resolution potential. Larger apertures are going to be more sensitive to poor atmospheric seeing, they resolve more, and they resolve bad seeing just as well as good signal from a subject. This is why when you reduced your aperture on your lens to 18mm, it was "sharper." You threw away the system's resolution potential and it no longer was resolving the poor seeing from the signal and you get a steady low resolution image as a result, but it will lack any sort of fine detail on the subject and if sharpened will just be a bunch of bulbous artifacts on a disc circle.

 

Aperture size has nothing to do with "filling your camera's sensor." What fills your camera's sensor is the focal length relative to the sensor size.

 

Taking hundreds of single shots in blurry seeing conditions will give you a consistent result of poor seeing. This is not validation.

 

Exposure time of 10ms (1/100th of a second) or less is ideal for freezing the seeing. You generally need to take many hundreds to thousands of sequential images (ie, video at high FPS) to beat the seeing (lucky imaging). F11~F50 is not a problem in solar, there's plenty of signal, your exposure time should still be short. If it's not, then your filters are blocking too much signal and it's ok to use some gain/ISO as needed to fill your histogram.

 

When you close down the iris in a camera lens, the blades mask the light cone which effectively reduces aperture. Because the focal length is constant and the aperture just reduced, the resulting focal-ratio changes. This is not important until you get into sampling, where you relate wavelength to pixel pitch size to focal-ratio to sample resolution. This is not a concern for your needs, you will virtually always undersample and that is fine for this purpose.

 

Instead of comparing your system through poor seeing conditions, instead, use your system on a terrestrial subject without your solar filters. Just camera + lens and camera + telescope and look at a distant object terrestrially like the top of a light pole or building windows, etc. Something with detail. Compare the results of your lenses how you intend to use them to your 72mm refractor and expose them the same, then simply look at the differences on the images. They shouldn't be that dissimilar, but there will be some local heat (seeing) effects if shooting over roads or buildings, etc. Still it should give you an idea of resolution and contrast differences and your ability to fine focus either one for a sharp in focus image. Do this on the same subject and share those images here if you wish.

 

It's very common for people new to imaging in daytime in poor seeing to have problems with even small telescopes due to poor seeing conditions. 3~4 arc-second seeing conditions, or worse, are no joke. You can't even get a focused disc limb in that without patience and if your focus is even slightly off, the whole thing is quadratic function blurred with poor seeing in addition to out of focus. Larger physical apertures are more difficult as they resolve this even better. It even happens with smaller 60~80mm aperture refractors, let alone 200mm apertures where people immediately think they'll use their trusty C8's only to see nothing different than the resolution of a 50mm finder scope or worse. Seeing is everything.

 

If you want to improve:

 

Practice solar imaging now with the gear you intend to use. Don't go back and forth on several things comparing seeing condition results. Single shots, 100 of them, is a grain of sand compared to what you should be doing for daytime lucky imaging through poor seeing. It takes hundreds, thousands, via high speed video to really lucky image in poor seeing in a short time frame. If you're comparing single shots, you're just seeing poor seeing in each one. And yes you will absolutely get 100 back to back bad seeing shots easily in daytime seeing conditions.

 

Local seeing conditions matter too. If you're doing this on pavement, driveway, street, parking lot, etc, anything that holds heat, this is bad. If you're shooting over engine blocks, roof tops, etc, this is bad. Set up in some grass or wood deck, avoid shooting over things that reflect and release heat all day. Shooting "high in the sky" is not ideal here, that's not when your seeing is best. Seeing is best morning and evening. But eclipses happen when they happen, not at the best times of seeing, so prepare for poor seeing and that time of day the eclipse will happen for your area and get used to that time of day so you can get consistent practice in that kind of seeing conditions that you will contend with.

 

My suggestion since this is eclipse oriented:

 

Use whatever lens/refractor gives you the ideal field of view you want on your camera.

Get it focused as closely as you can.

Set your histogram exposures (brackets if you need to) with short enough exposure times to freeze seeing conditions. Do not be shy with gain/ISO.

Take as many sequential images as you can back to back through the event.

And don't waste time on the gear and miss looking at the eclipse with your eyes during totality. "Getting the shot" is not worth it missing the primordial experience, unless you're a seasoned eclipse imager/chaser.

This should be basically automated so you can hit a button and ignore it and watch the eclipse and then review data later and if you get lucky, great.

 

Very best,


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#6 tcifani

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Posted 23 March 2024 - 10:59 AM

Hi all -

 

I've been taking my first few test shots in perperation for april 8.   I plan on bringing two nighttime imaging rigs with me:

 

AT72EDii (430mm f/6) w/ Orion glass solar filter, imx571 OSC on an iExos-100 mount
Takumar 200mm or Canon 300mm kit lens, modded Canon 77D, 100,000ND filter on my 3D printed go-to star tracker

 

Right now I'm testing both options with the same DSLR.   One thing I've noticed over and over is that the two camera lenses appear to be much sharper than the 72mm refractor. 

Would you mind posting a few test shots? How are the camera lenses sharper? On axis or across the entire field? Have you tested both lenses against your AT72ED at approximately the same F/stop? ~F/6, even just visually as mentioned above during the day. Closed down to F/11, you are possibly reducing various optical aberrations of the camera lenses. And, as a doublet, your AT72ED could just be less sharp than the multi grouped/multi element camera lenses, although I don't think this is the problem.


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#7 GuitsBoy

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Posted 23 March 2024 - 03:05 PM

 

My suggestion since this is eclipse oriented:

 

Use whatever lens/refractor gives you the ideal field of view you want on your camera.

Get it focused as closely as you can.

Set your histogram exposures (brackets if you need to) with short enough exposure times to freeze seeing conditions. Do not be shy with gain/ISO.

Take as many sequential images as you can back to back through the event.

And don't waste time on the gear and miss looking at the eclipse with your eyes during totality. "Getting the shot" is not worth it missing the primordial experience, unless you're a seasoned eclipse imager/chaser.

This should be basically automated so you can hit a button and ignore it and watch the eclipse and then review data later and if you get lucky, great.

 

Very best,

Thank you for the detailed information.  Its a bit over my head, and probably well beyond my goals here.   While it might be nice to dabble in solar and planetary once in a while, my primary focus has always been deep sky, which is possibly why I'm meeting such a learning curve in terms of seeing and mitigating it's effects.  I have used registax in  the past with video, however with the equipment I plan to use, it may not be feasible.  The DSLR resamples video down to 1080x1920.   And I dont believe the IMX571 OSC camera is capable of video, since it takes a couple seconds  to download each sub even over USB3.  ROI may speed things up, but only to the  tune of 1-2 FPS by my estimation, not the tens of thousands of frames to properly sort through for lucky imaging.  But again, those are probably loftier goals than mine are.

 

I am using two focal lengths that should work well with APS-C sensors.  It should be close enough to resolve some detail of the sun, yet wide enough to capture the corona stretching out during totality.   I plan to have both rigs running as close to autopilot as possible.   I may need some fiddling as the eclipse edges closer to totality and I need to increase the exposure length / gain / iso.  But once the diamond ring hits, I plan to use my pre-configured routines for totality and just let them run in the background while I take in the once in a lifetime specticle with my wife and children.  Its been a wise suggestion shared by a lot of people, and I fully plan to be in the moment for it.

As you suggest, I am practising as much as I can with the equipment I plan to use, but that has led me to wondering why the camera lenses seem to be sharper than the refractor.  But the answer may indeed lie in the knowled youve shared above.

Thank you again.


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#8 GuitsBoy

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Posted 23 March 2024 - 03:23 PM

Would you mind posting a few test shots? How are the camera lenses sharper? On axis or across the entire field? Have you tested both lenses against your AT72ED at approximately the same F/stop? ~F/6, even just visually as mentioned above during the day. Closed down to F/11, you are possibly reducing various optical aberrations of the camera lenses. And, as a doublet, your AT72ED could just be less sharp than the multi grouped/multi element camera lenses, although I don't think this is the problem.

I'll post a comparrison.  Please remember that I'm still extremely new at this particular niche of astrophotography.  The equipment is general purpose, geared more towards deep sky targets.  As such, I'm not expecting the kind of images a seasoned vet would get.  I'm simply trying to make the most out of  the gear I have, and hope to use for the event.  I dont have a good way to test across the entire field, since my FOV is roughly 3-5 degrees, and the sun is roughly the half degree centered.

comparison.jpg

 

The left side is the image as shot (1/500" iso100 f/6), however scaled down in photoshop to match the same size as the camera lens.    This was essentially the best of the bunch from the refractor, and you can see its noticeably soft.    The image on the right is from the 300mm lens, 1/500" iso100 shot at f/11.  The size is as it was shot, however I did bump up the exposure in camera raw.  Perhaps this now makes it "apples to oranges".    Just about any random frame shot through a lens looked as sharp as this sample.

 

I'm guessing that I can further test by making a simple aperture mask for the refractor.  I can also open up the f-stop on  the lens to see if that seems to invite blurring.  

 

Thanks for your thoughts.



#9 GuitsBoy

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Posted 23 March 2024 - 03:33 PM

Perhaps two other factors are playing a role here. First, you note that though the camera lenses result in a much smaller image scale, the lenses are much sharper. Take a look at these 2 images of Jupiter:

 

attachicon.gif AB.jpg

 

It certainly looks like the image on the right is sharper than the one on the left, no? But they are the same image (they, it, is mine). I just shrunk the left one down to get the right one. Scale can make things appear to be sharper when the object is adjusted in size.

 

Second, you noted that you were using the Orion glass solar filter. Garbage. In the scale of quality WL imaging we have:

 

basic glass filters < glass (polymer) filters << Baader solar film filters < Herschel wedge, with the difference between the last two being minuscule.  I don't know what ND5 filter you are using on the DSLR (Hoya ND5?) but the difference you see could easily be attributed to the difference in the filters being used.

Thanks for the response.  Its not a matter of scaling the image.   Scaled to the same, one is noticeably softer.

The orion filter may indeed be cheap.  However I'm surprised that the baader film is substantially better, especially since I was specifically cautioned to avoid film filters.  As for the filter on the camera, it's a K&F 100,000 neutral density filter (16.6 stops).  From memory, the camera filter was considerably cheaper.   

Thanks again



#10 Ulysses

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Posted 23 March 2024 - 03:35 PM

Mid-day at Zenith is not it likely. Morning sunrise and sunset are commonly when its better for most areas.

Marty, can you please explain why this is observed to be the case even though at sunrise we are looking through a much thicker barrier of air and presumably dealing with a lot more atmospheric lensing?


Edited by Ulysses, 23 March 2024 - 03:58 PM.

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#11 Jamey L Jenkins

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Posted 23 March 2024 - 05:23 PM

Sometimes seeing is better in the early morning because local air has not been disturbed by solar heat and re-radiating surfaces have not absorbed heat. Sometimes better seeing will occur with the Sun high in the sky (such as when near the meridian) because the local air is simply not turbulent.

The key word here is "sometimes"

 

Cheaper glass filters are often made from lesser quality float glass. It's kinda like looking through a piece of window pane glass. The Baader film typically out performs inexpensive glass filters in regards to resolution.

 

Good luck at the eclipse, hoping we all have clear skies!


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#12 GuitsBoy

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Posted 23 March 2024 - 06:18 PM

Cheaper glass filters are often made from lesser quality float glass. It's kinda like looking through a piece of window pane glass. The Baader film typically out performs inexpensive glass filters in regards to resolution.

 

Thanks for the information.   I did some searching and found a few other people with similar issues, sunspots were not very sharp with the orion or thousand oaks filter.   Thats a bummer.   

 

The baader film seems rather expensive, if you can get it at all.  Not sure if its been marked up lately for the eclipse, but I dont remember it being 50 bucks for a 9x12 sheet.     

 

Amazon happens to have the 82mm version of the K&F camera filter I'm using for a very reasonable $25.   It would be very simple to 3D print up an adapter to use it with my scope.  For some reason, the glass just feels like a better option.

 

Of the two, is the baader film really the better or safer option?  At least we 100% know what we're getting?   Odds are I'll probably wind up getting both.

 

Thanks again



#13 MalVeauX

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Posted 23 March 2024 - 07:10 PM

Marty, can you please explain why this is observed to be the case even though at sunrise we are looking through a much thicker barrier of air and presumably dealing with a lot more atmospheric lensing?

It's geography and weather related, so its not a hard rule. It's just commonly observed for most people who are not in ideal observatory class locations where they are on a mountain side, peninsula, island, etc, where its common to have more periods of laminar winds flowing from one pressure to another giving much better steady seeing. If you're land locked and in flat land without laminar winds, zenith will have heat pushing winds in many directions and then its just based on surrounding weather, surrounding geography, etc. When the sun is rising and setting, it's warming up one side and the heat increases pressure and the air over you is cooler temp and lower pressure, so it begins to move away from the high pressure, creating moments of laminar flow resulting in good seeing. Any time you have two pressures and things are moving one way due to that, it's a good time to try and get lucky. While thicker atmosphere has its own issues, they're lesser issues compared to chaotic daytime seeing above you where seeing is 5~8 arc-seconds (not even good enough for a 40mm aperture to suffer through). 3 arc-seconds will be ok with a 40~60mm aperture in 656nm. 2 arc-seconds is 80mm territory. 1.6 arc-seconds is closer to 100mm territory. 1.2 arc-seconds is closer to 120mm terriatory. 1 arc-second is where 150mm starts to open up, again, in 656nm. You need sub-arc-second to really get the most from 150mm, and its critical to have better than sub-arc-second (like 0.6~0.8 arc-second) to use something like 180~200mm or larger.

 

Very best,


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#14 Jamey L Jenkins

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Posted 23 March 2024 - 07:33 PM

Try here for Baader visual sheet to make your own.

 

https://www.scopestuff.com/

 

Yes, the Baader will perform better....here's a shot through a visual Baader filter with a 5-inch refractor.

Attached Thumbnails

  • 27461067110_b39354a8bd_o.jpg

Edited by Jamey L Jenkins, 23 March 2024 - 07:47 PM.

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#15 GuitsBoy

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Posted 23 March 2024 - 08:27 PM

Try here for Baader visual sheet to make your own.

 

https://www.scopestuff.com/

 

Yes, the Baader will perform better....here's a shot through a visual Baader filter with a 5-inch refractor.

Thanks, I picked up the 8.5x5 sheet for 22 bucks shipped.  Seems plenty reasonable.   I should be able to make a few different filters from the one half sheet.   Perfect.  Thanks again!    Ill post back  to confirm if this corrects my issue.


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#16 gstrumol

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Posted 23 March 2024 - 08:37 PM

 However I'm surprised that the baader film is substantially better, especially since I was specifically cautioned to avoid film filters.  As for the filter on the camera, it's a K&F 100,000 neutral density filter (16.6 stops).  From memory, the camera filter was considerably cheaper.   

Thanks again

I'm surprised you were cautioned against film filters, especially Baader, because it is probably the most used and recommended WL solar filter. You see, the film filter goes on front, so it can be used on any type of scope - refractor, SCT, MCT, Newtonian - whereas its nearest competitor for quality, a Herschel wedge, can only be used on refractors. The film is much stronger than it seems, and with something like an Astrozap filter it attaches quite securely to the front of the scope (properly sized, of course).

 

Because it is so thin, the light wavefront experiences negligible distortion/deflection as it passes through, unlike a glass filter which isn't very optically flat and so causes the image to be blurred as the two surfaces aren't perfectly parallel. With a Baader film filter on your AT72ED scope the images should be super sharp (assuming seeing is good). I took this image with my TAL100RS and a Canon DSLR:

 

BestTAL.jpg


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#17 ch-viladrich

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Posted 24 March 2024 - 07:33 AM

Generally speaking, refractors are optimised for on-axis performance. When you want to have a good field coverage with a refractor, you need to add a field corrector, or use a more elaborate optical design (like Pezval Taka FSQ, or ZWO FF 80/600 refractors with four lenses, or even more).

 

Camera lenses are designed to give an "average" performance all accross their field of view. Still, on-axis performance is better than off-axis performance. But generally speaking, the off-axis performance of "good" telephoto lenses will be better than off-axis performance of "good" refractors.

 

These are just general statements. Quality can change dramatically from one lens to the other, and from one refractor to the other. And each lens (telephoto, zoom, wide angle) has its own optimal f-ratio. Just check specialized web sites to find out the optimal f-ratio for your lens.

 

In the case in question, first and foremost, forget about K&F neutral density filter and other low quality filters. Just stick to Baader Astrosolar ND5 which has been known for a very long time as the best solar filter afordable. If you want to improve on it, your use a solar wedge (but it is more expensive).


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#18 GuitsBoy

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Posted 24 March 2024 - 08:05 AM

Generally speaking, refractors are optimised for on-axis performance. When you want to have a good field coverage with a refractor, you need to add a field corrector

I do have a field flattener / reducer, however I'll probably omit this in order to get a little extra reach (430mm instead of 345mm).    On axis is really the primary concern.   In nighttime astro, the refractor doesnt show star elongation until the edges of my asp-c sensor, so I believe it shoudl be flat enough for eclipse duties, specifically the corona during totality.  The camera lens will add coverage with a wider field of view, but a little less reach.

 

Since both  the K&F filter and the 8.5x5 sheet of baader film were cheap, I purchased both.   I should have enough film to produce one filter for the telescope and 4 camera lens filters, giving two away to family and friends.   I'm 3d printing slip-on filter frames for them as we speak.

 

Thank you for your knowledge and advice.



#19 BYoesle

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Posted 24 March 2024 - 11:13 AM

I'll just throw this in for you and others to ponder. Been there and done that, and regretted it.

 

If this is your first total solar eclipse (or second... ), I'd advise not to waste your time on trying to photograph it unless you've got the experience, equipment, and eclipse software down pat to automate the process.

 

And that's the consensus of most of the experts you can hope to consult. You'll want to give your undivided attention to experiencing the total portions of the eclipse. Other veteran eclipse chasers will generally get far better pictures than you will for keeping a memory of what it looked like.

 

 

On July 11, 1991, I saw a total eclipse of the Sun that affected me so deeply that I vowed to see the Great American Eclipse of August 21, 2017. This time I determined that I would not photograph the eclipse, I would just watch it and soak it all in. I felt that I had missed out on the emotional experience by all the videography and photography I had done during the 1991 experience... You will love it. It will change your life.

Gary Fouts

 

 

If you’ve never done astrophotography before, don’t spend Totality fiddling with equipment because you’ll miss the experience. Just get yourself a nice comfortable lawn chair, sit back, relax and just experience Totality – don’t let anything else distract you.

Edward Mahoney


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#20 Jamey L Jenkins

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Posted 24 March 2024 - 09:51 PM

I'll just throw this in for you and others to ponder. Been there and done that, and regretted it.

 

If this is your first total solar eclipse (or second... ), I'd advise not to waste your time on trying to photograph it unless you've got the experience, equipment, and eclipse software down pat to automate the process.

 

And that's the consensus of most of the experts you can hope to consult. You'll want to give your undivided attention to experiencing the total portions of the eclipse. Other veteran eclipse chasers will generally get far better pictures than you will for keeping a memory of what it looked like.

Hi Bob...right on about that observation. My first total solar eclipse was the 1979 event visible from Brandon, Manitoba, Canada. We spent two days driving there in dreadful winter weather. The day of the eclipse turned out to be beautiful clear skies although with a -15F temperature. I spent totality looking through the viewfinder of my Praktica Nova SLR attached to my Montgomery Ward 60mm refractor trying to focus and vary exposures to capture the corona. I got one "sneak peak" of totality with my naked eyes...no real impressions to remember. I did get a pic in Sky and Tele of the event (see attached) but would rather have the memory of seeing it first hand.  Sometimes lessons are hard learned.

 

Jamey
skytele.jpg


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#21 BYoesle

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Posted 25 March 2024 - 09:24 AM

Hi Jamey - that exactly mimics my 1979 experience in Goldendale!



#22 GuitsBoy

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Posted 25 March 2024 - 11:43 AM

Hi Bob...right on about that observation. My first total solar eclipse was the 1979 event visible from Brandon, Manitoba, Canada. We spent two days driving there in dreadful winter weather. The day of the eclipse turned out to be beautiful clear skies although with a -15F temperature. I spent totality looking through the viewfinder of my Praktica Nova SLR attached to my Montgomery Ward 60mm refractor trying to focus and vary exposures to capture the corona. I got one "sneak peak" of totality with my naked eyes...no real impressions to remember. I did get a pic in Sky and Tele of the event (see attached) but would rather have the memory of seeing it first hand.  Sometimes lessons are hard learned.

 

Jamey
attachicon.gif skytele.jpg

 

I'll just throw this in for you and others to ponder. Been there and done that, and regretted it.

 

If this is your first total solar eclipse (or second... ), I'd advise not to waste your time on trying to photograph it unless you've got the experience, equipment, and eclipse software down pat to automate the process.

 

And that's the consensus of most of the experts you can hope to consult. You'll want to give your undivided attention to experiencing the total portions of the eclipse. Other veteran eclipse chasers will generally get far better pictures than you will for keeping a memory of what it looked like.

 

Gary Fouts

 

Edward Mahoney

Thank you both for the suggestions.  While I do agree and appreciate the sentiment, I would still, respectfully of course, disagree.  

 

I've been in the astrophotography game for some time now, and while solar (and particularly eclipse) photography is a bit of a niche requring a different skillset, there still seems to be considerable overlap.   I plan to use equipment that I already frequently use, some of which I designed myself.   I'm quite comfortable operating multiple astrophotography rigs at the same time, usually from the comfort of my own couch, or while fast asleep in bed.  My original question is not "how do I photograph the eclipse?".   Its more of a specific question of which filters will optimize the equipment I already have and plan to use. But I am fully aware that this is a once in a lifetime event, and as such, I plan to spend the most important precious few minutes embracing my wife and children, not fiddling with mechanization, chasing after the perfect histogram.  

 

Of course, I'll be using tracking mounts, so I won't be constantly framing the sun on a pripod, and focus should be set it and forget it.     Ive got some very simple routines planned to help automate things as much as possible.   If all goes well, it shouldnt require much interaction leading up to the event, and ideally, none during totality.   But most importantly, my expectations are fairly low.   I'd like to have the pride and satisfaction of taking and processing my own pictures to add to my collection, however I do not expect in any way shape or form to hang with the big boys.   Rather than micromanage capturing the event through the viewfinder, I plan to be as automated as possible, and mitigate any SNAFUs through redundency.  I plan on running two automated setups, in addition to a hand held DSLR for point and shoot duties, while my father is planning on running his own mount as well.  

 

To give you an idea of the nut and bolts of my plan:

The DSLR/lens will be riding on my 3D printed go-to capable mount.  I'll simply point the mount north as best I can, and set it for solar tracking, then center the sun in the field of view.    Test runs show that I may want to recenter every 15 to 30 minutes, but with 5º+ field of view, there's some room for error.  I'll be running the DSLR with a simple intervaolmemter probably clicking every 60 seconds on the run up to totality.  I'll simply flip the wheel to increase exposure time as needed on the run up.  I wont be bothering with opening up the aperture, snd shouldnt need to refocus.   Since Illl be shooting in raw, the iso can more or less be adjusted in post processing/stretching.  Just before the diamond ring appears, I do plan to increase intervalometer frrequency to 15 or 20 seconds throughout totality.  I'll remove the filter, set the final exposure length for totality, and I'll be hands off from that point out.  I can switch back to shorter exposures and slower frequency whenever I get around to it, after the event is over and any emotions have run their course, but hopefully before I cook my camera's sensor.

 

The telescope (AT72EDii) will be on my explore scientifis iEXOS-100 mount.  Similarly, this mount will be set to solar tracking.   I'll be shooting with my risingcam imx571 OSC camera, running my routines through NINA on my laptop.  I'll have two routines ready to go:  The ramp up to totality, where exposure time increases every ten minutes.  The second routine will be started right at the diamond ring, just before I pull the filter.  It will have 6 or so minutes of my planned exposure for totality, followed by the inverse of the first routine.   

 

Both my cameras, particularly the OSC camera, have very deep wells, which should afford me some wiggle room against overexposure. And with plenty of signal, as compared to shooting faint nebulas, I shouln't have much difficulty stretching the shots as needed.   I have no plans to sit there trying to get my native subs to show the ideal histogram mountain.  Whatever I get, I get.   I'll make the best of it in processing.  

 

Now of course, even the best laid out plans can and will expeirence wrinkles.  I get that.  But I'm hoping most of  those can be addressed before totality while there's otherwise just a lot of sitting and waiting around.    But I do plan to be present and in-the-moment.   I have it in my head to remind myself frequently.  And no doubt, my wife is also well prepared to remind me.   But as the eclipse reaches crescendo, I can say with certainty that my eyes will be glued to the sky, and my arms around my children and wife.

 

Now all we need is a break in the weather...

 

All that said, I truly do appreciate the sage advice and wisdom that youve left here.   It's important to remember the experience is the primary goal, not the pictures.


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#23 GuitsBoy

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Posted 25 March 2024 - 12:27 PM

For what it's worth, I can now confirm that the original Orion solar filter was at fault.

I ordered both another K&F filter large enough for the objective on my refractor, as well as the baader film.   The K&F was first to arrive.  I had 3d printed up a quick adapter, and hung it on the front of the scope.  Instantly, I could see that focusing was much easier with the K&F compared to the orion.  I grabbed five or six test shots at different exposure lengths, and this was the best of the bunch (1/2000").  Not much processing, just some quick tweaks in camera raw.

IMG_3606.jpg

 

For a very quick white light grab, I'm happy with the detail.   I'll keep playing and dialing things in, especially once the baader film arrives. 

 

Thanks again for all the information added to this thread.


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#24 GuitsBoy

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Posted 20 April 2024 - 11:28 AM

Hi all, just a final update to this issue.   I had the K&F ND filter in 55mm for the camera and 82mm for the telescope.  I also ordered a sheet of baader film, and 3d printed two dozen filter housings in various sizes.  The baader film was every bit as sharp as the K&F filters, but it was a bit more monochrome.  In the end, I didnt find the baader film to have an advantage, so I prefered the coloring of the neutral density filters and wound up using those.

 

Day of the eclipse, the weather was touch and go in upstate new york.  But we had fairly thin clouds for the main event, and imaging aquisition went off without a hitch.   I had my canon 77d (and the stock 250mm lens) controlled by eclipse orchestrator.  The DSLR was piggy packed on top of my AT72EDii 3 inch recractor with my risingcam imx571 OSC controlled by NINA.  All riding atop my portable iExos-100 mount.  With the brief exception of removing the filters, all 3 minutes 1.4 seconds were spent taking in the views and embracing my family.   What an amazin show.   While I appreciate everyone's suggestion not to photograhp the eclipse, I'm very happy to have accomplished both.

My short shory, and some images I came away with can be found here:   https://eclipse.ihearyou.com

Thanks again for all the knowledge and suggestions here.  You guys helped me have a very successful eclipse trip, maximizing a truly once in a lifetime opportunity.

 

closeup_2024-04-08_14-21-47__31.80_0 (Custom).jpg

 

superstack5 (Custom) (1).jpg

 

2024-04-08_15-24-41__29.90_0 (Custom).jpg

 

2024-04-08_15-27-49__27.80_0 (Custom).jpg

 

prom2.jpg

 

prom3.jpg

 

mosaic5 (Custom).jpg


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#25 Daniel Dance

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Posted 20 April 2024 - 12:29 PM

Hi all -

 

I've been taking my first few test shots in perperation for april 8.   I plan on bringing two nighttime imaging rigs with me:

 

AT72EDii (430mm f/6) w/ Orion glass solar filter, imx571 OSC on an iExos-100 mount
Takumar 200mm or Canon 300mm kit lens, modded Canon 77D, 100,000ND filter on my 3D printed go-to star tracker

 

Right now I'm testing both options with the same DSLR.   One thing I've noticed over and over is that the two camera lenses appear to be much sharper than the 72mm refractor.   I find it very difficult to focus the sunspots clearly with the telescope.   Though the camera lenses result in a much smaller image scale, the lenses are much sharper.      Is this due to the slower focal ratio of the lense?   Ive been stopping the lenses down to about f/11, whereas the refrator is wide open at f/6.   Would I benefit from using an aperture mask on the refractor?  My exposure is in the 1/500" to 1/640" on both rigs, and testing was done at the same time so its doubtful the atmospheric distortion changed much.

 

Honestly, I would have thought the glass in the refractor was better than the stock kit zoom lens, but my test shots dont support this.  Any suggestions on why this is, and how I can improve it?

Thank you for any thoughts on this...

It all depends on the lens / refractor.

 

I've owned Takahashi refractors made with legendary "japanese glass" costing upwards of $15,000 that are beat by the sharpness of a $400 Rokinon 135mm chinese camera lens.





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