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05-20-2012, 10:27 AM   #1
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Shooting into the sun

Hi there Kind Folk,
From a kD20 to a k7 I want to shoot some photos of the eclipse here in So. Cal. that we'll have on Sunday, 20.May.
Just new here, but love the camera and how it works, does anyone have good ideas for shooting into the sun?
Thanks,
imouse

05-20-2012, 11:21 AM - 1 Like   #2
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first - don't look at the sun.
05-20-2012, 11:30 AM   #3
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LOL, of course not.
05-20-2012, 12:31 PM - 1 Like   #4
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How I'm approaching my first attempt at heliography: I didn't get a SolarFilm filter screen, so I'm relying on what I have at hand, which includes:

* Pentax K20D
* M42 Alpa (Chinon? Cosina?) 300/5.6 lens
* M42 Vivitar "matched doubler" 2x TC
* M42 Sears 3x TC
* generic 950nm IR filter
* generic CPL filter
* P-R-O ND2 filter
* Opteka TR74 EVA tripod (74in / 185cm tall)
* wired and wireless remotes
________________________________________

I just did some test shots of the overhead noon sun. I've already weeded-out some items: CPL (exposure is already sufficient), 2x TC (not enough with a 300mm lens), and wired remote (unsatisfactory with LiveView).

Settings: The lens at f/8, the IR+ND2+CPL filters mounted, the camera at Av with SR off (of course), and LiveView on.

Results: Test 'success' came via the 2-second timer. CPL definitely isn't needed -- that first decent exposure showed the camera shot at 1/100th second at ISO 320, so I'll adjust for the next tests, after I cool off a little. (Tis about 90f out there!) Chimping, I see that the solar image is ~8mm wide on a ~56mm-wide screen, so the next test will use the 3x TC. And the ND2 may be unneeded then. Or with the 3x TC and the lens at f/8, I might remove the IR filter and try just the ND2 and the CPL.

Stay tuned for a report on the next results, to be added here.
________________________________________

Follow-up: With the 3x TC, the ND2 and CPL filters, the lens set to f/22, I overexposed at 1/4000 second, so stronger filtering is definitely needed. With the 3x TC, the 950nm IR filter, and the lens at f/8, it exposed fine, 1/200 second at ISO 100. Or as fine as it can be at mid-day, with Sol right overhead with minimal atmosphere.

Conclusion: I should have bought some SolarFilm. The mid-day IR shots aren't quite finely detailed, even though the lens+TC combo is pretty sharp, as unfiltered test shots show. This evening should be interesting. I may have some shots framed by conifers.


Last edited by RioRico; 05-20-2012 at 01:34 PM.
05-20-2012, 01:25 PM - 1 Like   #5
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QuoteOriginally posted by RioRico Quote
How I'm approaching my first attempt at heliography: I didn't get a SolarFilm filter screen, so I'm relying on what I have at hand, which includes:

* Pentax K20D
* M42 Alpa (Chinon? Cosina?) 300/5.6 lens
* M42 Vivitar "matched doubler" 2x TC
* M42 Sears 3x TC
* generic 950nm IR filter
* generic CPL filter
* P-R-O ND2 filter
* Opteka tripod
* wired and wireless remotes

I just did some test shots of the overhead noon sun. I've already weeded-out some items: CPL (exposure is already sufficient), 2x TC (not enough with a 300mm lens), and wired remote (unsatisfactory with LiveView).

Settings: The lens at f/8, the IR+ND2+CPL filters mounted, the camera at Av with SR off (of course), and LiveView on.

Results: Test 'success' came via the 2-second timer. CPL definitely isn't needed -- that first decent exposure showed the camera shot at 1/100th second at ISO 320, so I'll adjust for the next tests, after I cool off a little. (Tis about 90f out there!) Chimping, I see that the solar image is ~8mm wide on a ~56mm-wide screen, so the next test will use the 3x TC. And the ND2 may be unneeded then. Or with the 3x TC and the lens at f/8, I might remove the IR filter and try just the ND2 and the CPL.

Stay tuned for a report on the next results, to be added here.
The size of the solar image at the image plane is approximately focal length/107.
05-20-2012, 01:49 PM - 1 Like   #6
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Interesting comments Rio.

I read your post and went out and did my own test shots. I don't have the absolutely correct equipment nor even a teleconverter.

My tests have been using my Pentax 55-300 at 300 mm with 8 stops MC ND filter + a polarizer. My most successful tests have been using the following settings:

K5

f32, 1/4000 sec, and ISO 80. (No Shake Reduction and Live View for composing).

At this setting, the sun has very limited size on the image, but I was aware of that having shot the moon many times with this lens. At f32, I am able to sharply resolve and distinguish sun-spots. At f22, I can see that there are sun spots, but they appear as small specks (still relatively sharp), at f16 they are small fuzzy specs, and anything less they don't show up. It kind of reminds me of dust-spots on the sensor although I've moved the sun around the frame to confirm that what I am seeing are in fact sun spots.

Everything is sharp enough that I feel I'll be successful at getting some reasonable eclipse shots. The smaller size sun will allow me to compose more of a landscape with the eclipse. That should be fun.

I'm near Sacramento, California, so I'll get about a 92% eclipse... places along the main path of the eclipse will get 96% (for comparison). I think it should look pretty cool. It has been about 20 years since the last time any eclipse of that magnitude was in my location, and I was too young to remember much.
05-20-2012, 03:10 PM   #7
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QuoteOriginally posted by emalvick Quote
At f32,
Would like to see how that turned out, can you post a sample.
05-20-2012, 04:42 PM   #8
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I've seen cameras permenantly damaged; sensors and pentaprism assembly (also including inner eyepiece) by the sun.

Inorny is ;that the shutter speed was set at 1/8000. It's just the idea of having the sun basically focused onto a sensor.

I've also seen it burn - or basically melt through film

05-20-2012, 04:53 PM - 1 Like   #9
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Ok... I quickly ran these threw Photoshop (ACR) which basically involved some minor CA correction... I didn't do any sharpening for the sake of speed. Both attached images are 100% crops (shows you how small the sun is at 300 mm).

Anyway, the first image is at f32 (PKE21765.jpg). This one definitely isn't as sharp at the f22 image (the other image) is. The f32 image, however, benefits from not being as overexposed allowing the sunspots to be more apparent (remembering that I only have 8 stops of ND to help me out). However, they are definitely not that sharp.

The f22 image shows sharper sun spots, but they are less visible. The f16 photos end up with the sun being overexposed enough that I don't see any sunspots, and it appears my focus wasn't quite right on those anyway. As far as the sun goes, and in getting the eclipse, I am satisfied with the sharpness of the perimeter of the sun in the f22 image, so I'll probably stick with that. I'm not sure I could clean up the f32 image enough in sharpening to make it look better. Sun spots won't matter since they'll be blocked.

I'm sure I'll mess around with a few apertures as I take my real shots.
Attached Images
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05-20-2012, 04:58 PM   #10
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QuoteOriginally posted by Medium FormatPro Quote
I've seen cameras permenantly damaged; sensors and pentaprism assembly (also including inner eyepiece) by the sun.

Inorny is ;that the shutter speed was set at 1/8000. It's just the idea of having the sun basically focused onto a sensor.

I've also seen it burn - or basically melt through film
I have actually burnt a hole through a cloth focal plane shutter by not having enough filtration. Solar filters are best as some filters like ND may block visible light but may allow all the nasty IR through. Also small diaphragm settings affect resolution and show up all the crud on the sensor. I did shoot the sun last week using a solar filter on a 300mm but it would appear the lens was set to f/22. The sunspots were obliterated due to the drying marks left from a previous clean, which have not been at all obvious in some 6 months of day to day usage.
05-20-2012, 05:07 PM - 1 Like   #11
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QuoteOriginally posted by Medium FormatPro Quote
I've seen cameras permenantly damaged; sensors and pentaprism assembly (also including inner eyepiece) by the sun.

Inorny is ;that the shutter speed was set at 1/8000. It's just the idea of having the sun basically focused onto a sensor.

I've also seen it burn - or basically melt through film
I've heard of it melting through film and seen that, but I have yet to see that on a digital camera and I know a few people who will shoot without any filters. I suppose tripod mounting your camera and aiming at the sun could cause problems. I usually hand hold sun shots to avoid that long term exposure.
05-20-2012, 07:52 PM   #12
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I'm back from our little Eclipse Party. (A few other folks also thought our chosen viewpoint was good.) I left the K20D mounted on the tripod with LiveView on for most of 1.5 hours with the optics aimed at Sol. 300mm @f/8, 3x TC, 950nm IR filter, wireless remote with 3-second timer, Gatorade, and that's all. Afterwards I took some 'normal' shots. As expected, see no signs of sensor damage. Not surprising, since only the IR-filtered LV system was actually seeing Sol except for the brief bracketed exposures.

I won't be able to develop the RAWs till my workhorse computer comes back from the shop soon (hopefully tomorrow) but my LV reviews seem decent. As I mentioned, this was my first attempt at heliography. I never did get a full-ring shot; I think I'm a couple degrees south of optimum. I'll try to prepare better for the next eclipse. That may involve getting some SolarFilm for my Rubinar Makpo 1000/10 mirror. Onward!

Last edited by RioRico; 05-20-2012 at 08:18 PM.
05-21-2012, 07:12 AM   #13
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Shooting into the sun

Just one shot came out, and not that well. The ones I compose for the moon reflecting off the solar panels comes out pretty good anymore. I got some fun shots of the crescent sun refracting through leaves onto our back door, or the cat box.
Thanks for all the ideas, I now have a much better idea on how to proceed when Venus crosses the sun.
See: Transit of Venus .org, which won't happen again until 2117.
Cheers!
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