Solar (eclipse) Photography

Just a quick question.
I purchased a sheet of the Baader Astrasolar ND3.8 photo film.
On delivery the EXTENSIVE (!) warnings specifically state it should only be used with a telescope and NOT a short focus DSLR.
I thought this was Kevin Clark above used on his Canon lens filter?
Can anyone explain why?
FYI a I am actually intending to use it with an M43 body and lens and so will NOT be using an optical view Finder of any kind.
 
ajf said:
Just a quick question.
I purchased a sheet of the Baader Astrasolar ND3.8 photo film.
On delivery the EXTENSIVE (!) warnings specifically state it should only be used with a telescope and NOT a short focus DSLR.
I thought this was Kevin Clark above used on his Canon lens filter?
Can anyone explain why?
FYI a I am actually intending to use it with an M43 body and lens and so will NOT be using an optical view Finder of any kind.
Click to expand...

Basically it's because if you're running 100mm then you're not spreading the energy over the sensor but into a single/few sensor cells, worse still your fabric shutter.. also the rear elements of the lens may also take a high energy point of light. If you put another ND filter on the front.. it should reduce the energy further.

I was running ND5 at 1340mm (f/13) with an IR/UV cut filter today for hours and took about 8GB of raw images for later processing. Scope has a rear doublet flattener so the more you can do to reduce the energy, the better. The exposure time I was using was 0.002-0.004 seconds (1/200sec).

I'd recommend putting a UV and IR blocking filter behind the filter film. It will help reduce the energy further.
 
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ajf said:
Just a quick question.
I purchased a sheet of the Baader Astrasolar ND3.8 photo film.
On delivery the EXTENSIVE (!) warnings specifically state it should only be used with a telescope and NOT a short focus DSLR.
I thought this was Kevin Clark above used on his Canon lens filter?
Can anyone explain why?
FYI a I am actually intending to use it with an M43 body and lens and so will NOT be using an optical view Finder of any kind.
Click to expand...
The stuff I've got it ND16.5 (I ordered from a link on another photography forum). If it was only ND3.8 I wouldn't have got the shot I did with the settings I used.
Although the instructions are in German they clearly show it on a DSLR.
 
Ah right, OK.
I have not seen any film that was at ND 16.5.
The annoying thing is, having checked back on the site I got it from it does mention using it on cameras - which is why I bought it.
They also sold a ND 5 version too, but for direct viewing.
 
The folks here have ND 3.8 and 5.0 here.. ND16 seems a little odd.. all depends on your f-ratio probably.

Typically scopes used for solar are long focal length and so they tend to be slower (i.e. high f-ratio).. mine starts at f/6.38 at 670mm. I've used ND5 for hours continuously.
 
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Well, decided to risk the filter film I bought.
Tried a few shots this morning with my M43 camera and 75-300mm lens. Slightly hazy which probably helped to a degree.
I wasn't finding I was needing either super fast shutter or very small apertures.
Not quite in the league of the photos above but happy for a first go. I think there is even a sunspot in the top left?

The Sun by ajf.350d, on Flickr
 
Bones said:
Anyone else find it amazing that the moon is exactly the right size required to eclipse the sun?
Click to expand...

Not only the size, but the distance too. "The sun’s diameter is about 400 times larger than that of the moon – and the sun is also about 400 times farther from Earth" so they appear to be the same size.
 
ajf said:
Well, decided to risk the filter film I bought.
Tried a few shots this morning with my M43 camera and 75-300mm lens. Slightly hazy which probably helped to a degree.
I wasn't finding I was needing either super fast shutter or very small apertures.
Not quite in the league of the photos above but happy for a first go. I think there is even a sunspot in the top left?

The Sun by ajf.350d, on Flickr
Click to expand...

Yes - that is a sunspot.

I had a look through an Ha scope today.. the amount of activity is phenomenal.

The slight graininess is the 'continuum' which is the basic 'surface' of the sun that you see being emitted (there's no surface, but the density becomes high enough to appear as a surface).

Sun spots show you're getting good exposure and focus.

I was attempting to image that sun spot at 3350mm f32. The earth's atmosphere is wobbling all over the place.
 
NickK said:
Yes - that is a sunspot.

I had a look through an Ha scope today.. the amount of activity is phenomenal.

The slight graininess is the 'continuum' which is the basic 'surface' of the sun that you see being emitted (there's no surface, but the density becomes high enough to appear as a surface).

Sun spots show you're getting good exposure and focus.

I was attempting to image that sun spot at 3350mm f32. The earth's atmosphere is wobbling all over the place.
Click to expand...

Thanks for that.
I must admit I never really think of the sun for observing, I guess partly as it is generally difficult to see.
The focus was a bit of luck to be honest.
I managed to use AF to get a general focus then tried to manually fine tune. The one downside of the M43 system lenses is they (generally) have no focus scales.

Do you think this is as good as I am likely to get with current camera setup?

I might start looking a bit more into this. I do have an older TAL Refractor telescope which I assume could be converted with the necessary filters. I just need to blow the dust off!

Couple of general sun questions. I notice some of the photos posted by you and others show quite a few sunspots. Is this down to the high magnification used for the image or just due to the rotation and sunspot activity?
 
ajf said:
Ah right, OK.
I have not seen any film that was at ND 16.5.
The annoying thing is, having checked back on the site I got it from it does mention using it on cameras - which is why I bought it.
They also sold a ND 5 version too, but for direct viewing.
Click to expand...

You were right actually.
I was looking at the wrong page when I said it was ND16. Sorry!
It is indeed ND5 but from what I've read, the nature of what it's made of reflects '99%' of the light so it gives the impression of using a regular ND16 filter. People who haven't got the film reckon that stacking two ND10s or a 10 and a 6 would give the same result. And as far as I can see it's fine for cameras as their site has lots of pictures of it on DSLRs. I'm not planning on viewing the whole even on the camera just in case, If the weather is ok I'll take a snap every 5-10 minutes and I'm pretty sure it's fine for that.
 
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