# Alternate uses uses for solar eclipse filters



## squarebox (May 9, 2012)

Is there any use for a ND100000 filter outside of taking a solar eclipse?

The only thing I could think of is doing a super long exposure in the city to remove people.


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## Drizzt321 (May 9, 2012)

That's a good thought.

I'm having trouble finding a Photography Solar filter film right now  I'm trying to get ahold of some of the BAADER AstroSolar Photo film (ND 3.8 according to BAADER). Unfortunately, nobody has a sheet of the thing in stock, although supposedly a few places are going to get some more this week. I found 1 Canadian place that supposedly has some in stock (according to the online part), but I'm going to call and see if they really do, and how fast I can actually get it.

NOTE: The ND 3.8 is for Photography only, *NOT* for visual use, so if anyone gets some only use the LiveView or similar functionality. Get the ND 5 if you want to use it visually.


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## TrumpetPower! (May 9, 2012)

Drizzt321 said:


> That's a good thought.
> 
> I'm having trouble finding a Photography Solar filter film right now  I'm trying to get ahold of some of the BAADER AstroSolar Photo film (ND 3.8 according to BAADER). Unfortunately, nobody has a sheet of the thing in stock, although supposedly a few places are going to get some more this week. I found 1 Canadian place that supposedly has some in stock (according to the online part), but I'm going to call and see if they really do, and how fast I can actually get it.
> 
> NOTE: The ND 3.8 is for Photography only, *NOT* for visual use, so if anyone gets some only use the LiveView or similar functionality. Get the ND 5 if you want to use it visually.



Just this afternoon I bought the last Baader filter that will fit the 7" lens hood of the 400 f/2.8. The lady had to bo back to the inventory room to make sure it hadn't been sold to somebody else or otherwise placed on hold.

If you don't already have your eclipse viewing gear, don't expect to be able to find it. Pretty much everybody is cleaned out.

As to what to do after the eclipse? Well, not only are we in an active sunspot cycle, but there's the transit of Venus coming up.

I should add: I'm not planning on using a filter for the money shot. That'll (hopefully) be your typical wide angle sunset-with-sun-in-the-frame picture, except the sun will be a ring, the light will be utterly bizarre, and who knows what that'll do to the Grand Canyon.

Cheers,

b&


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## Drizzt321 (May 9, 2012)

True TrumpetPower!, I'm still hoping to get it. Maybe I should just go for the pre-made filters, I just need to measure my lenses. 

Do I need a Solar Filter if I'm doing a wide angle (~24-35mm) shot with the landscape? I've got 2 cameras, so one will be setup for that, the other I'm experimenting with the Opteka 800mm mirror lens with the 2x TC to give me ~1600mm close up of the sun. For that, I'm definitely going to need the solar filter. I'll likely make a 'hood' for the Opteka so the filter will stand off from the front element a good bit. Even at 800mm, I can do a pretty deep hood.


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## emag (May 9, 2012)

You could always photograph sunspots. Wish I was going to be able to see the eclipse, but it's not going to happen. I have my fingers crossed for the Venus transit, I got a nice series of photos of the 2004 transit at sunrise here in Florida. This one will be a late afternoon until sunset event. Shooting through a 2000mm f/10 with full aperture solar filter, the sun will more than fill the frame on my 40D.


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## jabbott (May 9, 2012)

Drizzt321 said:


> That's a good thought.
> 
> I'm having trouble finding a Photography Solar filter film right now  I'm trying to get ahold of some of the BAADER AstroSolar Photo film (ND 3.8 according to BAADER). Unfortunately, nobody has a sheet of the thing in stock, although supposedly a few places are going to get some more this week. I found 1 Canadian place that supposedly has some in stock (according to the online part), but I'm going to call and see if they really do, and how fast I can actually get it.
> 
> NOTE: The ND 3.8 is for Photography only, *NOT* for visual use, so if anyone gets some only use the LiveView or similar functionality. Get the ND 5 if you want to use it visually.



One option is to stack ND filters to reach the desired optical density. Being that the ND scale is logarithmic, it is possible to stack an ND3 and ND0.9 together to get an effective optical density of ND3.9 (~8000x light reduction). That optical density works well for solar photography when using very fast shutter speeds and strongly stopped down apertures. I definitely agree that Live View should be used to confirm framing and focus instead of the viewfinder. I will be using this technique for the May 20th eclipse as well as the upcoming solar transit of Venus on June 5th. B&H has many B+W ND3 and ND0.9 filters in stock so that is an option for folks who can't find dedicated filters. Just make sure you don't buy an ND .3 instead of an ND3.  The added benefit of getting two separate filters is that later you can use the ND3 and ND0.9 individually for varying levels of smoothing out water and cloud movement in your photos. See more on this effect here: http://www.redbubble.com/people/peterh111/journal/4421304-the-ultimate-guide-to-neutral-density-filters


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## Drizzt321 (May 9, 2012)

jabbott said:


> Drizzt321 said:
> 
> 
> > That's a good thought.
> ...



I'm not sure that the normal ND filters will work, as they don't block enough of the IR & UV that the direct sun produces. Especially if the sun is a large portion of the with a super-telephoto.


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## jabbott (May 9, 2012)

Drizzt321 said:


> I'm not sure that the normal ND filters will work, as they don't block enough of the IR & UV that the direct sun produces. Especially if the sun is a large portion of the with a super-telephoto.


CMOS sensors for DSLRs already have highly efficient IR filters built-in, and you can always add a UV filter to the ND stack if you are concerned about UV effects. The detail you would get is nowhere near as good as having a dedicated Hydrogen-alpha filter though. I purchased my ND filters for waterfalls and only afterward realized they could be used for solar photography when stacked... so there are definitely better options out there. According to transitofvenus.org, you can use #14 or greater welding glass as an option. I'm not sure if or how that would alter color however. The most interesting photos of the sun I've seen online use an H-alpha filter which brings out a *lot* of detail.

Here is a photo of the sun I took with stacked ND3 and ND0.9 filters with a 70-200 II, 2x Extender II and a Rebel T2i. I used 1/800s shutter with f/22 aperture at ISO 100 and 400mm focal length. I shot this indoors through unclean windows so that likely distorted the image somewhat. Using a diffraction-limited aperture also reduced sharpness. The dark spots shown are sunspots that I verified using the SDO/HMI Continuum image from the same day. I probably could have focused better but I kept focus time to a minimum to avoid frying things. 





Back to the original poster's question, I would say other uses would include 1) _really_ long exposures of waterfalls / the ocean in brightly lit scenes, 2) photos of welding or 3) molten metal in crucibles.


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## Drizzt321 (May 9, 2012)

Hmm...that's interesting jabbott. I'll look into that if I can't get the right kind of solar filter. I'm going to bracket every single shot anyway, that way I can try and do some stacking & maybe some HDR on the wide angle shots, or even just cut out the sun to get the correct exposure on the landscape & the sun.


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## PeterJ (May 9, 2012)

squarebox said:


> Is there any use for a ND100000 filter outside of taking a solar eclipse?
> 
> The only thing I could think of is doing a super long exposure in the city to remove people.


I bought a Thousand Oaks Optical solar filter on a recommendation from here, it was the kind made from a blank polymer and it worked well for a partial solar eclipse. However with the idea of using it for other purposes I took it out in the back yard and manually focused a 70-200 on a rose bush, worked out the rough exposure change, fitted the filter and took a few shots around my estimated exposure time.

I seemed to get the exposure right but the colour reproduction was beyond bad, so bad you couldn't tell the difference between primary colours and the loss of contrast between features meany it was actually hard to tell what it was a photo of. No doubt it would depend on what the filter is made from but if you're considering a new one you'd want to check into it and not assume it will be OK for general photography. I didn't keep that photo but did like the results from that filter with the sun:


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## squarebox (May 9, 2012)

PeterJ said:


> squarebox said:
> 
> 
> > Is there any use for a ND100000 filter outside of taking a solar eclipse?
> ...



Thankx Peter, that's the kind info i was wanting to hear. I'm wondering if that is an issue with polymer. Hopefully, a dedicated camera filter won't have the same issue, but I will keep a look out for this and report back with my results as I just ordered a ND100000 filter was expensive as hell to.


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## Neeneko (May 9, 2012)

I picked up an old B+W ND113 a while back and have been using it for long exposure stuff. To be honest, anything over the 10 stop ND filters I would not recommend. The exposures are long enough that the image gets ruined by dead/stuck pixels in the sensor.... though on a cool day or maybe with a higher ISO camera then I have this would not be an issue.

On a bright day though it makes for some very nice cloud shots.


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## wockawocka (May 9, 2012)

If you want to photograph all the buildings in time square without traffic or people it would do for that.

Out interest though, at ISO1600, F4 how long would the exposure need to be?


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## Neeneko (May 9, 2012)

wockawocka said:


> If you want to photograph all the buildings in time square without traffic or people it would do for that.
> 
> Out interest though, at ISO1600, F4 how long would the exposure need to be?



With good light, maybe 30 seconds.

Unfortunately for this type of photography you generally want to use F11 or F22, which I have found results in exposures closer to 3-5 minutes, at least for the 17 stop filter.


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## TrumpetPower! (May 9, 2012)

jabbott said:


> One option is to stack ND filters to reach the desired optical density.



*THIS IS A RECIPE FOR DISASTER.*

If you're exposing either your eyes or your camera to dangerous sunlight such that you need protection in the first place, photographic filters of any kind and in any combination will *NOT* provide said protection.

Now, you certainly don't always need protection when the sun hits your eyes or the front element of your camera. However, it really doesn't take very much to overdo it, _especially_ when you're adding optics to the mix.

If the camera or your eyes are going to be pointed at the sun for more than a second more than once or twice, you need some sort of real protection. For your eyes, that means welding glass or eclipse glasses or the like. For your camera *most especially if you yourself will be looking through the viewfinder* that means either comparable protection or covering the front element (with the lens cap, _etc._) when you're not actively making an exposure.

For the eclipse next weekend, I'll have two cameras going. The 5DIII will have the TS-E 24 (possibly with the 1.4x or 2x TC), and the 5DII will have the 400 f/2.8 (with the biggest TC left over). The 400 will have a Baader filter and will double as a viewing telescope. For the 24, I'll frame the shot early, almost certainly well before the sun enters the frame. I'll then hang a hat or something over the front of the camera. When things get interesting, I'll remove the hat, remotely trigger a rapid-fire bracket, and hang the hat back on. Lather, rinse, repeat when the light changes enough to make it worthwhile. The whole time I'll have eclipse sunglasses either on my nose or perched on my forehead, depending on whether I'm looking at the sun or not.

I most strongly encourage others to do likewise.

Cheers,

b&


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## jabbott (May 9, 2012)

TrumpetPower! said:


> *THIS IS A RECIPE FOR DISASTER.*
> 
> If you're exposing either your eyes or your camera to dangerous sunlight such that you need protection in the first place, photographic filters of any kind and in any combination will *NOT* provide said protection.


Here is a description of the B+W Neutral Density Filter 113, which has an optical density of ND4.0:

_With its light reducing capability of 13 f-stops, this B+W Neutral Density Filter is *used in astronomy for photographs of the sun* and for recording the relative movements of heavenly bodies as light traces in extremely long exposure times. For photographs of the sun, this filter must be positioned in front of the lens and under no circumstances should it be located near the primary focus in front of, or behind the eyepiece because of the intense heat at those locations. *It must not be used for observation of the sun (danger of blindness)* due to its greater transmission in the infrared range. The filter factor is 10000x._

The optical density I've used is ND3.9, which is ~8000x light reduction. ND4 is 10000x. Because of this difference I only use a highly stopped down aperture and a fast shutter speed when photographing the sun. My camera appears completely fine after doing this, as do my lenses. My eyes were protected because I exclusively used Live View for framing, focus and the shot. While I would agree that lower optical densities would certainly cause damage, in my own experience ND3.9 or greater optical density provides sufficient protection for very short framing/focus time and exposures. The biggest danger in my opinion is that Live View continuously exposes the sensor to the sun, so the time spent framing and focusing must be minimized.

[quote author=TrumpetPower!]
If the camera or your eyes are going to be pointed at the sun for more than a second more than once or twice, you need some sort of real protection. For your eyes, that means welding glass or eclipse glasses or the like. For your camera most especially if you yourself will be looking through the viewfinder that means either comparable protection or covering the front element (with the lens cap, _etc._) when you're not actively making an exposure.
[/quote]
I already said in an earlier post that it would be unsafe to look through a viewfinder at ND3.9, and this echoes Drizzt321's comments. Only use Live View instead. I agree that minimizing framing/focus time is important, as well as using eclipse glasses if you are actually going to look at the sun at all. Also essential is to use manual focus because the camera can't do phase correlation auto focus with black glass in front. Here is what happens when you point a 600mm lens at the sun without adequate protection (see the section titled "Don't Try This at Home"): http://www.the-digital-picture.com/Help/Flare.aspx


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## Drizzt321 (May 9, 2012)

jabbott said:


> TrumpetPower! said:
> 
> 
> > *THIS IS A RECIPE FOR DISASTER.*
> ...


I already said in an earlier post that it would be unsafe to look through a viewfinder at ND3.9, and this echoes Drizzt321's comments. Only use Live View instead. I agree that minimizing framing/focus time is important, as well as using eclipse glasses if you are actually going to look at the sun at all. Also essential is to use manual focus because the camera can't do phase correlation auto focus with black glass in front. Here is what happens when you point a 600mm lens at the sun without adequate protection (see the section titled "Don't Try This at Home"): http://www.the-digital-picture.com/Help/Flare.aspx
[/quote]

The other issue with standard ND filters (even the B+W one) is that it still passes a lot of IR through, which can easily damage your eye. Only the special Solar filters that are rated to filter out enough IR/UV will be safe to use visually. Even if you stack standard ND filters up to 20+ f-stops light reduction, it's still not safe to with your eyes because of the IR transmission. As someone said earlier, the sensor usually has an IR filter over it (unless it's been converted for IR photography), and so the sensor will generally be fine unless exposed for extended periods of time such as being left in LiveView for the entire time, or for extremely long exposures.


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## squarebox (May 11, 2012)

For what it's worth, I'll be using a ND5 filter rates at 100,000x. It is specifically for use during the eclipse and on the back of it is all kinda of warnings not to use it it with anything else besides liveview because it doesn't filter out IR.


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## PeterJ (May 12, 2012)

squarebox said:


> For what it's worth, I'll be using a ND5 filter rates at 100,000x. It is specifically for use during the eclipse and on the back of it is all kinda of warnings not to use it it with anything else besides liveview because it doesn't filter out IR.


The one I bought was rated for IR blocking / viewfinder use but originally I intended to use liveview regardless. One blindingly obvious thing I overlooked (if you'll excuse the pun) is that I was standing in direct sunlight while trying to frame / focus initially and reflections made the LCD just about impossible to see, so given the above I ended up using the viewfinder.

Anyway given it's a rare event just in case you hadn't thought about that it's worth having a dark cloth sheet or something on hand just to make sure you can see the LCD properly. I normally only use liveview for indoor or low-light tripod shots so hadn't given that much thought.


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