Solar filter

[neuroanatomist]

Can you let me know which lens hoods you got for the Canon 10x42? I have the same binos and agree that it's tough to attach the filters to it. I tried the size 50 first and it was too small. Then I went with a pair of size 70, and could not get them both on at the same time.

Apologies, I missed this question. I use the Baader ASBF 50. Given your comments above about needing to quickly remove the filters during the totality, I wanted to avoid threaded filters. Looking at the binos, I assumed the Baader filters would not have anything to grab onto, so I took advantage of the threading and ordered a pair of these 52mm threaded hoods. The setup with the ASBF 50s and the hoods works great, and the hoods are short enough they don't vignette at all.

[Kayaker72]

This is just a friendly reminder to the forum....the eclipse is about 3 months out (April 8, 2024). If you want a solar filter, you likely want to order yours soon. As I recall in 2017, you could get the eyeglasses ~2 weeks before, but legit photography solar filters ran out early, and even a quick review of solar telescopes, those are listed as backordered in a number of outlets.

BTW, I have recently discovered the app "astrospheric" which has a layer on their map for the 2024 eclipse...some great information on the path, % eclipse by location, and duration.

[Jonathan Huyer]

Brant and Neuro -- thanks for the great info. The screw-on filter from Thousand Oaks is a good option for sure, although it might be better to just use one of them. Then you could view the eclipse through the filtered lens during the partial phase while keeping a lens cap firmly on the unfiltered lens. Then when totality hits, you can pop the lens cap off the unfiltered side and gawk away safely until totality ends. Or I suppose you could carry two pairs of binoculars, one with filters and one without! Either way, I found viewing totality through unfiltered binoculars to be the greatest sight in nature I have ever seen. You get incredible details, from the prominences to the exquisite filaments in the corona. It's definitely worth having some magnification to enjoy that to the fullest.

I'll go with the lens hood that Neuro suggests, since I already have the Baader filter.

Thanks again!

[Kayaker72]

Hi Mike...

I know we've chatted about this. I do worry that the Ha filters you are talking about are for astro, not solar. Ha filters for astro fall into "narrow band" imaging as light for astro is typically coming from reactions involving oxygen, hydrogen (Ha), and sulfur. Thus, if you look for a "narrow" band around those emissions, you can pull out different and get more detail of nebula, etc.

But the real purpose of narrow band imaging is to avoid issues from light pollution. By focusing on wavelengths from space, you minimize the impacts of light emanating here on the planet (which is different wavelenghts) and bouncing around our atmosphere, interfering with the final image. So, the intent of narrowband imaging is to clean up the light hitting a sensor and to focus it on what is coming from Space.

But, "narrow band" for astro is typically 10-30 nm. When I've looked at Ha filters for solar imaging, they are trying to tightly focus on the peak of hydrogen alpha, 656.3 nm. Single stack are typically getting you a 0.7 nm range around the peak, and then double stack are usually less than 0.5 nm. So, solar imagers are really trying to be ~656.0 nm to ~656.5 nm, or tighter.

While I do not know this for sure, my concern is that 10-30 nm is not narrow enough and will let too much other light through, thus washing out Ha. So, it would be a red, detail-less image. I could be wrong. I know this as I was looking into the exact same thing but have so far opted to not go for it.

BTW, why Ha? This stuff facinates me, different light (and gravity for that matter) come from different layers of the sun. The different layers being at different temperatures, pressures, and even compositions support different reactions. At the very surface, the chromosphere which is hotter (~20,000C), is a reaction where the electron in hydrogen changes state with the temperature causing it to rise (to n=3), and as it falls (to n=2) it releases 656.3 nm light. Electron state change from n=3 to n=2 is called an "alpha"...as this is coming from a hydrogen atom, you get "hydrogen alpha" light.

White light mostly comes from the photosphere, which is just below the chromosphere. But the chromosphere being the surface, to see what is happening on the surface, you look for Ha bandwidth.

Getty back to my concern, if you do not get narrow enough around 656.3 nm, other light from the photosphere may still drown out the Ha light, thus the details of the chromosphere that we all want to see.

Like I mentioned, I've looked into it. I've decided to save my money at this point, but if I was to do it, I was leaning toward getting a Lunt 50 mm single stack dedicated solar telescope. The primary reason being, turns out, to get good photos of Ha, most solar photographers are using monochromatic cameras as our darn Bayer arrays actually are not tuned to Ha light. So, to do it well, you likely need both a dedicated telescope and a dedicated camera. That is a bridge too far for me.

So, for now, I am still thinking of just using white light filters with my camera lenses.

Thanks,
Brant

[Busted Knuckles]

I am going to at least double stack.

The 1st filter will be the solar film - 1st attempt - with the Ha after it. 2nd attempt will be the 10x nd filter with the HA after it. I will absolutely test the the 2nd attempt w/ a non camera rig - basically a large magnifying glass projecting to a board of some sort with temps being measured from ambient. Much of a step up in temp is a no go.

The higher reputation youtube folks pointed out that about 40% of the light from the sun - getting through the atmosphere/ozone layer - is IR we can't see, 50% visible and 10% UV. Excluding IR/Visible make UV exposure values drop.

I totally get that the visible/uv cut filters likley allow a very broad IR light stream in which might be too diffused in its origin to create any texture in the sun surface - we will find out when the filters arrive.

[neuroanatomist]

Getting close now. We're fortunate here, the weather forecast for northern Vermont is clear and sunny (though this is New England where they say, "If you don't like the weather, wait 5 minutes,"). Looks like much of the rest of the US path has less of a chance of clear weather.

I'm planning to use the R3 with the 600/4 II + 1.4xIII with the Baader ASTF 140 filter, mounted on the RRS TVC-33 with a side gimbal. We have eclipse glasses for the whole family, the Canon 10x42L binos with Baader ASBF 50 filters, and a couple of Nocs Provisions 8x32 monoculars with eclipse filters that the kids can look through and/or use for digiscoping with their phones.

My daughter has decided not to bring her telescope, so I have a 'spare' Baader ASTF 120 filter, thinking about what (if anything) to do with that. It will fit the hood of the 100-300/2.8, so I could set that up with the 2x TC on my travel tripod (RRS TQC-14)...but honestly one camera is probably sufficient, and I was planning to use the travel tripod for the 10x42L binoculars (I have a little Hejnar plate on it that used to go on my M/M2 but I don't use on the M6/M6II since the dedicated Acratech M5/M6 plates fit better). I could mount it in front of a camcorder and video the eclipse in addition to taking photos.

Mike, any results from playing with your full spectrum camera? I have a full spectrum M6 (along with a UV bandpass and several IR longpass filters). Given the discussion above, I could clamp the ASTF 120 to a tripod leg (i.e. held in a Justin clamp connected to an RRS multiclamp on the leg) and shoot through it with the M6 handheld (or tripod-mounted). I haven't had a chance to play with that with the sun, and we may not have sun here until Monday anyway.

Certainly, I plan on just viewing the eclipse with binoculars and with eyes using regular eclipse glasses (and not, during the totality) – I don't want to spend the whole time looking through/at the camera.

Brant, are you heading north? We're likely going to Newton, VT.

[Busted Knuckles]

Have to get the raw files onto the computer and fiddle w/ the red channel - the IR is clearly very hot compared to visible light. The image in the viewfinder was substantively different than the screen/sensor. I don't know if the dial back on the red and push of the blue/green has any value. Will find out soon

Camera JPG at https://www.flickr.com/photos/77760916@N05/

[Kayaker72]

Hey Neuro…I am down just outside of Austin Texas in a house I rented under the path of totality.

Honestly, the forecast isn’t looking great. As you mentioned, I may have left the area with the best weather to come here. But, I have turned this into a mini family vacation so we decided to take the chance.

I decided to go with the RF 200-800 with Baader film filter. I also have multiple binos (supplying for the extended family) with various daystar or thousand oak filters.

Hoping for the best! Good luck everyone!

[neuroanatomist]

Nice, Mike!

I decided to KISS, just brought the R3, 600/4 and 1.4x. Better to enjoy the event with family than juggling two cameras, filters, etc. I set the camera to a 7-shot bracket covering a 12-stop range, and triggering with the BR-E1 remote fires the whole bracket with one press, which meant I could enjoy the experience with just an occasional repositioning of the gimbal (and removing/replacing the solar filter for the totality. RAWs are still in the camera, will post pics once I get them processed.

[Busted Knuckles]

The answer is that the IR blows out everything else. There is some enhancement not enough to post yet.