AstroSolar Photo Film OD 3.8

[mikeyjames]

Hi all,
Wondering if anyone knows where you can get this? Seems to be out of stock just about everywhere in the world.

BTW - I'm well aware it's not for visual use, just for photography (my eyes are about the only thing still working at nearly 50 so I love them). The reason I ask is I saw some interesting shots of the sun with someone using the photo film with a UV/IR and H-a filter. People were saying it couldn't be done and then someone piped in with some great shots, linking to the following thread.

http://www.cloudynights.com/topic/179082-granulation-but-now-at-c11-theoretical-res-limit/#entry2312683

The site with his pics has moved so you need to copy and paste the last bit of the url with the image name in it into the new domain.

Thanks
Mick

[Merlin66]

I don't know about the availability of the Baader film, but the combo of a DSO bandwidth Ha filter for solar can take advantage of the seeing conditions to give good "white light" images.

[mikeyjames]

Hi Ken
Appreciate the advice, but I'm still very much in the learning stage and not too sure what you mean. I'd really appreciate if you could expand a little on what you mean.

I suppose my main question is that using normal ND 5.0 solar film to some other combination?

Cheers
Mick

[Merlin66]

Mick,
Unfortunately some observers think they can add a DSO Ha filter to a solar filter and achieve views/ images of filaments/ prominences etc. to compete with the specialised Ha scopes like the Coronado and Lunts.
This is definitely not the case.
Using an Ha filter isolates the longer wavelengths which are less susceptible to the seeing conditions during the day. A red (or Ha) filter combined with a safe Baader Solar Screen filter can give good performance.
IMHO for visual solar observing the addition of the Continuum filter gives much better surface contrast.
Hope this helps.

[mikeyjames]

It does, thanks Ken

I was just pretty impressed with the granulation the guy was able to achieve with the ND 3.8 film, Ha filter, amd UV/ IR filter. As you said no filaments or anything like that.

[iborg]

Looks like some is avavilable here at the moment.

http://www.baader-planetarium.uk.com/productinfo.php/filters/astrosolar/astrosolar-10m-x-05m-nd38/3416

I've wondered about using this with filters as well.

Having just read the warning, I personally would only use it with a camera.

Philip

[mikeyjames]

Wow, thanks Phillip. In my obsessive searching over past few days this never came up for some reason.

so far I have found a German Baader specialist and a Pommy astro shop that have it, but they won't ship to Australia.

Thanks again
Mick

[mikeyjames]

Hi again,
Still waiting on the UK store to confirm stock. Someone else got back to me and told me that Baader have discontinued the 100cm x 50cm and now only make the 20 x 30cm photo film. Seems an odd decision.

What are my options as I'm still considering a 10" scope. Would making a smaller inner diameter on the filter work? Or could I use two pieces to make the filter?

Thanks again

Mick

[Merlin66]

Mick,
Making a sub diameter filter is OK (just make sure the support frame covers ALL the aperture and is firmly fixed).
Based on the experienced solar observers over on solar chat http://solarchatforum.com/

the sweet spot for aperture - based on seeing conditions - seems to be around 5" (125mm)

[mikeyjames]

Thanks for that, so I should be okay with the 20cm wide film. I do understand your advice that whatever I make needs to cover the entire telescope width and be securely attached.

Out of interest: I know the ND 3.8 is not to be used for visual. If the solar film got damaged could it ruin the camera or damage the telescope mirrors in some way?

Thanks
Mick

[Merlin66]

Quick answer - No!!
The "Damage" to a solar filter is usually, but infrequent, small pinholes in the coatings.
Even with such pinholes they are 100% safe, just a loss of contrast....
I still use Baader solar film which is over ten year old, with no issues, no drama.

[sil]

Mick, You will want to look after your DIY filter as best you can. dont let the film "crinkle" and whn you make your filter dont try to Stretch it to keep it flat as this can stretch the film a ruin its characteristics. It is possible to damage a camera sensor with damaged filters but its not likely and easy to look after them. Mine are fine after years and give good flat images despite some waviness of the film surface from a loose (but secure and safe) fit. Dont stress what your filter looks like on the table, it'll perform admirably if you get the proper Baader film. It was a good wy for me to repurpose a monocular and small tabletop Dob I no longer used.

[mikeyjames]

Thanks Ken and Sil.

BTW I seem to have located the Baader solar film for photography at 100cm x 50cm in Australia @ Astronomy And Electronics Centre in South Australia.

Cheers
Mick

[OzEclipse]

Mikey,

There is a detailed description of how to make filters from thin film material on my website.
http://joe-cali.com/eclipses/EQUIPMENT/solarfilters.html

I am in the process of updating the first part of the article talking about filter materials but the section on construction of the filter holders won't change.

I have used the same method to make a full aperture 8" filter for my Vixen VC200L. However I make the flange double thickness foam core.

Cheers

Joe

[mikeyjames]

Thank you very much Joe, much appreciated.

[mikeyjames]

Hi all,
Just in case anyone comes across this thread and is interested, I found one place in Australia and one in England (that will ship) with the large size.

http://www.astronomy-electronics-centre.com.au/

and

https://www.widescreen-centre.co.uk

Cheers
Mick