As a side note to the question about the 300mm lens this is what I just got although it's probably a touch out of focus it shows AR 11476 easy enough so it should show Venus.
This was stopped down as far as I could go f/40 and used my fastest exp 1/40000. Even though the ND400 says it's good for use on the Sun I would not recommend it unless you had it connected to a laptop or at all.
Most keen amateur astronomers probably know this already, but for readers who are not familiar with the Baader AstroSolar ™ Photo Film (3.8) versus the Baader AstroSolar ™ Safety Film (5), the Baader website writes:
“AstroSolar™ PhotoFilm is not intended for visual observation. PhotoFilm is only for use with telescopes for high magnification photographic work. Do not use it for producing solar eclipse viewers, do not mount it onto DSLR camera lenses.”
The last sentence re: “…do not mount it onto DSLR camera lenses” is worth reiterating.
I wouldn't use the ND400, I never plan on using that again anywhere near the sun.
I did it out of curiousity seeing as Hoya advertise it as something that the filter can do but frankly I think they should take that information off their website and packaging as it's not good for you or the camera.
Stick with the thousand oaks stuff and that will be fine.
I wonder if the warning about not using OD3.8 on SLR lenses is more about operator safety than equipment damage, i.e. people looking through the viewfinder?
My fast telephoto lenses (e.g. f/2.8 or faster) act like finderscopes when I look through the viewfinder at night - I can see far more stars than with my naked eye alone. I can imagine this wouldn't be a good result pointing it at the sun with only a OD3.8 filter.
Quick back of the envelope calculations:
OD5 solar film blocks 99.999% of light, so it's like a log(10^5)/log(2) = 16.6 stop neutral density filter.
OD3.8 would block log(10^3.8)/log(2) = 12.6 stops of light.
Considering that OD5 film results in exposures nowhere near the maximum limit of my 5DmkII (1/8000 sec, ISO 100, f/32), I'd be a bit surprised if OD3.8 damages the camera.
For the record... Hoya's NDx400 filter that they claim is safe to shoot the sun with is only a 9 stop filter! In solar film terms, it would be equivalent to a OD2.7...
*** Note: the above is just my personal speculation, I don't actually know what I'm talking about so please be careful
For the record... Hoya's NDx400 filter that they claim is safe to shoot the sun with is only a 9 stop filter! In solar film terms, it would be equivalent to a OD2.7...
*** Note: the above is just my personal speculation, I don't actually know what I'm talking about so please be careful
This is what their site promotes....
"Photographing solar eclipses and ultra-bright light sources can be extremely dangerous. This filter reduces light values by 9 stops to less than 1/500th of its original intensity and allows safe photography."
They also show a pic of a full sun with sunspots. http://www.hoyafilter.com/products/hoya/oef-07.html
There is absolutely nothing safe about it, they certainly don't give any intructions on safe use and there is absolutely no way anybody should be looking through the view finder thinking it'll be safe. It's not.
There may be a safe way to use it but I wouldn't recommend it.
It’s also worth noting that when I connect my DSLR to my (dumb) Mewlon 180mm F12 ‘scope, the effective viewing aperture is F12 at prime focus and F19.6 with the Tak x1.6 extender.
With a DSLR lens, light throughput to the viewfinder is at the maximum aperture of the lens, as the camera meters the scene wide open and only stops down at the moment of exposure.
So, if you fit an F2.8 lens, then you are essentially viewing at 4 to 5 stops wider than my F12 ‘scope, even if you have set the aperture to F22.
I will be setting up my 10" LX200 at Yeronga AFL Club in Cansdale St, Yeronga, Brisbane, I should have the polar alignment done well beforehand, as I will be there at 6am. Anyone is welcome to come and have a look. I will probably have some pin hole devices as well as some of Mike's glasses for viewing.
It is my work site and I have my bosses permission, but please wear some sturdy shoes, thongs will not be allowed on site.
I will be setting up my 10" LX200 at Yeronga AFL Club in Cansdale St, Yeronga, Brisbane, I should have the polar alignment done well beforehand, as I will be there at 6am. Anyone is welcome to come and have a look. I will probably have some pin hole devices as well as some of Mike's glasses for viewing.
It is my work site and I have my bosses permission, but please wear some sturdy shoes, thongs will not be allowed on site.
Yep Dave, it is a work day after all.
Long time between posts for me, been busy for 3 years doing nothing until now. Now teaching the long term unemployed how to work again and doing flood recovery work at the same time.
I used Starry Night to help plan my transit images. These screen shots are the 'natural' views from Brisbane. I will have to invert and flip the images to match the eyepiece views. I hope we all get clear skies.
Just for information, the IPS (Ionospheric Prediction Service) of BoM will be providing a live broadcast using the Culgoora solar telescope.
The Culgoora Solar Observatory is located 25 km west of Narrabri, in north-west New South Wales. The observatory conducts continuous optical and radio observations of the sun every day of the year.
Observing instrumentation includes:
a 12 cm solar telescope fitted with an hydrogen-alpha filter, used to observe solar flares and other phenomena
a 30 cm heliostat, used to observe sunspot evolution
a solar radiospectrograph which sweeps through a frequency range of 18 - 1800 MHz every three seconds, used to monitor solar radio bursts
I dropped in at my kids High School yesterday to find out what they will be doing for the Transit and if they'd like me to set up my gear so the students can see this very rare astronomical event.
The Science teacher said they are doing nothing about the Transit, and no they don't need a telescope, thank you and good bye.
Soooo, it looks like I'll be free to do as I wish on the day. If it's clear I'll set up in the back yard.
If it's cloudy I'll put into place Plan B. ie. I'm going to pack the gear in the car and keep driving west until it's clear.
If anyone cares to join the convoy just drop me a PM.
How can teachers instil enthusiasm for science in the students, if they have none themselves.
It is disappointing to hear that a Science Teacher is not willing to embrace this as a chance to inspire the Students. As you said, you are free to chase the Sun if it is cloudy in your corner of the world.
Most keen amateur astronomers probably know this already, but for readers who are not familiar with the Baader AstroSolar ™ Photo Film (3.8) versus the Baader AstroSolar ™ Safety Film (5), the Baader website writes:
“AstroSolar™ PhotoFilm is not intended for visual observation. PhotoFilm is only for use with telescopes for high magnification photographic work. Do not use it for producing solar eclipse viewers, do not mount it onto DSLR camera lenses.”
The last sentence re: “…do not mount it onto DSLR camera lenses” is worth reiterating.
Cheers
Dennis
Good on you Dennis for posting that and worthy of bringing it to everyone's attention again.
I've just ordered my Baader solar film from Sirius Optics here in Brisbane. And now to work out what to do with it .
Not having done this before I'm as nervous as a bull at an abbertoir.
I'm planning on using the Canon DSLR camera (not on the dob) and my 10" dob and stopping down the aperture (and covering the hole with the solar film). I think.... Can't decide between that and my Stellarview 9x50 finder. . Hmmm much thinking to do.
Ron said he still has some available, so if anyone's interested this is what he has:
250 x 250mm sheets (visual) $49.00 (2 left in stock)
250 x 500mm sheets (visual) $69.00
250 x 250mm sheets (Imaging) $49.00
Jarrod: thanks so much for posting and putting up a pic of what it it'll look like through the camera, I've been wondering the same thing (never having done this before), so you've helped me greatly, thank you.
Time to start making sacrifices to the "gods of skies clear"...
.
