I know there is another thread about the eclipse. But I am wondering what would be an ideal setup for imaging it.
I presume a high quality DSLR is the ideal setup with maybe 300mm focal length? Perhaps a bit longer?
Or a lightweight APO around 500-600mm focal length.
I guess its all about FOV. I found my TEC110 was a handy focal length with a full frame camera or even APS camera for the sun during the Venus tranist.
But then the question is do you use some sort of solar Ha filter or simply the Baader solar film (images though are very plain with that white look) or do you simply shoot with fast shutter speed, leave it all on auto so it compensates for the changing light conditions and take lots of shots.
Or do you use a neutral density filter to pull down the brightness so the camera can handle it without blowing out the highlights which I imagine is going to be the issue. There are also circular variable ND filters (basically a pair of circular polarising filters) that you can spin and increase/decrease the amount of filtering easily. With the camera set to auto that may be very flexible.
I'll experiment with one of those with my DSLRs and post the results. I am sure there will be some interest in that.
So a lightweight tracking unit like a Vixen Polarie could be very handy just to keep the sun in the frame as I found getting the sun stable in the frame manually was hard with my TEC110 during the Venus transit.
I was thinking of a time lapse as well at the same time.
Suggestions?
Greg.
Last edited by gregbradley; 14-09-2012 at 08:31 AM.
Greg I was going to use a polarie for 1 camera, just tripod fr other;
1. Trying o mod my PST, have. Borg helical focuser, repve the guts of the PST & insert helical, then ep holder to 1.25" t adapter -this setup for before during & after
2. Have a Borg 45ed, f/l about 320mm, just to fire shots of totality (pro without solar filter
3. Not sure yet whether bother to do any w/f
LXD75 (2 axis motor drive), loaded with 1000mm+400D for chromosphere & prominences, 300mm+60D for outer corona and chromosphere spectrum (if I have enough time...).
Control of 2 cameras from single lap is a problem I haven't solved yet...
The setup on attached picture is put together just as a part of feasibility study.. it will be much more stable and rigid at the end (I hope..)
LXD75 (2 axis motor drive), loaded with 1000mm+400D for chromosphere & prominences, 300mm+60D for outer corona and chromosphere spectrum (if I have enough time...).
Control of 2 cameras from single lap is a problem I haven't solved yet...
The setup on attached picture is put together just as feasibility study.. it will be much more stable and rigid at the end (I hope..)
Impressive setup. Is that transportable though?
Is 1000mm too long or just right? With APS C that is more like 1600mm and that would be quite a magnified view. Perhaps its just right - I am not sure. I used 600mm with the Venus transit and full frame camera and the sun could have been a bit larger. So perhaps an APS sized camera and 600mm would be a nice size. I'll have to test that.
Quote:
Originally Posted by dannat
Greg I was going to use a polarie for 1 camera, just tripod fr other;
1. Trying o mod my PST, have. Borg helical focuser, repve the guts of the PST & insert helical, then ep holder to 1.25" t adapter -this setup for before during & after
2. Have a Borg 45ed, f/l about 320mm, just to fire shots of totality (pro without solar filter
3. Not sure yet whether bother to do any w/f
I suppose the key thing here is to practice with it well in advance and iron out any bugs.
Is 320mm a bit short? It might be fine with an APS sized sensor.
Is 1000mm too long or just right? With APS C that is more like 1600mm and that would be quite a magnified view..
Greg, 1000mm is 1000mm.. with APS or not..
It should be OK for chromosphere and prominences, as well as for lower corona, as the whole sun will be in the frame, see attached.
For extended corona, I have 300mm (with 60D, also APS size sensor).
Planned control software is Eclipse Orchestrator + DSLR Sutter on the same laptop (to be tested yet)
Transportability-wise, it is 12kg in total.. packed in 3 small suitcases (cabin luggage), tripod is 3kg and will be check-in..
Greg, I don't know of a Ha filter option for a DSLR and standard lens, you would need to shoot through a PST or Lunt scope (i.e. something with an etalon) to get a Ha image.
If you have the $$ a Lunt60 is a great and tiny scope for Ha viewing and imaging, and you can get away with a tiny mount like the iOptron cube.
I'm thinking of something like this. ED is 700mm & the little Mak is 800mm. Still have to see whether I can get the optical axes parallel which is the next challenge.
True, I was referring to the crop factor which is like a digital zoom so the object will fill more of the frame with an APS versus a full frame sensor.
It should be OK for chromosphere and prominences, as well as for lower corona, as the whole sun will be in the frame, see attached.
For extended corona, I have 300mm (with 60D, also APS size sensor).
Planned control software is Eclipse Orchestrator + DSLR Sutter on the same laptop (to be tested yet)
Transportability-wise, it is 12kg in total.. packed in 3 small suitcases (cabin luggage), tripod is 3kg and will be check-in..
That looks good. The only thing for me is these Baader solar shots aren't that attractive in that they are kind of mostly whitish. I've used them a few times. But I suppose the Ha filters are very expensive.
1000mm on an APS-C gives a FOV 78x52 arcsec for a Canon and a couple of arcsec more on other brands.
1000mm on an a full frame like a 1Dx gives a FOV 127x85 arcsec. 2000mm would give you a sun that almost filled the frame.
I used a Sony a200 (APS-C) on an ED127 for a FOV of 85x57 to shoot the TOV.
Quote:
Originally Posted by gregbradley
That looks good. The only thing for me is these Baader solar shots aren't that attractive in that they are kind of mostly whitish. I've used them a few times. But I suppose the Ha filters are very expensive.
Yes Baader film gives a grey/white image. I have one for my C8. I also have a couple of Thousand Oaks glass filters for my ED127 and ST80 which give a yellow image.
Location: '34 South' Young Hilltops LGA, Australia
Posts: 1,462
Loose ends
Just to pick up on some bits and pieces discussed in this thread:
Variable ND filters
Variable ND filters made from crossed polarizers are not visually safe (I think they pass too much IR) and probably won't give sufficient ND for solar photography. They only go down to a few % transmission. A solar filter is 0.01% to 0.001%. I am assuming you were talking about using them for the partial phases.
If you were thinking of using them for totality, I recommend against this. It's unnecessarily complicating things AND the corona is polarized so as you rotate the filters, different streamers will come into view. you will have a very hard time trying to stack and radially merge these images to make a composite or HDR image.
Using Auto exposure
Works really well for wide field exposures - wider than 28mm where you are trying to capture sky and landscape. It does not work for close ups of the eclipse and corona. At ISO100 & at f8 the inner corona needs about 1/4000. Then just keep increasing the exposure to about 4s to capture out to about 8 solar radii. Note that sky conditions may be brighter than the brightness of the corona at 8 Rs.
Colour of Sun with Baader film
Pictures taken with Baader film can be easily recoloured to any colour.
Filter types
Glass filters are not much good for eclipse photography because you have to refocus for totality after removing them. The Baader film is so thin that the focus remains unchanged. When removed 10-15s before you really don't want to be mucking around with focus.
Baader 48mm filter?
I think you're referring to the Baader solar continuum filter which gives a green image. It must be used with a full ND filter 4 or above and would be difficult to remove before totality, unless you have it on a separate optical system that you won't use during totality. It gives better definition for solar surface detail.
Ideal focal length or field of view
There isn't one. There are reasons for using short, medium and long focal lengths. In my reading of the posts, some writers seem to be thinking about this in terms of photographing the 30 arc minute disc of the Moon. You are not. The corona extends out to to 20 or more degrees diameter. Look at the C3 coronagraph images. I saw 7 degrees of corona visually when at high altitude in November 1994. It has been captured photographically during an eclipse out to about 13 degrees. You need to decide what of the many phenomena you are trying to capture and then decide on the best image scale to capture it.
Mithrandir wrote "2000mm would give you a sun that almost filled the frame." This is true but only if you center the sun in the field. You don't have to. If you are trying to capture inner corona in great detail, you can offset the sun to the edge of field and pick up nearly 1 - 2 solar radii of inner corona.
Conclusion
Whatever you do, don't leave yourself anything to do apart from removing a solar filter during the last 30s before totality. There is so much going on around you, it's not the time to be staring into a camera. Keep it nice and simple.
Great post Joe. Thanks for posting your invaluable experience.
My Nikon D800 has ISO 50 so that may be useful as well. Also it has auto ISO which if coupled with aperture priority mode could work.
If you want to capture those streaming corona then up to 15 radii of the sun would give a calculation for the ideal focal length for that type of shot.
Peter Ward had a nice shot of this from the Libya eclipse. I wonder what focal length lens he used there.
Location: '34 South' Young Hilltops LGA, Australia
Posts: 1,462
Quote:
If you want to capture those streaming corona then up to 15 radii of the sun would give a calculation for the ideal focal length for that type of shot.
Yes sort of 1 solar radius (Rs) is 1/4 degree
15 radii from the limb is 16 from the center and if we assume a symmetrical corona is 32 side to side or 8 degrees. Solar max corona are typically more compact though more symmetrical than a solar min corona which typically has big streamers coming from the equatorial region and little "polar brushes" north and south.
So that's a 100mm lens on APS and a 150mm lens on full frame if I use the short dimension of the sensor.
I don't want to mislead you. Capturing that extent of corona is by no means easy. Druckmullers 2006 image is a composite made from about 230 images taken with 5 lenses 200mm, 400mm, 600mm, 1240mm to 1640mm (GSO RC8) on canon 5D bods.
You can get an idea of the extent and shape of the corona by looking at the LASCO C3 image. But you can't translate where the corona's luminosity will get lost in the sky glow during an eclipse. I think I've seen Peter's shot from 2006. I was referring to one by Miloslav Druckmuller also taken during tse 2006. The Sun was very high in the sky that day. The solar min eclipse was assymetrical so he put the long streamers diagonally. http://www.zam.fme.vutbr.cz/~druck/eclipse/Ecl2006l/Tse2006l_39r3_102s_26d33_231n_v1/00-info.htm
Looking at this image again, I think he is measuring the diameter in radii which would double those focal length calcs ie 200mm for APS-C and 300mm for full frame.
One other thing I could have mentioned in my last post. If you are using a camera lens, then auto focus can sometimes work very well providing the camera AF zones lock onto the lunar limb. But I've also seen out of focus images and/or cameras run by computer where the AF couldn't lock and therefore wouldn't fire the shutter. Owner came back at end of eclipse to find no images.
I checked out your astrophotography site today - fantastic work!
Joe
Last edited by OzEclipse; 16-09-2012 at 11:01 PM.
Reason: adding links & paragraph
This is my third total and being on mainland Australia I have chose the following options.
I am using my CGE mount for stability. Setup will be around 3 am in the morning to beat out the crowds from our location. Perhaps earlier.
I am using my TSA refractor for white light imaging with my D3 Nikon. Viewing the phases and imaging those with a Lunt wedge. At totality or very near to it I will change this out to image the corona.
For Ha I am using (I hope) my new Lunt LSHa80 with Point Grey Research 2.8mp camera and lap top. I am still working up some ideas about how to sustain power on the beach for the duration of the eclipse.
All piggy backed. It is an imaging challenge, not for everyone but something I want to do.
Great post Joe. Thanks for posting your invaluable experience.
My Nikon D800 has ISO 50 so that may be useful as well. Also it has auto ISO which if coupled with aperture priority mode could work.
If you want to capture those streaming corona then up to 15 radii of the sun would give a calculation for the ideal focal length for that type of shot.
Peter Ward had a nice shot of this from the Libya eclipse. I wonder what focal length lens he used there.
Greg.
I used a William Optics 80mm APO and Pentax *istD. WO have a new GT81 which has even better optics...but make sure you get a modded version as early production runs had woeful internal tube reflections which killed contrast.
As I posted elsewhere, I'll be running a Canon 5dMkIII and 500mm L series F4 on a Starlapse this year....which should deliver way less noise, and much better resolution than the non-tracking system I used in 2006.
15 Solar radii would be tough...Miloslav Druckmuller uses unique software
(he wrote it) with highly calibrated flats etc. to get simply amazing dynamic range that I have yet to see replicated.
Peter - have you heard of any success with teleconverters?? I have a 2x converter that I was thinking of using with my Nikon 70-200 F2.8.
I'm wondering if internal reflections might be a problem.
DT
Could you try it.. (on new Moon.. overexposing) and let us know.
But I think the bigger problem will be their own distortions (mainly cushion, coma and CA) they are always adding to existent lens.
