Imaging setup for transit of Mercury 9th May

[megauravk]

Hello,

Please help me to capture maximum of upcoming event Mercury transit over
Sun on 9th May.

I have following setup with me to image this event:

Scope: Celestron 130 SLT
CCD: Imaging Source DFK21AU04
DSLR: Canon 600D
Filter: Baader 5"x5" ND5 Solar Film
Barlows: 2x, Televue Powermate 5x

Should I use DSLR or CCD mentioned above, what should be the
format/settings to image on both setup? Should I use barlow/powermate to
get Mercury's significant size shadow on Sun? My scope has 2" hole on cap
for this filter, will this be enough get lights to image? 

This is my first attempt to image sun so not much idea about this. As per
my location I would have max 45 minutes window to image. 
Any help will be greatly appreciated. 

Thanks,
 

[DRT]

I am not an imager but would suggest that you spend the next week trying the various options that you have to find out what suits your set-up best. There are lots of little sun spots on the disk at the moment that you can use to test your equipment and ability to achieve sharp focus.

...and Mercury will not cast a shadow on the Sun

 

[megauravk]

13 minutes ago, DRT said:

I am not an imager but would suggest that you spend the next week trying the various options that you have to find out what suits your set-up best. There are lots of little sun spots on the disk at the moment that you can use to test your equipment and ability to achieve sharp focus.

...and Mercury will not cast a shadow on the Sun

 

Hey, Thanks for Reply,

I will get my Sun filter in two days and then I will try to check its capability meanwhile I am trying to get more and more information on this.

And yes, I know mercury will not cast a shadow on Sun but it will look as a shadow dot on Sun disk and obviously no details with transit path only  

Thanks,

[Louis D]

Mercury looks like a small black hole cut into the sun.  Venus by comparison looked rather large and had a fuzzy edge due to its significant atmosphere.

I've only used an ancient Olympus C-4000 afocally coupled to an eyepiece to take solar images.  It worked pretty well.  I might try direct imaging using a barlow or coma corrector Monday with one of my DSLRs.

[michael8554]

Whatever setup you decide on, consider setting up the night before so you can focus on a star - very hard to get good focus on the sun's disc.

Michael

[Louis D]

16 hours ago, michael8554 said:

Whatever setup you decide on, consider setting up the night before so you can focus on a star - very hard to get good focus on the sun's disc.

Michael

Interesting.  I've never had any issues getting focus with afocal projection.  I first focus the eyepiece sharply on the sun while wearing eyeglasses to ensure best infinity focus.  I then lock the focuser and attach the camera to the eyepiece's M42 thread.  Next, I move the edge of the sun to center of the frame and let the camera achieve sharp autofocus on the high contrast edge, and then I turn off autofocus.  I can always touch up focus with the scope's focuser after that using the camera's live-view image, but it's usually not necessary.

[michael8554]

Autofocus? - that's not fair !  :->

There are many Prime Focus imagers who won't be able to use electronic aids to get best focus on the shimmering edge of the sun, it'll be eyeballs only, which is hit-and-miss even on a star.

Michael

[Louis D]

I guess then that there are some advantages to afocal projection for the sometimes astrophotographer over prime focus photography.  Best of luck to everyone photographing the transit on Monday.  I'm just hoping for clear weather right now.

[wellsi]

On 05/05/2016 at 15:35, Louis D said:

I guess then that there are some advantages to afocal projection for the sometimes astrophotographer over prime focus photography.  Best of luck to everyone photographing the transit on Monday.  I'm just hoping for clear weather right now.

As a newb to astro-imaging, can you explain what afocal projection is?  We have been trying to get decent focus attaching the Canon 6D to our Evolution 8; there are no lenses on the camera body of course, the body attaches directly to the T-ring adapter and so the only way we've been able to focus is via the scope's focussing, using live view. Which generally brings fuzzy useless results......

Ian

 

[DRT]

Ian,

Have you been using the zoom feature on Live View? If not, set it to the lowest zoom setting (i.e. zoomed out), put the target in the centre of the screen and then zoom in as far as your camera will allow. You can then adjust the focus to get a sharper image. It takes some getting used to as the image moves across the FOV quickly if you don't have a tracking mount.

I've managed to get some decent single shots of the Sun and Moon using that method without any tracking

[michael8554]

Ian

Not sure if your problems are only with focusing on the sun, or on stars as well.

As I said previously, in my opinion it's very hard to judge best focus on a sunspot, or the edge of the sun, as the seeing is varying so rapidly (maybe visually judged best focus is good enough, since you can reject the out of focus frames when they're stacked - what do you think folks?)

So I'm going to set up on a star on Sunday night. There's every chance that on Monday, when the scope has warmed up, or the SCT mirror has flopped at bit, the focus will be out, so I will have to adjust on the current sunspot after all.

As for stars, fit a Bahtinov Mask (plus "Bahtinov Grabber" software if you're tethered to a PC) and set LiveView at maximum zoom (adjust exposure with the ISO setting), this will give you pretty good focus.

Michael

[Louis D]

Afocal projection is using an eyepiece to project an image into a camera's normal taking lens.  To make it work effectively, you need the exit and entrance pupils of each to match well.  This usually means the eyepiece needs to have a large eye lens allowing long eye relief and wide field of view.  The Pentax XW and Baader Hyperion eyepieces both work well because of this, and because they have an M42 thread on top to solidly attach a camera lens to.  To make this work well, your camera lens's front element should be no bigger than the eyepiece's eye lens or you'll get massive vignetting.  This pretty much excludes using DSLRs which have lenses with relatively huge front lenses.  I use an old Olympus C4000.  It couples perfectly at it's widest setting with 65 to 70 degree eyepieces with at least 18mm of eye relief.

Some people have good luck mating cell phone cameras with eyepieces because the lens on the camera is so small.  You have to experiment to find out what works well together and what doesn't.

[wellsi]

Thanks gents

We've been using a full sensor camera (Canon 6D) and whilst we were using liveview, we hadn't tried zooming all the way in.  We've only been trying on our Moon and Jupiter so far...  With pretty poor results.  Moon was fine as we could focus on the terminator.  But Jupiter was just a blurred mess......

I think we may try Afocal projection; I hadn't heard that term for it.  We had been fixing the 6D to the scope with the T-Ring.  I did try my cellphone against the scope's eyepiece the other night and I did get a reasonable shot of Jupiter, but we want to stack layer shots so a T-ring is the only way to go for that....

 

All good fun...

 

[Louis D]

You could try something along the lines of the Televue Fonemate to attach your cellphone to an eyepiece.  You could then set it up in an intervalometer mode (perhaps with an app if not natively supported?) to take a series of stills to stack.

[wellsi]

3 hours ago, Louis D said:

You could try something along the lines of the Televue Fonemate to attach your cellphone to an eyepiece.  You could then set it up in an intervalometer mode (perhaps with an app if not natively supported?) to take a series of stills to stack.

They have something for everything!    Thanks for that

 

Ian