3Qs re Mercury Transit

[ronnierigel]

Hi folks

3Qs regarding the upcoming Mercury Transit.

1) I have just purchased the Baader solar film (a4) size. I have two scopes an 8 inch Maksutov-Cassegrain(f12) and 10 inch Shmidt Newtonian (f4).
Which scope should I use? (I don't have a focal reducer but have a barlow).

2) Tha Baader film is too small for the 10 inch---If I use this scope how should I create the aperture? One 3.5 inch aperture? (this fits between the corrector plate and rim). Two 3.5 inch apertures on opposite sides? or cut a square slightlty smaller than the Baader film and hence include the coorector plate?

3) for capturing the event should I use a toucam or canon dslr (350d) unmodded?

Thanks for any opinions.....I would experiment if I had the time!!

regards

ron

[Dennis]

Hi Ron

Here are some considerations rather than recommendations.

Q1 - Have you used these 2 'scopes on the Moon for imaging? The apparent size of the Moon is the same as the apparent size of the Sun. If you have imaged the Moon through these 'scopes, using both cameras, how did the images turn out? I suspect the 8" f12 and the ToUcam will give too much magnification for the conditions (daytime and low Sun).

The ToUcam is generally used in hi-res imaging so maybe use the DSLR?
I suspect the 8” F12 and DSLR will not give you a full Solar disc image for animations or a composite.

So, that leaves the 10” SN with the DSLR which should give you full Solar disc images.

Q2 – If you were to make an off-axis (front of ‘scope) solar filter for the 10”, I would make it so that it avoided the central obstruction.

Q3 - The ToUcam is generally used in hi-res imaging so maybe use the DSLR? The ToUcam comes into it’s own for stacking 100’s of frames to capture those fleeting moments of good seeing. It has a narrow FOV so will not capture the full solar disc. A highly magnified image of a small black dot against a bright background may look, well, boring? Unless, of course, you manage to capture the 3rd and 4th contact, or Mercury near a sun spot.

An image of the full solar disc with a series of dots showing the transit may be more pleasing?

Cheers

Dennis

[gbeal]

Good advice from Dennis. My initial thought was to make the filter fit the 8", (mainly cos it won't fit the 10") and from there make a stepping arrangement that allows this 8" filter on the front of the 10". I suspect though that the 10" will be better suited, mainly due to its shorter focal length. be nice to be able to mix and match on the day though, hence the multi fitting filter concept.