Canon 40D and a (Jewel) Box of chocolates!

[Dennis]

Hello,

The second outing with the canon 40D was marred by cloud bands constantly rolling in from the SE.

In between sets of clouds I managed to squeeze in a single 5 minute shot of the Jewel Box and a prime focus shot of the Moon.

I then turned to M42 again and tried to make sure my exposure time was equal to the clear patches between the sets, so the ICNR was performed during the cloudy spells. Nature wasn’t being very co-operative; the sets that rolled had differing wavelengths and frequencies so I couldn’t predict the clear patches accurately and therefore had to expose on the fly.

This restricted the exposures to between 60 secs and 180 secs so I couldn’t go as deep as I would have liked. Also, the camera orientation was altered to prevent a grub screw from fouling the penta prism, so I couldn’t re-use the previous evening’s data.

Here is M42 made up from 10x30 sec and 4x180 sec exposures.

Tak Mewlon 180 F12 at prime focus (2160mm).

Cheers

Dennis

[peter_4059 (Peter)]

Great terminator detail in the moon shot Dennis. I thought some different coloured stars might show up in the Jewel Box though?

[h0ughy (David)]

OK Dennis i will be picky (throwing stones in a glass house LOL), could you have gone a higher ISO or shorter stacked exposures for the jewelbox to retain the star colours? I love the details in the m42 shot! the moon is a top shot - those subtle hues of colours are contained within, wonderful shot with heaps of detail. Wished i could get something like that (green with envy!!)

[duncan]

Hi all,
Great shots Dennis.
The one of the Moon is a ripper! I can clearly see all the craters that i shot at 333X last night.
Cheers,
Duncan

[Dennis]

Thanks for the feedback guys – it is always welcome and appreciated.

My inspiration for the Jewel Box (NGC 4755) was the AAT photo in Hartung’s 2nd Edition in the colour plates starting at P 148 (Plate 18).

I was also a little surprised at the relative lack of colour; I’ll certainly be having another go when the weather permits. The AAT photo shows heaps of blue/white stars.

Cheers

Dennis

[jase (Jason)]

Hooley dooley! The jewel box is a treat, but wow, the moon... speechless! Its almost exactly how I remember it looked through the ol' C11 with a 22mm Nagler. Big WOW factor. Don't stop now Dennis... you're on a roll. Keep them coming, but don't forget the humble ST7. It might be getting a little lonely

[Garyh]

They are all Beauties Dennis, I just can`t decide which one I like better

cheers

[kljucd1 (Daniel)]

Hi,

What an amazing shot of the Moon, that is exactly the type of shot that I am aiming for.

Good one!!!

Daniel...

[edwardsdj (Doug)]

Great images Dennis

I particularly like the Moon image. Tack sharp and very detailed.

[skeltz (Rob)]

excellent moon shoot dennis,superb

[erick (Eric)]

Love Jewel Box and Moon, thanks.

[Dennis]

Thank you for your nice words. I have been quite surprised at how (relatively) flat the field of view is on such a large image sensor, 22.2mm x 14.8 mm according to the Canon manual.

The Tak Mewlon 180 F12 is a Dall-Kirkham design and it is written that this design of Cassegrain suffers from noticeable off-axis coma, with only a small central region of the FOV being corrected.

Although I have noticed comatic stars at the edge of the field of view, and softness at the edges on the full frame Moon image, it is not as bad as I had expected, although the Canon 40D is not a full frame sensor like the 5D and 35mm film cameras.

Cheers

Dennis