"Decisions.....But how much do you love your Canon 6D 
?"
That's not a fair question. I'm biased. I love it, of course. The 6D more than meets my enthusiastic amateur needs. What I like most about it is the DETAIL that I get from the full-frame sensor. The number of megapixels from an image sensor is not as signficant as the amount of light per pixel that the sensor can collect! I think the images from a 10 megapixel full-frame sensor are at least the equal of a 20 megapixel APS-C sensor, if not more so.
In low light situations, the only special knowledge you need is common sense and good instincts, also known as experience, IMHO. I have the "new nifty fifty", Canon EF 50mm f/1.8 STM, lens and have captured dozens and dozens of beautiful shots with it. I have not used that lens at night, or in low light, in the field. I have done lots of test shots, both with and without a tripod under low light conditions, and have settled on the fact that A TRIPOD IS A MUST in low light conditions. A tripod will give you at least one f/stop in low light, depending how much light we're talking about.
Taking pictures of lit candles is one of the more challenging shots to take. Taking pictures of lit candles that are not stationary will test the capability of any camera/lens combination out there. Under those conditions, really great shots will be produced in post processing, but you still need to begin with a good starting point.
"You cannot age bad wine, and expect to turn into good wine."
For capturing low light shots without a flash, you might want to consider purchasing a wide aperture prime lens, such as the 50mm f/1.2L, or the EF 35mm f/1.4L II USM lens. I have never used either lens, so do not think I am speaking from experience.
@Weetbix wrote:just get a 6d and throw the 50mm on it and zoom with your feet 😛
if you do get a 6d you should also consider pairing it with the Tamron SP 24-70mm 2.8 Di VC usd, for some odd reason canon doesnt have a 24-70mm 2.8L lens with image stabilization
the 18-135mm stm is garbage and the sigma is a bit hard to sell off when your done due to its bulk and people not wanting to be stuck with a efs mount lens
as for the the 24-105 f4L (IS) starts off sharp but drops in resolution at the other end and at f5.6 to f8 you would have trouble trying to spot the difference between this and the kit lens on 40d
Wow, you're pretty hard on the 24-105L. The only real knock against it is that it is not state of the art. I wouldn't expect a 40D to realize much of the potential of the lens. But, on a 6D it looks pretty darn good.
That shot was taken with a 6D at 24mm, f/8, 1/160, ISO-100. from a slowly moving and rocking boat.
@Waddizzle wrote:
@Weetbix wrote:
.....
as for the the 24-105 f4L (IS) starts off sharp but drops in resolution at the other end and at f5.6 to f8 you would have trouble trying to spot the difference between this and the kit lens on 40d
Wow, you're pretty hard on the 24-105L. The only real knock against it is that it is not state of the art. I wouldn't expect a 40D to realize much of the potential of the lens. But, on a 6D it looks pretty darn good.
That shot was taken with a 6D at 24mm, f/8, 1/160, ISO-100. from a slowly moving and rocking boat.
I think the 24-105 f/4L IS on a 6D can produce some pretty sharp photos. Can you see something orange in the top left window?
It is one of the lighthouse museum's curators, the boss. She oversaw the multi-year restoration project. There are about 12 more people/hosts in orange shirts hiding out on the inside, just so that folks can take clean pictures.
"just get a 6d and throw the 50mm on it and zoom with your feet 
if you do get a 6d you should also consider pairing it with the Tamron SP 24-70mm 2.8 Di VC usd, for some odd reason canon doesnt have a 24-70mm 2.8L lens with image stabilization
the 18-135mm stm is garbage and the sigma is a bit hard to sell off when your done due to its bulk and people not wanting to be stuck with a efs mount lens
as for the the 24-105 f4L (IS) starts off sharp but drops in resolution at the other end and at f5.6 to f8 you would have trouble trying to spot the difference between this and the kit lens on 40d"
Just curious, are you a user or just a reader? Never waste a bad review.
@ebiggs1 wrote:"just get a 6d and throw the 50mm on it and zoom with your feet
if you do get a 6d you should also consider pairing it with the Tamron SP 24-70mm 2.8 Di VC usd, for some odd reason canon doesnt have a 24-70mm 2.8L lens with image stabilization
the 18-135mm stm is garbage and the sigma is a bit hard to sell off when your done due to its bulk and people not wanting to be stuck with a efs mount lens
as for the the 24-105 f4L (IS) starts off sharp but drops in resolution at the other end and at f5.6 to f8 you would have trouble trying to spot the difference between this and the kit lens on 40d"
Just curious, are you a user or just a reader? Never waste a bad review.
a user, I used to have ef 24-105 f/4 usm L (IS) sold it cause i wasnt using it after aquiring the tamron 24-70 f2.8 SP Di VC, and I'm not that hard on the lens, i was refering to its the performace on the 40d and to be honest i find the kit lens 18-55mm f3.5-5.6 (IS) & 55-250mm (IS) f4-5.6 to be adequate on all aps-c bodies (even more so now newer bodies correct for chromatic abberations and peripheral fall off) I'm still shooting with the made in taiwan 1100d which only has the peripheral fall off correction
"just get a 6d and throw the 50mm on it and zoom with your feet "
But you recommended a 6D and a 50mm? If you never used a 6D how could you recommend it to someone else? Or, how the Canon EF 24-105mm f/4L IS USM Lens will work on it?
That is what I was wondering?
I share you thoughts on the Tamron SP 24-70mm f/2.8 DI VC USD Lens for Canon. It is a wonderful lens which I can highly recommend from personal experience with it. My personal rating puts it in 2nd place to the Canon EF 24-70mm f/2.8L II USM Lens. Maybe a distant second but 2nd never-the-less.
@ebiggs1 wrote:"just get a 6d and throw the 50mm on it and zoom with your feet
But you recommended a 6D and a 50mm? If you never used a 6D how could you recommend it to someone else? Or, how the Canon EF 24-105mm f/4L IS USM Lens will work on it?
That is what I was wondering?
I share you thoughts on the Tamron SP 24-70mm f/2.8 DI VC USD Lens for Canon. It is a wonderful lens which I can highly recommend from personal experience with it. My personal rating puts it in 2nd place to the Canon EF 24-70mm f/2.8L II USM Lens. Maybe a distant second but 2nd never-the-less.
I admit I've never used a 6d, but i have used/hired the 1Ds mark2 (about 45 hours) and the 5d mark2 (3 weeks), but if i were to go out tomorrow and buy a fullframe camera it will be the 6d because i dont shoot for a living
