LMC - Canon 100mm macro tripod mounted

[tah997 (Tim)]

Another canon 100mm macro tripod mount, this time LMC, 145x10sec.

Amazing how much larger the LMC when digitally imaged compared to what you see with your eyes.

Tim

[orestis]

Awesome shot Tim, lovely detail.

One thing tho, definately not an expert but your stars look a tiny bit egg shaped maybe you should take 8 sec shots to try and stop trailing.

Is this the canon 100mm macro ef ?

I need to get myself one. You are producing amazing images.

Try it out on the orion nebula.

Orestis

[Larryp (Laurie)]

Very nice, Tim!

[Irish stargazer (John)]

Nice shot tim. The 100mm lens frames the LMC very well

[rcheshire (Rowland)]

Very well done.

[bato (Luke)]

Nice pic Tim. I cant get over how much detail you can get out of a 10sec exposure.

What method did you use for focusing? I have this lens and have always wanted to try it out but have had dificulty with focusing in the past.

Thanks very much.

Luke

[naskies (Dave)]

Nice work. Has this wet your appetite for a tracking mount? Or perhaps you could build a barn door style mount?

[tah997 (Tim)]

Hey folks,

Sorry for the slow reply.

Yeah 10sec was probably a little too long.

Focus is a little tricky to get setup. I start off finding a nearby bright star and focus manually through the viewfinder (remember to switch to manual focus), then I switch to live-view (I have already turned the LCD brightness right down). I then zoom in to 5x and move the zoomed in area to where I remembered the brightest star to be. Sometimes it takes a few attempts with refocussing manually because the focus will be slightly off and the star cannot be seen at 5x zoom. When I have found the bright reference focussing star, I zoom into to 10x and then ever so slightly adjust the focus. You have to be very delicate, once you have found focus, then I just turn live view off and start snapping away.

I use a remote timer, the 2sec internal timer and mirror lockup to prevent camera shake. A sturdy tripod with the camera as low as possible to the ground is recommended.

As for a tracking mount, yes I would like a tracking mount one day, currently I can't justify one: expensive, and where I live at the moment, I am close to ocean spray and light pollution from Sydney and the Port Kembla Steelworks so I wouldn;t be able to use often. I am fiddling around with a barn door mount atm. Currently I am pretty happy with the results I am getting using the 100mm macro and lots of short exposures. I have some other recent shots I have taken, one of the Sculptor Galaxy that I was amazed my 100mm macro was able to pick up, it's definitely no world beater but pleasing considering the setup.

I'll keep you posted with the results.

[Poita (Peter)]

What f-stop are you using?

[mithrandir (Andrew)]

Originally Posted by tah997

Yeah 10sec was probably a little too long.

Tim, there is the "Rule of 600". This says you should divide 600 by the focal length of your lens to get the maximum exposure time before stars start to trail. If you do not have a full frame camera you need to apply the crop factor to the focal length.

So on a full frame like the Canon 5D MkII, 600/100 would give you 6 seconds. A 550d with its 36/22.3=1.6 crop would give 600/(100*1.6) or 3.7 seconds which you could round off to 4.

The numbers are affected by the pixel size, but this is a reasonable approximation.

[tah997 (Tim)]

Hey mithrandir,

Yeah I use the "600 Rule", sometimes even "500 Rule", however, my understanding is that is for worst case scenario with the object being on the equator, however, LMC is close to the SCP, so I assumed that I could increase the exposure time. I settled on 10sec as it produced good images on the camera LCD.

Next time, I'll slow it down a fraction.

Your explanation of the "600 Rule" is a good reference to others.

As for f-stop, I use it fully wide open at f2.8, I have tried f3.2, but not enough to know if there is a noticeable increase in sharpness for the decrease in light.

Tim