Clear skies Saturday night. Left home at 9.00pm, 1 hour drive north of Melbourne and I was imaging by 10.45pm. EQ5 RA motor not performing well, had to throw away many subs with periodic errors. Ended up with 10 x 30 sec subs for the Horsehead and only 5 x 30 sec subs for M42 which was shot through a Baader nebula filter.
Unguided prime focus of a 200mm f5 Newt with a modded Canon 550d @ 3200iso.
Thanks Marcus, I had taken more subs but the stars looked like worms so I deleted them. The motor gears may not be meshing correctly or they may have burrs or grit between the cogs. Eq5s aren't the best for astrophotography I've come to realise. I can only manage 30 second subs with the RA motor attached. I would like to buy a Heq5 or Eq6 with auto guiding one day.
At a 1000mm f/l a consistent 30 seconds is not bad, and even then some
subs will be unusable due to periodic error. The majority of high volume
production mounts will not do much better, including HEQ5s, NEQ6s etc.
Of course, the greater the declination of your target, the longer your exposures can be. At Dec 60 I got 95% usable subs @ 30secs, around
60% usable @ 60 secs, and 40% usable @ 90 secs, around 25% @ 120 secs,
and the odd usable one @ 150 secs.
raymo
Thanks Andrew, they're a bit noisy, more subs would have helped.
Also, in case you didn't use it, the "In Camera Noise Reduction" feature will help.
Even though it will double your overall exposure times it will help greatly until you start taking darks manually.
Mirror Lockup also helps with shutter slap, I use it when astro imaging.
Flats are also a big help.
These did have Dark's and flats applied. Interesting about the mirror lock up. I would not have thought the short mirror/shutter slap would make much of a difference being so quick and gentle. I'll have to try that and compare it to one without. The shape of the stars on the subs I discarded didn't look like it was caused by vibration but I'll try the mirror lock up function and see what difference it makes. Thanks Andrew.
These did have Dark's and flats applied. Interesting about the mirror lock up. I would not have thought the short mirror/shutter slap would make much of a difference being so quick and gentle. I'll have to try that and compare it to one without. The shape of the stars on the subs I discarded didn't look like it was caused by vibration but I'll try the mirror lock up function and see what difference it makes. Thanks Andrew.
Good to hear that you applied Darks and Flats, well done.
With Mirror Lock up, you may not notice the effects of Mirror Slap in some situations but it is a good idea to use it anyway.
Not that that was the cause of the ones you discarded per se' but it's always a good idea to use it, I always do because you'd be surprised at the amount of vibration that's going on in the camera from 'Mirror Slap'.
Also it's a good idea to leave the camera idol for a minute or two after taking a few long exposures because this allows the sensor to cool down thus reducing noise.
Also along that same vein, try not to use or leave the screen on too long as well, this too will reduce heat buildup inside the camera.
These are just little things you can do to help reduce noise and blur in your astro imaging, every little bit helps.
RB
Mirror Lock Up for Sharper Long Exposure Photographs:
Clear skies Saturday night. Left home at 9.00pm, 1 hour drive north of Melbourne and I was imaging by 10.45pm. EQ5 RA motor not performing well, had to throw away many subs with periodic errors. Ended up with 10 x 30 sec subs for the Horsehead and only 5 x 30 sec subs for M42 which was shot through a Baader nebula filter.
Unguided prime focus of a 200mm f5 Newt with a modded Canon 550d @ 3200iso.
Wow, 5 x 30 seconds for M42. Looks really good.
I hope you don't mind a question. With the modded camera what are you doing for white balance when taking these pics?
Thanks Mick. Auto white balance (AWB) shooting in Raw. A dark sky really helps, of course but processing the Raw files in DSS, rather than converting to Tif or Jpg first also gives a less noisey result. I'm finding that processing Raw files show less noise but at the expense of less colour. The image I posted here was converted toTif first then processed in DSS. It seems to be able to extract more colour than if I use the Raw CR2 camera file but I have to fix the noise in PS. I guess it depends on what you are targeting.
Thanks Mick. Auto white balance (AWB) shooting in Raw. A dark sky really helps, of course but processing the Raw files in DSS, rather than converting to Tif or Jpg first also gives a less noisey result. I'm finding that processing Raw files show less noise but at the expense of less colour. The image I posted here was converted toTif first then processed in DSS. It seems to be able to extract more colour than if I use the Raw CR2 camera file but I have to fix the noise in PS. I guess it depends on what you are targeting.
.
Thanks Michael. Good to know as there seems to be varying opinions about what to do with white balance in the modded camera. Can't argue with your results so I'll give it a go.
Keep in mind Mick that in DSS I always align the RGB channels if the opening histogram shows a tendency to place primaries at different points on the X axis. Once I do that I then go on to play with luminance and saturation levels. An alternative is to check the 'auto white balance' box in the 'opening Raw files' settings. That way, the RGB channels in the Autosave Tif file created, should be automatically aligned.
Keep in mind Mick that in DSS I always align the RGB channels if the opening histogram shows a tendency to place primaries at different points on the X axis. Once I do that I then go on to play with luminance and saturation levels. An alternative is to check the 'auto white balance' box in the 'opening Raw files' settings. That way, the RGB channels in the Autosave Tif file created, should be automatically aligned.
Thanks, I will keep that in mind. Looks like this weekend is going to be cloudy so I may be waiting for a while to have a go. Tonight looks great but I've been late home from work every night this week, so if I went home early tonight and got the scope out I may get killed
