|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
ASTRO: breaking up an exposure into subexposures: how to get the same s/n ?
here's something I threw together today to look into how much I am
complicating my life by using more and shorter exposures instead of fewer and longer exposures |
#2
|
|||
|
|||
ASTRO: breaking up an exposure into subexposures: how to get the same s/n ?
"Richard Crisp" wrote .... here's something I threw together today to look into how much I am complicating my life by using more and shorter exposures instead of fewer and longer exposures Richard, I'll take a look. Thanks for posting. Your tech stuff is always helpful. I find that short exposures work best for me because of factors that can mess up exposures - stuff like wind gusts, astronomers with big feet, visitors hitting the counter-weight, short periods of bad seeing, passing clouds, etc. If I take fifteen one minute exposures I sometimes lose one to three from one of these problems. The loss from read noise is a small price to pay to insure that an hour of imaging is not lost to a wind gust or someone walking into the dome and hitting the scope. Also, with the 1301E, if I go too much longer than 60 seconds with an exposure, some of the stars start over-exposing - even in red or green. George N |
#3
|
|||
|
|||
ASTRO: breaking up an exposure into subexposures: how to get the same s/n ?
those are all factors
indeed! "George Normandin" wrote in message ... "Richard Crisp" wrote ... here's something I threw together today to look into how much I am complicating my life by using more and shorter exposures instead of fewer and longer exposures Richard, I'll take a look. Thanks for posting. Your tech stuff is always helpful. I find that short exposures work best for me because of factors that can mess up exposures - stuff like wind gusts, astronomers with big feet, visitors hitting the counter-weight, short periods of bad seeing, passing clouds, etc. If I take fifteen one minute exposures I sometimes lose one to three from one of these problems. The loss from read noise is a small price to pay to insure that an hour of imaging is not lost to a wind gust or someone walking into the dome and hitting the scope. Also, with the 1301E, if I go too much longer than 60 seconds with an exposure, some of the stars start over-exposing - even in red or green. George N |
#4
|
|||
|
|||
ASTRO: breaking up an exposure into subexposures: how to getthe same s/n ?
George Normandin wrote: "Richard Crisp" wrote ... here's something I threw together today to look into how much I am complicating my life by using more and shorter exposures instead of fewer and longer exposures Richard, I'll take a look. Thanks for posting. Your tech stuff is always helpful. I find that short exposures work best for me because of factors that can mess up exposures - stuff like wind gusts, astronomers with big feet, visitors hitting the counter-weight, short periods of bad seeing, passing clouds, etc. If I take fifteen one minute exposures I sometimes lose one to three from one of these problems. The loss from read noise is a small price to pay to insure that an hour of imaging is not lost to a wind gust or someone walking into the dome and hitting the scope. Also, with the 1301E, if I go too much longer than 60 seconds with an exposure, some of the stars start over-exposing - even in red or green. George N At Hyde we had to go to all fork mounts. We had a GEM with an 8" scope at first. But after hearing many streams for profanity from guys who caught the crotch high counter-weights a few times -- even a couple volunteers who should have known better got nailed by them -- we went to a fork mounted 12.5" scope. I was sorry to see that old 50's era Cave go as it had fantastic optics! Right after I put in the Paramount here with the 6" f/4 I ran into the shaft one night when doing a T-point map run. I didn't have any CCD so a friend was at the eyepiece while I was running the computer. While the friend was centering the star on the cross hairs I walked into the chest high shaft without its rubber protector on. Broke cartilage joining ribs to breast bone knocking me to the floor. But the star just jumped a couple seconds of arc then went right back to dead on the cross hairs. That's when I knew the mount was solid. But it was two weeks before I could take anything but very shallow breaths! Now I run from inside so am safe from that shaft. I also put on the end piece. Though that's more for preventing flat toes from a falling counterweight it does spread the pain over a larger area. Not sure if that's better or not. Rick -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". |
#5
|
|||
|
|||
ASTRO: breaking up an exposure into subexposures: how to get the same s/n ?
ouch
that must have hurt keep that "foot saver" on the cwt bar too Rick... "Rick Johnson" wrote in message ... George Normandin wrote: "Richard Crisp" wrote ... here's something I threw together today to look into how much I am complicating my life by using more and shorter exposures instead of fewer and longer exposures Richard, I'll take a look. Thanks for posting. Your tech stuff is always helpful. I find that short exposures work best for me because of factors that can mess up exposures - stuff like wind gusts, astronomers with big feet, visitors hitting the counter-weight, short periods of bad seeing, passing clouds, etc. If I take fifteen one minute exposures I sometimes lose one to three from one of these problems. The loss from read noise is a small price to pay to insure that an hour of imaging is not lost to a wind gust or someone walking into the dome and hitting the scope. Also, with the 1301E, if I go too much longer than 60 seconds with an exposure, some of the stars start over-exposing - even in red or green. George N At Hyde we had to go to all fork mounts. We had a GEM with an 8" scope at first. But after hearing many streams for profanity from guys who caught the crotch high counter-weights a few times -- even a couple volunteers who should have known better got nailed by them -- we went to a fork mounted 12.5" scope. I was sorry to see that old 50's era Cave go as it had fantastic optics! Right after I put in the Paramount here with the 6" f/4 I ran into the shaft one night when doing a T-point map run. I didn't have any CCD so a friend was at the eyepiece while I was running the computer. While the friend was centering the star on the cross hairs I walked into the chest high shaft without its rubber protector on. Broke cartilage joining ribs to breast bone knocking me to the floor. But the star just jumped a couple seconds of arc then went right back to dead on the cross hairs. That's when I knew the mount was solid. But it was two weeks before I could take anything but very shallow breaths! Now I run from inside so am safe from that shaft. I also put on the end piece. Though that's more for preventing flat toes from a falling counterweight it does spread the pain over a larger area. Not sure if that's better or not. Rick -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". |
#6
|
|||
|
|||
ASTRO: breaking up an exposure into subexposures: how to get the same s/n ?
"Rick Johnson" wrote
At Hyde we had to go to all fork mounts..... Right after I put in the Paramount here with the 6" f/4 I ran into the shaft one night when doing a T-point map run. I didn't have any CCD so a friend was at the eyepiece while I was running the computer. While the friend was centering the star on the cross hairs I walked into the chest high shaft without its rubber protector on. Broke cartilage joining ribs to breast bone knocking me to the floor....... Rick, et al: I keep trying to remind people that safety of people is the first consideration, equipment second, and any observations or classes are a distant third. The counter-weight (painted black) on the OGS 100 GEM is about the size of my head! A long time ago we did put a tennis ball on the end of the big steel screw that the weight is on and more recently someone has gone around and put glow-in-the-dark strips on stuff including the counterweight. There are still problems: a week ago I was testing the scope during the day time and the last user had not shifted the tube weights so the metal nose cover nearly hit me on the head when it fell off - although surprised I was able to catch it. Our biggest recurring problem results from poor dome design: the switch to open the slit door plugs into the wall, which means that if you forget to pull the plug out and rotate the dome you will rip the plug off, or at least bend it. Several people have been knocked on their behinds when plugging in a damaged cord and gotten hit with 110v ac. I recently noticed that the plug was damaged yet again! It seems that the Staff can't resist rotating the dome when they take people on tours during the day, but the fail to look to see if the slit motor is plugged in. ....and then there are big Dob's and their &()*&)* ladders, but that's not a subject for an imaging group! George N |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
ASTRO: OT; maximum exposure time, read noise and cooling | Richard Crisp[_1_] | Astro Pictures | 0 | January 19th 08 06:33 PM |
ASTRO: Cass A at 17 hours (and still accumulating exposure time) | Richard Crisp[_1_] | Astro Pictures | 4 | October 14th 07 09:47 AM |
ASTRO: M106 in LRGB + Ha (9 hours exposure) | Richard Crisp | Astronomy Misc | 3 | March 10th 04 02:49 PM |
ASTRO: M106 in LRGB + Ha (9 hours exposure) | Richard Crisp | Amateur Astronomy | 3 | March 10th 04 02:49 PM |
ASTRO: M106 in LRGB + Ha (9 hours exposure) | Richard Crisp | CCD Imaging | 3 | March 10th 04 02:49 PM |