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Old Dinosaur
Pooh-Bah
Reged: 05/08/07
Posts: 1262
Loc: Out in the sagebrush
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Things are happening pretty fast along the Suns limb.
What are folks ideas about maximum AVI lengths?
2 minutes- 1 minute?
Aperture and resolution ought to be the determining factor, so I'm thinking with my PST at only 40mm, I could go for longer times.
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WRS Observatory
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swisswalter
sage
Reged: 03/29/09
Posts: 417
Loc: Eastern-Switzerland
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hi
for me i'm happy with 20 sec
walter
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only dust in the wind, TAK on GM8, Lunt 60, DMK31,still greenhorn, but as a golfer used to be humble
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nini et titi
member
Reged: 08/27/09
Posts: 88
Loc: Mesnil Panneville ,Normandy,FR...
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for me :
with the DMK 21 and Lunt 60 /Barlow 2.5x,I limit recording at 60 sec
for prominences : about 1/20 sec or 1/30 sec exposure = 200 MO on hard drive,
for the disk : about 1/250 sec exposure = 1 GO on hard drive
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Old Dinosaur
Pooh-Bah
Reged: 05/08/07
Posts: 1262
Loc: Out in the sagebrush
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Thanks. With my old SPC900NC and now my DMK, I've always stayed at 60 seconds of recording, no matter if barlowed or not. With good alignment so there's no drift.
I might just try 120 seconds with a 2X barlow to see if there is some obvious blurring.
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WRS Observatory
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brianb11213
Carpal Tunnel
Reged: 02/25/09
Posts: 2121
Loc: 55.215N 6.554W
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Quote:
With my old SPC900NC and now my DMK, I've always stayed at 60 seconds of recording, no matter if barlowed or not.
You get away with very short AVIs if the gain is low - for full disk imaging & the DMK, I can set the gain to 450 and get away with 150 image AVIs. When using a barlow to increase the image size, the gain has to be turned up to get the exposure down enough to counteract seeing, with the gain turned up it's necessary to shoot more frames to get a decent signal to noise ratio. 500 frames at gain 640 is a common setting, so is 1000 frames at gain 800 on planets.
Obviously if very fast movement of proms is occurring, movement blur may be an issue when working at 4x as 500 frames takes getting on for a minute to acquire.
As always, everything is a compromise - are you happy with a slightly blurred but smooth image, or do you prefer a sharper imager with loads of noise?
The seeing usually has the final say so far as I'm concerned - there are many days when I simply can't use a 4x barlow as the seeing isn't good enough.
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Old Dinosaur
Pooh-Bah
Reged: 05/08/07
Posts: 1262
Loc: Out in the sagebrush
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4X barlow?  , in this mountain valley I get seeing good enough for that even at night only on rare occasions.
I have great dark sky, but seeing generally sucks.
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WRS Observatory
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Fish
sage
Reged: 10/13/07
Posts: 470
Loc: Norridgewock, ME
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Personally I take about 500 - 600 frames per AVI file. This is 10 seconds for the DMK21, 20s for the DMK31 and all of 30 seconds for the DMK41.
Regards, Marc
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Goseck Observatory
Kunming 152 f/5.9 & Baader Wedge
Orion ED80 & LS75FHa2/B1200
Meade 102ED & LS18CaKMDd2
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molniyabeer
Confused and Asleep
Reged: 01/08/05
Posts: 2559
Loc: Central Coast, California
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I have been shooting around 1000-2000 frames, so 1-2 minutes or there about. Seems to work for me, with seeing usually more of a limiter than motion.
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Steve
16" Meade LightBridge (Beowulf)
10" Hardin DSH, StarMax 127mm Mak, PST H-a
Oberwerk 11 x 70 binocs, Tasco 10 x 50 binocs
Santa Maria Clear Sky Clock
Figueroa Mt Clear Sky Clock
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Tom Masterson
member
Reged: 08/08/09
Posts: 14
Loc: Pacific Northwest - Astronomy'...
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If the seeing is good I use my camera's default of 300 frames. Sometimes these images can end up with a little noise depending on the number of frames I actually stack. 500 frmaes worsk better and I sometimes go as high as 1000 frames.
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Tom
12" Meade LX200 Classic
AstroPhysics 6" f/8
Brandon 94 f/7
Meade 30mm 5000 UWA, my primary weapon
20mm Nagler Type2, my back up weapon
16 and 12mm Nagler Type2s, in case the first two didn't finish 'em off
17mm and 13mm Stratus, 9mm and 6mm TMB Planetaries
Coronado ,6a SMn-35 w/90mm ERF
Lunt LS50/BF1200
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