Last night I do an experiment to shoot the same object Tree_02 but using short exposure time (2 seconds ) , taking 272 flames and do stacking in IRIS .
http://www.hkastroforum.net/viewtopic.php?p=184006#184006
Result of all the previous simple experiments , we can know something :
1. Long time ago 2 seconds is used to take M42 , and the M42 is much brighter than this time Tree_02 of one individual flame. That implies this Tree_02 is much dimmer than M42 under the nearly same condition .
2. For this time experiment , final stacked flame looks much better than individual one flame . That implies stacking is neccesasary and a good tool to get better image .
3. For same 9 min exposure of the Tree_02 , Last time (60s X 9) and this time (2s X 272) , the one 60s is much better than this 2s . That means longer exposure of each flame , get better image if the total exposure time is same .
4. In shooting DSO that are moving , shorter exposure implies on each flame implies less requirement of tracking ability on the mount . EQ3 should allow much longer exposure than 2 seconds for each flame exposure without bias in shifting . Becasue EM8 can also get M42 without much bias within 2seconds in previous experiment .
5. IRIS can align the all flames very accurately , pixel accuracy can upto 2 decimal point . Even there is a very big shifting in pixels among all the flames .
6.
Let say for example , the EQ3 can allow 16 seconds without bias shifting , each flame can be shooted for 16 seconds , 200 flames will have 3200 seconds ( 1 hour) , during thsi 1 hour , there should have big shfited in the images , Within the same flame area , IRIS can handle the shifting . Once the star go outside the flame area , it can be readjusted back by manually stop the exposure and trace back the star , and start shooting again . That means the total exposure time actually can be unlimited .
In conclution of above implies :
DSI I + EQ3 , should be no problem to get most of the Deep sky objects . Now , only wait a good day to do actual practice of the DSO imaging .
MANDII
2010/04/27 |
显身卡
我晕，无语了，强悍~！！不知道LZ那里星空怎么样啊、？？
