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AlwaysGoodskies

New M42 and Rosette

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These are my first real attempts at the Orion Nebula and Roestte nebula. single 2 minute exposures at 250mm on my DSLR. I used my new EQ mount with a RA motor. A bit of processing with Gimp, not too good at it... What do you all think?

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M42 is bright and you imaged it quite well with the single exposure, but Rosette is faint and needs more exposures. If you make 15-20 x 2min it will allow you to make harder processing and to show some real detail :)

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Hi AlwaysGoodskies

Nice first attempt at M42. Doesn't it make you heart beat a bit faster when you see your own work like that for the first time?

For the Rosette you need a much longer exposure time. At iso 800 I would suggest taking at least 30 x 2 min exposures this will really get you going. If you can manage 2 or even four hours then so much the better.

Watch out for focus or poor polar alignment. I use a Bahtinov mask and BackyardEOS to get very good focus without much mucking around

Edited by Star Gazer

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Thanks Star Gazer. the problem is not with the focus i think, but with the alignment. I have since this attempt tried to use more subs, but when i got 20 90Second subs and stacked them in Deep Sky Stacker, i got little ninja star like stars!! my RA motor is fine i think, but i do not have a polar scope or guide scope. this may be normal cause i am not shooting through a telescope; just a 250mm lens. any suggestions to get my PA more accurate w/o any computer or guide scope? it is very frustrating to get so close by so far....

thank you to all ye who respond!

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Hi AlwaysGoodSky,

I suggest you use EQAlign in order to align your mount, don't know if it works with a DSLR, but it does with a webcam. It perform the drift method to align precisely your mount, and it is free.

Anyway, nice first attempt!

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looks like a very good start. M42 looks really nice. with more frames you'll get rid of most of the noise. :icon_scratch:

rosette, well, i'm not at all good at that one myself, but you seem to be needing much longer exposures, and many subs to separate the details from the random noise.

i have to say though, both of the pics looks quite a bit out of focus, where rosette is worst (out of focus, no doubts). I'm guessing you focused first, then shoot M42 shortly after, then moved over to rosette without touching the focus?

If this is the case, then my guess is also that the camera+lens was not cooled to outdoor temp before shooting, and after you had focused the first time, it started to cool down slowly and started to get more and more out of focus.

it's very important to refocus often if the camera was warmer then the outdoor temp when you started to take pics, and the focus point changes with the lens temperature.

for the strangely shaped stars you mention - does your lens have IS? Also, did you remember to use mirror lockup?

i tend to get same result if i have IS on, as the IS isn't always able to start up fast enough in manual focus mode on my canon lenses at least (the 18-55 IS and the 55-250 IS struggle, the 18-200 IS seems to work fine though). The IS causes the image to move around a tiny bit just as the IS system stars up, causing weird stars. I recommend to disable IS in most cases. I only have it on if it's very windy and have no choise.

also, without mirror lockup, the mirror can shake the camera enough to cause weird stars, so try to always use mirror lockup if able.

what camera and lens did you use (1000D + 55-250 canon lens?)? and what iso settings?

Edited by Jannis

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I used the entry level canon 55-250mm lens. IS is probably the culprit. never even thought of it. what exactly is mirror lockup?

Thanks!

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mirror lockup means that you press the shutter once to lift the mirror, and press it one more time for the actual exposure. normally the mirror flips up, and exposure starts directly. But as the mirror had just been lifted up, some vibrations often still remains in the camera/scope. Therefor we like to lock up the mirror first, and let the camera settle down before the exposure starts so we are sure the camera is 100% still.

this prevents vibrations that we doing astrophotography often can see (more often at long focal lengths or on cheaper and more unstable mounts).

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