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350d Widefield Help

Grant

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Grant

Grant

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Hi everyone,

Spent a little time tonight having a first play with the 350d and widefield imaging just using the standard 18-55mm canon lens...

Following the instructions in Ants post about f-ratios, I set it to 6.3 which is the second lowest option I have... I tried doing a 15 minute exposure, had no trailing but the whole frame was a mass of orangeness and alot of noise, I tried dropping the iso from 1600 down to 800 then I tried at 400, slightly less noise but the orange was still painful!

Alot of stars were showing through but the orange was so bad it wasn't really possible to remove it, I dropped the exposure time right down to 1 minute subs and still the orange was washing everything out...

I've not really had problems with light pollution before, theres a couple of lights nearby but they aren't that bright and its never been a problem, is it possible I've set something up wrong on the camera? Or is it just lots and lots of light pollution?

Any tips, tricks, methods, thoughts gratefully received :(

Cheers,

Grant

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Ant

Ant

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It's fairly easy to remove the LP.

Duplicate layer, select difference, then do a gaussian blur on the copy. The screen will show you what it looks like so you can adjust the level of BLUR. Once happy flattern layers.

But I get an orange sky after 30 seconds, but at F14 I managed to get a dark sky after 15 minutes. Didn't get many stars either though :(

Ant

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moondog

moondog

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Grant

Widefield imaging is notorious for orange glow from all but a dark sky site. F8 for the Canon standard lens seems the sweet spot. Problem is with a scope you can use a CLS filter, but it won't fit your Canon.

You can lower the light pollution levels by stacking. Instead of one 15 min sub, try say 10no. 2 min subs @ 800 ISO. On the final stacked image use Ant's suggestion to remove the remaining orange glow - I use the same method.

Keep trying you'll get there !

8)

MD

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Ant

Ant

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The CLS filter will fit the canon lens - you need an adapter - I bought an adapter to fit the standard 2" filters to my canon lens.

It cost around £6.

From memory it's a 49mm thread step down ring.

Ant

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Grant

Grant

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Thanks guys, lots of stuff to try there! Itching to get out and play some more now :(

A CLS filter is definitely high up on my shopping list now!! Might have to get one of those adaptors too Ant, where did you get it from?

Cheers,

Grant

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jcm

jcm

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I bought an adapter to fit the standard 2" filters to my canon lens.

Great idea!

My D40 has a 52mm thread so what thread is a standard 2" filter

so I can get the correct step up/down ring ?

I think its a step down ring you need. ( so its 52 down to 48). The 2" filters have a 48mm thread.

John

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Ant

Ant

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Can I just add that the CLS is an excellent filter. It's just that in my opinion you need to be able to expose the chip for so long to get the light through that without more expensive than I had it was not worthwhile.

But all the light that does get through is the RIGHT STUFF :(

Onto the step ring, for the standard canon lens with the 300D the ring you want is a 58 -> 48 Step DOWN ring. John was right.

Regards

Ant

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