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AbsolutelyN

NGC 7000 widefield HRGB

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Posted (edited)

This is my first attempt with the 1600mm pro and a Canon lens. It's taken with the 100-400mm mkII @ 100mm at f/5.6. About 8 hours exposure in total, moon was past first quarter during both nights, skies not very transparent and ngc7000 still relatively low in sky. Found it very hard to focus accurately - used bahtinov mask and stopped down slightly - but unlike scope could not automate focus as temp dropped. 

45x Blue @2min
45x Green @ 2min
23x Red @ 2min
53x HA @ 5 min

https://www.astrobin.com/405980/?nc=user

NGC7000_100mm_v4.jpg

Edited by AbsolutelyN
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Stunning shot there one of the best I have seen, I use to have that lens, alot of glass inside it but sharp all the way through the range, I only have fixed lens now at 200mm plus, should try and mount up the 300 and 500mm the trouble is guiding them.

Alan

 

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Thanks, yes the 100-400ii is very sharp pretty much to edge of field on full frame and you are only using centre with a smaller chip. I used to have the 200 2.8, wish I'd held on to it now, very fine lens. I'm finding the issue is focusing though rather than guiding - this is just piggybacked on my esprit 100 with azeq6. Planning on trying a few of my wider lenses next. 

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Very nice image. NGC7000 is on my list to have a go at with the 135mm + ASI1600. I don't have any 2" rgb filters though!

Adrian

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I was worried about filter sizes but this is with the 1.25" filters and EFW mini.  I used low gain and vignetting was not even slightly a problem. I was at f/5.6 so perhaps that is too slow for filter size issues. I'm going to try my f/1.4 lens next to see how bad it is with 1.25" as that really should require 2" filters.   

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1 minute ago, AbsolutelyN said:

this is with the 1.25" filters and EFW mini

I'll have to give it a go with my 1.25" filters and wheel. Thank you!

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10 minutes ago, AbsolutelyN said:

Are you stopping your 135 down or using it wide open?

I always use it wide open. I have found the spacing is absolutely critical using it at f2; the slightest issue on spacing and it won't focus.

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3 hours ago, AbsolutelyN said:

Thanks, yes the 100-400ii is very sharp pretty much to edge of field on full frame and you are only using centre with a smaller chip. I used to have the 200 2.8, wish I'd held on to it now, very fine lens. I'm finding the issue is focusing though rather than guiding - this is just piggybacked on my esprit 100 with azeq6. Planning on trying a few of my wider lenses next. 

Yes I found that I sat my very old 300mm L on top using a mounting device I bought years ago and it is OK with the F4 lens but I have an F2.8 as well, that is too heavy. I found focus was hard and with the shutter going off all the time also found it moved focus a tad With is being a APS C chip in the 40D it was in real terms 480mm. Probably the reason I never bothered with the 500mm as that works out at 800mm, same as my APO which is easier to manage.

Alan

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Ah I see what you mean. I've never had issues with shutter vibrations as I use my 300 2.8 with a Sony A7R3 - no mirror so no vibrations. 

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