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Narrowband

Full spectrum camera vs h-a filter on scope


vertigo262

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At the moment, I don't think my bottleneck is so much the camera, as much it is the light pollution

lp creates limitations, unfortunately :( There's no substitute for dark skies - they say! DSLR's create noise so cooled ccd's are better even if they don't have so many pixels!

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I have read a few articles that HA cuts through lp pretty well. That was why I wanted to try it. The spots I am at are around a 2 on the lp charts. Not horrible, but could be better. And you've seen my results. So really seems that you need a spot with less the 1 on the scale to really get a good image or do dark nebulas.

But this is all just theory from reading. Not any experience.

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I have read a few articles that HA cuts through lp pretty well. That was why I wanted to try it. The spots I am at are around a 2 on the lp charts. Not horrible, but could be better. And you've seen my results. So really seems that you need a spot with less the 1 on the scale to really get a good image or do dark nebulas.

But this is all just theory from reading. Not any experience.

Yeah though depends on the nature of the lp. If the lp is white light then maybe it that will still create a problem. And you still need the rest of the colour. See how you get on with a lp filter - which one are you getting?

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Yes, 2" the part that attaches to the camera has filter threads on the end 

http://www.ebay.com/itm/2-inch-to-T-Adapter-Telescope-Astrophotography-2-Imaging-Metal-Great-Value-NEW-/331475561919?pt=LH_DefaultDomain_0&hash=item4d2d7badbf

My normal spot which is closed right now from mud slides on the roads is about a 1.7, where I am now is a 2 - 3 I think

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Ok - not half as bad as mine then! I can just about make out Orion (the constellation) on a good night. No chance of seeing the Milky Way here... :(

So you should be fine doing long exposures with a lp filter :) You've probably already noticed that the full-spec mod results in a significant increase in sensitivity. The 8-bit capture screen images can be quite disconcerting but the 14-bit raws are always a lot darker so give room to stretch :)

Louise

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I don't know how you'd be able to get anything at all in a 9. My one spot which is 1.7 maybe even 1, I still have a difficult time with.

when I was learning how to use the scope, I was by my place which is a 6. Couldn't get anything but white glow. although you are using narrowband. So that is probably why,

But 9 seems like it would be like trying to take a picture through a cloud

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I don't know how you'd be able to get anything at all in a 9. My one spot which is 1.7 maybe even 1, I still have a difficult time with.

when I was learning how to use the scope, I was by my place which is a 6. Couldn't get anything but white glow. although you are using narrowband. So that is probably why,

But 9 seems like it would be like trying to take a picture through a cloud

It's very challenging! It never gets dark here. I haven't been doing narrowband either. I need a lot of data to make an image....

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I don't know how you'd be able to get anything at all in a 9. My one spot which is 1.7 maybe even 1, I still have a difficult time with.

when I was learning how to use the scope, I was by my place which is a 6. Couldn't get anything but white glow. although you are using narrowband. So that is probably why,

But 9 seems like it would be like trying to take a picture through a cloud

Most of us imaging from the cities and the suburbs in the UK suffer from horrendous levels of LP as well as bad weather particularly in the north of the UK. The country is very small compared even to the smallest of the US states and  heavily populated in and around major cities. I have a friend who is in the retail of astronomy gear as well as being an avid observer and he told me that the LP was up to 30 degrees of elevation in Manchester a few years ago, now we have to point the scope nearly vertically up if we wanted to avoid this scourge of imaging. More and more with the introduction of LED lighting, white light pollution,  even the best of LP and nebula filters are becoming ineffective. As you have said quite often it is like imaging through an orange cloud. Imaging from a dark location with an uninterrupted  6 or 7 hours imaging run remains the stuff of dreams for most of us. Cherish your location if your LP is low .

Regards,

A.G

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I don't help my self by imaging through a window which severely limits the area of sky I can see and limits the altitude of targets that I can see to a max of maybe 35 deg. Add to that a streetlight just below the window and less than 10m away then imaging is a real challenge! But, TBH, if it was easy then I probably wouldn't bother doing it!

Still here's an M3 I attempted last night. It's just the 3 best out of 4 x 600s subs I took (damn clouds!). Stacked in DSS with bias, darks and flats. Post-processed in StarTools and CS2. It has a noisy gradient on the left caused by the streetlight. I've tried to minimise it (at the cost of a fair bit of detail) but it's still there. I really need to improve my processing skills... I'd probably benefit from using PI and maybe I'll get it one day :)

post-33532-0-47912300-1424192791_thumb.p

Another 10-12 subs might help too - 3 is not enough...

Louise

Edit - should have mentioned this was taken with a qhy8l on a 150pds

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I don't help my self by imaging through a window which severely limits the area of sky I can see and limits the altitude of targets that I can see to a max of maybe 35 deg. Add to that a streetlight just below the window and less than 10m away then imaging is a real challenge! But, TBH, if it was easy then I probably wouldn't bother doing it!

Still here's an M3 I attempted last night. It's just the 3 best out of 4 x 600s subs I took (damn clouds!). Stacked in DSS with bias, darks and flats. Post-processed in StarTools and CS2. It has a noisy gradient on the left caused by the streetlight. I've tried to minimise it (at the cost of a fair bit of detail) but it's still there. I really need to improve my processing skills... I'd probably benefit from using PI and maybe I'll get it one day :)

attachicon.gifM3_2_st_adj_flip2.png

Another 10-12 subs might help too - 3 is not enough...

Louise

Edit - should have mentioned this was taken with a qhy8l on a 150pds

It amazes me what people can achieve in less than ideal conditions, let alone trying to take a picture of something that is millions of miles away, through a window, with a street light. 

Nice one.

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It amazes me what people can achieve in less than ideal conditions, let alone trying to take a picture of something that is millions of miles away, through a window, with a street light. 

Nice one.

Hi

I'm gradually getting together the bits I need to image outside :) I'll still have the bad lp but lots more sky to choose from :)

Louise

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I am in the Los Angeles area, city makes the sky glo. you can't see anything. So I drive to areas I find away from the city. surprisingly, I found a few spots with a lot of driving, and using lp maps to find them, and google earth to find clearings. although, we have 12 hrs of dark which I'm not sure where you are at, but without dark. there isn't anything. But that's the reason I have the visibility I do. which I still stumble around with. 

I think the only real dark location, when I mean, real, perfect dark is the Mojave Desert, 4 hrs away. I'd love to see what imaging was like there. But I'd spoil myself. So it's not as good as you might think where I am. 

My one spot, which is around a 1 - 2 lp. Took a lot of driving and time to find. I choose it because there are no lights south over the ocean, and the mountains block the city lights. It takes me about 45 mins to get there. But it's worth the drive instead of shooting in a 6 where I am.

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Plus if I go to Mojave, it's on the way to Las Vegas! PARTY!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :o )

Glad you have all those possibilities! Alas, I have no car so I'm stuck in the city though hope I'll be able to point away from the worst and to higher altitudes once I can get outside. I live on the second floor with no lift - another obstacle to overcome!

Louise

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Tonight I went out and tried out, APT since Backyard eos doesn't have ccd support. So I'm planning for the future. APT seems much better thought out. No need to center scope to focus and just seems faster to use. But is it just me or are the preview images horrible? I open up the same file in other viewers and it looks normal

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