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Correct Imaging Train?

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#1 Star Slinger

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Posted 15 May 2021 - 02:52 AM

I really need help before I waste many nights trying to get it right.

I have been doing narrowband imaging and am not picking it up as fast as I thought SO I thought I’d knock myself back a few notches and go back to DSLR. I currently have a C8, OAG, and O.7x reducer. I would like to apply my 8 position filter wheel as well. I am wondering what the correct backfocus would be for such an imaging train, and what order should I have all my bits in?

I feel like I have so many little black plastic bits and endless possibilities to put them all together but any sort of guidance would be of great help to me so I’m not struggling!

I mostly want to use the filters to counteract the light pollution I’m experiencing. I have a Skyshed POD but unfortunately it ironically lives under the ONLY bright LED street light on the rural road I live on! Annoying. Thank you in advance.

#2 Dynan

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Posted 15 May 2021 - 05:45 AM

Call 'The Powers That Be' and see if they'll shield it. Tell them it's ruining your use of your property. All they can say is "No".



#3 Tapio

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Posted 15 May 2021 - 07:11 AM

Narrowband requires a lot of exposure and pretty long subs too.

I'm not sure what you hope to achieve with DSLR and filter wheel but doesn't sound like good idea.


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#4 Sacred Heart

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Posted 15 May 2021 - 07:56 AM

I know nothing about using narrowband filters,  except people who use them with DSLR's  either slip them on in front of the mirror or screw them on to the nose piece.   Spacing for a camera, DSLR or CMOS / CCD is what it is to achieve focus and should be the same if you put a focus wheel in front or not.

 

Me, if I had my focus down - I use a Bahtinov mask -  I would play with exposure settings to get it right.  Exposure time, gain, offset, whatever.   You are at the threshold of the door,   you are looking for that one thing to get you through.   Keep plugging.

 

Ask this question, with pictures of what you have taken,  to the guys over in the imaging section.  Can't hurt.    Joe


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#5 Star Slinger

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Posted 15 May 2021 - 03:42 PM

Call 'The Powers That Be' and see if they'll shield it. Tell them it's ruining your use of your property. All they can say is "No".

I've written multiple emails and have even called the power company. They ignore me...I am a loss for what to do.



#6 AhBok

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Posted 16 May 2021 - 07:32 AM

If this is the only direct light, you may have a better situation than you think. The goal should be to prevent direct light from entering your scope. This can usually be accomplished using some sort of screen to block any direct light from entering the scope. I’ve made them in the past with plastic pipe and opaque material.

The light from one street lamp has a small effect on light pollution in the sky. The contribution of lights from nearby houses and the light dome from nearby towns (or large cities within 50 miles) far outweighs the contribution of a single nearby light on actual sky brightness.

I would not give up on having the street lamp disabled. My daughter recently purchased a mountain home in very rural North Carolina. It had an annoying street lamp that lit up her house like a Wally World parking lot. She requested the light be turned off and less than a week later is was.
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#7 Dynan

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Posted 16 May 2021 - 07:36 AM

I've written multiple emails and have even called the power company. They ignore me...I am a loss for what to do.

You're not talking to the right people then. Talk to their bosses...go up the chain of command. Rattle the right cage and you'll get results. The alternative is to suffer in silence.


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#8 alphatripleplus

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Posted 16 May 2021 - 07:44 AM

I mostly want to use the filters to counteract the light pollution I’m experiencing. I have a Skyshed POD but unfortunately it ironically lives under the ONLY bright LED street light on the rural road I live on! Annoying. Thank you in advance.

If you have heavy LP and are using a colour DSLR, I'm not sure filters are going to help much. However, with your mono camera if you target emission nebulae with  a narrowband H-alpha filter, it would be a different story.


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#9 Star Slinger

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Posted 16 May 2021 - 05:26 PM

Ok fair. Thanks all. Yes I have another rig. I have an ED80 I use with my FW and ASI1600 combo. I guess I'm just trying to get back into DSLR for a while and wondering what my options are with this awful street light. Thought about a LP filter.

 

It's closer and brighter and more annoying than I can describe. I don't want to be a "Karen" about it but I'm very darn close to being one lol. I wrote another letter to power company who manages the light. If they keep ignoring me what should I do? Who would you contact if you were in my shoes?

 

I would move it but unfortunately not only is this where my nice flat cement patio is located but also the best view of the sky/pole star. Sad. Attached is the view from INSIDE my POD.

 

If you have heavy LP and are using a colour DSLR, I'm not sure filters are going to help much. However, with your mono camera if you target emission nebulae with  a narrowband H-alpha filter, it would be a different story.

Attached Thumbnails

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Edited by Star Slinger, 16 May 2021 - 05:47 PM.


#10 Dynan

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Posted 16 May 2021 - 06:20 PM

Write/email to the people in charge of your municipality...Public Service Commission, City/County Govt'/Board, Mayor,... The Power Company takes orders and licensing from someone.

 

Keep going up the ladder until you get results. SOMEONE wants your vote!


Edited by Dynan, 16 May 2021 - 06:34 PM.

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#11 Star Slinger

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Posted 19 May 2021 - 12:33 AM

So after complaining like a true Karen to the power company I got in touch with a super nice guy who stated that they would be willing to replace this light with a 2700k flat bottomed version for FREE. This new light would point towards the ground rather than spray out. The only hurdle I need to get through is to get approval from the landowners (I rent) who pay a monthly fee for these lights. I have written two letters to said landowner and no response back yet. Going to keep pestering him until he gets back though haha. I’ve sent him examples of my photos so he knows what I truly do, as I’m sure most of my neighbors probably think I’m cooking up meth in my POD or something lol.

I’m truly not thrilled that the light won’t be entirely removed but I guess this is something after 6 years! What are your thoughts on a 2700k dark sky compliant street light? Will it still be intrusive you think?

Edited by Star Slinger, 19 May 2021 - 12:37 AM.

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#12 Sacred Heart

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Posted 19 May 2021 - 08:53 AM

So after complaining like a true Karen to the power company I got in touch with a super nice guy who stated that they would be willing to replace this light with a 2700k flat bottomed version for FREE. This new light would point towards the ground rather than spray out. The only hurdle I need to get through is to get approval from the landowners (I rent) who pay a monthly fee for these lights. I have written two letters to said landowner and no response back yet. Going to keep pestering him until he gets back though haha. I’ve sent him examples of my photos so he knows what I truly do, as I’m sure most of my neighbors probably think I’m cooking up meth in my POD or something lol.

I’m truly not thrilled that the light won’t be entirely removed but I guess this is something after 6 years! What are your thoughts on a 2700k dark sky compliant street light? Will it still be intrusive you think?

The town replaced the street lights with flat bottom LED,   not sure about 2700k.  My front yard is not as bright, therefor my backyard is way less lit.  I'm about 120' from the light.  The street is brightly lit though. About the same or better.  Joe


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#13 speedster

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Posted 20 May 2021 - 12:29 AM

Your POD has some round pockets in the top of the walls.  Dowel rods into the holes and then clamp light proof fabric between to block out the direct light.  Helps a lot.   Easy up and down.

 

As for the imaging train, from the back of the scope, reducer, OAG, spacers if needed, filter wheel, DSLR.  Your back focus distance is 105mm and this is measured from the back of the reducer to the imaging sensor.  So it's 105 - OAG - filter wheel - T-adapter - camera flange focal distance and then add spacers to get to 105. 


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