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midtskogen
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Astrophotography

A-L-E-X wrote:
Source of the post Does anyone know what the minimum effective focal length needed is to show separation of Saturn from its rings in an image?

The minimum separation of Saturn's surface and the innermost ring is between 1.7 ans 2.4 arc seconds (depending on the distance to Saturn), and the horizontal resolution of your camera is 4608 pixels, so for the gap to make up one pixel, the horizontal field of view of your camera must be no more than about 2.2 - 3.1 degrees.  So a 1000 mm lens (36x24 mm sensor equivalence) should suffice.  When Saturn is at its closest, maybe that can be pushed down to 600 mm.
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A-L-E-X
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Joined: 06 Mar 2017

Astrophotography

midtskogen wrote:
A-L-E-X wrote:
Source of the post Does anyone know what the minimum effective focal length needed is to show separation of Saturn from its rings in an image?

The minimum separation of Saturn's surface and the innermost ring is between 1.7 ans 2.4 arc seconds (depending on the distance to Saturn), and the horizontal resolution of your camera is 4608 pixels, so for the gap to make up one pixel, the horizontal field of view of your camera must be no more than about 2.2 - 3.1 degrees.  So a 1000 mm lens (36x24 mm sensor equivalence) should suffice.  When Saturn is at its closest, maybe that can be pushed down to 600 mm.

Thanks!  Looks like I have what I need to get it done.  I take it I need to use a tripod and manual focusing?  Vertical field of view is 1.5 degrees at 1000mm, around 1.0 degrees at 1500mm (with the teleconverter), and 0.5 degrees at 3000mm (using the TC and 2x IDZ).  With the last combo the top and bottom part of the full moon is cropped, which confirms that it is 3000mm.  I'm not sure how to convert this to horizontal FOV, the sensor is 4:3 so that means the horizontal FOV is 1/3 larger?  So it would be 2.0 degrees at 1000mm? 1.3 degrees at 1500mm and 0.7 degrees at 3000mm?

A-L-E-X
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Astrophotography

Please correct me if I'm wrong....I used moon pictures I took from the full moon of May 18th and measured the pixel width of the moon, it was 1,250 pixels at 1000mm.  I then found the actual angular measurement of the moon and it was

(3456/1250)*(1900/3600)=1.4592 degrees vertical FOV

(4608/1250)*(1900/3600)=1.9456 degrees horizontal FOV

site I used to find actual angular width of the moon on that day

http://www.astropixels.com/ephemeris/moon/moon2019.html

FOV calculator

https://www.scantips.com/lights/fieldofview.html#top

midtskogen
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Astrophotography

Sounds reasonably correct.
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Phunnie
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Astrophotography

A-L-E-X wrote:
Thanks- I have light pollution filters also but got the wrong size unfortunately- I have eyepiece size O3, UHC and Imaging filters- all are 1.25"   What size did you get?

I had special clip in filters that clips directly in front my my camera sensor and not on to my telescope. LP filters can only do so much anyways. I upgraded my setup a full tier this time around (instead of just the mount) and so once everything arrives, light pollution will no longer be an issue for me as I'll be shooting in narrowband =D

A-L-E-X
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Joined: 06 Mar 2017

Astrophotography

Phunnie wrote:
A-L-E-X wrote:
Thanks- I have light pollution filters also but got the wrong size unfortunately- I have eyepiece size O3, UHC and Imaging filters- all are 1.25"   What size did you get?

I had special clip in filters that clips directly in front my my camera sensor and not on to my telescope. LP filters can only do so much anyways. I upgraded my setup a full tier this time around (instead of just the mount) and so once everything arrives, light pollution will no longer be an issue for me as I'll be shooting in narrowband =D

I'm interested in that too, especially with LED lighting becoming more prevalent, which LP filters dont fight off so efficiently.  Any idea on how many stops of light the narrowband filters block?  I imagine exposures will need to be at least 8 stops longer?  With my UHC they're already 3 stops longer.  Boost the ISO to 3200 and then do a lot of stacking with DSS to reduce signal noise lol.
I actually replaced my old Meade DSI-3 color imager with the Olympus E-PL6, this mirrorless camera is the first camera in that class I've owned that's actually as light as a CCD imager (no flash, viewfinder or mirror box) and I like the really short flange distance (the distance from the CCD to the imaging plane) which gives me an unvignetted image (there is some slight light fall off in the corners) even when using the reducer and filters.

A-L-E-X
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Posts: 2305
Joined: 06 Mar 2017

Astrophotography

midtskogen wrote:
Sounds reasonably correct.

Mid do you have any idea what the effective focal length should be to clearly see the following:
1) Cassini's Division in Saturn's rings.
2) Great Red Spot on Jupiter
3) Martian Polar Ice Cap
I think 1) is doable with my super zoom, dont know about 2) or 3) though- I did see an image of Mars with the white of the Polar Ice Cap clearly visible through the Nikon P-900 though (a 2000mm effective focal length zoom lens camera.)

On the astropixels page, when they mention the angular size of the moon on a specific day, do you think they mean midnight GMT/UT on that day or noon GMT/UT on that day?

Phunnie
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Astrophotography

A-L-E-X wrote:
Phunnie wrote:
A-L-E-X wrote:
Thanks- I have light pollution filters also but got the wrong size unfortunately- I have eyepiece size O3, UHC and Imaging filters- all are 1.25"   What size did you get?

I had special clip in filters that clips directly in front my my camera sensor and not on to my telescope. LP filters can only do so much anyways. I upgraded my setup a full tier this time around (instead of just the mount) and so once everything arrives, light pollution will no longer be an issue for me as I'll be shooting in narrowband =D

I'm interested in that too, especially with LED lighting becoming more prevalent, which LP filters dont fight off so efficiently.  Any idea on how many stops of light the narrowband filters block?  I imagine exposures will need to be at least 8 stops longer?  With my UHC they're already 3 stops longer.  Boost the ISO to 3200 and then do a lot of stacking with DSS to reduce signal noise lol.
I actually replaced my old Meade DSI-3 color imager with the Olympus E-PL6, this mirrorless camera is the first camera in that class I've owned that's actually as light as a CCD imager (no flash, viewfinder or mirror box) and I like the really short flange distance (the distance from the CCD to the imaging plane) which gives me an unvignetted image (there is some slight light fall off in the corners) even when using the reducer and filters.

If you shoot narrowband you will most likely be shooting with a monochrome camera. Shooting in narrowband also won't increase the exposure time per frame on a target. You get a higher SNR as you remove light pollution and sky glow for the same exposure time. The exposure time can also vary quite a bit depending on the target and the FL. Dedicated mono cameras are much more sensitive than DSLR's and thus increase SNR even more. I'm currently waiting for my ZWO ASI 1600MM cooled to arrive so I can start shooting essentially noiseless shots under Bortle 8 skies
Example of a 5 seconds very stretched exposure of heart nebula under bortle 7 skies with a Ha filter on the 1600MM. (500mm FL, f/6.25. Not taken by me)

midtskogen
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Astrophotography

A-L-E-X wrote:
Source of the post Mid do you have any idea what the effective focal length should be to clearly see the following:

I don't know.  I'm on travel right now, but you should be able to figure out the angular size for these things by a bit of googling, and compare that to what I found above, i.e. you need nearly 1000 mm to resolve 2 arc seconds.
Cassini's division sounds hardest, then the red spot, then the Martian polar cap (my guesses, I didn't look up).
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Cantra
Pioneer
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Location: Sedna

Astrophotography

I do not have any photographic equipment as I just took these pictures of the moon with my phone camera.

I use a Meade 130 Polaris reflector series telescope. It is far better and easier to use than my 114 lcm which has been gathering dust. I got my new telescope 1 and a half months ago, and it's a beast. I hope to capture better pictures of planets though with my current situation I am unable to get good pictures until I get the proper equipment.

A-L-E-X
Star Engineer
Posts: 2305
Joined: 06 Mar 2017

Astrophotography

Phunnie wrote:
A-L-E-X wrote:
Phunnie wrote:
I had special clip in filters that clips directly in front my my camera sensor and not on to my telescope. LP filters can only do so much anyways. I upgraded my setup a full tier this time around (instead of just the mount) and so once everything arrives, light pollution will no longer be an issue for me as I'll be shooting in narrowband =D

I'm interested in that too, especially with LED lighting becoming more prevalent, which LP filters dont fight off so efficiently.  Any idea on how many stops of light the narrowband filters block?  I imagine exposures will need to be at least 8 stops longer?  With my UHC they're already 3 stops longer.  Boost the ISO to 3200 and then do a lot of stacking with DSS to reduce signal noise lol.
I actually replaced my old Meade DSI-3 color imager with the Olympus E-PL6, this mirrorless camera is the first camera in that class I've owned that's actually as light as a CCD imager (no flash, viewfinder or mirror box) and I like the really short flange distance (the distance from the CCD to the imaging plane) which gives me an unvignetted image (there is some slight light fall off in the corners) even when using the reducer and filters.

If you shoot narrowband you will most likely be shooting with a monochrome camera. Shooting in narrowband also won't increase the exposure time per frame on a target. You get a higher SNR as you remove light pollution and sky glow for the same exposure time. The exposure time can also vary quite a bit depending on the target and the FL. Dedicated mono cameras are much more sensitive than DSLR's and thus increase SNR even more. I'm currently waiting for my ZWO ASI 1600MM cooled to arrive so I can start shooting essentially noiseless shots under Bortle 8 skies
Example of a 5 seconds very stretched exposure of heart nebula under bortle 7 skies with a Ha filter on the 1600MM. (500mm FL, f/6.25. Not taken by me)

Wow you could even do deep sky imaging with an SE mount if you can get detail like that in such short exposures!  It's fine up to 30 sec exposures.

A-L-E-X
Star Engineer
Posts: 2305
Joined: 06 Mar 2017

Astrophotography

midtskogen wrote:
A-L-E-X wrote:
Source of the post Mid do you have any idea what the effective focal length should be to clearly see the following:

I don't know.  I'm on travel right now, but you should be able to figure out the angular size for these things by a bit of googling, and compare that to what I found above, i.e. you need nearly 1000 mm to resolve 2 arc seconds.
Cassini's division sounds hardest, then the red spot, then the Martian polar cap (my guesses, I didn't look up).

This is what I found out about Mars
https://cochinblogs-hobby.blogspot.com/ ... t-max.html

Phunnie
Space Pilot
Posts: 134
Joined: 02 Aug 2017
Contact:

Astrophotography

A-L-E-X wrote:
Phunnie wrote:
A-L-E-X wrote:
I'm interested in that too, especially with LED lighting becoming more prevalent, which LP filters dont fight off so efficiently.  Any idea on how many stops of light the narrowband filters block?  I imagine exposures will need to be at least 8 stops longer?  With my UHC they're already 3 stops longer.  Boost the ISO to 3200 and then do a lot of stacking with DSS to reduce signal noise lol.
I actually replaced my old Meade DSI-3 color imager with the Olympus E-PL6, this mirrorless camera is the first camera in that class I've owned that's actually as light as a CCD imager (no flash, viewfinder or mirror box) and I like the really short flange distance (the distance from the CCD to the imaging plane) which gives me an unvignetted image (there is some slight light fall off in the corners) even when using the reducer and filters.

If you shoot narrowband you will most likely be shooting with a monochrome camera. Shooting in narrowband also won't increase the exposure time per frame on a target. You get a higher SNR as you remove light pollution and sky glow for the same exposure time. The exposure time can also vary quite a bit depending on the target and the FL. Dedicated mono cameras are much more sensitive than DSLR's and thus increase SNR even more. I'm currently waiting for my ZWO ASI 1600MM cooled to arrive so I can start shooting essentially noiseless shots under Bortle 8 skies
Example of a 5 seconds very stretched exposure of heart nebula under bortle 7 skies with a Ha filter on the 1600MM. (500mm FL, f/6.25. Not taken by me)

Wow you could even do deep sky imaging with an SE mount if you can get detail like that in such short exposures!  It's fine up to 30 sec exposures.

Well yes, but you see, the price is... pricey.
And doing sub 30s exposures really does not let the camera shoot to its full potential.

A-L-E-X
Star Engineer
Posts: 2305
Joined: 06 Mar 2017

Astrophotography

Phunnie wrote:
A-L-E-X wrote:
Phunnie wrote:
If you shoot narrowband you will most likely be shooting with a monochrome camera. Shooting in narrowband also won't increase the exposure time per frame on a target. You get a higher SNR as you remove light pollution and sky glow for the same exposure time. The exposure time can also vary quite a bit depending on the target and the FL. Dedicated mono cameras are much more sensitive than DSLR's and thus increase SNR even more. I'm currently waiting for my ZWO ASI 1600MM cooled to arrive so I can start shooting essentially noiseless shots under Bortle 8 skies
Example of a 5 seconds very stretched exposure of heart nebula under bortle 7 skies with a Ha filter on the 1600MM. (500mm FL, f/6.25. Not taken by me)

Wow you could even do deep sky imaging with an SE mount if you can get detail like that in such short exposures!  It's fine up to 30 sec exposures.

Well yes, but you see, the price is... pricey.
And doing sub 30s exposures really does not let the camera shoot to its full potential.

How do you feel about stacking?  I've been playing with DSS and wonder if stacking 40 15 sec exposures will result in a better SNR than doing one 10 min exposure?  I wonder if it will help with light pollution too.

Phunnie
Space Pilot
Posts: 134
Joined: 02 Aug 2017
Contact:

Astrophotography

A-L-E-X wrote:
Phunnie wrote:
A-L-E-X wrote:
Wow you could even do deep sky imaging with an SE mount if you can get detail like that in such short exposures!  It's fine up to 30 sec exposures.

Well yes, but you see, the price is... pricey.
And doing sub 30s exposures really does not let the camera shoot to its full potential.

How do you feel about stacking?  I've been playing with DSS and wonder if stacking 40 15 sec exposures will result in a better SNR than doing one 10 min exposure?  I wonder if it will help with light pollution too.

It won't be like a 10 mins exposure, but it will definitely still go very far as to increasing SNR. Just make sure you take callibration frames too (flat, dark, bias.) Extremely important no matter what camera you use.

In other news, I managed to finally make use of my new camera and got 3 hours of Ha data on IC 1396 last night. Now I just need 3 hours of OIII and 3 hours of SII approx to make my first fully colored narrowband image In retrospect I wish I had chosen a brighter first target as this one is unbelievably faint. I attempted it on my DSLR before but I just could not pick up any significant amount of signal over my light polluted skies. Well it's not like I have many choices anyways right now being pretty far north so eh, can't complain.

single frame comparison with DSLR: