ES HR and camera

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turboscrew
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ES HR and camera

#1

Post by turboscrew »


How do you use a camera with Explore Scientific HR coma corrector?
I understood that for photography you are supposed to remove the CC's helical focuser, and you use the telescope focuser to get the CC to correct position.
How do you focus your camera then?

The manual says:
For Astrophotography the helical focuser of the HR Coma Correctors has to be removed.
- Juha

Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5

I don't suffer from insanity. I'm enjoying every minute of it.

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Re: ES HR and camera

#2

Post by SkyHiker »


turboscrew wrote: Tue Sep 28, 2021 2:58 pm How do you use a camera with Explore Scientific HR coma corrector?
I understood that for photography you are supposed to remove the CC's helical focuser, and you use the telescope focuser to get the CC to correct position.
How do you focus your camera then?

The manual says:
For Astrophotography the helical focuser of the HR Coma Correctors has to be removed.
For AP, the combined telescope + CC is the lens. Use the telescope's focuser to focus it on the sensor.

There's probably something I misunderstand?
... Henk. :D Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall, Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS, DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK, Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17", Website:Henk's astro images
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Re: ES HR and camera

#3

Post by turboscrew »


SkyHiker wrote: Tue Sep 28, 2021 5:36 pm
turboscrew wrote: Tue Sep 28, 2021 2:58 pm How do you use a camera with Explore Scientific HR coma corrector?
I understood that for photography you are supposed to remove the CC's helical focuser, and you use the telescope focuser to get the CC to correct position.
How do you focus your camera then?

The manual says:
For Astrophotography the helical focuser of the HR Coma Correctors has to be removed.
For AP, the combined telescope + CC is the lens. Use the telescope's focuser to focus it on the sensor.

There's probably something I misunderstand?
The CC itself is "focused" with the telescope's focuser. I think the camera focusing should be done with something between the CC and camera. Or maybe I have misunderstood something. Maybe I don't have a clue how CC actually works.
- Juha

Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5

I don't suffer from insanity. I'm enjoying every minute of it.

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Re: ES HR and camera

#4

Post by SkyHiker »


turboscrew wrote: Tue Sep 28, 2021 6:06 pm
SkyHiker wrote: Tue Sep 28, 2021 5:36 pm
turboscrew wrote: Tue Sep 28, 2021 2:58 pm How do you use a camera with Explore Scientific HR coma corrector?
I understood that for photography you are supposed to remove the CC's helical focuser, and you use the telescope focuser to get the CC to correct position.
How do you focus your camera then?

The manual says:
For AP, the combined telescope + CC is the lens. Use the telescope's focuser to focus it on the sensor.

There's probably something I misunderstand?
The CC itself is "focused" with the telescope's focuser. I think the camera focusing should be done with something between the CC and camera. Or maybe I have misunderstood something. Maybe I don't have a clue how CC actually works.
The CC will change your focal length somewhat. For instance my Paracorr II changes it from 1200 to 1380 mm. That does not mean that I have to add 180 mm worth of extension tubes. It will bring the light to focus not far from the CC-less case. Try focusing without the CC first, then put the CC in between and move the camera around to see where it focuses. If the extension length is a problem just hold it in your hand, it's easy enough to tell when it is in focus. I mean daytime tests. If the focus has moved inward (hard to believe) then put longer collimation screws in.
... Henk. :D Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall, Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS, DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK, Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17", Website:Henk's astro images
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Re: ES HR and camera

#5

Post by turboscrew »


SkyHiker wrote: Tue Sep 28, 2021 7:31 pm
turboscrew wrote: Tue Sep 28, 2021 6:06 pm
SkyHiker wrote: Tue Sep 28, 2021 5:36 pm
For AP, the combined telescope + CC is the lens. Use the telescope's focuser to focus it on the sensor.

There's probably something I misunderstand?
The CC itself is "focused" with the telescope's focuser. I think the camera focusing should be done with something between the CC and camera. Or maybe I have misunderstood something. Maybe I don't have a clue how CC actually works.
The CC will change your focal length somewhat. For instance my Paracorr II changes it from 1200 to 1380 mm. That does not mean that I have to add 180 mm worth of extension tubes. It will bring the light to focus not far from the CC-less case. Try focusing without the CC first, then put the CC in between and move the camera around to see where it focuses. If the extension length is a problem just hold it in your hand, it's easy enough to tell when it is in focus. I mean daytime tests. If the focus has moved inward (hard to believe) then put longer collimation screws in.
Tha manual only gives instructions for setting it up for visual. In that case some frosted tape should be put on the top of the helical focuser to be used as a screen, and the helical focuser should be turned into the nautral position (13.5 mm). Then using something bright, like moon, one uses the telescope focuser to get a well focused image on the tape-screen. Then the telescope focuser should be locked, the tape removed. After that the eyepieces should be focused using the CC's helical focuser only. One shouldn't touch the telescope's own focuser.

I got the impression, that the CC works as it should only when it is placed right in relation to the telescope's focal point, and that's done with the telescope's focuser. And if the CC's helical focuser needs to be removed for astrophotograpy, there's no focuser left to do the camera focusing. Am I totally in the woods?

The manual says also:
The HR coma corrector
is delivered such that you have the focus position 55mm behind the corrector with the T2-adaptor. Those 55mm are ideal for a
200mm f/4. If you are using telescopes with a longer focal length this optimal focus position is shifting outwards. Here are a few
numbers:
800mm focal length: 0mm
1000mm focal length: +1mm
1200mm focal length: +1,5mm
1600mm focal length: +2mm
2000mm+x focal length: +2,5mm
Please don ́t take those number as gospel
- Juha

Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5

I don't suffer from insanity. I'm enjoying every minute of it.

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Re: ES HR and camera

#6

Post by SkyHiker »


turboscrew wrote: Tue Sep 28, 2021 8:33 pm
SkyHiker wrote: Tue Sep 28, 2021 7:31 pm
turboscrew wrote: Tue Sep 28, 2021 6:06 pm

The CC itself is "focused" with the telescope's focuser. I think the camera focusing should be done with something between the CC and camera. Or maybe I have misunderstood something. Maybe I don't have a clue how CC actually works.
The CC will change your focal length somewhat. For instance my Paracorr II changes it from 1200 to 1380 mm. That does not mean that I have to add 180 mm worth of extension tubes. It will bring the light to focus not far from the CC-less case. Try focusing without the CC first, then put the CC in between and move the camera around to see where it focuses. If the extension length is a problem just hold it in your hand, it's easy enough to tell when it is in focus. I mean daytime tests. If the focus has moved inward (hard to believe) then put longer collimation screws in.
Tha manual only gives instructions for setting it up for visual. In that case some frosted tape should be put on the top of the helical focuser to be used as a screen, and the helical focuser should be turned into the nautral position (13.5 mm). Then using something bright, like moon, one uses the telescope focuser to get a well focused image on the tape-screen. Then the telescope focuser should be locked, the tape removed. After that the eyepieces should be focused using the CC's helical focuser only. One shouldn't touch the telescope's own focuser.

I got the impression, that the CC works as it should only when it is placed right in relation to the telescope's focal point, and that's done with the telescope's focuser. And if the CC's helical focuser needs to be removed for astrophotograpy, there's no focuser left to do the camera focusing. Am I totally in the woods?

The manual says also:
The HR coma corrector
is delivered such that you have the focus position 55mm behind the corrector with the T2-adaptor. Those 55mm are ideal for a
200mm f/4. If you are using telescopes with a longer focal length this optimal focus position is shifting outwards. Here are a few
numbers:
800mm focal length: 0mm
1000mm focal length: +1mm
1200mm focal length: +1,5mm
1600mm focal length: +2mm
2000mm+x focal length: +2,5mm
Please don ́t take those number as gospel
OK, so position the CC at 55+1.5=56.5 mm away from the sensor using extension rings, then use the telescope's focuser to focus. The visual instructions are irrelevant.
... Henk. :D Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall, Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS, DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK, Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17", Website:Henk's astro images
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Re: ES HR and camera

#7

Post by turboscrew »


Now that the focusing a camera, with coma corrector in place, became clear ( viewtopic.php?f=108&t=20702 ), my next headache is, what kind of extenders to use, if I might want to put something, like barlow, in between?

I don't think there are many barlows with T2-threads around.

Ho do people handle this situation?
- Juha

Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5

I don't suffer from insanity. I'm enjoying every minute of it.

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Re: ES HR and camera

#8

Post by turboscrew »


My guess now is that you usually don't use coma corrector with barlow, because when you use barlow, the target is usually small enough to fit into the small area around the optical axis that doesn't really suffer noticeably from coma.

If you use both (might be sometimes useful, like, for photographing the moon) you use 2" barlow into which you put the coma corrector, and the rest is handled with 2" to T2 adapter, T2 extension tubes/rings and T2 to C-mount adapter.
The extension tube lengths need to be recalculated due to the shifted focal plane, though.

Does this make any sense?
- Juha

Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5

I don't suffer from insanity. I'm enjoying every minute of it.

Image
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