Hello, Comparing the: - Orion Newtonian Astrograph 10-inch f/3.9 ($680) + coma corrector ($280) - Orion Ritchey-Chrétien 8-inch f/8.0 ($1000) Both are almost the same price and both have bafflles inside the tube to increase contrast. With the coma corrector the newtonian will reach flat field images as the RC. So..... Would it be better the astrograph that is faster and with more aperture? Or... Is the 8-inch RC with hyperbolic mirrors superior to the 10-inch newtonian with parabolic mirror and coma corrector?
Hi Ken many thanks for your answer about visual use with the RC scope(8inch). Your demo mentions possibly a focal reducer.Would you recommend one for this scope ,also which separate guide scope would you recommend. Also what ccd camera(Orion brand) would you choose for the RC. My interests for DSO,s mainly include PN,s nebulas, and galaxies. Many thanks for your reply! Good work! Clear skies. Jeff
+Jeff Dunne Hi Jeff, it all depends one what type of object you want to image to determine if you want a focal reducer. If you're trying to image a very large nebula that spills over the edges of the frame, then a focal reducer can help fit it all into the camera's field of view, as well as shorten the exposure. But a small object would benefit from the native higher focal length in order to give it a good scale on the chip. As for a guide scope, my favorite is the 60mm guidescope, #13008. www.telescope.com/catalog/search.cmd?form_state=searchForm&siteCode=US&keyword=13008 And for imaging, check out the G3 (either color or monochrome), as a good starting point for getting into CCD astronomy. Thanks! -Ken Orion Telescopes
Hi Andy, No, that combo should be fine on the CGEM mount. Celestron states a 40 lbs capacity for the CGEM, and the RC is just under 20 lbs, and everything you mentioned to add would still be well under the capacity limit. You may need an extra counterweight depending on how many you currently have, but it should work fine once balanced. Thanks -Ken Orion Telescopes
Hi Ken, Does the focuser has any threads on the camera side or only the 2" compression ring for the connection? It would be nice to thread the camera directly to the focuser.
Hi Doramason, There are no threads on the end of the focuser for direct attachment. The reason is that it accepts a 2" eyepiece, and in order to have t-threads, the size of the focuser would have to be smaller (42mm or 48mm). You can use a 5308 2" nozzle with a t-thread coupled with a t-ring for your camera (5205 nikon, 5224 Canon). Thanks! -Ken Orion Telescopes
Thanks for the answer Ken. I didn't mean 48 or 42mm but M69 or something like that which is not uncommon for focusers to have it. It's a pity that it isn't avaliable, it would be nice to have it to prevent flexure.
Hi Ken, thanks for this clear presentation. I'm considering this 8 inch RC but have read threads about the difficulty to collimate an RC, what's your opinion on this? And would the 2 inch focusser be good enough to keep my zwo1600mm Pro and 8 position filterwheel in place? Thanks again for these presentations, really informative and helpful.
The focuser runs on linear bearings and is quite sturdy, you shouldn't have trouble with your camera and filter wheel. RC's can be tricky to collimate. A collimation eyepiece with crosshairs is a good tool, and practice can speed up the process.
RC collimation is hugely difficult, because there are 6 elements (3 screws on each of the primary and secondary) that interact. Those six screws control 5 independent degrees of freedom (tilt in X/Y for primary and secondary, plus central distance between primary and secondary). Each DOF depends on multiple screws, so the DOFs "mix" (interact with each other). So there's no optimization algorithm (contour following) that can be done in steps independently; the optimization minima are peaks and valleys and not a monotonic slope. And if the collimation is just a little off, aberrations result which ruin the image resolution, unlike a newtonian where the image just shifts. Simple tools like a collimation eyepiece don't solve this. You need three or more point source test targets at infinity around the edge of the FOV for a collimation target, which means an elaborate artificial star setup indoors, because there's no bright real stars that provide that pattern. The artificial stars themselves have to be optically precise, an apparent size on the order of the telescope's resolution, to be able to detect aberrations from mis-collimation. Both the manufacturer and the dealer are derelict in not explaining the collimation difficulty, or providing any effective tools or process.
@@RichardKinch Thanks Richard, i found out the hard way. Tried to collimate my RC for days with simple collimation tools but wasn't succesful. I switched to the Celestron Edge HD 8", which is much easier to collimate but also more expensive. Cheers.
Hi Ken is this RC also good for visual use as well as AP? Really like the product. Your demo,s are excellent.I like the optics of the RC and tube length over newts.Thank you for responding. Clear skies! Jeff
+Jeff Dunne Hi Jeff, The RC would work for visual use, but it's really optimized for photography. What that means is that even though you will get a good visual image, you won't have the same contrast and resolution visually over a similar sized Newtonian. The reason is that the secondary mirror is much larger over a comparable newt. That gives you better photographic performance for a large format chip, but a little less visual performance due to the large obstruction. Thanks -Ken Orion Telescopes
@@oriontelescopes The MTF of an RC is deficient at low spatial resolutions. Edges look sharp, but broader features suffer loss of contrast. Star fields are stunning, but planets are washed out. This low-spatial-frequency contrast deficiency is the trade off for the better correction of aberrations, inherent to the RC.
Hi Ken, is this mount Orion Atlas Pro AZ/EQ-G will hold the 10 inch Ritchey-Chretien ? Or you will feel little vibration while using it? Including astrograph accessories (filter wheel,camera, barlow)
+Страж Истины Hello, The 10" weighs 35lbs, so with your camera and attachments you might get to around 40 lbs, which is still under the weight limit of the mount. So under calm conditions, I think it would work fine, but if there is any kind of breeze, then you might notice a little extra vibration. If you are going to be using it in those conditions, I would recommend getting some time of wind break around the scope, or moving up to a larger mount if a windbreak is not feasible. Thanks -Ken Orion Telescopes
Hi Ken, I have a HEQ 5 mount. I don't think the Losmandy dove tail will fit my mount. Looks like the "top" dovetail would. are they interchangeable? Can i get a smaller dovetail to fit my mount for this scope?
Hi Nick. Yes, the "top" dovetail would work - you can mount the optical tube from either dovetail so you can certainly flip the OTA upside-down and it'll mount to your HEQ 5.
iOptron rates the CEM60 at 60 pounds of payload minus the 20 pound counterweight, this telescope is just under 20 pounds so there should be a good amount of extra capacity for guide scope and cameras.
+Quad Bot Hi Quad, yes this should work fine for a full frame camera. It includes a 2" focuser, so there may be a slight amount of vignetting at the edges, but nothing a flat field exposure can't fix. Thanks! -Ken Orion Telescopes
Matthew bail Hi Matthew, You won't be using a laser on this RC, but instead a collimation cap, or perhaps a Cheshire eyepiece like our #3640. If you want more detailed instructions, you can download the manual for this scope on our website and read about collimation in the appendix. Thanks -Ken Orion Telescopes
I have this scope. Cheshire is not enough, I need a laser to make a perfect collimation like Howie Glatter's. It takes me time to understand how to collimate this scope, almost frustrated because of this alone.
Collimating an RC indoors requires an multiple artificial star rig such as a multiple laser fixture which is itself collimated. Otherwise you're hunting around without direction and can't find the goal. It's like trying to sniff the direction of an odor when you can't walk around or turn your head.
Yes it's possible. However this 8" RC Astrograph features a Losmandy style bar for mounting, so you would need something like our Losmandy to Vixen (narrow to wide) adapter to connect it to the Celestron AVX: bit.ly/2JIyYc0
![[안방1열 풀캠4K] 베이비몬스터 'DRIP' (BABYMONSTER FullCam)│@SBS Inkigayo 241110](http://i.ytimg.com/vi/AQ4RIghEvUs/mqdefault.jpg)
Hello,
Comparing the:
- Orion Newtonian Astrograph 10-inch f/3.9 ($680) + coma corrector ($280)
- Orion Ritchey-Chrétien 8-inch f/8.0 ($1000)
Both are almost the same price and both have bafflles inside the tube to increase contrast. With the coma corrector the newtonian will reach flat field images as the RC.
So..... Would it be better the astrograph that is faster and with more aperture?
Or... Is the 8-inch RC with hyperbolic mirrors superior to the 10-inch newtonian with parabolic mirror and coma corrector?
Hi Ken many thanks for your answer about visual use with the RC scope(8inch). Your demo mentions possibly a focal reducer.Would you recommend one for this scope ,also which separate guide scope would you recommend. Also what ccd camera(Orion brand) would you choose for the RC. My interests for DSO,s mainly include PN,s nebulas, and galaxies. Many thanks for your reply! Good work! Clear skies. Jeff
+Jeff Dunne
Hi Jeff, it all depends one what type of object you want to image to determine if you want a focal reducer. If you're trying to image a very large nebula that spills over the edges of the frame, then a focal reducer can help fit it all into the camera's field of view, as well as shorten the exposure. But a small object would benefit from the native higher focal length in order to give it a good scale on the chip.
As for a guide scope, my favorite is the 60mm guidescope, #13008.
www.telescope.com/catalog/search.cmd?form_state=searchForm&siteCode=US&keyword=13008
And for imaging, check out the G3 (either color or monochrome), as a good starting point for getting into CCD astronomy.
Thanks!
-Ken
Orion Telescopes
Hi Ken,
Would this be too heavy for a CGEM (if you also include ST80 guide scope and DSLR, etc)?
Thanks.
Hi Andy,
No, that combo should be fine on the CGEM mount. Celestron states a 40 lbs capacity for the CGEM, and the RC is just under 20 lbs, and everything you mentioned to add would still be well under the capacity limit. You may need an extra counterweight depending on how many you currently have, but it should work fine once balanced.
Thanks
-Ken
Orion Telescopes
Hi Ken,
Does the focuser has any threads on the camera side or only the 2" compression ring for the connection? It would be nice to thread the camera directly to the focuser.
Hi Doramason,
There are no threads on the end of the focuser for direct attachment. The reason is that it accepts a 2" eyepiece, and in order to have t-threads, the size of the focuser would have to be smaller (42mm or 48mm).
You can use a 5308 2" nozzle with a t-thread coupled with a t-ring for your camera (5205 nikon, 5224 Canon).
Thanks!
-Ken
Orion Telescopes
Thanks for the answer Ken. I didn't mean 48 or 42mm but M69 or something like that which is not uncommon for focusers to have it. It's a pity that it isn't avaliable, it would be nice to have it to prevent flexure.
Hi Ken, thanks for this clear presentation. I'm considering this 8 inch RC but have read threads about the difficulty to collimate an RC, what's your opinion on this? And would the 2 inch focusser be good enough to keep my zwo1600mm Pro and 8 position filterwheel in place? Thanks again for these presentations, really informative and helpful.
The focuser runs on linear bearings and is quite sturdy, you shouldn't have trouble with your camera and filter wheel. RC's can be tricky to collimate. A collimation eyepiece with crosshairs is a good tool, and practice can speed up the process.
are the rc collimate so big of a problem? i mean no1 start astrophotography because it is easy.
RC collimation is hugely difficult, because there are 6 elements (3 screws on each of the primary and secondary) that interact. Those six screws control 5 independent degrees of freedom (tilt in X/Y for primary and secondary, plus central distance between primary and secondary). Each DOF depends on multiple screws, so the DOFs "mix" (interact with each other). So there's no optimization algorithm (contour following) that can be done in steps independently; the optimization minima are peaks and valleys and not a monotonic slope. And if the collimation is just a little off, aberrations result which ruin the image resolution, unlike a newtonian where the image just shifts. Simple tools like a collimation eyepiece don't solve this. You need three or more point source test targets at infinity around the edge of the FOV for a collimation target, which means an elaborate artificial star setup indoors, because there's no bright real stars that provide that pattern. The artificial stars themselves have to be optically precise, an apparent size on the order of the telescope's resolution, to be able to detect aberrations from mis-collimation. Both the manufacturer and the dealer are derelict in not explaining the collimation difficulty, or providing any effective tools or process.
@@RichardKinch Thanks Richard, i found out the hard way. Tried to collimate my RC for days with simple collimation tools but wasn't succesful. I switched to the Celestron Edge HD 8", which is much easier to collimate but also more expensive. Cheers.
Hi Ken is this RC also good for visual use as well as AP? Really like the product. Your demo,s are excellent.I like the optics of the RC and tube length over newts.Thank you for responding. Clear skies! Jeff
+Jeff Dunne
Hi Jeff,
The RC would work for visual use, but it's really optimized for photography. What that means is that even though you will get a good visual image, you won't have the same contrast and resolution visually over a similar sized Newtonian. The reason is that the secondary mirror is much larger over a comparable newt. That gives you better photographic performance for a large format chip, but a little less visual performance due to the large obstruction.
Thanks
-Ken
Orion Telescopes
@@oriontelescopes The MTF of an RC is deficient at low spatial resolutions. Edges look sharp, but broader features suffer loss of contrast. Star fields are stunning, but planets are washed out. This low-spatial-frequency contrast deficiency is the trade off for the better correction of aberrations, inherent to the RC.
Hi Ken, is this mount Orion Atlas Pro AZ/EQ-G will hold the 10 inch Ritchey-Chretien ? Or you will feel little vibration while using it? Including astrograph accessories (filter wheel,camera, barlow)
+Страж Истины
Hello,
The 10" weighs 35lbs, so with your camera and attachments you might get to around 40 lbs, which is still under the weight limit of the mount. So under calm conditions, I think it would work fine, but if there is any kind of breeze, then you might notice a little extra vibration. If you are going to be using it in those conditions, I would recommend getting some time of wind break around the scope, or moving up to a larger mount if a windbreak is not feasible.
Thanks
-Ken
Orion Telescopes
+oriontelescopes Thanks, i'll probably take the Orion HDX110 then
Hi Ken,
I have a HEQ 5 mount. I don't think the Losmandy dove tail will fit my mount. Looks like the "top" dovetail would. are they interchangeable? Can i get a smaller dovetail to fit my mount for this scope?
Hi Nick. Yes, the "top" dovetail would work - you can mount the optical tube from either dovetail so you can certainly flip the OTA upside-down and it'll mount to your HEQ 5.
This is no longer for sale?
hello. can it be mounted on bresser exos 2 GOTO ? will it work without problem?thanks
Hi Ken, Can I Mount This Telescope Into A iOptron CEM60 Mount?
iOptron rates the CEM60 at 60 pounds of payload minus the 20 pound counterweight, this telescope is just under 20 pounds so there should be a good amount of extra capacity for guide scope and cameras.
+oriontelescopes Would this work well with a full frame camera by any chance?
+Quad Bot
Hi Quad, yes this should work fine for a full frame camera. It includes a 2" focuser, so there may be a slight amount of vignetting at the edges, but nothing a flat field exposure can't fix.
Thanks!
-Ken
Orion Telescopes
can it be used just for viewing ?
It _can_ but its much better fitted for imaging according to Orion Telescopes.
hello, how do you collimate this telescope? with a laser like a regular newtonian? thanks
Matthew bail
Hi Matthew,
You won't be using a laser on this RC, but instead a collimation cap, or perhaps a Cheshire eyepiece like our #3640. If you want more detailed instructions, you can download the manual for this scope on our website and read about collimation in the appendix.
Thanks
-Ken
Orion Telescopes
oriontelescopes ok thanks ken, ill take a look at the manual
I have this scope. Cheshire is not enough, I need a laser to make a perfect collimation like Howie Glatter's. It takes me time to understand how to collimate this scope, almost frustrated because of this alone.
Collimating an RC indoors requires an multiple artificial star rig such as a multiple laser fixture which is itself collimated. Otherwise you're hunting around without direction and can't find the goal. It's like trying to sniff the direction of an odor when you can't walk around or turn your head.
can I mount this to a celestron AVX?
Yes it's possible. However this 8" RC Astrograph features a Losmandy style bar for mounting, so you would need something like our Losmandy to Vixen (narrow to wide) adapter to connect it to the Celestron AVX: bit.ly/2JIyYc0