HEQ5 enaugh for Skywatcher 200pds? - Forums

Topic starter

Mar 19, 2023 · Edited: Mar 19, 2023

Hey there,

I've been imaging with a 130slt on a heq5 for some time now and I just want a bit more mirror size. 8 inches seam to be the limit of the heq5.
So now my question, is the heq5 enaugh for a small guidescope and a camera (not a DSLR) paired with a 200pds or equivalent?
My imaging location is fairly save in terms of winds if that would be a problem.

Clear nights,
Philip

average_pluto_enjoyer

Mar 19, 2023

Yes. I have a 200PDS with a DSLR, Coma Corrector and USB Hub, which is all mounted on a Celestron CG5-GT. The CG5 Supposedly has the same weight capacity as the Heq5 but I think it's actually lower, as its the same model as the skywatcher EQ5 which only has a payload of ~7kg, and I can easily get sub-arcsecond guiding, although I may have 1 or 2 subs ruined by shaking. But yes the Heq5 can handle the weight and theres definitely no point in buying an entirely new mount which would just be overkill, at least in my opinion.

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PhilosaurAstro

Topic starter

Mar 19, 2023

Yes. I have a 200PDS with a DSLR, Coma Corrector and USB Hub, which is all mounted on a Celestron CG5-GT. The CG5 Supposedly has the same weight capacity as the Heq5 but I think it's actually lower, as its the same model as the skywatcher EQ5 which only has a payload of ~7kg, and I can easily get sub-arcsecond guiding, although I may have 1 or 2 subs ruined by shaking. But yes the Heq5 can handle the weight and theres definitely no point in buying an entirely new mount which would just be overkill, at least in my opinion.

I thank you for answering. Great, I am thinking about upgrading the scope. You said that you have a coma corrector. Which one do you use?

Brian Puhl

IOTD Staff

Mar 19, 2023

I wouldn't do it. 8" newtonian will put you into sub arc-second sampling, or close to, depending on your coma corrector. I run mine on an EQ6, with OAG my guiding gets down into the 0.2 arc second territory… but typically around 0.4-0.5" The second a light wind kicks up, i'm easily 0.7 arc second, which puts me out of the 70% of image scale guide rule. Once you sling a 200PDS + imaging gear, you're pretty much at max capacity for the HEQ5.

Since you have it, you could try it, but I wouldn't expect it to work very well.

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PhilosaurAstro

Topic starter

Mar 19, 2023

I wouldn't do it. 8" newtonian will put you into sub arc-second sampling, or close to, depending on your coma corrector. I run mine on an EQ6, with OAG my guiding gets down into the 0.2 arc second territory... but typically around 0.4-0.5" The second a light wind kicks up, i'm easily 0.7 arc second, which puts me out of the 70% of image scale guide rule. Once you sling a 200PDS + imaging gear, you're pretty much at max capacity for the HEQ5.

Since you have it, you could try it, but I wouldn't expect it to work very well.

Thank you for your reply, I Don’t have the scope yet. I looked my sampling up and I have a .78 arc second one. My guiding is usually a bit better but may not be that accurate because of my very small guide scope. Maybe I am gonna go save and choose a 6 inch. Bdw can you tell me what the 70% rule is?

average_pluto_enjoyer

Mar 19, 2023

Yes. I have a 200PDS with a DSLR, Coma Corrector and USB Hub, which is all mounted on a Celestron CG5-GT. The CG5 Supposedly has the same weight capacity as the Heq5 but I think it's actually lower, as its the same model as the skywatcher EQ5 which only has a payload of ~7kg, and I can easily get sub-arcsecond guiding, although I may have 1 or 2 subs ruined by shaking. But yes the Heq5 can handle the weight and theres definitely no point in buying an entirely new mount which would just be overkill, at least in my opinion.

I thank you for answering. Great, I am thinking about upgrading the scope. You said that you have a coma corrector. Which one do you use?

I use the skywatcher 0.9x Coma Corrector, which gives me a pixel scale of ~1.16"/px (using canon 1100d) https://www.firstlightoptics.com/coma-correctors/skywatcher-coma-corrector.html

average_pluto_enjoyer

Mar 19, 2023

I wouldn't do it. 8" newtonian will put you into sub arc-second sampling, or close to, depending on your coma corrector. I run mine on an EQ6, with OAG my guiding gets down into the 0.2 arc second territory... but typically around 0.4-0.5" The second a light wind kicks up, i'm easily 0.7 arc second, which puts me out of the 70% of image scale guide rule. Once you sling a 200PDS + imaging gear, you're pretty much at max capacity for the HEQ5.

Since you have it, you could try it, but I wouldn't expect it to work very well.

What's your pixel scale with your main camera? I get guiding of ~0.8-1"/px, sometimes more on a very bad night and still get perfectly fine stars with a main pixel scale of 1.16"/px. I'm guessing how well using a heq5 would turn out depends on the pixel scale of the camera, as with a high pixel scale of >1"/px getting great guiding doesn't matter as much.

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Brian Puhl

IOTD Staff

Mar 20, 2023

I wouldn't do it. 8" newtonian will put you into sub arc-second sampling, or close to, depending on your coma corrector. I run mine on an EQ6, with OAG my guiding gets down into the 0.2 arc second territory... but typically around 0.4-0.5" The second a light wind kicks up, i'm easily 0.7 arc second, which puts me out of the 70% of image scale guide rule. Once you sling a 200PDS + imaging gear, you're pretty much at max capacity for the HEQ5.

Since you have it, you could try it, but I wouldn't expect it to work very well.

Thank you for your reply, I Don’t have the scope yet. I looked my sampling up and I have a .78 arc second one. My guiding is usually a bit better but may not be that accurate because of my very small guide scope. Maybe I am gonna go save and choose a 6 inch. Bdw can you tell me what the 70% rule is?

You should be guiding under 70% of your image scale for nice round stars. Thus meaning if your imaging scale is 1 arc second, your guiding should be 0.7 or less, to include the spikes.

I wouldn't do it. 8" newtonian will put you into sub arc-second sampling, or close to, depending on your coma corrector. I run mine on an EQ6, with OAG my guiding gets down into the 0.2 arc second territory... but typically around 0.4-0.5" The second a light wind kicks up, i'm easily 0.7 arc second, which puts me out of the 70% of image scale guide rule. Once you sling a 200PDS + imaging gear, you're pretty much at max capacity for the HEQ5.

Since you have it, you could try it, but I wouldn't expect it to work very well.

What's your pixel scale with your main camera? I get guiding of ~0.8-1"/px, sometimes more on a very bad night and still get perfectly fine stars with a main pixel scale of 1.16"/px. I'm guessing how well using a heq5 would turn out depends on the pixel scale of the camera, as with a high pixel scale of >1"/px getting great guiding doesn't matter as much.

I have two coma correctors, the paracorr puts me at 0.82" image scale. My guiding needs to be around 0.6" or better, which I can manage easily, provided the wind doesn't kick up.

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