Guiding and findercope

[AlistairW]

Hello,

This may seem an obvious question, but here goes.

If I point my scope to a star and look through live view on my Canon camera then I have no trouble in centering it up . Now if i turn on my guidescope and PHD, should that star be center on the display in PHD too ? - Also if it is not center then how would that effect guiding overall ? ( Something else I just thought - I use a QHY5L with a finderscope - does the orientation of the camera in the finderscope matter ?)

Thanks

Alistair

[Ouroboros]

I doubt it matters at all. I use a very similar arrangement. I do make sure the guide camera and DSLR are centred on roughly the same region of the sky. But that's so I can easily re-point the scope if things drift off for some reason.

[Tinker1947]

You will need guide scope rings so that you can adjust the star in your camera sensor to match the one on the PHD screen, i use this method with EQMod to centre DSO's it works very well when both screens are aligned......

My guide scope

[Jarno_c]

There's absolutely no need for your guidescope and your main scope to be absolutely parallel. It's far more important that the connection between the two is very rigid so they'll move as one. Think of it this way: PHD doesn't care whether your guide star is in the center or near the edge of the FOV (within reason of course). Now if you were to select a star near the edge of the FOV and then adjust your guidescope -without moving the main scope-  to center the star, would that change anything as far as PHD is concerned? Ergo, there's no need to align the two scopes.

Having said that, I'd still recommend to have them more or less aligned for practical reasons. Firstly, if you're imaging something at lower altitude and there's a large pointing difference between the main and guide scope, atmospheric refraction could theoretically cause the guide scope to see the star move differently than the main scope. Second, I like to use my guidescope as a finder. The Lodestar is more sensitive than my D810 so I usually work the other way around: I first center the object in the guidescope and then check if it's centered in the DSLR. And since the D810 doesn't have a swiveling screen it's a lot more comfortable to look at the laptop screen than having to bend over to look at the camera screen.

The orientation of the guiding cam doesn't matter, that's why PHD does the calibration before guiding starts - so it'll know how the camera is oriented and how fast the mount moves. But once again I prefer to more or less align the camera with the mount for practical reasons. Centering an object through the guidescope is easier when the buttons on the hand controller align with what I'm seeing on the screen.

Jarno

[Tinker1947]

There's absolutely no need for your guidescope and your main scope to be absolutely parallel. It's far more important that the connection between the two is very rigid so they'll move as one. Think of it this way: PHD doesn't care whether your guide star is in the center or near the edge of the FOV (within reason of course). Now if you were to select a star near the edge of the FOV and then adjust your guidescope -without moving the main scope-  to center the star, would that change anything as far as PHD is concerned? Ergo, there's no need to align the two scopes.

Having said that, I'd still recommend to have them more or less aligned for practical reasons. Firstly, if you're imaging something at lower altitude and there's a large pointing difference between the main and guide scope, atmospheric refraction could theoretically cause the guide scope to see the star move differently than the main scope. Second, I like to use my guidescope as a finder. The Lodestar is more sensitive than my D810 so I usually work the other way around: I first center the object in the guidescope and then check if it's centered in the DSLR. And since the D810 doesn't have a swiveling screen it's a lot more comfortable to look at the laptop screen than having to bend over to look at the camera screen.

The orientation of the guiding cam doesn't matter, that's why PHD does the calibration before guiding starts - so it'll know how the camera is oriented and how fast the mount moves. But once again I prefer to more or less align the camera with the mount for practical reasons. Centering an object through the guidescope is easier when the buttons on the hand controller align with what I'm seeing on the screen.

Jarno

My point with aligning the guide scope with the main scope allows me to use the handset PA option viewing the chosen star on the PHD screen not the Polar scope, so adjustments are while i sit next the scope not on my knees, its also very handy when EQMod slews to a faint DSO, the guide scope + lodestar will show this on the PHD screen and centering it so its in the middle of the CCD Sensor is positive and easy.....

[AlistairW]

Many thanks for the replys !