Guide cam and Barlow

[Earl]

Can you use a Barlow on a OAG which has a reduced input going into it?

This is to increase the focal length the camera on the OAG for more precise guiding.

I see problems getting it all to focus but curios.

[kalasinman]

I think that's a bit complicated. Getting 2 cameras parfocal takes a little work. The small pixels and chip of my QHY5L-II make me a little oversampled anyway. Imaging at 1.3" and guiding at 1.08" . Curious as to why you would need more? Isn't too much oversampling a problem. Sorry Earl, I'm sure you know more than me about it. I will say guiding with the OAG has been good, considering I am clueless.--Jack

[Earl]

Oversampling is not really and issue with the guide cam, however id like to get a longer focal length as that should in theory make guiding better? if using a separate scope its easy enough to do just not sure with a reduced scope and oag not to sure if i can add a barlow in and get it to focus either its a random musing. (do that lots when its cloudy, then fight with gear when its clear LOL )

Does it make any difference, Im not sure

[kalasinman]

So true. I fought ikt last night. This time of year, often cloudy till after midnight. Old guys like me don't like late nights as much as when 30ish.

From the short experience I've had, my guider is quite sensitive, but if I could change anything a reducer would be more useful than a barlow, I think. Don't know howthat would work, though. guiding through the optics of the main scope really narrows the FOV from a guide scope. I do think that gives much better guiding. Faster responses.

[Xplode]

What you want to do will only cause problems and since you guide at the focal length of the main scope the accuracy is much better than you actually need. An accuracy to around 0.15-0.20 of a pixel is usual if you use PHD and the mount works great.

Because of the subpixel guiding you are already guiding at the maximum resolution the atmosphere allows so there is no gain in guiding at a longer focal length.

[Earl]

thanks for the clarfication