Getting a Megrez 80 mm into focus with a Medae DSI

[g__day (Matthew)]

Guys I'm challenged and a bit stumped by this. I have a Meg that focuses using a 22mm eyepiece with the barrel extended only 1~2 mm from the start of the OTA tube.

When I switch to a Meade DSI to try astrophotography or auto-guiding I can't bring anything into focus, the rack and pinnion focuser would want to move the tube back into itself about 4~5 mm past its most retracted position.

Any ideas of what I can do to get past this? Should I try removing the 2" diagonal and extending the tube further to make up for the difference in light path length?

[Striker (Tony)]

Try a 2" extension tube and then the DSI without the diagonal.

Not sure what the DSI is equivalent to but its around a 6 mm eyepiece.

[jase (Jason)]

Hi G_Day,
I haven't researched the Meg or DSI. How much back focus do you have on the meg and how far away is the DSI chip from the nose peice? (Are you talking about forward focus?)

IMHO, I would not use a diagonal for imaging, only guiding. The more refractive/reflective surfaces you have before the imaging chip the less light will reach the chip. Sure, I may sound extreme, but if your going to do it, do it right. A note on guiding with a diagonal, make sure you calibrated the guider as the mirror may flip the axis, so X and Y measures may reverse (vice-versa). Not a big one as the software should compensate for this.

[Harb]

I use a megrez 80 and a DSI Pro......Remove the Diagonal and as mentioned us a 2" Extender only.....

Good Luck

[Harb]

Fogot to mention I usually remove everything and fit a meade 2" flip mirror with no spacers/diags at all.....just the 2" focusing tube itself

[Dennis]

With a WO 80mm F7 Megrez Apo ED II this is my auto guiding train:

WO 80mm OTA + WO 2” extender + WO 2” diagonal + Orion Deep Sky Star Shooter.

Cheers

Dennis