I have the Sky-Watcher ED80 Pro Gold tube and its F7.5. I have the Powermate 2.5x barlow and Celestron 2x barlow. Camera is ZWO ASI120MM-S. I know its not ideal but is it pointless to stack the two barlows to get Mars Jupiter and Saturn a little larger. I am sure its fine with shooting the moon. I shoot mostly DSOs so this is new to me. I included a test shot of Jupiter through smoke using an IR filter and the 2.5x barlow.