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Hi everyone, I can't seem to find the answer for this, but I'd like to know whether a final integrated stack of a given total integration time is any different depending on the gain value used. i.e would 100 images at gain 0 yield the same SNR etc as 50 images at gain 139 for instance (or whatever gain may be the appropriate 1:1 direct comparison)? I'm thinking of trying out gain 0 as I have reasonably dark skies. I know gain is an effective way to reduce exposure time, but does it have an effect on total integration time required? Thanks, Matt

Hi Michael, Thanks very much for the detailed reply! Sorry for any confusion - my main concern is definitely the platau part way into in the south movements of the backlash test and what might be causing it. And secondly as you've highlighed in your example of the DEC axis struggling to come back in line. This is my second EQ6-R after the first had issues, and I'm worried this mount is faulty as well or at least in need of a decent adjustment. The mount is doing a good job of guiding as far as round stars go but FWHM measuremnts range from 4 or 5 to 9 arc/s. I have previously tried backlash compensation but it caused very large overshooting and went into oscillations trying to correct each way. I will give it a go again next time though and see if PHD dials down the amount. Thanks, Matt

Hi everyone, I have a new EQ6-r Pro mount that is giving me some headaches. I'm guiding with an ASI290mm through a WO 50mm guide scope attached to my WO GT81. PHD2 calibration is inconsistent and the backlash test has a strange plateau halfway through the returning south movements at which point the DEC motor goes audibly quiet. This was repeatable in different parts of the sky (close to the meridian and equator where I was calibrating and then south where my target for the night was) with 3 examples below. There are no cables dragging, clutches are not loose and scope balance is good not being perfect so I don't think there are any issues there. I've attached guide logs however they do contain dithering which might not make things so clear. There are definitely points where DEC backlash appears and PHD2 fails to bring the mount back. I'm really at a loss as to what could be causing this and would love anyone's insights. - Thanks, Matt PHD2_GuideLog_2019-09-27.txt

Hi Bobby, Both axis look fairly unresponsive so hopefully this is just a belt tension issue. PA looks good enough for guiding and shouldn't be the reason for this much backlash. I would try tightening the belts and redo the calibration. I'm not sure about the NEQ6 but are you able to slew the mount with the motor cover off and see how the pulleys behave when you change slewing directions? If they aren't tight enough you'll get bunching as you reverse directions and see a noticeable issue before there is enough tension in the belt to move the axis again. The belts shouldn't visibly distort in shape. Try reaching the tension described in the guides - just enough to take up slack and allow for movement of a few mm with slight finger pressure, then tighten it a little more.

I add with my WO GT81 and Flat6Aiii and I get very good results. If you calculate that you need 55mm of back-focus you will need 57mm physical distance measured to achieve the 55mm. I think the confusing part is that glass etc shortens the back-focus distance from an optical light path point of view, so while you will have say 55mm of physical back-focus, the light path travel distance is actually shorter at about 53mm meaning you need a few more mm added to your physical requirements. So because you subtract, you need to add. But then, I also found that a mm had very little noticeable effect on my stars when tweaking the spacing so who knows really! 🤯

Looks like you've made your decision and hopefully you can get that mono! OSC is fine and you'd no doubt get great images, especially with the 294MC, but just for what it's worth, I went through the same dilemma and ended up going mono. To put it short I couldn't be happier. I have a 1600MM-pro and recently upgraded from my 150PDS to a WO GT81-ii and I'm now considering the 183MM for a smaller field of view. Your ED80 will do well with it