alexbb

I edited the post above, but I saw no pictures through it in the thread: https://stargazerslounge.com/topic/319495-skywatcher-72ed-just-arrived/ At teleskop express, they recommend the TSRED279 and the backfocus is specified at 65mm. Maybe drop them an email and ask for more. How does the flattener attach? How does an image look?

At about 60mm backfocus I managed to get this But I remember I read somewhere that the TS flattener fits better and performs better. Can't say where I read that, maybe even on this thread. Will look when I get back at the PC. Edit: not sure if better, but it seems it fits inside the focuser which should help with the backfocus issues.

Yes, just that the "72" one has an extra threaded adapter. I believe FLO offered an adapter for the 80, one that you insert in the focuser, not a threaded one.

You'll need a flattener too. Be it the SkyWatcher one or the OVL. The backfocus spacing is a bit more than 55mm with both, I found it acceptable with the SkyWatcher reducer at ~60mm.

I'm pretty sure you have a faulty mount then. Send it back for replacement.

I just checked this evening to power the mount with the Celestron lithium power tank pro and everything went just fine. The reported voltage on the handset was 12.9V when tracking at sidereal rate, 12.3V at full slewing speed on both axis and just below 12V when stopping the fast slew. Maybe there's a weak contact in your setup?

I cannot see very well on the phone, but I remember the same kind of behaviour when I used a power source not powerful enough. I'm very unhappy to find out that the new, bigger celestron lifepo4 power tank is not enough for the mount as this was exactly the reason why I bought one in the first place, to power the eq6r. I will check the following days too.

Does it make a strange noise? Something resembling grinding something between the gears. Does it stop suddenly or slowly decreasing speed? Make sure everything is properly configured. Position (correct hemisphere, west or east of Greenwich), date entered in MM/DD/YYYY format, daylight saving set to No. Kind of recently I forgot to set the daylight to No on one mount. I wouldn't expect any power issues if the led stays constant without blinking. If I recall correctly, the mount needs ~5A at 12V when slewing both axis at full speed. My smaller Celestron LiFePo4 Powertank couldn't deliver enough and it cut the power at alignment. I've yet to test the newer larger one.

I don't find anything really benefiting from a ~240mm focal length, but too tight in a 200mm. Moneywise, in the same ball park, you can get a second hand Canon 70-200 F4 L. The results I saw at 200mm with the aperture wide opened were good enough. Not to mention the backfocus is much longer and the imaging circle has to cover a full frame sensor.

I plate solved an image taken with the ovl non reducing flattener. Focal length turned out at about 431-432mm. I can easily think of at least one other 72mm scope advertised at 432mm focal length.

I would expect the longer dovetail and the flattener to add to the weight, though not by half a kilo.

I need to mention that I measured this by weighting myself with and without the scope and then subtracting. I cannot guarantee the measurement is 100% precise.

With rings, longer dovetail, flattener, it seems to weight 2.4kg. Here you can see some images I shot with it. The Iris is solely with it, unfortunately I didn't process it properly yet, the others contain some older narrowband data too. You shouldn't see any CA effects on narrowband though. Iris: https://stargazerslounge.com/topic/323530-iris-nebula-with-skywatcher-72ed/ Flaming star and Tadpoles: https://www.astrobin.com/373373/ Heart and Soul: https://www.astrobin.com/374116/ Clear skies, Alex

One more thing: with the OVL flattener I measured the FL to be ~430mm and with the "dedicated" flattener, ~377mm. These were with the extra-spacers I used. With the OVL I had the backfocus at ~57mm and with the SW one it was at ~60mm.

I have some results with the OVL field flattener. I only added a few mm to the flattener-sensor distance so about 57mm and I was left with enough focus travel.

According to this, it seems that the focal length with the 0.85x reducer/flattener for 80ED (at 60mm backfocus) is ~377mm, not 357mm. That means that the corrector reduces ~0.9x at 60mm backfocus.

Looks good!

Looks good! Did you manage to check the frames? Can you share a stretched one?

Could you post an image of the setup, please?

Another tease. This will take me a while to process properly.

On RGB, the little scope is quite sharp. Blue is a bit bloated, but still sharp. FWHM of 30x120s stacks from yesterday. R - 1.680px, G - 1.455px, B - 1.915px. And an RGB STF tease of the fish-head.

The TS reducer should work best with 420mm FL at 65mm backfocus. I'm curious if you can reach focus.

Are you sure about the forecast source?

Yes, you can find more details here: Stars still appear less round towards the corners, but this last image also had less than perfect tracking so you wouldn't see too much the aberrations.

I link this here too, maybe some will land here for results with the 72ED.