michael8554

Each 2 arcsec error in RA is taking 2 pulses to correct. Which then sends RA over to the other side. Where another 2 pulses are required to correct, etc etc. But notice the second pulse is always larger, which means PHD2 didn't see the expected correction from the first pulse, so then sent a larger one. Too-high Aggression isn't causing the overshoots, it's probably stiction, or tightness, in the RA axis. Need to see the GuideLog so that Calibration etc can be evaluated. Michael

Scrub that. I was reading it as a Panasonic G series non-astro camera for some stupid reason, my bad. Michael

Very typical. Dec usually needs little guiding, if PA is good, and Dec Backlash is minimal. RA has to cope with Periodic Error, which a belt mod can reduce, but sometimes worsen if the belt tension and worm adjustment are not correct on reassembly. And less than optimal guide settings. A screen shot only shows you have a problem, need the GuideLog to see why you have a problem. Michael

Nothing to do with the quality of the optics, only the design of the optics would impact (Newtonian, SCT, Refractor). To expand on what globular said, SCT's have a huge focus range, sometimes requiring many many turns of the focus knob to get coarse focus. Despite that, a diagonal + binoviewer + eyepieces may be too long for even a SCT, a Barlow will make it even "longer". Hopefully someone with this setup will post. Michael

Within reason and cost, try to avoid guidescopes that fit in the finder slot, that have adjustable rings, don't have provision for a screw-thread guidecam connection, instead of clamp screws. Michael

A Polar Alignment error results in drift in Dec, which your graph doesn't display. Your guide settings are struggling to correct +/- 3 arcsec swings in RA, so RMS is about 2arcsecs in that snippet of your guiding. Michael

As Peter said. Are you just pointing at the dawn sky, cos they look like clouds ! Also some have a hint of shutter shadow ? Michael

On non-astro cameras such as your G26, the ISO setting is effectively your "gain" setting. You will have to search for the best ISO setting. (It's APT, not AST) Michael

Canon DSLR models in the 600D, 650D, 700D etc range, sometimes seem to suffer from horizontal banding on long exposures. It seems to be worse on hot evenings. Not everybody experiences this. Michael

An often quoted Dither is 12 DSLR pixels. If the selected Dither is Random i.e. each Dither is in a random direction, and a random amount up to 12, then maybe a larger setting, to give an average of about 12 ? Michael

Are you asking if Canon lenses will fit on your Nikon ? Cos your title says "Internal Nikon LPF" ? Michael

Sounds like RA ran into one of the two stops that prevents the cables inside the mount getting twisted too much. Alignment should always be started with RA unclutched and moved to about halfway between the stops. There's more than 360 degrees between the stops. Michael

It's the "Fabric of Space" that is expanding, carrying Matter with it - Galaxies, stars, planets etc - which aren't getting "bigger". In the very early Universe, that Fabric briefly expanded at many multiples of the speed of light, which Einstein's Theories allow for. Beyond the "edge" of the Observable Universe at 13.8 Billion LYs, the galaxies and stars are being carried away at faster than the speed of light, so we will never be able to observe those galaxies. So the real "edge" of "our" Universe is currently about 40B+ LYs away from us. However, consider an astronomer looking at earth from a Planet 13.8 BLY away from us. If he turns his scope 180 degrees, he will see galaxies a further 13.8 BLY away. And an astronomer in one of those galaxies will see........ etc etc So how big is the Universe ? An infinite number of 13.8 BLY "bubbles" ? Michael

A lot depends on which scope you attach it to. It may fail on the 150P due to the usual Newtonian in-focus problem, I'm not acquainted with the 150P. If the OAG is connected directly to the C6 and Sony, the C6 should be able to focus. Now the 290MC - a colour camera is often not sensitive enough to reliably pick up a guide star on every target, mono is better. The key to OAG is getting the distance from the prism to the Sony sensor, and from the prism to the guidecam sensor, exactly the same, so that they're both in focus. Depending on the OAG that first distance would be roughly half-OAG thickness + T-Adapter + Sony E Flange Distance, say 5 + 11 + 18 = 34mm. If you can't get the guidecam that close to the prism, then you'll need a spacer on the imaging camera path, so OAG + Spacer + T-Adapter + Sony = more than 34mm. Michael

And about time to. Michael

Yes. A colour camera is often not sensitive enough for guiding, particularly with the Off Axis Guider (OAG) you should use with your very long FL scope. Michael

Hi Andrew I reread the PHD2 instructions and you're correct, 1.2 is the preset Min Star HFD - my bad. From the GuideLog: The Calibration Step Size on your guiding run was 900mS, not 5000ms - is 5000ms something you set in EQMOD ? Your HFD from the guidecam is 4.17pixels, you might be able to improve that. A Min Star HFD setting of 3 is too close to 4.17, so may be rejecting good stars, back that setting off to 2. Your guidestar SNR is only about 7 which seems low to me, but depending on the camera can be as low as 20, and up to 800 or more. You have Star Max Detection ticked, this might be rejecting good stars too. RA Error is 1.28arcsecs, and is quite choppy, so try Aggression = 80% or lower to smooth that out, changes of only 1 or 2 % are too small. Give each change time to settle. Or try the PHD2 PPEC Algorithm for RA guiding. PA is good, but Dec is still swinging around the axis due to Backlash, and taking 20 seconds to correct. If you do a Guide Assistant run on Target, that will give you Min Move settings, and a Dec Backlash Compensation setting, which you have switched off. And you should slightly unbalance Dec to stop it wobbling. Michael

Not sure what you mean by minimum star reference size - do you mean Minimum Star HFD ? If a Hot Pixel = 1, so a setting of 2 or 3 would work, not sure why you have fractions of pixels in the setting. The Pulse Duration of 5000 I suggested was for Manual Guiding, so that won't have made any change to normal guiding ? Although your guiding is looking good it would be worthwhile posting the PHD2 GuideLog. Michael

Hi George Your main expense - the CPC925 - is ideal for Planetary imaging with a Planetary camera. For DSOs the CPC925 with FR needs a larger chip camera to use it's full field of view, so consider short exposures with a cheap DSLR such as the Canon 600D, which is simple to use. Or sell up and start over with an EQ mount and a refractor........... Michael

An image of a wheel would really help......... If the boss protrudes you could drill through the boss and drive shaft, and nut-and-bolt the wheel onto the shaft. I think the motor torque will unlock any Araldite or LocTite connection. Michael

Hi Andrew A puzzler, some unusual conflicting results. From the GuideLog: You started with two brief guiding sessions. Guide Rates were RA = 1.3 arcsec/sec, Dec = 1.6 arcsec/sec Usual rates are 7.5 or more. Then I assume you increased the EQMOD rate to 7.5arcsec/sec and made four more Cals which took about 60 RA steps instead of the usual 12. Similar result with five more Cals at 13.5, still took 60 steps. Then at 1.5arcsec/sec, still took 60 steps. I can't explain that I'm afraid. Another puzzle. In half the Cals the West move was towards 11 O'clock, the other half towards 5 O'clock - all at the same RA and Dec and side of pier !! I'm unfamiliar with EQMOD, apart from the common Pulseguide Rate too-low setting, so hopefully someone will comment on your screenshot. Try this in PHD2: Tools / Manual Guide, Pulse Duration 5000. Try all four directions for correct movement and direction. Are W and E opposite, S and N opposite ? Each press will move 5000, holding down doesn't issue more pulses. You have Have a good read of the PHD2 Manual: https://openphdguiding.org/manual/ Michael

What spacing was that, have you tried at the recommended 55mm ? Experiments like this should be based on a single sub, not a stacked image that contains guiding and stacking artefacts. Take a single sub at max ISO and short duration, then stretch that to look for coma etc. Michael

Camera lenses typically have a Mounting Flange to Sensor distance of about 44mm. The ZWO ASI290MC is 12.5mm. Sounds like the lens has a M42 x 0.75 thread on it that fitted nicely. Or was it a M42 x 1 thread that seemed a bit tight ? Either way, you can get infinity focus at a shorter distance reading on the lens, if it's mounted too close to the sensor. Or if it's further away from the sensor............I can never remember which ! Good luck ! Michael

As alacant said. If the 750D is not retaining the Custom White Balance over battery changes, then perhaps the tiny data battery in the camera has failed ? Unlikely on a fairly new camera. It eventually discharges if the camera is stored without the main battery, If that's the case the date and time resets too. Michael