fwm891

Your background looks a bit dark - maybe my monitor but to me needs to be taken to a darkish grey rather than black...

😀

@Osprey Oops see below...

Typo in above... Total = 86,164.0905 seconds in a sidereal day which is the length of time the Earth takes to rotate 360° or 239.434469 (original calc showed as 234.34469 sec) sec per 1° = 3.989078 mins per 1° rotation

3.989078 mins per 1° rotation  then 360° = 1,436.06808 mins for 360°

If your motor does 200 steps per min. Then for 360° rotation = 1,436.06808 x 200 = 207,213.616 steps per sidereal day

Sorry about the typo

@Osprey You need to first break it down to give you the number of seconds in a sidereal day:

23 x 60 x 60 = sec in 23 hours = 82,800

Plus 56 x 60 = 56 mins in seconds = 3,360

Plus the odd 4.0905 sec

Total = 86,164.0905 seconds in a sidereal day which is the length of time the Earth takes to rotate 360° or 234.34469 sec per 1° = 3.989078 mins per 1° rotation

Your stepper motor will give 200 steps per minute = 47,868.9391666 steps

If you drive your horseshoe directly from the 5mm diameter shaft at 200 steps per minute then:

5 x pi = 15.70796 mm surface travel per shaft rotation in 1 minute.

There are 3.989078 mins per degree rotation = 62.6602776 mm travel per 1° x 360 for full rotation = 22,557.6999 mm or 22.5577 metres for your horseshoe circumference

Divide by pi = 7.180.34 meters diameter.

You will need to gear down the motor by some factor to bring the mount to reasonable proportions or use micro stepping...

Hope that helps...

I use a TS Optics 80mm guide scope and ASI120mm camera combo which I switch between scopes. For the f2 RASA I get 1:1.104 ratio, with the Altair 115 EDT APO I get 1:2.04 and the little William ZS 73 +ASI294MC pro and 9x 50mm guider (ASI120mm camera) I get 1:2.06

Great little prog.

43 minutes ago, AbsolutelyN said:

Looks great. How are you finding the star shapes in the corners? Rather curious about how easy it is to get the right spacing for good flat field. Cheers, Tristan

There's very little tolerance with the f2 RASA. I've made my own spacer/filter holder to give me the 25mm back focus. The filter at present is not sitting quite square on and causing a few distortions (left to right in above image) though that may also be due to the IDAS NB-1 filter not being well corrected for the f2 light cone. Correcting the mount PA last night has made a big difference and something I will check more often especially after working round the mount / tri-pier.

Great image and the mono reproduction does it great service - well done. 👌

Longer session last night. Spent some time checking and adjusting the mount's PA. Then to hours total integration time on M78 and it's surrounding area. 20 subs: 10 x 240s and 10x 480s.

Details:

iOptron CEM60 standard mount on tri-pier

RASA f2 OTA

ASI294 MC Pro OSC camera with Idas NB-1 filter

SG Pro as capture software, Processing mixed APP & PI

Really wanted to make a session of this image tonight but clouds cut it down to 3 subs: 2x 240s 1x 480s.

Will try again tomorrow....

You need to align the focuser with the secondary optic first, then you can align the optics. If the focuser isn't aligned orthogonal to the OA then your plane of focus will never match the plane of the sensor.

Well done Peter - great imaging.

Thanks @johninderby - no hadn't seen that just a blank screen...

Anyone else using Photobucket - haven't been able to log in for a couple of days. Tried different browsers no luck that way either...

Like it very much 👍

5 hours ago, Skyline said:

Very nice Francis, I take it was done with your ASi294MC Pro ?

@Skyline Yes shot with the ASI 294. Earlier problems I had with amp glow have gone since using flat darks, flats and dark frames for calibration and dropping bias frames. Also I now do early processing using APP then move to either PI or PS. I can't get the hang of colour in APP (yet).

@carole & @JamesF Thanks for the comments

Thoroughly enjoyed this imaging session gathering the light frames. Now came the task of gathering the calibration subs. I pulled together: darks, flats and flat/darks, no bias frames.

These were all put through APP and some 3 hrs later out came a joined up mosaic. I used APP to remove light pollution and calibrate the background. Further processing has been done in PS-CS3. This mainly entailed saturation with Hue/saturation selecting different colours and either increasing or decreasing their levels.

I'm sure I could keep playing with the image and make use of masks to control M42's core more. What I will probably do though is take a set of shorter exposures and blend them in.

Probably the final on this one. Hope you like.

Just a mad thought but you have set the commander software to 'sidereal' not lunar or solar rates? Just seems that whatever your doing regardless of exposure the results look similar - hence the wrong guide rate thought...

Out with the CEM25P again last night. I mounted the William Optics ZS73 again + a Baader 7nm H-alpha filter and the mono Nikon d5100.

NGC1499 (California nebula) was one of the targets. This image is 15x 300s subs, processed in APP and PS-CS3.

This is a partial process - only the 60 second subs from each panel have been merged to see if the whole thing worked. Shot last night it comprises four horizontal panels, stacked vertically then rotated for posting. Each panel has 3x 60s subs, processed in APP and PS-CS3.

Details:

Scope: RASA 8

Mount CEM60 Standard on tri-pier

Camera: ASI294MC Pro (gain 122 - offset 30)

Guiding: PHD2 via TS 80mm guide scope and asi120MM-S camera.

Capture: SG-Pro

Now to process the other subs...

Hope you like

All subs:

Each panel has: 4x 30 s, 4x 60s, 5x180s and 5x 240s.

Processing as above, no calibration frames taken for this image yet. This is a lights only mosaic.

With my iEQ45 Pro when telling it to go to zero I loosened both clutches, let the mount do it's thing then set the clutches with weights down scope pointing north...

I don't have an EC version of the CEM60 but have a similar set-up.

You've run a PA drift align and got fairly flat traces for both axii so that should be fine.

The CEM's are dead easy to balance so I presume you've balanced first the dec then RA axles - ruling out balance problems

The encoders are just providing a constant drive rate (PPEC) they're not sensing against the stars so your guide pulses should be OK. However your problems do look RA oriented.

I have a Williams 73 ZS with finder guider, my calibration steps are much higher circa 2500 and calibration steps are usually 14/15 west, 6 east and 8/10 for north/south steps. At 500 it would take probably 30-40 steps to reach the +25 threshold. Is the focal length of your guider set correctly?

Hysterysis I set to 30, guiding 1 rarely use anything other than 2 seconds, minimum mo 0.15 (dec & RA) aggression 70% RA 30% dec.

To me your Calibration steps are too short (Brain / Guiding tab) and your minmo set to zero doesn't allow the mount to settle and it's always chasing itself.

Cables: are they dragging or fouling anything...

@Danjc Great thread. I have the same PPB and it works a treat. I run 2 dew bands, camera, mount and focuser. While my USB's plug into the back of my CEM60. Like you I ended up getting Lindy USB cables to make sure the USB's didn't cause issues. I find the 4 power out puts, 2 dew bands and the environmental indicator do all I need. Thanks.

I've only really used this mount once seriously but I have to say I've been surprised: it's smooth, it's quiet, it tracks well unguided (though only taken to 60s so far), guides well too (5 min subs). Guiding here used a 9x50mm finder and asi120MM-S camera.

I chose a couple of well know targets and shot them using a William Optics ZS 73 + (1x) flat73a + Nikon D5100 mounted on the CEM25P. Each image is built from 5x 300s subs, processed in PI. Capture via APT. No filters used.

I purchased the mount and light weight tripod from FLO and set the tripod, mount and OTA assembly on our patio area. Comprising stone slabs. I have a motor cycle 12 VDC power source which I've hung from the equipment tray. USB cables from the guide camera, 2 leads from the Nikon and the mount all fed into a non powered USB hub at the mount with a single USB extension cable back to the laptop in the conservatory.

iOptron's Commander software was installed, APT used for captures, Bahtinov mask (built into the ZS 73 hood) used for manual focusing all images saved to camera card (card slot on my old laptop U/S).

Images imported into PI for alignment, stacking and levels adjustment, resizing and saved as jpg files. My D5100 is a mono modified DSLR so some cropping has been done to remove the ragged edges around the chip/sensor. See uncropped single sub.

Setting up. I started by assembling the head onto the tripod minus scope and counterweight but including the motor cycle battery. Getting the head polar aligned using a phone app to indicate the position of Polaris. I then added the OTA and counterweight and rechecked the PA via the polar scope (minor adjustment required) I find this unloaded/loaded approach to PA easier than making bigger adjustments with a loaded tripod.

Connected the four USB leads to a hub located on the equipment tray/leg spreader at the mount and USB extension to a Win 7 laptop. Fired up Commander, PHD2 and APT. APT's plate solve used to centre objects and sync when centred. As this was a first real outing with the CEM25P I did a two star alignment/sync to on a couple of widely spaced stars before heading foe Andromeda and M45.

I set-up a plan in APT to take 5x 300s subs. These were processed in PI only.

Will follow this up later when weather permits.

1 hour ago, tooth_dr said:

Thanks Francis. What pixel scale do you get when this combo?

Pixel scale 2.39 sec/p

9 minutes ago, tooth_dr said:

Lovely image and a nice FOV. Is that a mosaic or single frame? Did you post full resolution?

@tooth_dr Thanks. Single frame, slight crop due to meridian flip not fully registering. Not full res as files size circa 60Mb but posted as png to retain better bit depth.