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Images of the eccentric added

I've been playing and come up with an adapter allowing me to fit my Nikon lenses to my ASI294MC Pro cooled camera body. The adapter is based around a Nikon lens to Canon body adapter (it was in my kit box doing nothing !). This is fitted into an aluminium body (main body in photo) with 6x 2mm metric machine screws. The 294 has a 42mm male T thread, I've used this to fit the camera body to a small aluminium insert which slides into the main body of the adapter. I've threaded the front of the insert to take 48mm filters. To allow the lenses to be changed easily I have inserted an eccentric cam to depress the release lever - operated by the brass lever on top of the adapter. The main body has a slip ring/clamp arrangement to allow the whole adapter/lens/camera combo to rotate for framing. I've etched (scratched!) 10° markings around the main body to act as an aid when framing. Currently fitted to a shortish Vixen bar but this will be altered so when using longer lenses to front of the lens will be supported to reduce loading on the adapter/lens mount. Photo of the adapter with the 294 and a 24-85mm Nikon lens. Also a section through the adapter (not exactly as built I made a couple of minor changes as the machining progressed. An image of the rosette nebula from it's first light session last night. It needs a few tweaks but it works. Images of the eccentric and adapter/294 with IDAS NB-1 filter in place

I've been making an adapter to fit Nikon lenses to my ASI294MC Pro (uncooled test) and last night cleared for a short while to get a few test frames with this set-up. Mount iOptron CEM25P (Unguided) also unbalanced as the original counterweight was way too heavy so shot with no CW. Lens Nikon 24-85 f2.8 zoom (D series) Camera: ASI294MC Pro (uncooled) for test. Filter used: IDAS NB-1 filter Processing: APP for stacking, PI and PS for colour. I should have got out earlier for the Orion frames (2x 60s) as it was disappearing into my gutters so switched to the rosette and the Heart & Soul areas where I had a little more imaging time. Rosette: Lens set at 50mm but heavy crop for final frame Orion: Lens set to 24mm again heavy crop H&S: Lens set to 50mm and cropped.

I like to tinker with bits like adapters so when I came this morning to test my latest gadget to link my Nikon lenses to my ASI294 MC Pro I couldn't quite believe my screen images - there was this round object where a round object shouldn't be? Quick check: stars in focus, aircraft moving across FoV, clouds passing (fast) and it's still there! I had the camera and 24-85mm lens mounted on a bean bag on the window sill with the lens leaning on the double glazing pointing up at about 45°. I'd pushed the gain up to about 500 in SharpCap(3.2) with 3 sec exposures to avoid too much trailing. I took a couple of snapshots to plate solve later then tried SharpCap's live stack to see if I could reduce the noise around this mystery object. That's when the penny dropped (plonker) that mystery object was a water droplet hanging under the gutter and catching a local street lamp... It wasn't moving with the star background but with the short single frames that wouldn't show. It was only viewing the livestack that things began to register (no pun intended)...

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

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@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.

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 👍

@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...