Gina

Thanks for your reply I'm going to have to give all this some more thought. I've put a question on FLO about using Astrodon 5.25" filters in the ZWO filter wheel (in the Q&A section of the ZWO FW page) as they apparently won't fit. Probably get a reply tomorrow. The ZWO filter wheel in small and light and designed specially for the ASI1600 camera - ideal for a lightweight WF imaging rig that could go on a lightweight mount.

Hmm... Things are not looking good. Checked the measurements again and yes, I do need 4mm more back focus from the camera. Also the adjustment for the guide camera is way less than the extra 11mm required. This filter wheel will simply not work with camera lenses, all of which have a back focus of about 45mm. I think there may be another problem too - the rear element of the lens is only 28mm and looks like it will only cover about half of the prism when this is far enough out to clear the camera sensor. So it's looking like an OAG isn't going to be possible with a camera lens after all Not sure yet about the Esprit scope. Drat!! Looks like I shall have to work out how to use another lens for the guide camera and mount it...

I'm doing more measuring... I'm not sure the guide camera can be brought into focus with the camera sensor being 11mm or so nearer with the adjustment available on the guide camera stalk.

I really don't want a separate guide scope! I wonder if the ZWO filter wheel could be modified to get that extra half millimetre room for the filters.

Ah yes - that's it! I guess I should have guessed the delight with the new camera and imaging rig couldn't last - I'm just not that lucky!!!!

The FW problem is my fault I guess - I forgot to check the optical length before I bought it Just checked now and the measurements are there on the web site

Maybe but "I'm depressed" is what I really meant. Or something like that - I forget now - long time ago...

I feel like the robot in HHGTTG now

That's good then You're having more luck than me! Been looking at other filter wheels on FLO's web site. The ZWO one looked just the job at first - very narrow and designed for their 1600 camera meaning that I would have room for the OAG I have. BUT the spec says " Important Note: 1.25" filters require threads shorter than 3mm and the height without threads must be less than 7mm. " The thread length is fine at about 2mm but the height without threads is 7.5mm for the Astrodon filters! So it seems the ZWO filter wheel cannot take Astrodon filters Bummer!! (excuse my "french"!) Really don't know what to do now! I guess email to FLO for suggestions.

I have a serious problem! The SX filter wheel is 15mm thicker than the Atik EFW2! I could save 11mm by buying an extra female SX adaptor plate and dispense with the ASI1600MM gender changer but that would still mean I need an extra 4mm travel on the lens focus and it just isn't there. I think the same would apply to the field flattener for the Esprit scope and it's adapter

The SX mini filter wheel with OAG has arrived and looks very nice Since I'm waiting for the Astrodon 3nm SII filter from Ian King (getting more in) and not yet managed to capture RGB M31 subs, I think I'll set it up with Ha, OIII, R, G, B as the five filters. OTOH I could do the RGB before changing filter wheels - I'll see how I feel this afternoon. I think I'd really like to get the new wheel installed and tested I'm thinking of adding Ha to the RGB image of M31 so to be able to add longer Ha subs would be useful.

That's interesting - thanks Wim

Processed the Cygnus Loop with the new master bias and dark plus the Ha flat with CPP then had a play in Ps - rotating and cropping and saving full size image as PNG.

Took some more bias and dark frames tonight but at -24°C to -25°C rather than -30°C as a compromise in the hope of improving on no calibration at all. It has worked to a large extent. Not removed all the noise of course as it doesn't really fit but it's certainly an improvement and shows that the data has promise. This is the result of running the CPP script. This is all the image, full size, histogram stretched and saved as PNG.

Thought I'd just rotate it and crop it and upload that.

Well, here's IC1396. Clearly the noise calibration hasn't worked!

The run came up with some errors - like no correlation between light and master dark or something like that. Yet I carefully checked that I had the right darks. I don't understand this - what is there to correlate between the master dark and the lights? No stars in a dark... I think I tried to do too much last night Trouble is we only get one good clear night in a week or two - maybe more. Forecast is warm again tonight so I don't think I shall be able to repeat the darks.

Hopefully I've got things sorted out now!! I'm now using what I think are the correct sets of bias and dark frames, the master flat for Ha and IC1396 lights. Batch PreProcessing is now running...

Just been checking up on the FITS info and find I got the biases and darks mixed up - I used the ones for the RGB data with a gain of 148 and 10s exposures for the darks instead of g600 and 30s I'll now do IC 1396 with the right bias and dark sets. Considering that I used the wrong bias and dark sets, the Crescent looks remarkably noise free That doesn't explain the horrible stars though.

Not sure what the star problem is but there was a very heavy dew last night - might have been one side of the lens dewing up. I shall have to have another go at that. The "full size" image here is actually half the captured image size. That looks awful!! I was hoping for better results from last night as the temperature was lower and I got the camera sensor down to -30°C. The noise was very noticeably reduced even compared with -25°C. I shall now try the other DSOs I captured last night. To capture the Soap Bubble I shall need a much narrower FOV. Probably try with the SW Esprit 80ED Pro. The FL is 400mm whereas the lens is 135mm. I shall need longer exposures with the scope at f5 compared with the lens at f2.5. 120s with the scope would match the 30s with the lens. The little SX FW+OAG is due to arrive tomorrow and then I can use guiding.

Here is the processed image histogram adjusted and resized in Ps.

All done - saved file as TIFF ready to transfer to Win7 desktop and resize in Ps.

Stacking now - also taking a couple of seconds a frame.

Calibration part finished and now registering images - taking about a couple of seconds per frame.

Created new folders on SSD and copied over the bias and dark frames for my Ha sets of subs. Also folders for lights and "Calibrate". I have copied the Crescent Nebula lights to the SSD as well as I shall probably read these again when I improve my processing. I am now running BPP on the Crescent lights with bias, dark subs and master flat. I certainly seems quicker than when I did similar on HD