symmetal

'Fraid so Jay. 😀 I don't believe this feature is mentioned in the information with the flattener so don't feel so bad. Your method achieves the same result in the end. 😉 Alan

This assumes the flattener is screwed directly onto the focuser. If it's attached by a 2" nosepiece adapter you can of course rotate the nosepiece to rotate the camera instead. The nylon grubscrews around the rotator are to set the rotator friction when the knurled screw is loosened, so it doesn't rotate on its own under gravity. Alan

It's the locking screw for the camera rotator at the front of the flattener. Rotate the flatter, with fixed camera attached, for your preferred image orientation. Then tighten the screw to lock it. 🙂 Alan

Another set of excellent images MalVeauX with loads of detail. Alan

I've had the same grubscrew work loose on my lakeside focuser on my FLT98, the obvious sign being the first V curve step being near horizontal. Also it shows as significant free movement if you operate the dual speed focuser on the opposite end of the shaft to the lakeside fitting. On the Voyager setup it takes HFD 40 as its upper V curve limit which is what your first V curve was showing at the horizontal section, which may have caused it to be horizontal for so long, rather than just backlash which wouldn't have helped. Rather than just manually setting a V-curve step size which you can then adjust as required to get the most useful V shape, Voyager sets the step size to a value that gives a HFD change of 1 which is why it needs an initial setup trial to determine it. I assume it doesn't step so far out now on its initial focus move, and takes less than your indicated 60 focus steps to determine correct focus. 🙂 Glad it's all working now though. 😀 Alan

As you're using a guidecam it would be much easier to use the polar alignment tool in Sharpcap Pro. You have to buy the full program to get the polar alignment option, but it's not expensive and is worth it for that tool alone even if you don't use its other features. 😀 I used to find using the polar scope awkward and time consuming and never got it to work accurately but using Sharpcap alignment only takes a minute or so with no hassle. As long as the guidescope is looking roughly towards the celestial pole when the scope is in the home position is all that is required. A single plate solve pointing towards the NCP is not recommended for determining pointing accuracy as all RA coords are bunched very close together when near to the NCP. Sharpcap takes two platesolves with the scope turned roughly 90 degrees in RA between solves to determine where the actual NCP is and tells you to move an indicated star to a specific location on the screen to get accurate alignment. Alan

At the correct spacing there should be tight round focused stars over the whole field especially in the corners. Without a field flattener the further from the focused centre of the image, the more distorted and out of focus the stars will be. So examine the stars towards the corners of the image and adjust the spacing until they are as sharp and round as you can get them having refocused at the centre after each adjustment. You'll probably find that they may not be perfect, depending on the quality of the scope and flattener. Sometimes you will have image tilt where the sensor image is not perfectly orthogonal to the scope centre axis, or maybe shifted to one side, so you'll find that some image corner stars are better than other corners. It can be quite a chore trying to get all corners looking the same so you may end up with a compromise. 🙂 Some image processing packages or plugins are able to correct for distorted star shapes to some degree. Alan

For only 80mins that's pretty good. 🙂 As you say there is some tilt left to right, possibly the focuser drooping slightly when the scope is 'on its side'. Check there is no play in the focuser parallel to the camera's long axis. Alan

Yes and yes. 😀 However, the ASI290 is a small sensor at 5.6 x 3.2mm, so the reducer/flattener may not be necessary to get a useable flat field but if you do use the reducer/flattener you won't need to space it at exactly 50.5mm, and a mm or two either side should be fine. The Canon 700 being an APS-C size sensor will need the extension spacing to be more exact. The Canon T2 adapters can vary slightly in their length by 0.5mm or so depending on the manufacturer, so the extension may need to vary slightly from 8mm to get optimum results. 🙂 Alan

Striking colours and detail. 🙂 Alan

Thanks Ivo for the explanation. I'd be very happy to try the 1.8 preview and see what extra goodies it has. Much appreciated. 😀 Alan

Here's it reprocessed again using the Startools noise reduction as @jager945 recommended 😀. The 'Equalized Grain' added noise did give a more natural look to the image, though I also found reducing the de-noise wavelet Scale 1 to 85% and the Scale 2 to 90% left some residual fine noise in the image and so less Equalised Grain was needed, and 5% Equalized Grain kind of filled in the gaps in the residual noise that was left. The overall result was extra detail revealed in the dust which wasn't readily visible in the non de-noised version and which the Photoshop Define2 denoise had removed. I've also added a crop of the Iris itself showing the three noise methods. They're high quality jpegs, so some artefacts are present but the general difference is seen. It's down to personal taste how much de-noiseing you prefer of course. 🙂 Full image. Click for full size. No de-noise Startools de-noise: 3.0 pixel grain size, 85% Scale-1, 90% Scale-2, 5% Equalized Grain Photoshop define2 de-noise. On the original I did overlay the un de-noised Iris core back in. The only problem now is I have to go and re-process my older images. Thanks Ivo. 😁 One final question Ivo, on the Binning module you have 4 pre-defined presets of 25%, 35%, 50% and 71% binning. The 25 and 50 are obvious, but is there an advantage of choosing 35 or 71 over say 33.3 or 66.6 which might seem more intuitive numbers. I notice 35% (actually 35.38%) is the square root of 1/8, and 71% (actually 70.71%) is the square root of 1/2, so there may be a clue there. 🙂 Alan

Like you when starting out I tended to flit from target to target getting a little from each, but now concentrate on one target for several nights if necessary. As you say with so few clear nights at the moment that's not so easy. Dithering every 3 frames as you did should be fine, as long as you take enough frames in total to give the dithering a chance to do its stuff. Six dithers in your imaging run of 18 frames is not really enough I would say. You fooled me with the Startools repair module too. 😁 Alan

Very good. The choice of colours makes it stand out nicely, and the stars have a fairly 'natural' colour too. 🙂 Alan

Very nice star shapes over all the frame. Some flats and more data will make it even better. It doesn't look like you're dithering between subs, which should improve the blotchy background too. You need at least 12 pixels of dither for DSLRs generally. 🙂 Alan

Most impressive. Alan

That's pretty good for just an hour of data. 😀 Alan

Thanks Ivo. Much appreciated. 😀 Ah! that's interesting. Before I used the higher dither setting the coarse blocky background 'mottle' noise was more noticeable than the fine noise and the Startools noise reduction removed the fine noise well, and so made the mottling more apparent. The grain size parameter had to be set high to start combatting the mottle which gave the results a plasticky look. I did tinker with the 'Equalized Grain' but not properly. As you say, some fine noise in an image makes it more 'natural' and also gives the effect of it looking sharper. I'll give it another go and see how I get on. I'll pay the de-noise module more attention. 🙂 I look forward to seeing what version 1.8 offers. Alan

Thanks Carole. That certainly helps. It is classed as Bortle 2 or 3 depending on definitions. I measured 21.1 with the SQM meter in the middle of the nautical darkness period. Alan

Thanks Stuf1978 and the others. 😀 I found using a higher dither setting helped greatly in reducing the coarse background noise mottling leaving just a fine noise which is less noticeable. While Startools noise reduction does reduce background noise without affecting the subject detail it still gives an obvious noise reduced look so I don't use it. I found the Nik Define2 plugin for Photoshop gives more 'natural' looking noise reduction so I used that and just layered the Iris centre without noise reduction on top. There are two galaxies in the image though one is hard to spot without knowing where it is. 🙂 Alan

Due to trees to the North I can only see these in the Summer from my fixed pier so thought I'd give them a go as I was impressed with gorann's similar view posted last month with all the extra dusty features. I didn't expect too much but imaged it over 4 nights waiting until 45 mins after nautical dark to start, so got around 2.5 hours a night. FLT98 with ASI6200, Astronomik Deep Sky RGB and L3 luminance filters. 1.9 hours each of RGB and 4.6 hours of L so 10.3 hours total. Stacked in APP and processed in Startools binning 50%, and finished off in PS. I was pleased with the result, although not much colour detail in the dusty bits. Can't really compare with gorann's 15 hours with a RASA 8 though 😁 Click for full size and thanks for looking. 🙂 Alan

The individual focus points appear to be around 16 stepper motor steps apart. You only need around 9 or so focus points centred on the optimum focus position to dertermine optimum focus. The two lines through the V shape would then follow the V graph slopes and intersect at the correct focus position. This is as SGP used to do autofocus, although it now uses curve fitting to the V graph instead. You just needed to specify the stepper distance for each focus step and the total number of focus steps. In my case it was 25 stepper movements for each focus step and 9 focus steps in total. That meaned it moved the stepper out by 4 x 25 steps initially and then took 9 focus values moving in by 25 steps each time. You have to be in the ball park of correct focus before starting the routine or it may be unable to find focus. From your graph you appear to have selected 16 stepper movements for each focus step and around 60 focus steps in total. This is causing the focuser to move out around 500 stepper steps when you initiate the focus routine which is way too high. I would make your focus setup similar to mine which also uses a lakeside focuser, 25 stepper movements per autofocus step and 9 autofocus steps in total. I assume Voyager has similar setup parameters to achieve this. As Starflyer says horizontal focus steps at the right of the curve generally indicates backlash correction not being set high enough in the focuser setup, but that is indicating an awful lot of backlash which is unlikely. It's possibly the focus is so far out at that point that the focus routine can't determine a proper HFR value and just keeps stepping in until it starts responding to changing HFR. Alan

As I've talked you into it Grant, I hope you'll be happy with it. 😀 As you say, the Xeen range are true cine lenses. You can imagine the extra cost of their zoom cine lenses. 😬 Alan

A lens suitable for full frame will be fine on a smaller sensor, in fact it should appear to perform better, as the full frame edge performance roll off will not be present on a smaller sensor which doesn't cover the same distance from the lens centre axis. That's right. It will function on a film or TV camera, as it has the gear connections for the servos on a film/TV camera enabling local or remote control of focus and exposure, (and zoom, if it was a zoom lens.) For a film camera it's controlled locally by the cameraman, while for a TV camera the exposure is often controlled remotely. It's the critical zoom performance, maintaining perfect image focus and no image shift or degredation during the zoom which is the main cost of cine lenses. Film companies generally rent cine lenses when required, as the cost of buying them outright can be prohibitive. Here's a good run down on the differences between cine and regular lenses. Not having click stops on the aperture shouldn't put you off as it will be stiff enough not to move on its own. The T-stop scale is more precise than F-stops with more marked graduations for setting it. T-stops allow different lenses to be used which will give the exact same exposure as long as they are set to the same T-stop setting. That means they have the same light transmission. F-stops are just a mathematical ratio and the light transmission of the lens is not factored in. Here's an explanation of the difference compared to F-stops. The T2.2 Samyang lets in the same light as the F2 Samyang, it's just the light transmission factor of the lens is taken into account when giving the T value. I'd be happy buying one in place of a standard lens for astrophotography as the settings are all manual, which is what you want anyway, with easier external automation of focus and aperture if required. Optically, in this case, the cine Samyang will be the same as the standard lens version so if you can get it easier I'd go for it. It's not been 'tampered with' as such as both are made by Samyang. 🙂 Alan

By the price it appears to be the standard lens but fitted with geared focus and aperture rings. True cine lenses are much more expensive than their standard counterparts as they are made to higher standards, being sharp to the corners with much reduced chromatic aberration, and no barrel distortion, vignetting or focus breathing. Having the geared focus ring would be handy if you wanted to automate the focus as it's a standard pitch gear. The aperture ring is continuous with no click stops and is calibrated in transmission T stops rather than the normal F stops. Alan