Adam J

Your saying that you cant see any stars on a Ha image and that you think that is caused but the spacing? I very much doubt that is the case, you should be seeing stars even if its way off. Adam

That's a small sensor it's very unlikely to be crytical.

As you say the filter are parafocal... To be honest I would have thought that if your losing lum which is always going to cause a little bloat in a doublet then there is not much point in re-focusing for RGB anyway? Adam

Its they are over correcting, it looks like an issue with settings in APP to me. I suggest that you go through APP setting on calibration line by line and see if you can find something out of place. Are your flats being correctly calibrated with bias?

No single scope will compete with a duel rig mate certainly not at that focal length. Even at 500mm you would need something like a 115mm scope running at F4.5 to get close. Maybe if your willing to consider a 8 inch Newtonian F4 which would give you 800mm. Personally I would keep the duel rig and move to something like a Duel 100mm triplets @ F5.5 to get you more speed.

Ill have a go at processing it tonight after the kids have gone to bed.

On APT you will note that the cooler power is displayed on the top left of the screen. Once that had gone to zero there is no difference compaired to just letting it naturally warm. The most rapid warming occurs at the max temperature differential and that the bit that has the most potential to cause damage...if any.

I warm mine slowly but not too slow lol. I have had many camera disconnections etc and its not killed anything yet. But for the sake of a few mins to warm it..... Adam

Unfortunately converting it to JPG prior to stretching it wont work as the bit depth is lost. Hence as per this example all you can see are stars. You can only convert to 8-bit after processing.

Could be ice on the sensor. Really you need to post some images.

You can take darks any time if you can match the camera temperature in the fits file from the look of the images you sent last night 8.3c. I cant view fits at work, i assume you have amp glow due to no dark frames? If that a single sub or a stack? Adam

Accounting for filters is going to be interesting when I get mine, I have baader LRGB at 2mm thickness and astrodon narrowband at 3mm thickness but am hoping that is i tube it to the astrodons the 0.3mm difference in licght path wont make any difference for the baaders.

my understanding is that with the space on the flattner its 55mm back focus. Could be wrong though.

something dried out most likely.

he already tried and still got significant coma although the colimation looked good, might be the tiny pixels showing it up.

Just dont let it hit mate you can damage the worm gear. Those subs are looking nice though. Just need over 500 of them lol. Coma corrector is clearly working looking at that. When you flip really try and get the center of the bubble in the center of your image. It will make for a much better final product. Adam

I dont even own one and have not missed it so far. Eventually there will be a target which I want to try SHO on but not right now, I like HOO better, its more natural.

did you get it fixed?

It should not change the FOV significantly. I.e. not so much that you would be able to see the difference from visual inspection alone. Most correctors will change it a little tiny bit even if they are stated as 1.0x but like i say it wont be noticeable without plate solving to measure it.

If its back its not likely to be the sensor. I would say that the camera most likely has a fault of some sort by the sounds of it.

Looks great to me, OIII is always going to come out green in an OSC as it peeks in the green channel. Apart from that you do have a little sensor tilt that could use sorting.

If I only had a 5 position wheel I would do one of three things, 1) Focus fully on narrow band, Ha, SII, OIII, Lum That combination would allow me to do three channel SHO images and take mono images of objects such as galaxies. I might then change things over for galaxy season later in the year. 2) Do something half way, R, G , B, Ha, OIII So I can take bi-color narrow band images and I can take RGB images without lum, using all RGB subs stacked in place of lum. 3) Sell the 5-position wheel and get a 7-8 position wheel. Thats the hardest one to swallow as it involves admiting that you made an error getting the 5 position wheel in the first place. I almost made the same error and then at the last min realised it was always going to turn into a false economy at some point in the future. Adam

Yes having a permimently aligned system saves a tone of time. When I had my kids I built an obsy so that I would have time to continue imaging, if not for the obsy I would never get any done most likely due to not having the energy at the end of a day to drag the scope outside.

You really do need a pier with some hard standing around it mate. Condensation will be a killer if you don't control it.

The sombrero is a very very bright galaxy. I think I actually did the full calculation for you on that telescope once before ill look to link it tonight. The problem is that in the community we tend to decide on our camera first and our scope second, that is normally because the choice of camera is constrained even more than the choice of scope by financial considerations. Or if we do have a scope already then we just bung the sensor that we can afford onto it as opposed to the one that best matches the scope and the desired FOV. People cant generally afford a large sensor and a large aperture fast F-ratio scope to match it to and to cover the sensor with a flat field. What that results in is compromise on either the sensor the scope or more likely both. So lots of the time when people discuss wanting faster f-ratio scopes to reduce imaging time then its under the assumption that they will be forced down the path of using the sensor they have with it as opposed to the sensor that matches it best trading image scale for FOV and speed. As such with that fixed sensor type you will always image faster with a lower f-ratio scope as larger optics at a higher f-ratio will just result in increasingly sub optimal image scale. As you note looking instead at achieving a fixed image scale independently of focal length, in that case and assuming that your read noise is fixed at a per pixel level you will end up with the imaging rig being faster independent of f-ratio. The problem is that its not possible to do as we don't have access to a infinite range of sensor types in the same way as we have access to scopes that cover all focal lengths. Although you can bin in software and or hardware it all becomes impractical because the sensor has gotten no bigger and you cant afford a bigger sensor with larger pixels to go hand in hand with you cheap 120mm F9 doublet and allow you to continue to fit the whole of M31 into your FOV at a fixed image scale. With the "affordable" cameras having relatively small pixels and small sensor area these days trading image scale for increased Signal to noise and FOV via a focal reducer is a good trade. Are you better off having the same FOV with a larger sensor and larger and bigger pixels to maintain image scale irrespective, coupled to a larger aperture higher F-ratio scope....of course you are....can people afford to do that, no. The sombrero is a fantastic top quality image, but I seem to remember from previous discussion that I dont believe that on very close inspection detail is being resolved down to the pixel level, as such it was my previous conclusion that its was slightly over sampled for the seeing and that as such a similar result could have been achieved in less time if the Barlow had not been used. But even regardless of that the argument here is not that it could not be accomplished at F15 its that the same SNR would have been achieved in less time if it had been taken at F9. Finally as above the Sombrero is very bright, not sure I would want to try that with even something like M101. Adam