Adam J

Should that not be Cheshire for primary and laser for secondary??

I would not expect any actual technical level information from Astro Backyard its more show and tell level advertising. My personal opinion is that all things considered the ASI071mc Pro is a better camera, no amp glow, no weird dark frame calibration issues leaving background artefacts. Certainly some of the more modern OSC cameras coming out like the QHY268c will blow it out of the water if you can afford it. Narrow band with OSC cameras can be achieved and some of the new duel narrow band filters are a step forward but most people with them are not processing the data correctly currently leaving the images red dominated, part of the issue also being the lower transmission of the Green / Blue micro filters to OIII. But if your going to spend that much money and want to do narrow band you are still much better off with a mono camera. I would say get a mono camera, in the long run you will be more happy with it. Adam

Its an ideal starting scope on a budget. Easy to move and store. You will also need a Newtonian colimation (laser / Cheshire) tool and I would suggest a 2 x Barlow lens for some higher magnifications and you are ready to go. In terms of astro photography, I am not sure its the ideal scope with the weight of the camera on the helical focuser. Dont expect any Dobsonian to do DSO imaging for that matter, but you could dabble in a little solar system imaging. Adam

I know what your saying and to an extent there is a point at which it can be so bad that you can only make it better no matter what you do, but those rear elements can still be poorly seated and if its that bad just send it back as that way you will not infringe the warranty.

stunning work.

Yes don't do this, you are adjusting the front element but you cant even be sure that is the one that is out of place, for all you know its the rear element pair and you just changed moved the front element out of alignment.

I dont think that you would like the results from a 0.5x focal reducer on a Dob, you will need a coma corrector for a dob and the best you can find without spending a fortune is a 0.9x reduction. Your current scope is suitable for imaging planets without any reducer but unfortunately neither the scope or the mounting type are suitable to any degree of DSO imaging. You will want a tracking EQ mount and a much much shorter focal length scope to start out with DSO imaging.

Yes those are micro lensing from the ASI1600mm pro a well known issue. I was more interested in an example from a OSC full frame CMOS as per what Olly was discussing. I think its worth noting that the micro lensing is caused by a un-coated cover glass not the sensor technology itself and so if you placed an uncoated cover glass over a CCD you would have micro lensing on the CCD too. Actually you do see this as in the QHY9m which uses the budget version of the KAF8300 without coating, although its less pronounced due to the larger pixels of that chip.

Micro lensing would show a pattern as opposed to just larger stars and CCDs also have micro-lenses, my guess would be something more along the lines of too high a gain setting. Would be interesting if you could post an example.

Not sure how CMOS technology could result in large stars unless someone is using it incorrectly, i.e like you would use a CCD sensor.

Whats your price limit?

That would be the pro model (with cooling) which was not the original subject of the thread.

F4 Newtonian are a pain in general in my opinion too hard to keep colimated and you are better off with a well colimated F5 with a bit more focal length than a poorly colimated F4 with less focal length. Also lots of galaxies are not so faint as you might think hence when imaging in luminescence you can accept the trade off in F-ratio / integration time for better real world optical quality and a flatter field.

I have heard of that problem with ZWO 36mm and 31mm unmounted filters without blocked edges. I have not heard about any issues with Baader 36mm filters. Personally if it was me I would get Ha and OIII first then get the LRGB later as opposed to the other way around as if you want to image emmission nebula you will get vastly better results in narrow band. Of course if you want to image galaxies or M45 then go LRGB. Try to work with filters that are close to the same thickness as it avoids issues, ie. using Astronomik LRGB (1mm) and Astrodon Narrow-band (3mm) might lead so back focus issues. Adam

I cant really help you with that as I am using 1.25 inch without any vignetting at F5 so unless your going sub F4 or think you will get a bigger sensor in the future I really would not advise you to go any bigger, all its going to do is cost you money for no benefit and in fact the biggest result will be that you wont get as many slots in your filter wheel. I have performed the calculation myself, there really is no vignetting on 1.25 inch filters. Certainly not on any of the scopes you are listing in your signature block. I use Astrodon for my narrow band in addition to the Baader LRGB filters. No chance of affording those in 36mm or 2 inch. Adam

I use Baader with mine and love the colour balance that I get from them, I tend to think this idea that they are matched to the sensor is a bit of cleaver marketing. Baader are well known in the hobby as a producer of fine quality filters, on the other hand ZWO have had quality issues with some of their filter products although they have made improvements.

You will end up with a pixel scale of <0.5 arcseconds per pixel. Along with the weight of a 200/1000 (don't go with the F4 for galaxies) you will be struggling to guide to the required accuracy without an extremely capable mount / probably in a obsy. Also you will be struggling to get sufficiently good seeing (atmospheric conditions) to enable you to resolve objects down to <0.5 arcseconds per pixel unless you are imaging from an elevated location. Thats not to say you cant do it though, its actually potentially a very good galaxy combination, your just setting yourself up for a challenge. The 183 is useful as a pure galaxy imaging at between 750mm and 1000mm focal lengths and for wide field nebula imaging at focal lengths <400mm. I would seriously consider the 183m though as opposed to the OSC if you want to image galaxies in any light pollution at all as using filters with an OSC will result in horrible colour balance. Adam

As I said "that still applies to duel band filters". Third line of my post. What I am trying to say is that although you can always image two channels it's not that simple as sometimes the oiii will not be usable and often you will be better off with a narrow single line filter in sub optimal conditions for this reason. But in good conditions duel band filters are a good way of increasing efficiency.

Yes and no. You can't really do oiii in moon or light pollution so it's good to be able to use a narrow filter for just oiii on moonless nights. That still applies to duel band filters. So if you image over a lunar cycle most of your ha will be good but a big chunk of the oiii will not be usable. However you are always collect information both channels all the time as opposed to one after the other so on good night's it's more efficient than desperate filters. Usually you will fine the separate filters to be better quality though. My thinking is that I always want oiii to be as narrow as possible.

Its not dark enough for RGB imaging at the moment, also its very warm weather for an un-cooled camera in mid summer. Things will improve for you greatly once the weather gets cooler and the nights longer. I would got for some Ha and OIII narrow band in this image.

Its most likely coming out red because you have either pushed the red channel independently to get the red nebula to pop more. However there are a large number of bright red stars in the background anyhow.

did not wait long for a reply lol. Either would have been fine.

I would say that the lack of micro lens diffraction effect on the 183 against its presence on the ASI1600mm pro is a significant difference to consider between the two chips too. Different people have different views on it based on personal preference.

At those short focal lengths I would recommend a IMX183 based camera. You do have to take care with pixel scale with very short focal lengths though as they tend to be associated with small aperture optics and so the diffraction limited resolution of the optics and exceed the pixel scale with very small pixels. When combined with the 130PDS the IMX183 will be surprisingly good at galaxy imaging. However, not quite so good as the IMX178 with its lower read noise and higher dynamic range via its 14bit A/D as opposed to the 12bit A/D used in the IMX183. On the other hand the difference is not too big and the larger sensor of the IMX183 makes it more useful across a range of targets and focal lengths and will work very well with your Canon 200mm lens and 60mm refractor. Other people here are suggesting the ASI1600mm pro and that is another good option that will provide you with wider views due to its larger and slightly more sensitive sensor. However its is more expensive and be warned, prior to going down that path look up something called micro lens diffraction pattern as associated with the ASI1600mm pro and other cameras using that sensor. If you can live with it then sure, get the ASI1600mm pro. If you cant live with it or the additional cost then you are best off getting a IMX183 based camera. Hope that helps. Adam

Got to agree with others, those look fine for a full frame sensor. I would be less pleased if it was a APS-C but I would find the performance acceptable for full frame. Its certainly worlds better than many of the examples images I have seen from the red cat. But the thing to remember with that is the large number sold over a short period and the bias involved, people don't post test images to forums when its working correctly only when there is an issue. That makes it really difficult to determine how wide spread any problems are or are not as the case may be. Best thing to do is look on astrobin and see how its performing over a wide range of images as opposed to a thread like this one. Adam