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Hi Stellaris, If you use a barlow you should not be using the camera lens. Your camera can probably come to focus without either camera lens or barlow - attached directly to the telescope focuser (if it has an M42 thread). Cheers

Hi Olly, What about chaos theory? Does this fall into "being consitent"? Cheers

... so FR on camera side

Hi Michael8554, you mean it should be on the camera side (of the focuser) - for the reason you stated?

Hi SteveBz, Maybe you can try on the NASA/IPAC Extragalactic Database. There are fit images you can download. Cheers.

So the problem seems to be fixed. It may have been that the camera was not on manual mode. I remember seeing a warning in Ekos but had disregarded it since everything seemed to be working. Anyway I did not think it would lead to errratic exposure time - maybe the warning should be more strongly worded Best

Hi almcl, So both High ISO and Long Exposure noise reduction features were off. I found the "CCD Temp" value in the FITS header, as can be seen by the KStars image viewer and all subs were at 16 degrees. Best

I will check if I have not disabled the noise reduction in the camera, I don't have the raw files - just the FITS.

Hi All, I noticed a few times while imaging with my Canon 700D (KStars/Ekos) that one of a series of subs will have much less background noise than those immediately before and after. At first I just though it was the way the FITS viewer displayed the images but when I check later there was a huge difference. I attached a screenshot (to reduce size) with successive images side by side opened in AIJ. I captured the sequence automatically and did nothing between subs. The subs are 60s and maybe max 30sec between the subs while the image downloads over WiFi. Any ideas? Best

Maybe you have to post a series of bloopers to be appreciated again - before posting the big one 🙂. I would like to know which of your scopes/lenses did you use?

Very nice and interesting. I checked the specs of your scope and it seems to be corrected to APS-C size with no additional accessories - and at f5.3. Just wondering why this kind of scope is not more popular for astrophotography. I searched SGL for your image of And XXX but could not find it. I would appreciate it if you could link it. Best

Well, the FWHM will be smaller for a larger aperture regardless of magnification . But for the theoretical PSF intensity profile, there seem to be intensities (like at the level of the red line) where the airy disk is narrower for the smaller aperture. What i would like to know is how that translates to what we see at the eyepiece. Cheers.

Hi Viaiv, I understand that our vision is extremely complex. But surely we can speak of broad thresholds, like the 6th magnitude naked eye limit or that specified for their instruments by the likes of Celestron. In my plot the red line could be like the limiting magnitude for the Green scope. But let me ask a related question. If we had two APO scopes (perfect optics) differing only in aperture and ignoring other factors like seeing, sky brightness etc. Would we see the airy disk of the same star to be the same size in each scope - or will it be "bloated" in the scope of larger aperture? I think the latter 🙂. Best

Our vision will have an intensity threshold for some particular situation, though of course will vary from time to time and from person to person - for example if dark adapted etc. What I was attempting to illustrate was that if the threshhold for a particular observer at the time of observation (no suggestion that it is linear) is at the level of the red line then it is possible that the size of the disk seen for a certain star might be bigger for a scope of larger aperture vs one with a smaller aperture - which we might interpret as bloat. Hi CraigT82, actually the size of the airy disk depends only on the aperture and not the focal length for a point source like a star.

Hi All, I have heard of that SCT views are "soft" or "mushy" several times on the forums. I was curious about this because I could not really imagine the views through my SCT being any crisper. On globulars and open clusters, if the faint stars were any more pin point then I wouldn't see them (and I don't use glasses). So I tried to simulate the Point Spread Functions (PSF) for different apertures of scopes shown in the image below, and this is my take on it... The curve for the lowest aperture is the flatest Purple curve, the next flattest Green curve has double the aperture, and the tallest Blue curve has three times the aperture of that of the Purple. If the threshold intensity that our eye can see is at the Red horizontal line, we can see that the width of the PSF is larger for the Blue curve than that of the smaller aperture Green - meaning it will appear more "bloated". We can also have a similar situation between the Purple and Green a little lower down. Thus for certain stars the image would appear more pinpoint in a scope of smaller diameter than that for a larger one. Together with the larger image scale of SCTs, and the fact that larger apertures are more susceptible to seeing conditions, this could explain why we might perceive SCT images as soft, bloated or mushy. Best

So you can love astronomy and not love CATs???

Hi Jamesnewbe, If it is indeed the Powerseeker 127, I have used this scope and it is seriously problematic. The mount is shaky and the eyepieces supplied with the scope are pretty bad. However if you learn to collimate and are very determined, you can still see a lot with this scope. You can use it to familiarize yourself with the night sky and get some idea of the kinds of objects you like to observe (for example planets vs deep sky). You can eventually discover how passionate you are about the hobby, and determine if you need to buy further accessories or a different scope in the future. Best

I was just wondering about the "mushiness" of SCT views as compared to Newtonians. Is there any comparision of the views between that of an SCT and a non-premium Newtonian of similar aperture, but say with the Newtonian "barlowed" up to the same f-ratio as the SCT? While I have not had the opportunity to look through a large dob, faint stars throught my CPC 1100 seem to be really pinpoint (for example in open clusters like M37). Best

Hi timwetherell, Very interesting. Could I ask the equipment you used? I am especially interested in how you did the 1𝜇m IR. Best

Greetings hjw, could I just ask what material did you use for your dome? Best

Guess you meant 11:30 PM?

I think I can get the value of the eVscope for people that already do astronomy and know some of the science, like those mentioned above who use them to acquire images then post process. But for outreach I feel it is too detached from the science. I think some will remember these which kids were always eager to look through. I feel that these digital scopes are just a step removed. Best

Hi Parziva1, I have some experience with the 130 SLT, and have mixed feelings about this scope. The mount is not very robust so it is troublesome to use above a magnification of about 100X. To get that you would need a 6.5mm eyepiece which should be a decent quality to be able to use comfortably. Secondly, collimation is critical. I don't have any collimation tools so I have just tried on a defocused star, and I feel that I never got it to be optimal. As a wide field scope and with lower magnifications, it is good on things like open clusters but it will not be ideal for planets. For astrophotography, you will not be able to use it with a DSLR as it will not reach focus without a barlow (a 2X will make it f10 and probably unusable on its mount) . If you have a mirrorless though it might be a decent option to get started. Hope this helps you decide. Best

I think this is a great image though of course each of us may have our own criteria - and I am no astrophotography expert. I imagine you might not get as much scale and resolution on your WOStar71. The corrected image size for the 6.3 reducer is specified as 24mm so in theory it should be okay for the 4/3" sensor of your camera to the edge of the field. The soft stars are also expected because of the 0.75 vs 2.7 arcsec/pixel image scale. Do you know the reason for the coarse noise patten of the background ? Best!

Atmospheric refraction can actually significant and observable. For example it can be several minutes between the times the Sun actually rises or sets and the time we see it doing so. The effect of atmospheric refraction is greatest near the horizon because we see objects through a greater length of atmospheric thickness as compared to strait up to the Zenith. Best