ollypenrice

Yes. The smaller galaxies can be imaged with an 8 inch SCT but it won't be easy because high resolution imaging needs very precise tracking and guiding. This needn't be impossible. Consider, also, that you might do much better on DS imaging with an SCT if you used a mono camera which could be binned 2x2 to improve the speed and ask less of the guiding. Olly

Nice. To check the exposure you could just measure the brightest part of the galaxy cores in the linear stack. This will tell you if it's saturated. If it isn't then it can always be preserved in the stretch. Olly

You are asking for three capabilities, visual, planetary imaging and deep sky imaging. Vlaiv has identified scopes which can just about offer all three but, personally, I would say that you really have to choose between visual-planetary and visual-deep sky imaging. Imaging is hard enough without throwing yourself curved balls in the form of compromises and the two kinds of imaging, certainly for a beginner, are not catered for by a single instrument. The good beginner targets for deep sky imagng are mostly large, bright nebulae requiring a short focal length. Deep sky imaging at long focal length and high resolution makes heavy demands on autoguiding and shouldn't be attempted without it. There are other ways to attack the problem: - Inexpensive Dob for visual and small apo refractor for deep sky imaging (and widefield visual.) - SCT for planetary imaging and visual, plus simple camera lens for widefield deep sky imaging. Nutshell: if the Universal Telescope existed we'd all be using it. But it doesn't. Olly

You've nailed it with the second one. Very good indeed. Olly

As Vlaiv says, there is no need to match integration time. What you're after in short subs is the right exposure for a small part of the target and you'll only be including the bright signal into the final image anyway, so noise won't be an issue. For this reason I don't shoot luminance for the short subs either. The purpose of luminance is to get more signal and here we want less. If you feel like a change from PI then this is a great Photoshop tutorial. http://www.astropix.com/html/j_digit/laymask.html This is how I did my own M42, using LRGB for the long subs and then just RGB for those of 50 and 11 seconds for the core. Olly

It might be worth remembering that hot air rises. However, the baffle tube goes a long way into the main tube. I can't say I've ever had this problem so I wonder if the scope has a particular issue, or maybe its local environment. Olly

Lovely image, Dave, and one which whispers enticingly rather than shouts. This puts me in mind of the way M33 appears visually, too. The tiny stars are also very fine. Olly

Lovely. Personally I'm a strong colour enthusiast but this often gets me reprimanded on the French forum, though I seem to get away with it here! What's the LRGB issue? When you have strong luminance it can easily dilute out the colour. In Photoshop I address this by adding only a low opacity of luminance, increasing the colour saturation of the bottom RGB layer and then putting a slight blur into the top L layer before flattening and repeating the process. On the final, full opacity iteration of luminance addition I omit the blur. Olly

I think this is a really good idea for all the reasons expressed by the FLO team. Bravo. Creative and generous thinking all round. Olly

The French NHS fixed my heart rate using the same technique... ly

I think this is a mistake. It leads people to suppose that, in making the object fill the frame, a small chip is creating a larger or more detailed image of that object. It simply isn't. The only way, in given optics, to make an object's image larger is to put more pixels under it - meaning choosing smaller pixels. Or you can use a longer focal length. If an object is too small in its full field of view, as imaged, we simply crop it for presentation. Olly

I always found the need to hand-track the Dob to be quite a big negative on the planets. For this reason I might be temped by the Mak. Olly

Nice and rarely (if ever) seen on here. Olly

Very attractive and I do prefer the Hubble when the processing keeps away from green like this. Olly

Don't fight noise or gradients with the black point! For me your first process was the best but it needed a dose of SCNR Green in PI. I'd go easy on the noise reduction, too. If you can see it it's too much! A bit of grain beats a bit of visible vaseline... But this is a mighty fine début! Olly

This is certainly possible but it means that we must attribute the alignment of the duplicate stars along the lines of RA to chance. (Had the OP's camera been orthogonal to RA and Dec we might have suspected the stacking software of having erred in one up-down alignment which wouldn't be surprising.) However, coincidences do happen. Olly

More importantly (or more jealous-making) many of them can also fly! Back on the psychological aspect of binocular observing, I suspect it's quite variable between individuals. I've never been overly fussed by bino viewing. It does have something natural and relaxing about it but only once I've got my eyes and the oculars into exactly the right position - and this takes some slightly stressful fiddling about. But then I have a very lazy eye which, on its own, gives a dismally soft image. Perhaps those with two good eyes get more out of the bino experience. And here's one for the pot: how do dyslexics feel about bino viewing? They have no dominant eye. Olly

This makes sense to me but you say, 'EDIT: To add to his, the only advantages for us and other animals of havng two eyes are to get stereoscopic vision, that aids in determining distance, and in getting a wider field of view, but none of these advantages applies to a bino telescope.' Might there not be another factor? In an accident of evolution, as I understand it, we are 'sided' creatures with two brain hemispheres, something which produces many curious by products. Could this have knock-on effects in regard to perception? I'm only speculating since I've no expertise in this matter. Olly

I think it would be true to say that a DSLR works best with an Epsilon (see Maurice Toet: https://www.mauricetoet.nl/ ) but I can't see any reason to think that an Epsilon works best with a DSLR, at least now that dedicated cooled cameras with tiny pixels and large chips are available. Anyway I think Adam has made a great start with an excellent, if challenging, scope. Olly

I go for the Giraffe because a chicken, though very good in a curry, does not have the long, elegant neck seen in the asterism! Olly

I never knew this. It's also very visible when focusing in NB using a Bahtinov mask but I never thought about why. Olly

What we see here are pretty good star shapes but with every star duplicated, the doubles offset from each other and superimposed, one larger than the other. This would be explained by the mount tracking well but with a sudden nudge of the OTA position during the sub. It is not drifting slowly, it is recording two quite distinct stellar images and spending longer in one position than the other. We are, therefore, looking for something capable of causing this effect. The first thing we need to know is the orientation of the camera relative to RA and Dec to see if the angle between the double images aligns with one axis or the other. I image with my camera orthogonal to RA and Dec (a good practice for several reasons) and, as I expected, we find that your doubles lie precisely along one axis. I asked Registar to rescale your image and apply it over mine: So your problem is a single-axis one and from the star charts we can see it's RA. As well as the possibilities mentioned above, backlash in the drives could very easily cause this. The mount could spend some time resting on one side of the backlash then flop over quickly to the other, so recording two stellar images. While wind or snagging cannot be eliminated I would not expect either to affect only one axis or to hold the scope still for long enough to record a round star. Personally I think backlash in RA would actually give the best fit with the evidence but it is never possible to be sure. Olly

One can only dream... of two! Our friend and guest Ralf Ottow once appeared with a C11 bino but it was a crafty one since he'd ground new corrector plates and secondaries to extend, slightly, the focal length. Although you can get it to focus with the double diagonals needed for bino use the scopes cease to be diffraction limited when using so much back focus. His subsequent creation, an entirely self-made giant SCT 'Binosaur,' is too large to leave the Netherlands, alas. The question of light grasp is an interesting one though. Obviously it's doubled, but this does not appear to be how we perceive it. If I close one eye while in a low light environment, for instance, the image I see does not become dimmer. Does anyone know the physiology of monocular and binocular vision? Olly

I'm watching with interest but removing the noise from the exercise reminds me of a joke about a statistical formula for betting and winning on the horses. The formula is perfectly correct... but only works for spherical horses racing in a vacuum. lly

That's what I found as well. Olly