Ags

Just documenting my progress. Here is M3 - 21 x 2 minutes SER sequences of 333ms frames at 360 gain. I kept the best 75% in Autostakkert, then stacked the 21 resulting TIFFs in Deep Sky Stacker (after cropping all the TIFFs to the same dimensions). I also shot 6 minutes of darks and lights at the same gain and 333 millis. I shot in 2 minute sequences because Autostakkert doesn't handle field rotation. After a night of cropping in Gimp, I may pay for Registar... I think my focus could be a little better, maybe. If we get more clear weather these coming weeks I will try to add color.

Here's Messier 3 - AZ-GTi and C6, 333ms frames, kept the 75% best of 42 minutes of data. 6 minutes of lights and darks.

Hmm, if the front thread is M37, the lens can't be F1.8 as if it was the front lens would have to be over 40mm....

My ASI 178 MM has a little sensor and the below lens (75mm, F1.8) is WAY cheaper than a Canon 85mm f1.8 (less than 50 euros). It supports 8 megapixel resolution for a 15mm image circle, so it is best suited to sensors with 4.8 micrometer pixels (I don't know if that is the wide-open resolution). The ASI 178 pixels are half that size so it would require binning. It is easier to make a small lens than a big one, so is it possible this could work for AP? Also note it has M37 filter thread on the front. https://www.aliexpress.com/item/32656983113.html?spm=a2g0o.productlist.0.0.45767326eAzVYZ&algo_pvid=7634b0a7-7f6c-4e05-acb5-aaf4b936a63a&algo_expid=7634b0a7-7f6c-4e05-acb5-aaf4b936a63a-19&btsid=0b0a182b15847098141292503efe8c&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_ The lens body says F2.8 but the product description says F1.8... 😐

I don't think that would work for an AZ GTi at all, it's more for an AZ3. An AZ GTi needs a straight bar with a weight on the end, just like counterweights for an EQ mount

I've thought about it for my C6 but never tried it. Yes load would be more balanced but total load is higher...

My third cat. Cats are where it's at!

Clothespeg? I think my contraption is classier...😀 I have tried a clothespeg on my Skymax 127 but it seemed too long and needed repositioning. This way I can leave the Wire Based Fine Focusing Device permanently in place.

I made this simple focus improvement for my C6. It's so basic anyone can do it with a bit of garden wire. The idea is the scope doesn't vibrate because you only nudge the spokes, instead of gripping the focus knob like a drunken sailor. I thought the spokes might be too short and I would need more leverage, but it actually works really well - precise focusing, no wobbles. The spokes can't go longer on a C6 because of the visual back of course. The spokes also help with counting turns - now I know for example that my ASI 178 MM comes to focus 2 1/2 spokes from my ES 24/68 eyepiece. Of course the spokes don't stop you using the knob as originally intended for coarse focus. This was already posted elsewhere but I think it is neat enough for its own thread.

I shot a dark SER sequence last night, but now I see Autostakkert wants a still image as a master dark file - it does not accept the SER file. Is there any way to get Autostakkert to turn my SER file into a master dark? Otherwise I guess I have to turn the SER file into a sequence of PNGs using VLC and then stack in DSS?

Here is my first attempt - 50 2.7 second exposures (150 discarded). At 2.7 seconds I am throwing away bad tracking and wind gusts not bad seeing, but I never thought I would be able to image a galaxy at 1500mm focal length with an AZ GTi. Obviously I need at least 10 times as many exposures. Also need to figure out how to apply darks in AS3!. It takes a bit of patience as you have to keep the galaxy on the chip manually. I have had more impressive looking results doing live stacking with an ST80, but this is at 4 times my usual focal length and at F10 instead of F5 - I am keen to have another go but shooting a proper series of subs - at least 1000.

And I have ordered a dew shield and Bob's knobs.

Have you had your eyes checked?

Added a fine focusser:

I'm very happy to talk about my setup so don't worry! My long-suffering family can testify to that... 😀 And thank you for the compliments. My idea with the setup was to get the most aperture out of the smallest and lightest possible setup. The AZ-GTi and Berlebach Report 112 weigh 4kg together. I added a Berlebach Uni extension tube of 25 cm to get a bit more height and to let me retract the tripod legs slightly so that I can carry the whole setup through doorways easily and without bumps. By the way, there is a cheaper and better SkyWatcher extension tube specifically for the AZ-GTi but it doesn't attach securely to the Report tripod so I payed more for the Uni extension tube. I hemmed and hawed about getting a Skymax 127 or C6 for the setup. In the end aperture won out! There didn't seem much point upgrading from 102mm to 127mm, I knew I would regret that so I went for the C6. It is too early for me to say how well the combination works unfortunately, both regarding the mechanicals and the opticals. I have only had two proper sessions, the one in this thread and last night I had another session - but I was just messing about with a camera not looking through it. Why a C6? Firstly it is a good choice for planetary imaging with my ASI 178 MM. Secondly I need the aperture to enjoy planetary visual observations as my eyes don't do well with small exit pupils (I have lots of floaters in my eyes). Thirdly I also have a Berlebach Castor giro-style mount, and the C6 will be dual mounted on that alongside an ST80 for no-electronics visual astronomy - the ST80 does the finding and the C6 provides the aperture. The AZ-GTi offers many possibilities. For example, I am also going to try doing ultra-short exposure DSO lucky imaging with C6 on it - that's what I was experimenting with last night (but I got dewed out). In combination with camera lenses I will do widefield DSO imaging. The GTi even offers the possibility of guiding down the line for me. Being so small and light it's a great travel mount (and the C6 is the biggest aperture that fits in airline carry-on baggage). With the ST80 I do some EEA (or is it EAA?) astronomy. I am thinking of getting a 100P reflector for EEA/EAA duties though so that the ASI 178 MM chip can utilize all wavelengths - with the ST80 I have to filter out a lot of light due to chromatic aberration. Into your specific questions: You can use the GTi manually with clutches released but only for rough pointing, it is not in my experience really good for undriven astronomy and at 1500 mm focal length that is even more true. I know some people do use it like that though with 3-4 inch refractors. From the point of view of a beginner, maybe 1500 mm focal length is a bit long and if the goto fails to find stuff it might get frustrating due to the narrow field of view. A beginner might want to look at the AZ-GTi + Skymax 127 package deal available - that will be a lot cheaper, offers a nice upgrade over the Travelscope 70 and the tripod can be easily upgraded when funds allow. The Mak is also more robust and but of course it is also a 1500 mm FL scope. One thing to think about is the C6 can be paired with a 0.63 reducer, cutting the focal length to 945mm, which would make life generally easier! That's something i am going to add at some point.

I'm not using the SkyWatcher extension tube.

I normally use freedom find but not last night. I let the motors take me everywhere. This is because I wanted to avoid the risk (inevitability?) of slightly unscrewing the GTi from the extension tube and losing alignment altogether.

I am not using the stock tripod - I am using a wooden Berlebach Report 112 (rated for 25 kgs load) so it seems to cope very well. As for the mount it was stable and accurate. Only thing of concern I noted was that there was too much angular momentum when slewing at max speed - I an going to slew at a slower rate in the future. It might be worth noting that the tripod is topped with a 25cm Uni extension tube. Vibration damping is one second or so (bearing in mind the upgraded tripod) and that is more than adequate.

I want more things!

Ah, thanks to you I have learned something fundamental. The sky fog photons scatter randomly onto the sensor pixels, and the brighter the sky fog the more similar the totals on each pixel is, so I would be able to take a very good smooth picture of the sky fog... But the absolute difference between the totals on each pixel increases (at the square root of the total sky fog signal) so that when I "zero out" the sky fog in post processing, I only subtract the baseline from each pixel, leaving 100% of the noise component. If I was using an NB filter, the sky signal would be lower so the noise from random photon scatter would be reduced in absolute terms.

Assuming that gradients can be controlled, do narrowband filter offer any benefit with short (1 to 15 second) DSO exposures? I can understand NB filters enabling long exposures by preventing the image from saturating due to sky fog - but this won't happen with short exposures and the sky fog that is captured can be zeroed out in processing.

Yes looking forward to that. I am planning some early mornings in April to catch Jupiter and Saturn. Not just visual but also imaging. And I am waiting for the Moon to come back 😀

On the RC article, he writes "Refractor, 7" to 9" Apo, F8 to F11, or 8" to 12" achromat, F12 or longer." Seriously? He's recommending a 12 inch F12 achromat? I guess I'll just store it in my roll-off aircraft hangar! (I did once see Mars through a 26 inch achro, but I was too young to fully appreciate it....)

Tonight was my first real session with my new C6, which is the second attempt I am making to go up in aperture from a 4 inch Maksutov. I have been hankering after something bigger since 2009 - so no pressure on the C6 to perform! 😀 On the day my C6 arrived last week, I had a brief session with the uncooled scope looking only at the Moon in poor seeing. It was hard to judge from that but the views were exciting and detailed. Fast forward a few days and the Moon is out of the way. The skies were clear all day so the C6 went out at dinner time to cool in anticipation of the evening's activities. To be honest I wasn't in the mood for astronomy with my knee giving me trouble and it was a very windy night. I knew I would regret it if I just watched Rolling COVID News though! The first half hour was spent trying to get the red dot finder aligned with the telescope, but it's impossible - either I need a new red dot finder or I need to do something to the finder shoe. I've read in reviews other C6 owners have had the same problem. Not really acceptable in what is (for me anyway) a very pricey scope. Eventually I simply accepted the one-degree offset, and compensated accordingly for the rest of the evening. I didn't set up GOTO at first - I wanted to get on with looking at some brighter doubles to assess the star shapes and general "feel" of the telescope. First up was Procyon to do a star test - to my relief the rings were concentric inside and outside focus so good news. There was no annoying focus shift either. Then I moved to Polaris: it's been in the news because its mass calculated from its brightness differs wildly from its mass calculated from the orbit of its companion star. I thought it was an easy split at 60x. I pushed up the magnification to 150x but didn't much like the view, the stars were soft and the companion too faint at that magnification. I dropped back to 94x which was a good compromise. Aesthetically the star shapes in the C6 are better than the 150PDS Newtonian I used to have (slightly larger even when in good focus, but thankfully lacking the extended hairs of Newt stars). On some levels I preferred the C6 stars to refractor stars as the tightness of refractor stars makes it harder to see differences in stellar brightness and color. But I did have a nagging memory that the stars in my Skymax 102 were that bit better... Still overall I found the view through the C6 pleasing and competent. I quickly bagged Mizar and Alcor (60x, very nice), and Castor (94x, good color). Faint stars don't seem much brighter at 6 inches aperture than they did at 4 inches, but bright stars are really on fire! I did a quick one-star alignment on Capella - figured that this rough alignment would be enough to get me close to the Messiers in Auriga. Wow Capella is bright! M38, M37 and M36 were much improved with my increased aperture, particularly M37 and M36. The clusters were sitting over my upstairs neighbor's chimney so it's the end of Auriga season for me. Just for fun, I told the AZ-GTI to slew to M97. I've never seen this object so I hoped tonight I would get lucky although I did not expect the GTi to slew accurately that distance based on a one-star alignment. I still couldn't see M97 despite scanning the region carefully. How hard is that nebula? I sent the GTi to M82 and to my surprise the GTi got it in the 1.1 degree field of my scope. I couldn't resolve any detail in the galaxy however, while I have previously seen some mottling in it with the Skymax 102. I am sure that will come on another evening though - the scale of the galaxy was impressive in the C6. Writing this I regret now that I didn't slew back to M97. It must have been in the field of view and maybe knowing it was there would have helped me find it... Overall the evening was reassuring - the telescope produces pleasing views and the stories of horrible star shapes in SCTs don't seem to be true, for my eyes and this SCT anyway. The AZ-GTI carried the C6 well and even gave superb GOTO performance. I will however not slew at speed 9 in future - I had the sense that the highest slew speed produced too much torque when the AZ-GTi was slowing down at the end of the slew.

Still thinking about this one... Now thinking it might be really useful in combination with my ASI 178 MM.