Jannis

Depends on many things, and also a lot on the 50mm lens. Most likely you'll need to step it down, probably to around 2.8 or so to get a decent sharpness, maybe more. The canon FE 50 f1.4 lens i use only give acceptable stars at f2.8, and is optimally sharp at f4. Also depends on the camera temp, as this sensor is really noisy over 0-5c. I find it hard to use for imaging over 10c. At -10c it's good, and at -20c it's excellent. I found that calibration frames really can't save you with this sensor when it's warm. To get started, set gain to 100/max,and expose 1-5 sec. Make sure to expose long enough so you have something to align with, either it being stars or the core of galaxies. Shorter exposures will give less deep image but increased sharpness. Less gain will lead to less burned out stars (if you have very bright stars in the FOV), but sensor will not have as high sensitivity. For fainter targets where there are no brights stars that needs to be protected from burning out, i found gain 80-100 usually gave best result. If you only have 1 or 2 stars to protect it might be worth ignoring them, but if you're imaging a cluster it might be better with a lower gain. I've came to like FireCapture the most for high FPS (less then 5 sec) work with the QHY5L-II, and APT when doing long exposures. Sharpcap is a good alternative as well, especially for exposures under a couple of minutes. That's my experience at least, but i hope someone correct me if i'm wrong...

Looking really nice so far! As far as your 280mm pier, i would make it thinner at the top. I learned it the hard way after just testing the HEQ5 mount and Explorer 200 scope on my 250mm pier yesterday. I thought 250mm would work fine all the way up, but i regret that now. It still works, but i can't leave it unattended.

I've now started on the roof. After some more measurements I decided to keep the same hexagon shape as the walls instead of making it round. I also decided i had so little space to go on that making the top with smaller diameter then the bottom would be nearly pointless, so i didn't bother with that. I went ahead and bought some more materials. I went for 10mm OSB plates. They are not water resistant, so they will have to be coated. I've not quite decided on the coating yet, but it will most likely be either epoxy, gel coat, or fiberglass. Since i was keeping the hexagon shape, i made another set of hexagon rings and put them together using an angle iron that i simply bent into the correct angle. Each of the plates are 81cm wide and 90cm tall. The lower frame was attached 65mm from the bottom of the plates. The reason for this is because this space will be used up by the metal ring and the wheels. This way there will be just a minimal gap between the walls and the roof. I did not have time to finish the roof yet due to incoming rain - which the plates can't yet handle. I'm planning for the spacing between the laths to be roughly the aperture, and i will make a similar cut in one of the walls as well as soon as I've made the framework solid enough. I'm still just taking things as it comes, and I've yet to decide on how to open and close this thing. It seemed easily done manually at first, but i now realize that this thing is so tall i won't even be able to reach the top of the roof, so I'm thinking about a way to automate it. Oh, and so far this thing weighs in at 39KG - without the top plate, doors, coating, and the metal ring... Maybe i should have bought a more powerful motor...?

I just learned this the hard way with my setup. I can't do much about it now though, i just hope it will be fine for the most part, and i'll have to keep an eye on the scope when slewing or tracking for a long time. I like your work so far!

Really nice work there! May i ask why you have a small oven attached below the scope? I thought one wanted to have the temp very close to the outside temp, or do you have it just to keep things dry in case of high moisture?

The time has finally come to test if the scope fit or not. My nervousness on a scale form 1-10 was about an 11... I attached the scope as high as the bolts would allow me for now to be sure that even if i decide to attach it this high it won't hit the roof. The scope and mount fits nicely on the pier, and it's very solid compared to the original tripod. I wanted it tight, but i honestly think it would have been better had i made it 10cm wider. The scope really just fit without reaching the walls, but this will complicate how i will build and attach the roof. I did have a plan in my head for the roof design, but i had misjudged how tall the scope would be also towards the walls, and it's also a bit closer to the walls then i had hoped. It's still inside though, so it will work, it will just be very very tight. And finally i can take real closeup pictures of my cat! All in all i think it's a success so far. It's tight, but i think it will all fit together nicely once done. For the rotation of the roof i have a 2.2Nm Nema 23 stepper motor on the way, along with a 350W 60V power supply, Leadshine DM856 Digital Stepping Driver, and a digital rectangular wave signal senerator. These items should (hopefully) allow me to adjust the motor speed accurate enough to be pretty close to sidereal speed. 2.2Nm torque is not a whole lot, but as i will be gearing it down i hope it will be more then enough for this slow rotation, even with some snow and ice on the roof. The reason i went with a digital signal generator is that while i can get close enough with just a manual potentiometer, this would work fine fine for deep sky, but i want a way to quickly adjust the rotation speed between sidereal, lunar and planetary. That way i can simply record the frequencies, and type it in. I have not decided on how to mount the motor just yet, but i intend to have a way to either easily adjust the speed for slewing to new targets, aligning, and such - or a way to temporary disconnect the motor to rotate fast manually.

I've been working on the HEQ5 mounting plate to be able to attach the mount and scope to verity the height requirements for the roof. I had a large waterproof plywood plate available, and decided i would use that as it's very solid, yet easy to work with. I started by cutting out 3x 25cm plates from it. I then proceeded cutting a 60mm hole in the center for the HEQ5 and tested that the mount fits perfectly. The plate is thick enough so that the mount does not go all the way trough, and so it's very easy to attach it by simply gluing two plates together, drill a 10mm center hole, and use a 10mm bolt. The waterproof coating had to be sanded off first for the glue to make a solid bound between the plates. After the glue had dried for a coupe of days it was ready to test if it would fit and work as intended. So far it looks like everything fits together perfectly, and the next step will be to attach the scope and measure the minimum space required for the scope to swing around freely.

Personally i simply used a 5/10 liter bucket to measure. I don't think it's critical to get the ratio precisely (there are many different ratios anyway depending on your desired concrete strength), but i quickly found out that just counting shovels were no good. I aimed for a ~B20 mix. Remember to use as little water as possible. If you're measuring the water, don't pour it all in at once, leave a bit and add only if needed. When you think you are just about there with the water, adding just a few more drops can suddenly make it all too wet. I also thought i would just mix everything in a bucket, but i was only able to blend one single 50L bucket before my arms were all tired, my 700W drill was running hot, and the mixing tool had made a crack in the bucket (it was a thick bucket designed for this). I then proceeded with a proper mixing machine and in the end i realized i would never have been able to finish with a bucket. I ended up with about 3 tons of concrete in the end How much do you intend to mix?

Next step now was fastening the walls before i could do anything else. As i had to hold the entire thing up somehow while pouring in the concrete, i simply used the temporary laths to support it. I made a mold for the concrete to go into, and gave it a day to dry. Now the walls are holding together on their own, and all but two temporary laths are removed. I decided to remove the gravel and fill it up with more concrete for added weight and support. Gravel is gone, but mote materials were needed... Now that the ground was complete, i proceeded to finishing up the pier. I had decided that it would be ~150cm tall, and so i also decided to increase the diameter to 25cm. Naturally, before i could finish up the pier, i had to decide on how to attach the scope. It ended up with 6x M12stainless steel bars, and to make sure they would not budge in the concrete i reused some angle iron bracket that i tapped and screwed onto the bars and tightened them with a nut. For optimal stability i added some welding spots in addition to both the angle iron and the nut, and in the end added some rather thick steel wire to hold them all in position. Although i have no images of it i also added 4x 1 meter long 8mm thick armor iron from right over the angle irons. Although this pier is supposed to carry no more then 30-40kg i thought it's better safe then sorry. The wood brackets were only there to temporary hold the bolts in place while the concrete dried, so once it had dried for a couple of days it was time to remove it an see how it turned out. Next thing I'm working on now is the mounting plate. It's not quite done yet, but it will be made of 2 layers of ~22mm waterproof plywood. I will update with more pictures of that as soon as it's done.

Very nice image there, and i like the color balance!

The project was put on "pause" for a bit while i was doing a side project - the terrace, including a massive wall. The telescope project should also benefit from it as it will block lights from cars passing by very well. The hexagon frame is starting to take shape! Now the fun part starts - putting together the walls... Since the walls are 80cm wide, the space between an opposite wall is 138.5cm. I cut 2 laths for the top and bottom and connected 2 walls at the time. I then realized I had to take it down from the terrace as it was already very heavy with just 2 walls... I did the same for another 2 walls, and then the 5th wall i had to mount on it's own. Each wall is quite heavy, so holding it in place while inserting the screws wasn't the easiest, but eventually i got it together. It was a little extra work going for a hexagon shape, but i don't regret it. It's very heavy and solid, more space efficient then a square, and it i love the looks! However, i felt the smaller angle irons were not sufficient, and changed them out with larger ones. Now for the moment i was both most looking forward to, and worried about... Would the last wall fit, or had i messed up somewhere...? The last wall was not mounted like the rest as it will function like a door. This construction will be too tall for me to use without something to stand on anyway, and by making it a door i will easily be able to solve that issue, as well as have easier access later on. It fits!! I decided to install 4 hinges due to the heavy weight, as well as a handle and naturally a lock. The lock had to be bent into shape to fit, as i couldn't easily find one designed to fit on a hexagon corner. Now naturally this wouldn't work well at all standing on the ground, and neither was it intended to. So time to lift it up ~20cm as i originally intended and see if the door works and the hinges holds. Perfect! The concrete pier is not yet complete, as it will have to be much taller. I put on another 80cm just to see how it would fit together. Well, i think I'm going to have to work a bit more on that... The height is good though. Considering how tall the pier is going to be, I'm thinking about removing the paper from the lower one and make it thicker first. I'm not sure how well it will turn out if i go for this tall, and leave it this thin - it might not flex much, but I'm still worried about vibrations. Either way, i think it's looking great so far! Don't worry about the laths going everywhere on the top, they are just there to hold everything together solidly for now, they will be removed later so the scope can move around freely in there. The most difficult part still remain though, and i have yet not even decided on having a dome that i flip off, or one that i rotate. If i go for one that rotates with a small opening it means I'll constantly have to go outside and turn it depending on where i point the scope. I could motorize the rotation, but that would require significant more work and higher cost. I was originally thinking about one that i flip off completely, but if i go for that it might get so heavy i need some kind of help with it anyway, maybe by using gas dampers. Another option is where half of the dome flips over the other half. That might be the best and easiest option to both design and use, but I'm not sure if this might complicate things when imaging nearly straight upwards?

Gave it a quick try. Ended up with some huge stars compared to you though...

Awesome! I'm also leaning towards the QHY now. I'll probably get the same setup as you, with 36mm filters. May i ask where did you order the camera and wheel from? I know Bernard sell the camera for a good price, but I can't seem to find the QHY filter wheel at his web page.

I'm in the same situation - i just can't decide. I have (very) high humidity levels and usually things dew up very easily without heating, so because of that i'm thinking about the QHY as it have heated window and sealed sensor room - it's also cheaper (but add the cost of larger filters and we're pretty even?). I worry a lot about dew as I've had multiple nights ruined from mirrors, filters and sensor dewing up prior to designing a heating system for it. I do however like to use lenses, and from what i can see the QHY model can be used with Canon lenses and the QHY filter wheel with some modifications? But does the modification remove the heated front window - or does the sealed sensor room and heated window remain and it's just the heating resistors being exposed? With the ASI it seems very easy to use pretty much any lenses without any modifications. The ASI USB hub could also be useful as i'm thinking about an EFW and an autofocuser. Less cables hanging from scope is always a good thing.

I've made some (very) basic drawing of how i intend for it too look as far as the walls go. The drawing is not to scale however, but it's just to give a clue as to how i want it to look. I intend for the walls to be probably around 150-170cm tall, and thinking of a diameter of around 100-110cm. I want make sure my Explorer 200 PDS can at least run around freely without any ricks of bumping into anything. I've not yet decided on the top if i will have a rotating dome with an opening, or a dome that i simply flip off. The flip off would probably be easier to design and make, but harder to use when it's that high up and -20c.