Vroobel

Hi, I use the Bresser Messier Newtonian 10" F5 OTA and temporarily Sony Nex-6 camera to perform astrophotography. I wrote temporarily, because I will consider the A7 body in future, but cannot be sure. I will also consider a dedicated astro camera with full frame, if my plans succeed. I would like to ask you which coma corrector is the best for my set. I have read about: - the GSO/Revelation photo-visual cc (very cheap and quite good value for the money), - the Baader Mark-III MPCC (photographic) (still not bad price, doesn't change F), - the Explore Scientific HR cc (photo-visual, helical focuser, excellent correction). The last one is possibly the best among listed above. Moreover, ES = Bresser, so I would assume that this cc is designed for the ES/Bresser Newtonian telescopes like the Baader 2.25x Barlow lens is designed for the Baader 8-24 Zoom lens... But I found out that every cc causes troubles: some guys experienced issues with their focusers, others ones with back-focus distance of their cameras. And what about the asto camera? Do they cause any problems with the ccs? Is there any owner of ES/Bresser Messier Newtonian OTA (the best if it's 10" F5) and Sony mirrorless E-mount camera using one of the listed or another coma corrector? I'll appreciate every opinion. Tomasz

Hi, I just began building a heavier EQ fork mount for my 10" Bresser Messier. I own used 100:1 harmonic drive... ...which will be driven by Nema 23 stepper motor equipped with 25:1 worm gear (picture attached). Even without using micro steps mode I can obtain 500,000 steps per revolution. Simple use of 16 micro steps mode gives 8m steps in total, that is much more than needed for an astro-photo. Here is its live story: Tomasz. I'd like to add, that the harmonic drive should easily hold a static load 50+ kg as it worked in 5-axes milling machine similar to a robot's arm. So the advantages are: zero backlash, high precision and high load.

Thanks, Dave. Unfortunately I cannot trust the "similar" size. I have opportunity to make it universal, so I prefer to choose the bigger size and make a kind of adapter to the smaller size. The advice about place of focuser became significant. To be honest, how to observe (not astrophoto) objects close to the Polaris? 🤔

Hi guys, I just come back to the game. Presently I'm working on the EQ fork mount for my 10" Bresser Messier OTA, but if the project is successful I would consider moving towards something better, like the SCT 11. I'd like to ask owners of that stuff with the original fork mount, doesn't matter what kind of type , what is the distance between mounts of the fork? What is the distance between most far points of the OTA mounts? I'll appreciate your response. Tomasz

Probably you are right, as other people told me the same. They told also that cheap MIG welder is not good choice, but I don't have too much money to spend. I have to buy a good quality mitre saw (Evolution) and also high class bench drill press (Bosch). The welder is not only purchase related with welding. Years ago people didn't know MIG technology and used electrodes only and despite that they had not bad results. I think I could do it like many other, just have to be patient in learning.

I wrote "no so high accuracy", that means 1 arc sec / step or 0.5. It's not too bad I hope. 😁

BTW, I bought an arc welder last week together with everything necessary to weld. I have 2 weeks till end of the June to learn welding enough to perform solid and good looking joints. Later it will be difficult as I come back to work.

Thank you. You are right, I gonna use the small worm gear to drive the HD. Taking into account ratios of the HD and used worm gear, 200-400 stepper motor and its micro steps (LV8729) I can reach even 0.1 arc sec/step accuracy for the Ra axis. The Dec axis will have not so high accuracy, but sufficient enough. I want to use my earlier experience and make worm gear again, but this time I will use smaller fully aluminium blank. I have some sketches but excluding the fork I'm not sure if anything of my concept can be understood. It will be much easier to see that built step by step.

Good to know.

Hi, Usually I make my astro-toys, then make a video and show them on YouTube and astronomy forums. This time I will struggle with a subject whitch I am not familiar with, thus I have to ask You for help. Especially someone living not to far from Liverpool or Manchester. I gonna make a bigger EQ fork mount for my 10" Bresser Messier (ES) reflector. I wouldn't even try to think about that without some very important and remarkably expensive part which I have bought as it is no longer able to be used at original environment. I mean a harmonic gear. My one is a little bit broken in area of one of many screw holes, but it is nothing as the fork mount is doing incomparable slower movements and operates with much lighter load. The gear has 100:1 ratio and around 4.5 kg of weight. Here is link to the gear in action: The fork will be made using aluminium plate and profiles while the base has to be made of steel. An idea of the base is shown in the bottom. I hope I can design everything on my own, but the only thing that I can not perform is welding. Therefore I would like to ask mates living in Merseyside or Greater Manchester and familiar with welding for help. Its not urgent, but I would like to know if I can obtain the help or should I try other ways. I believe that the common passion gathers people having different experience. Please don't hesitate to ask if anyone would like to know more details of my idea.

Hi, I have the Sony Nex-6 camera, that doesn't support wired intervalometers, so I had to do something to solve a problem of longer exposures. Please watch my another video presenting my own IR intervalometer based on the Arduino.

Hi, As I used a theory described in article of The Royal Astronomical Society of Canada as a base for my derotator acting, I decided to inform them about my project. An effect of the correspondence exceeded my vision: the author placed an information about my derotator in the article. 😲 http://calgary.rasc.ca/field_rotation.htm

Thank you for the information. Inside my derotator is simple universal board with only LV8729 driver and set of jumpers for micro steps set up. I can think about it and add a feature of the rotator when I make step towards the ASCOM compatibility.

That is right. But that doesn't change the problem of positioning the rotator before every session. This feature requires the ASCOM as well. Moreover, I know that some indicator of "zero" position should be implemented there.

🤔 I cannot say that I didn't think about it. But how will you connect it to your exact stuff? The derotator needs 12V, that is easy. Beside that it gets Direction and Step signals from the Raspberry Pi. And GND of course. I made it this way to adapt it to ASCOM in future, but the future isn't now yet. I don't have mount compatible with ASCOM, so cannot test it anyway. Edit: The LV8729 stepper motor driver can work with 6-36V, so the 12V is there only because i operate with this voltage in my system.

Look, the derotator is a kind of proof that it is possible to make it at home. It was like a bet with some people from the community. Since I finished this quite nice project I gonna prepare to performing of a big fork mount able to drive my 10" OTA. Today I made a deal and I nearly have strong harmonic gear box. That should be strong like the EQ8. I don't expect any problem with astro-photography at all, maybe only the light pollution...

I wrote my system completely on my own. I calculate both Az and Alt and put them into equation shown in video. My Latitude is taken from GPS. Everything else is a calculation based on complicated algorithm developed on my own as well. Finally every picture presents objects with the same angle.

As you could see in my video I have Dobsonian mount so I cannot perform longer exposures than 25 seconds. Every longer one captures star trails. Presently, with the derotator, I am able to leave my camera set up for thousand pictures and go home to watch TV or movie. The only problem is that my drives have strange small movements invisible without capturing the pictures. Short exposures like 5 or 10 seconds show nothing, stars are simply points. But longer ones make patterns like butterfly., so I think the error is looped. I ordered better quality stepper motor drives and want to replace them and check. If that is OK, I want to play with astro-photography. My F5 scope and IDAS LPS-D2 filter (which I gonna buy) can do it even in Liverpool

Hi, I'd like to show my setup in the last action. Regards, Tomasz

Good morning After many months of theoretical preparation, and then the practical ones, I have finished work on my own field derotator. As usually, I would like to share the effect of this big project making a video-report in YouTube. I invite you to watch. Best regards, Tomasz

Hi, After quite long lack of activity here I'd like to present an another point of view about the Creation of the Universe. Simply watch the video... https://youtu.be/yKsO2Tf5TW4 🙃 Regards, Vroobel

I'd like to do first steps towards an early morning observation, maybe also simple astro-photo. I see main benefit related with better seeing in comparison with evening, when air is warmer and unstable after the day. But how to prepare for that? I expect a dew, so shouldn't do it without system of heaters. I work on that together with my friend. How do you prepare your stuff, do you set it up in evening and wait for the morning, or before the observation? Can you give me some advises? I have other questions, but they depend on answer for the first one. Tomasz

I can think about it, you are right. But I have another solution decreasing the risk: https://astrovroobel.wordpress.com/2018/09/07/zasilanie-wyjazdowe/ Please use the Google Translate, because it's in Polish.

Thanks! This is first silent movie since long time, several previous ones were too noisy, right? No problem. But it's not easy to record the silent footage with kids playing in garden.

Has become. I've made another YouTube video showing my GoTo system before and in action. Unfortunately, the night sky above my head can be placed on the 8th position on the Bortle scale (1 - best, 9 - worst), so I used multiple systems to see something at all. In addition, I have recently been the owner of a Sony Nex-6 camera and I cannot yet set everything right. I just didn't have time to play with the camera and put the material together for YouTube. As you can see in the film, I recorded my system's display and the picture in the mirror's focus at one time, and because I was doing this maneuver for the first time, it took a while. I have to invest in a newer computer and paid video editing software. Kdenlive is great, because it's free, but not without errors, which have caused strong sweats on my body several times ... I hope that the sense of the project has been showed well enough to be properly understood by people embedded in the subject. The project is open, so I encourage you to comments and suggestions - I really need them. I am an absolute amateur and I did all this in just over 2 years after purchasing the telescope, largely with your help. Thanks to Krzysztof B. https://www.youtube.com/watch?v=47WS1T9_UbI Tomasz