Gemini-II User Group

Re: Just out of curiosity...

chiplouie@... (Chip Louie) — Tue, 08 Apr 2025 19:10:09 -0700

On Tue, Apr 8, 2025 at 02:49 PM, Rainer wrote:

On Tue, Apr 8, 2025 at 03:21 PM, Paul Kanevsky wrote:

Very nice! But I think you need more weight on that mount to get it to full capacity ;)

The mount with TOA and ASKAR has 42.6kg of counterweight

I agree, the Askar optics seem to be pretty good, overall people are getting good results. This little Askar is an FRA500 is sharp at its native 500mm f/5.6 and a wonder at f/3.9. Okay so it's no match for the modern Takahashi FC-100DF with a CAA and FC-35 reducer but it was $1,200 used vs $4,500. Askar is a good deal IMHO.

The most counterweight I had on the G11G counterweight shaft was 41kg. In this photo I only had 37kg as the other 9.5kg weight was in use and I had to use the 5kg and move them down the shaft more. It works fine but I think this is pushing it with 34kg + in a Losmandy Side-By-Side saddle mount.

Chip Louie Chief Daydreamer Imagination Hardware

Astrospheric - South Pasadena, CA

Re: Autoguider Recommendations

chiplouie@... (Chip Louie) — Tue, 08 Apr 2025 17:13:53 -0700

For the last few years I've been using the ASIAIR and have not had any issues guiding with the same old piggybacked Stellarvue F050 50mm f/4 guidescope in the matching non-adjustable clamshell I've used for the last maybe 7-8 years. It worked great with PHD2 and people claimed it wouldn't because I needed adjustable rings and I was doing about a zillion other things wrong which were absolutely incorrect. The one thing I know is true and has remained true since way back when I first started using PHD2 is that the relationship between the imaging scope's image scale and the guide scope's image scale is critical. That ratio has changed over the years as PHD2 has improved tremendously with the addition of multi-star guiding, CMOS cameras taking over and the CMOS sensor photosites somehow managing get more sensitive with lower noise and somehow also getting even smaller, it's a win win IME.

All of these things have been making it easier to get better autoguiding with modern CMOS cameras. Back in the olden days, some OGs like to fondly imagine them as the "golden days" of CCD cameras, people all struggled to try and maintain a 1:1 or 1:2 ratio between the imaging camera and guide camera. This of course was absurd and only increased the likelihood of differential flexure due to all that extra mass and weight hanging off the main scope, obviously this was bad for guiding and everyone thought OAG was the way to go. It still is bad for auto guiding, lower mass is more easily corrected and makes your back hurt less the next day if you are a portable imager with a larger optic and OAG use while much better still a PITA and more expensive. Anyway as time as moved forward and autoguiding hardware and software has improved the ideal ratio has moved too.

I think the ideal ratio is now up to around 1:3 with good results and acceptable results on a good mount and heavy tripod (don't discount what a heavy tripod can add) out to 1:5 or so, once you get past around there stuff starts to get less reliable and at least my mount starts to behave less than ideally. I know this because in my driveway I have tested the idea using that same old Stellarvue F050mm f4 (210mm measured fl) with a new ASI678MM screwed on the back of the helical focuser clamped rigidly to the top dovetail of an LX200 8" f/10 ACF (2,000mm) and LX200 10" f/6.3 EMC (1,600mm) SCTs with good results. I have not managed to Barlow the ASI678MM yet but I expect it will return better results at 1:2.5. Testing shows that the 1:1-1:2 ratio works extremely well with my very typical focal length refractors which range from 350mm to 802mm focal length refractors.

Anyway that's where I'm at at the moment. Obviously, as per usual YMMV.

Chip Louie Chief Daydreamer Imagination Hardware

Astrospheric - South Pasadena, CA

Re: Gemini BOOTLOADER update available

brenatlilydale@... (Brendan) — Tue, 08 Apr 2025 16:57:58 -0700

Thanks Gents

I have a G2 tallboy on the way...ARM is hot. So needs new ARM and i'll try the new bootloader. I'll report back....shouldn't be to long

cheers

Brendan

Re: Just out of curiosity...

rsfoto@... (Rainer) — Tue, 08 Apr 2025 14:49:54 -0700

On Tue, Apr 8, 2025 at 03:21 PM, Paul Kanevsky wrote:

Very nice! But I think you need more weight on that mount to get it to full capacity ;)

The mount with TOA and ASKAR has 42.6kg of counterweight

Re: Just out of curiosity...

rsfoto@... (Rainer) — Tue, 08 Apr 2025 14:47:04 -0700

Some more images, but the configuration has changed now. On the mount in the back is a Mewlon 250S 1st generation which I modified to ASCOM focuser using a slim 22mmØ Faulhaber stepper motor with ZWO EAF electronics.

On the mount on the front the two Solar setup were replaced by the ASKAR 103APO.

I also attached an image of the encoder disc on the worm wheel. This is not from a CEM 120EC2 but from a CEM 60EC.

Rainer

Re: Just out of curiosity...

yh@... (Paul Kanevsky) — Tue, 08 Apr 2025 14:21:45 -0700

On Tue, Apr 8, 2025 at 05:11 PM, Rainer wrote:

Those are iOptron CEM 120EC2

On top a TOA 130 and ASKAR 103APO. BTW the chinese ASKAR telescopes are quality wise very very good. Takahashi is getting big competition. BTW I have a total of 5 Takahashi all bought in the years 2005 to 2010. Nowadays Takahashi is not worth. When I bought them there was no real good quality but nowadays chinese are showing what they are capable off.

:-)

Rainer

Very nice! But I think you need more weight on that mount to get it to full capacity ;)

Re: Just out of curiosity...

rsfoto@... (Rainer) — Tue, 08 Apr 2025 14:11:01 -0700

Those are iOptron CEM 120EC2

On top a TOA 130 and ASKAR 103APO. BTW the chinese ASKAR telescopes are quality wise very very good. Takahashi is getting big competition. BTW I have a total of 5 Takahashi all bought in the years 2005 to 2010. Nowadays Takahashi is not worth. When I bought them there was no real good quality but nowadays chinese are showing what they are capable off.

:-)

Rainer

Re: Just out of curiosity...

yh@... (Paul Kanevsky) — Tue, 08 Apr 2025 13:42:43 -0700

On Tue, Apr 8, 2025 at 04:26 PM, Rainer wrote:

stepper motors and encoder discs (big glass discs glued on the worm gear) on the RA and DEC axis

Any photos? I'm curious to see what it looks like!

Just out of curiosity...

rsfoto@... (Rainer) — Tue, 08 Apr 2025 13:26:51 -0700

Hi,

Now that I am here I have a curiosity question. Those who knew from the times before 2018 back to >2008 when I still had my Losmandy G11-RS, know that I like to tinker, and improve¿? (maybe make things worse :-0 ), everything I have.

I have two mounts, big mounts with 52kg capacity(counterweights not included), with stepper motors and encoder discs (big glass discs glued on the worm gear) on the RA and DEC axis Worm gear with 360 teeth and 216mm Ø.

According to the producer the resolution of the encoder is 0.035" (arcseconds).

Is it possible to use Gemini 2 with Stepper motors and the encoder discs?

Rainer

NHSA Observatory

Mexico (in order to not create confusion) :-)

Re: Autoguider Recommendations

rsfoto@... (Rainer) — Tue, 08 Apr 2025 12:05:08 -0700

Hi,

There are two ways of guiding.

Piggyback guide scope and Off Axis Guider.

Depending of your setup up eg. camera and other accessories like maybe Filter wheel and optical accessory be it a reducer, flattenner or extender optic.

OAG guiding is the best as as you avoid flexing differences between guide scope and Imaging scope.

When you decide for Piggyback guiding then the ratio between the guide scope and the Imaging scope should not be more then 1:2 and really max. 1:2.5 maybe but really not more then 1:3.

I do guide 560mm with a 420mm piggyback and 3200mm with OAG. In both cases I do use guide cameras with an IMX249 sensor.

when OAG guiding a G11-RS mount i achieved round stars troublefree with my Mewlon 250S at 3200mm focal length on 10 minute exposure on my favourite Galaxies which are the ARP's.

I would say F.X. Flinn's results is the exception to the rule. I do not know what imaging focal length he has.

IMHO Rainer

Re: Autoguider Recommendations

fxflinn@... (F. X. Flinn) — Tue, 08 Apr 2025 11:18:53 -0700

My G11T is so good I don't bother with autoguiding. I've mostly been using a TSA-120 reflector with a ZWO2600 and an ASIAir, and if my polar alignment is solid I have no trouble with 300 second exposures. Since most of my targets have been pretty standard ones that are fairly bright or large, an hour or two worth of 60 second exposures has provided excellent data files. Now if I could only find the time to process them with PI...

I've experimented with OAG autoguiding but my experience is that it creates unnecessary moves. I am probably doing something wrong but given how good the mount is once it's PA'd and the fact that I haven't found a target yet that I need to stay on for extended exposure ... I decided not to worry about it.

F. X. Flinn

e: fxflinn@... | m:802-369-0069

Re: Autoguider Recommendations

cwlfour@... (Willie) — Tue, 08 Apr 2025 10:57:39 -0700

Hi Jeremy,

I wanted to jump in and mention a couple things as a new (actually born again) hobbyist. I did basic visual stuff for many years with a Celestron CPC1100. Recently retired (for sure this time) I decided to re engage and invest in an equatorial mount. After lots of reading I decided to go with a Losmandy G11G and talked with Tanya. I was so excited to find a company that is clearly very proud of their products, work, and customers. What a great experience it has been for me so far. The quality and craftsmanship is unbelievable. And USA built to boot��.

Now the boxes show up and it’s time to get this all set up. Listened to all the videos and got lots of stuff done but still always more questions. It’s only been a month or so for me but I’ve come a long way from where I started. Chip Louie has helped me with tons of questions and given great advice.

I had the exact same question as yours and will investing in a guiding scope and camera soon. I hope you continue posting so we can all learn together.

Thanks to Losmandy, this forum, and especially Chip for helping me get out of the gate. I’m sure this is only the beginning, but I look forward to learning this new hobby.

Re: Gemini BOOTLOADER update available

chiplouie@... (Chip Louie) — Tue, 08 Apr 2025 08:04:16 -0700

On Mon, Apr 7, 2025 at 02:31 PM, Paul Kanevsky wrote:

Hi Folks,

René, as usual, has been busy with Gemini improvements. The new Bootloader is an update to the original one that was created when 2GB SD cards were all that was available :)

The new bootloader isn't required if your Gemini is working fine. You can skip it if you don't care about the benefits listed below, or if you feel uncomfortable performing the update.

The update process itself is about as complicated as the L6 upgrade to the new servo firmware, and requires:

A 20 pin ULINK2 emulator/programmer -- about $30 from Amazon

Keil ULink-2 software (runs on Windows)

MB_BL_2024.uvproj bootloader project file

Detailed Instructions can be found here:

/g/Gemini-II/files/Latest%20Firmware%20Files/Bootloader%20Update%20Instructions%20-%20April%202025/Gemini%20Bootloader%20Installation%20Instructions%20-%20Apr%202025.pdf

The new bootloader is based on a modern version of Keil middleware and helps with the following:

Faster boot-up time for Gemini

Better compatibility with different types and larger size SD cards

Resolves the issue with the dreaded M:Curr_Gem.bin file for those who have experienced it

Be careful if you decide to update your Gemini. Follow instructions!

Regards,

-Paul

My favorite little birdy told me about this a couple weeks ago. I think it is worth doing if you are one of the impatient people or like me (okay so I'm impatient) just want to keep up to date on code revisions. I'm a sucker for the latest and greatest LOL.

Chip Louie Chief Daydreamer Imagination Hardware

Astrospheric - South Pasadena, CA

Re: Autoguider Recommendations

chiplouie@... (Chip Louie) — Tue, 08 Apr 2025 08:00:23 -0700

On Tue, Apr 8, 2025 at 06:41 AM, Jeremy Benson wrote:

Thanks to everyone who responded to my question about autoguiders.

It seems I’m so new to the whole thing I didn’t even know the right questions to ask. I’ll do a little more research on exactly what I want to do and come back with my specs and a better idea of what I’m looking for.

Thanks!

Jeremy Benson

Keeper of Keys and Labs

NIU Department of Physics

NASA Solar System Ambassador

La Tourette 202A

815.753.1953

www.niu.edu/clas/physics

Hi Jeremy,

It's not that complicated. The way the autoguiding apps work like the free standing PHD2 guiding or an integrated system like ASIAIR etc. require certain conditions to be met in order to work well. We know you are working with a Losmandy G11G and Gemini 2 controller which is great but in order to help determine your best options for autoguiding we need to know what your imaging optic(s) and camera(s) used to image with. Many of us have and use more than one imaging setup to cover more of the sky at the desired scale. Give us the main telescope and imaging camera and I'll walk you through the process to determine what your best options are and why. Come on, this is how our little community gets it done.

Chip Louie Chief Daydreamer Imagination Hardware

Astrospheric - South Pasadena, CA

Re: Gemini BOOTLOADER update available

yh@... (Paul Kanevsky) — Tue, 08 Apr 2025 07:27:49 -0700

On Tue, Apr 8, 2025 at 08:29 AM, criscopenneys wrote:

Question-After updating the bootloader, do I just need to power up Gemini and then that M: file issue will resolve itself?

I know that the M: file will no longer be created by the firmware update process, but I don't know for sure if you'll be able to just delete it after the bootloader update (René, do you know?)

If you can't remove it, you may need to format the SD card, and then you can update it directly from GFU with all the files (or copy them to the card). After that one time, you should be able to flash new firmware without the M: file reappearing.

Re: Autoguider Recommendations

jjbenson@... (Jeremy Benson) — Tue, 08 Apr 2025 06:41:39 -0700

Thanks to everyone who responded to my question about autoguiders.

It seems I’m so new to the whole thing I didn’t even know the right questions to ask. I’ll do a little more research on exactly what I want to do and come back with my specs and a better idea of what I’m looking for.

Thanks!

Jeremy Benson

Keeper of Keys and Labs

NIU Department of Physics

NASA Solar System Ambassador

La Tourette 202A

815.753.1953

www.niu.edu/clas/physics

Re: Gemini BOOTLOADER update available

criscopenneys@... (criscopenneys) — Tue, 08 Apr 2025 05:29:59 -0700

I am one of those people with the M: file issue so I will definitely be doing this update.

Question-After updating the bootloader, do I just need to power up Gemini and then that M: file issue will resolve itself?

Already placed my Amazon order for the connector.

And again, thanks to all that provide ongoing support for Gemini.

Chris N

Re: Gemini BOOTLOADER update available

Rene@... (Rene Goerlich) — Tue, 08 Apr 2025 04:54:49 -0700

Daniel,

The 8 GB was chosen by Tanya Kennelly since it works w/o any problems for the new boards she upgraded. You can give your old SD card a chance and report here.

Regards,
René

Am 08.04.25 um 13:42 schrieb Daniel via groups.io:

Re: Gemini BOOTLOADER update available

daniel.rdrm12@... (Daniel) — Tue, 08 Apr 2025 04:42:17 -0700

I doubt you could brick a Gemini by bad or interrupted programming. I assume it's possible if you don't align the connector pins the right way. If you do connect it correctly, you should be able to reprogram the bootloader even after a failed attempt. I updated three Gemini units this way, and one had a corrupted bootloader when it was sent to me and would not start. The reprogramming fixed it right up.

Thanks for your answer. In instructions it is specified that a microSD card higher than 8Gb is needed. I assume that this implies that the new bootloader do not work for smaller cards, including those delivered by the Gemini II. In this case is enough to just copy one card to the another using a PC ?? Furthermore, is there any file format restriction to the larger microSD or can we use just a single partition FAT32 formatted?

Regards,

Daniel

Re: Gemini BOOTLOADER update available

astro@... (Michael A. Covington) — Mon, 07 Apr 2025 21:02:03 -0700

Thanks!

On 2025-04-07 23:32, Paul Kanevsky wrote: