kbrown

To my surprise I wasn't able to focus in enough with my recently acquired WO FLT91 using my Ascension 2" star diagonal. Since all my EPs are 1.25" I decided to remove the 2" holder and printed a M48x0.75 to M51x1.0 adapter so I could stick the 1.25" holder directly to the diagonal. This gave me an extra 18mm inward travel and I was able to focus with all my EPs STL attached...

The removed 2" holder on the left...

DiagonalEPHolder_v004.stl.zip

On 30/04/2021 at 17:42, kbrown said:

Can any of you give me an idea what sort of weight the focuser on the WO FLT91 can handle? I think this is my current favourite to get.

Answering my own question as I received this information from WO:

"Focuser loading capacity is around 8-10Lbs. If you have a heavy loading you will need to add some extra tension using two screws located on the top of the focuser."

I just received mine yesterday. Only been able to test it a little bit visually tonight between the patches of clouds. Here's my initial thoughts:

• Feels like a solidly built piece of kit.
• Focuser had some rough spots when going through from one extreme to another. A bit of silicone grease on the rack took care of that. Didn't have to adjust any screws.
• Was surprised not to be able to focus in enough with my Ascension 2" 90° Dielectric Star Diagonal using any of my 1.25" eye pieces. Had to "shorten" the diagonal by 18mm by printing a new EP holder for it.

Overall I'm very pleased with it so far. Next time it's clear I'll pop in my ZWO ASI183MC Pro together with my HoTech SCA Field Flattener and capture some images.

Can any of you give me an idea what sort of weight the focuser on the WO FLT91 can handle? I think this is my current favourite to get.

I have collimation experience only on a newtonian and to be honest it's not really that hard to do...  Sort of have become part of the routine for me at the beginning of each session. RCT might be more time consuming though...

Oh and refractors can be out of whack too...

38 minutes ago, tooth_dr said:

1. It couldnt hold a camera/EFW combo without sliding out c.1.8kg.  When I adjusted the focuser to increase tension the knob became spongy and difficult to use - you had to turn it past where you wanted to end up and it sprang back a bit!  There seems to be a no middle ground.  I havent used a rack and pinion focuser before, but this felt very hard to use.  It worked ok when I added a motor focuser.

I haven't used rack and pinion focuser before either. I was going to add a motor focuser anyway. Most likey a DIY one as I've done before on my newt. So I guess you left the tension knob rather loose when you added the motor focuser and relied it to hold the position more than anything else?

41 minutes ago, tooth_dr said:

3. I think the collimation was good, and any distortion to the stars was symmetrical.  The dedicated flattener couldnt deliver small stars across the field, and introduced astigmatism and chromatic aberration.

That is a bit surprising to hear. I initially wasn't going to get the dedicated flattener as I already have a HoTech SCA Field Flattener that should work with this in theory.

43 minutes ago, tooth_dr said:

4. The FWHM was high even when accurately focused.  In retrospect if I look at the spot diagrams, i think the scale is large (100um per square versus 20um for competitors) so to be expected.

Hmm... Certainly food for thought. Thank you! I will have a closer look now!

Cheers,

K

Hi,

I'm seriously considering purchasing a SharpStar 94EDPH. A couple of questions that I haven't been able to find answers to still remain though:

So I'm slowly getting into solar observing/imaging...

Instead of getting a commercial solar finder I though I'd just slap a piece of Baader  white light solar film which I already had in front of my SW finder scope with a 3D printed holder/cap. Does the job nicely.

Don't be a daft like me and forget to remove the lens cap on the Daystar Quark before putting it in a 2" focuser (happily goes in). It will melt as seen on the photo to the right! I printed a replacement cap that goes over the 2" part of the Quark so I won't repeat the same mistake again

STLs attached if you wish to print these yourself.

SWFinderSolarCap.zip

QuarkCap.stl.zip

So I've had the DayStar Quark H-alpha 'Eyepiece' Chromosphere for a while now but I don't really have a well matched refractor to use it with yet. Was hoping to get some recommendations on what to consider or to steer away from. I don't really have a rigid budget in mind but maybe somewhere between £1000-£2000. On that note I don't really want to be disappointed either so if it has to be more than that then I'll just save up a bit longer... The specs on the Quark constrains the options to be between F/4 - F/8 and aperture below 150mm (don't really want to get into the realm of having to get a separate ER filter).

This would be mainly for photography. I have a HoTech SCA Field Flattener which is supposed to be good for f/5 - f/8 but I'm not sure whether you actually can use any flatteners/reducers with the Quark? I have read that if you have extra optics between the objective and the quark, you might need additional ER in front of the scope or things might get a bit too hot. One example being a Petzval design...

Needless to say I'd like this frac to be a good performer for night sky imaging as well...

I currently have three CCDs: Atik 383L+ mono, QHY5L-II mono and ZWO ASI183MC Pro

I recently came across the SharpStar 94EDPH Triplet APO. Do you think this could fit the bill?

Thanks in advance,

Kari

4 hours ago, sloz1664 said:

The best cleaner / electrically safe lubricant is DeOxit. Used on old HiFi for cleaning switches, potentiometers and contacts.

Steve

I've heard a few people recommend this but at over £20 for a small can it seems a bit steep. Not that it would break my bank but just wondering if it's really THAT good?

Hi,

So as I've had some communication issues on my last couple of imaging sessions I thought it would be time to go over all the usb connectors on the cables and ports in the devices to clean them. So far I've just used 99.9% IPA and a cloth wrapped around a suitable plastic stick to clean them. But I don't think that will do much to any oxidation. Wouldn't want to use anything too abrasive as that would most likely wipe out any platings on the connectors.

I've read about salt and vinegar baths followed by sodium bicarbonate bath to neutralize the acidity but haven't had the courage to do it yet.

What is your preferred method?

Old topic I know but I only just managed to wire this into usable state.

On, under and around the tray there are:

• Battery that provides 12V and 5V.
• Switch and connectors for dew heaters and other 12V devices.
• LTC1871 based DC-DC converter for keeping the supply voltage for the CCD at steady 12.7V even when the battery voltage goes down.
• Raspberry Pi
• USB 3.0 Hub
• WiFi dongle
• GPS module

The battery life isn't great but it's useable. I tested it last night with the CCD cooled down 15 deg C below ambient and one dew heater constantly on. I managed to take 50x180s exposures (2.5hrs) and the battery was at 44% at this stage. Annoyingly I can't have it on the charger while using it as this prevents the 5V output from working. Strange...

Another hacky way to get around the potential config clash problem might be to run the other Kstars session under a different user. That way they would have completely separate configs...

2 minutes ago, JamesF said:

It's worth a try.  My first concern would be that the two instances could end up fighting over configuration files or external storage of state information.  If the configuration can be the same for both sets of kit that's probably a step forward, but the state data (eg. scheduling information and so on) might be more tricky.

Oh yes. Didn't think of that. Maybe I can run them in a container or something...

3 minutes ago, JamesF said:

The straightforward way to do things of course is to run KStars on each RPi and connect to them using VNC or something like that, but that may have its own speed and storage compromises to be made, and I'd assume you've already thought of that and discarded the idea.

I did this in the beginning and didn't like it. Just painfully slow and unreliable to use.

Thanks James. Certainly some food for thought. Think I'll try the two interfaces connected to each RPi first as that's the least amount of faffing about. I did manage to run two Kstars at the same time. Might try doing it for real soon.

K

I'm on Linux. My laptop has a built in wifi adapter and i have a wifi dongle too so I guess the easiest would be to have one of them connected to Kit A and the other one to Kit B.

Or maybe Kit B could be connected to Kit A which I connect to from my laptop... Hmm...

EDIT: Btw, I just tried I can run multiple sessions of Kstars so I guess there's no problems there...

Hi,

So far I've only dealt with one remote kit with Kstars/Ekos. It's Raspberry Pi 3 based configured as an WiFi AP running an INDI server + drivers. It has worked fine. But now I've slowly been building another similar setup. This then prompted the question, what if I want to use both of them at the same time? Obviously I can't be connected to two APs at the same time. Not sure if I can even run two sessions of Kstars either? Any ideas?

Cheers,

Kari

Hi,

This is probably not feasible at all but I thought I'd ask anyway. Has anyone seen anyone attempting to add GoTo feature of any sort to the SkyWatcher StarAdventurer? I know as a project it would be very ambitious and the result probably wouldn't be awesome but still it's intriguing me. The SA only has RA tracking (quite poor PE btw) and a very slow "slew" backward and forward buttons. With the DEC axis you'd have to get more creative. I have the optional L-Bracket DEC thingy that potentially could be motorised albeit it has rather large backlash on the gearing. Maybe that could be taken into account in software.

Anyhoo, just throwing the idea out there to see what responses I get

Slightly off topic but I figured since quite a lot of you tinker with electronics as well, I'd share these 3D printable interlocking SMD component storage boxes I designed. Inspired by a model I saw online but instead of being restricted by a set amount of boxes per print these can be printed as required and added to the gang as needed. You do need to sort of decide how many rows or columns you need and assemble them in rows or columns first before attaching them together. Nonetheless these are proving to be quite useful for me at least. STLs attached...

I printed mine with 0% infill but 4 perimeters with 0.4mm nozzle at 0.2mm layer height using amazonbasic and sunlu petg filaments on my prusa i3 mk3. Detect thin walls and detect bridging parameters were on too in PrusaSlic3r.

ComponentStorage.zip

I'll be using a stepper motor controlled by an Arduino and a TMC2209 based stepper driver. I'm not really trying to copy the steeldrive. It'll be a custom thing based on my current DIY focuser. At the moment I'm just stuck waiting for the focuser to arrive. 😕

I will be doing one as soon as I get my focuser from FLO (been on order for several months now :z). Although my priority is the opposite; I prioritise remote PC (INDI) control and don't really need the hand controller. I built a hand controller for my current DIY focuser but after initial fiddling about I realised I didn't really need it as everything else is remotely controlled as well. So to keep the size and weight down I will probably forget about the hand controller.

Just now, msacco said:

Oh, I thought you were referring to different type of calibrations, 1 for offsets which you do just once, and the other that you do just to get the current position or something in case it's manually moved, but yeah since you have the sensors there's probably no need to that.

Awesome, thanks

Yes. There is no need for homing. You can just put the wheel in an it'll just work...

7 minutes ago, msacco said:

So the calibration is just something you're running at the beginning of each session just to initialize the positions or something? Or you don't even need that since you can just know when you reach position x?

No. I only needed to do it once after I had my modifications ready and assembled. From there on it just re-uses the offsets from the Arduino EEPROM memory. You shouldn't have to touch them even if you open the housing to take out the wheel in order to change filters.

8 minutes ago, msacco said:

And that's great...When you say that you haven't had to touch the offsets since the initial calibration, do you mean that the calibration calculates the offsets and stores them 'permanently'?

The calibration in my case is just a manual/visual process to see where the filter slot stops and whether it needs adjustment. Then yes these adjustments are stored on board 'permanently'. Until you change them again that is. I haven't had to change mine

I can't remember whether uploading a new version of the Arduino code retains the values. Probably not...

3D printing threads isn't a problem. I've done it many times. However I would not 3D print the filter wheel housing as it needs to be quite sturdy due to the weight of the camera and other accessories hanging off of it.

Yes the sensors can detect the magnet before it's centred under the sensor. But this is a constant offset as long as the sensors are fixed in place so I take care of this in software. I turn the wheel until I detect the first magnet. Then I turn a little bit more to see if there's any other magnets coming "into view". From here I apply a user defined offset (backwards or forwards) to centre the filter on the optical path. There are two offsets per filter which can vary depending which direction the wheel was turning. These offsets are exposed in the INDI driver and stored in the Arduino's built in EEPROM so the stay there even when not powered. I haven't had to touch these offsets since I did my initial calibration.

You can see this in action here: