VectorQuantity

This is the two part [7704] flattener/reducer which comes with spacing rings for a Borg 101ED (amongst others).

I am or course missing these spacers. This is for use with an EOS and wondered if anyone can tell me what thickness they are since the only Borg info I can find usefully refers to them as being 'thick' and 'thin'.

6 hours ago, StuartT said:

So far I have only done OSC imaging and when I integrate the subs, they are first aligned with each other. But if I were doing LRGB, presumably only the Ls get aligned and integrated, then only the Rs and so on. So I end up with an L master, a R master etc which I then LRGB combine in PI. 

But what if the four masters are not aligned with each other? I'd then end up with an image with the channels out of alignment (which would look like CA). I don't think LRGB combination does any aligning does it?

Sorry if I have misunderstood something

Hello Stuart,

Having selected your usable sub-frames and calibrated and corrected, pick one of them. Align/register all other subs irrespective of the filter type to this sub-frame.

You could of course align individually for each filter having picked a suitable sub-frame as reference for each filter from that filter set, then you'd have to align the masters.

I believe some people (not me) if using the first method also run a subsequent step to align/register the LRGB masters prior to combination, not sure why.

n.b. make sure you correct the subframes i.e. get rid of artefacts prior to alignment/registration to ensure the software you are using does not detect hot pixels as stars.

On 22/06/2022 at 22:33, nfotis said:

Hello everyone,

 

in recent days I was playing with tracking airplanes with my Canon 100-400L IS II lens (and a 1.4x extender) on my crop sensor 80D.

The results were OK, but even with an effective 900mm lens (in film terms) these twin jets are quite small in my images shot while flying high.

I was thinking about using my Skymax 180 or my C9.25 as a possible tracking scope for these targets, but my own mount is a HEQ5 Pro GEM, which doesn't seem very suitable for the task.

An idea was to use a manual AltAz mount and try to manually track the overflying airplanes using my Canon or an ASI462 camera (I suspect the latter will be harder to keep the airplane in frame).

I append  a typical view with my Canon lens, and a typical crop I would like to attain with a scope, to give you an idea.

 

Cheers,

N.F.

 

 

There used to be fairly inexpensive software for this from optictracker.com. I considered purchasing it a couple of years ago but never did. It seems it's now no longer sold.

https://www.youtube.com/user/optictracker/featured

3 minutes ago, Enceladus Dan said:

Not sure but I have been using a dummy battery on a 12v3a ac adaptor till now. Just having made a 12v power box so I can go off grid to a bortle 4 site. I could put my multimeter inline and measure current used while doing some test long exposures. Then Average them out. 
 

I did find a post with someone who did lots of tests with a 700d and 30s Timelapse with screen off is 1w of usage. 

If it's only 1W then that's great, your peltier should have no problems.

26 minutes ago, Enceladus Dan said:

The buck boost module is this one. 

DollaTek ZK-4KX CNC DC Buck Boost Converter CC CV 0.5-30V 4A Power Module Adjustable Regulated https://amzn.eu/d/dMVOCbE

And the chosen peltier is a tec1-12704. 

On a side note I have disregarded the sensor temp for my bad image on friday gone. It was bugging me and darks were bright red which made me think temp. But seen another post and this is normal when opened in a programe (my case gimp) I popped sd card in my 600d and sure enough darks are actually dark and zoomed in sees the noise. My darks were at 32c as was my last 2 x 300 subs which were the best 2 as background was grey. I went to earlier sub at 32c before sensor peeked at 34c and the background was red. 

It turns out we had some saharan sand signals in the sky when I was imaging. Explains why my car looks like I've been in the Dakar rally. 

Thanks

Danny

Hi Danny,

PSU. Appears to be OK and it's a good price so not the end of the world if it turns out not to do the job.

You should indeed be able to use it to adjust the peltier heat pump to an optimal value.

here's a link to a more detaied description. https://www.aliexpress.com/item/4000197872662.html

1 hour ago, Enceladus Dan said:

Thank you for the reply, 

1. Was for the equation to figure out the hot side temp. Where ((Pin + qc)xC/W)+Ambient. the Pin figure I was unsure if I use the Peltiers rated power 36w or power applied. I went back to overclockers and it would appear to be power applied, so In my case 22w (which is good to reduce heat I need to extract). 

2. The adjustable buck/boost I have found claims to be both while offering constant current. Max Amps is 4A and I intend to only use 2 amps. I hoped this would give me the 11v 2A supply that the Peltier data sheet states. I guess I could just get it and test on a 12v 21w brake light bulb which should draw 1.75 amps, then try and limit to 1A and see if voltage remains at 12v. 
 

3. is again going to be a buy and see, I can’t find any data showing the efficiency in c/w, so will be some trial and hopefully not error. 
 

im trying to work it all out before I buy any of the parts, but with not knowing the C/W or the Qc values, it’s going to be a best guess. But at least I will have fun experimenting. 
 

thanks

Danny

re: 1. Yes you are correct, it's the applied peltier power.

re: 2. You would expect the o/p voltage to stay at its set point unless it's in current limit, i.e. not to change until you reach a current draw of 4A. Do you have a part number/link to the psu?

Do you know how much power your camera consumes?

8 hours ago, Enceladus Dan said:

Hello, 

a project I’ve had on my mind a while now is a cooler for my DSLR. After testing my car battery power box for 6hrs on Friday 17th June running a mini pc, 14” monitor, dslr power, guide scope, tracking motors and 3 dew heaters (not attached just running for a test) with good results as I still had 70% battery, however the images were not so good. The Ambient temp was still over 20c at midnight and APT was reporting sensor temp of 34c after 300s exposures. So now I think I need to get moving with the cooler. 

my plan is to adopt the cooler box idea from Gary Honis, but slightly deeper so my 600D screen can be open slightly. Allowing cold air to reach the warmest part of the camera. I do like the simplicity of the cold plate butted to the back of the camera like with  Martin Pyott, but think all round cooling with its own little ambient temp would be better. I have drawn up an idea to add a small plate, from the cold heat sink to the back of the camera. In an attempt to see if like a cold finger takes the sensor heat out to the Peltier, if this plate will take some heat from the back of the camera away to the cold circulating air or even to the cold heat sink. See if I can create the best of both. 

Not wanting to just copy parts from others I’ve seen, I wanted to look into and understand what I was doing. Im thinking of buying separate components rather than a kit, as most posts I have read indicate bigger heat sinks and fans are required. I have read up and watched videos from overclockers about Peltier and have managed to wrap my head around most of the technical details on how it all works, but I have a few questions for those who specialise in this area. 

After reading many data sheets, I finally realised adding more volts, amps or going to a bigger module was only using more power and not increasing the delta temp as the hot side was hotter. So I settled on a tec1-12704 at 11v 2A giving a -40c drop. Assuming the hot side is (Peltier power 36w + Qc (camera heat unknown) then multiply by heat sink C/W 0.5 (actual is unknown) and add ambient 20c) I’m looking at a guess of 40c on my hottest night. 

1. Peltier power - for the hot side, is it just the rated power 36w or the power used ie. 11 x 2 = 22w?

2. power supply - My limited knowledge from a past career in vehicle electrics 25 years ago, is telling me if I apply 11v with the module being 3 ohms will draw 3.6A. I found a buck/boost module that has constant current, but I don’t know if it somehow limits current or just alters the volts to keep Amps steady. 
 

3. Heat sink - thermal resistance? Overclockers said assume 0.5 if it’s unknown, I was looking at an arctic alpine 12 co 100w rated. Smaller and lighter than a tower cooler but bigger than the kit sink and fan. The website doesn’t give a C/W rating for this but a graph showing a 65w cpu running at 70c with this cooler, one of their larger tower cooler is rated at C/W0.8. Am I just over thinking this, as I can’t get my head round how at 0.8 I won’t even reach 10c, but on YouTube a setup with a 60mm heat sink and fan or a cooler from a 5v mini fridge has formed ice at the cold side. 

Any advice or experience welcome, especially on the Peltier power and power supply. For the heat sink, my gut is saying just do it, As the cpu cooler must be better. 
 

Thanks

Danny

Hi Danny,

1. Apologies it's a bit ambiguous are you able to re-phrase the question?

2. Is it a buck convertor (step down) or a boost convertor (step-up)? It could theoretically be both but that's unlikely. The majority of output protected convertors will current limit at which point it appears as a constant current. You shouldn't be running at the current limit point, this exists to prevent destruction of the PSU and the attached load.

3. The peltier isn't a cooling device, it's an inefficient heat pump, in addition to having to get rid of the pumped heat you also need to get rid of the applied power that provides the heat pump action, if you don't then the temperature delta falls eventually to zero then goes positive and you have a heater. The most important thing is getting rid of the heat which is hard to do with a non-blown heatsink. Your example of the cpu running at 70 degress unfortunately doesn't tell you much as the cpu is additionally connected to a significant PCB heatsink not just the added heatsink. The degC/W rating assumes perfect heat transfer into the heatsink, you'll also need to factor in the degC/W of the heatsink transfer material probably silicone pad or thermal oxide both of which have poor thermal transfer. The metal oxide is superior but likely to add 0.4 degC/W, the silicone thermally filled pads maybe 4 to 8 degC/W. As far as the fan goes you're interested in the total volume of air it moves rated in either cubic metres per minute or per hour.

Your fridge example is a thermal mass that's not being heated so easier to cool, and it's probably been on for many hours to get down to temperature, your camera heats itself so a comparison isn't that valid.

I'd start by having a peltier that doesn't have to be driven hard then you don't have added heat to get rid of, thermal oxide to the heatsink then a heatsink shape that ducts onto the fan and then a high flow/volume fan.

The other option is a non peltier and purely fan blown one, that may keep you close to ambient without all the hassle.

On 16/06/2022 at 18:56, Ozone said:

First off, thanks for the help. Maybe I will use my Orion starshoot autoguider. It's one of the originals (maybe had it for 10 years?). The only problem is PhD2 asks me the unbinned pixel size in microns? I know the chip is larger and mono. Does anyone know where I can find that info or old files?

It's 5.2 x 5.2 micron (SSAG #52064)

6 minutes ago, Ozone said:

Would I be able to use an st4usb adapter with this setup? Using the ascom platform and appropriate cables? Guide Camera to computer USB, computer USB to st4 adapter, st4 to mount?

 

 

You should be able to. Assume it's along the lines of - Guide Camera to computer USB to PHD2, PHD2 to computer USB to st4 adapter, st4 to mount.

But if your guide cam has an ST4 port then Guidecam (On-camera selection in PHD2) to mount ST4 would be simpler.

1 hour ago, vlaiv said:

Btw - take any set of darks and stack them with max operator instead of average and you will in one image how many hits you had over whole session of taking darks.

From a second camera for comparison. Kaf16200 139off 600seconds at minus 20. same effect is visible. Rescaled to 50%.

Just now, inFINNity Deck said:

Do I understand this right: this is 30 hours worth of darks?

Nicolàs

Yep. 

1 hour ago, vlaiv said:

I've found that majority of impacts in darks are not in fact cosmic rays but of earthly origin.

Once I created set of darks near some tools used to clean wood stove - bucket and small shovel and since those had some ash residue on them - I got much higher incidence.

Conclusion was that it was due to radioactive decay in ash (wood absorbs radioactive material) - quite possibly from Chernobyl era.

Btw - take any set of darks and stack them with max operator instead of average and you will in one image how many hits you had over whole session of taking darks.

This is a max stack of 179off 600 second darks at minus 20. KAF8300. It's covered with the things. Seems to have an average distibution across the frame. Also the track angles are random, I assume this means it's a not a point source.

21 minutes ago, vlaiv said:

I've found that majority of impacts in darks are not in fact cosmic rays but of earthly origin.

Once I created set of darks near some tools used to clean wood stove - bucket and small shovel and since those had some ash residue on them - I got much higher incidence.

Conclusion was that it was due to radioactive decay in ash (wood absorbs radioactive material) - quite possibly from Chernobyl era.

Btw - take any set of darks and stack them with max operator instead of average and you will in one image how many hits you had over whole session of taking darks.

The second doc (D.Groom) mentions something interesting in that there's an exception to gamma/X-ray generating these 'worms' and that's a beta particle orginating from Potassium decay in BK7 glass i.e. Crown glass which of course can be used in APO's even if some lenses are FPL51/53. I have however seen this effect when imaging with numerous scopes which may point to it being an external source and not 'scope glass' related.

1 hour ago, inFINNity Deck said:

Indeed most likely cosmic rays, the following article may be of interest: https://www.astro.rug.nl/~nobels/Characterising_the_cosmic_rays_in_a_CCD_nobels_and_bremer.pdf

Nicolàs

Thanks that's a useful doc. This document characterises this as most likely a 'worm' but without giving much information about how it arises, but it references  'D. Groom. Cosmic rays and other nonsense
in astronomical ccd imagers.' which I've found at https://www.astronomy.ohio-state.edu/MDM/OSMOS/CCD_CosmicRays_groom.pdf.

This one's more detailed and if I'm reading it correctly implies it's the result of a gamma or x-ray hit.

For years I've noticed artefacts similar to that in the attached image, a 60 second 300x300ish crop from a single CCD frame. Since these are removed by stacking it's not been an issue but I've always wondered what they are.

I have some ideas but thought I'd put this as an open question.

3 hours ago, Ozone said:

Thanks for the help. I switched to my starshoot autoguider and had a lot better luck. I still have one problem (may have been my alignment, or slight breeze). On PhD2, there is the connection box camera, mount, etc. Which one do I choose for mount? On-camera, GPINT 278, 378, 3BC, GPUSB, INDI mount, On-AO? (May just be old school, but they seem to have made phd more complicated than necessary 😊) I found a post that says use on camera, but I may have my asi st4 cable mixed up with the one for the starshoot, would that matter??

Fig 3b is an extract from the Starshoot auotguider manual, it uses a standard ST4 connection.

The other image shows ST4 compatibility across different mounts/manufacturers.

From this diagram SSAG and ZWO ASI have the same pinout (as you would expect) so your asi st4 cable and the SSAG cable should be the same and should work identically. Just be very sure the ST4 cable is plugged into the correct port on the mount.

1 hour ago, Rusted said:

The image was soft, mobile and impossible to focus.
I persisted until later and things settled a little.

 

Outstanding, especially the 'river' in the first image. Any idea what this structure is? Looks like a horizontal effect but that might just be the imaging angle.

Is this dithered? Are you able to?

18 minutes ago, Elp said:

Well, did the infinity focus ring adjustment on the 200mm, reds still there around stars, when I focussed up to remove the red rings a lot of the stars seemed to blur a bit, I felt a little red halo allowed for sharper stars, especially the smaller tiny ones. Overall happy with this considering its only 1 hour of exposure with all calibration files (flats, dark flats, bias, dark), the L-Extreme helped a lot. Makes me think if these lenses produce decent results do I really need the heavier Samyangs (I have a few)?

Now to figure out how to remove the banding artifacts...

Is this dithered?  Are you able to?

22 minutes ago, Jay6879 said:

First shots from my new 533mc. 300s preview exposure (beyond the star elongation at the bottom suggesting wrong backspacing?) what could these dark spots be? The weird thing is they weren't visible with a 5s exposure?

 

They don't look quite like dust motes? And what is happening on the bottom half of the image? The stars are radiating away from the center of the image. Its happening at the top as well but not quite as bad. Is this a spacing issue? This was taken on a Zenithstar 61 with the 1.0x adjustable field flattener.

 

Any help would be appreciated, this was my first night out in MONTHS. It took me awhile to aquire this camera and when the first test images came in I got pretty dejected with the results!

This may possibly give some indication

https://astronomy.tools/calculators/dust_reflection_calculator

5 minutes ago, stevewanstall said:

Thank you.  I shall buy some desiccant!

Is there no dessicant already inside? It can be dried out/reactivated in the oven and re-used if there is.

17 minutes ago, oymd said:

The box says m48x0.75mm??

Is it possible that they are just 0.75mm thick?

 

That's just the thread size.

Dimension of mine: from top of filter surround to filter plate i.e. height above filter plate = 3.75mm

22 hours ago, Peter_D said:

Hi,

I have a Vixen GP mount. The thumbscrew (top photo) for fastening the telescope's prism rail has developed a bit of play in its head so I'd like to replace it (medium term fix is to replace the saddle with the ADM replacement).

In the meantime, does anyone sell proper rounded headed thumbscrews? I bought one (bottom photo)  that seemed rounded but it had an edge around its tip and chewed into the prism rail.

Thanks

Peter

 

Hi Peter, does it have to have a plastic surround?

Uk supplier of metal thumbscrews:  https://www.accu.co.uk/search-uk?cs_ids=940&query=thumbscrews&page=1

2 hours ago, Anthonyexmouth said:

I guess what I really want to know is whats the extra £££ getting me on the Sesto/Pegasus over the zwo. 

Sesto senso Wifi, 12V so potentially better load handling (not 5V powered)

ZWO EAF 5V via USB lead, no 12V lead, integration with ASIAir. Adapters for SCT's. Add-on hand controller for standalone use without PC.

2 hours ago, Clarkey said:

I might be mis-understanding something, but isn't the collar of the focuser also the outer for the bearings? I'm not quite sure how it cannot be concentric. I can understand 'wobble' if the focuser is slightly misaligned to the shaft - I have had to adjust mine once because of this - but the fault was entirely mine.

FWIW I have used 2 Sesto units on half a dozen scopes and they have been faultless. If I was buying another focuser I would get the same again.

It's probably my poor description. The ID of the collar is the bearing surface. The OD isn't a bearing surface it just fits into the x1 section of the x1x10 focus knobs, although it should be concentric with the ID depending on the focuser it doesn't have to be. Yes on two of my scopes the 'wobble' means there must be a misalignment and I couldn't fix it, or at least I gave up trying to. On the third scope the same Sesto senso is perfect and has worked well for several years.

On 28/02/2022 at 15:42, Tomatobro said:

With Alt/Az finders

On 27/02/2022 at 05:24, spacegalaxy said:

What's the smallest scope you have own? Also, please include performance and details (Like aperture, focal ratio etc)

Clear nights!

MiniBorg50 Ach, 50mm FL 250mm, visually nice tight stars with low CA, imaging is surprisingly good but of course could do with a flattener.

It usually serves as a guidescope.