Hallingskies

I did the mod and now the mount judders in RA. Haven’t tried too hard to get to the bottom of it yet as I am using another mount, but it’s frustrating and I wish I hadn’t bothered.

Thanks for the reply.  I wondered if the diagonals were a usb issue but it seems the same on several different laptops.

This is a master bias frame made from 50 exposures, sigma stacked, from my SX-694.  With the dead column and diagonal banding, it seems a lot less smooth than the bias frames from my Atik 460.   It doesn't seem to give a problem in the final image but I just wondered if the SX is firing on all cylinders...? 

Any opinions, anyone?

Yes.  Next question?

Taken at Cuxton, Kent, on the evening of June 23rd, Canon 450D, 6s at f6.3.

Remember why the lorry park was built in such a rush?  It must be those sunlit uplands lighting up the sky at night...

Here’s Prof Cox in action. Or is it?  I can never tell these two apart...

2 hours ago, ScouseSpaceCadet said:

Time to practice my Brian Cox look into camera provoking thought from the viewer followed by a gentle but firm turn of the head to the right tilted up at a distant cosmic object contemplating existance while the soundtrack reaches a crescendo look... (Breathes).

 

Prof. Cox always reminds me of that Paul Whitehouse character from the Fast Show who used to stroll through random backgrounds while babbling on about how “BRILLIANT” things are.  

I’ve just done this mod myself and I don’t get the ticking noise.  I just wonder if the noise is the cog skipping over the belt teeth? You should be able to loosen the pulley plate to adjust the belt tension without taking too much apart.

Am I alone in being unable to open the FITs luminance data in Astroart?  The RGB data is fine.

I think the threads on the filters (if threaded) should point towards the lens but in practice I’ve found it doesn’t make much difference.  But yes, there seems to be a big difference in focus position between makes of filter.  I had the same problem with Baader LRGB and an Astronomik 12nm Ha - the narrowband was off the mark.  When I swopped it out for a Baader, all was good.  On the f2’s, yes they do seem to give brighter images when used at f2, but I see no difference to the standard 7nm filter at f2.8, which is where I tend to use the Samyang anyway.  

Not sure if this helps but my Win 10 laptop disabled USB outputs if they weren’t in continuous use.  There are options in the power management menu to stop that pointless and typically Microsoft aggravation.  I had no end of trouble with my ATIK kit in Win10 until I did that.

Not seen that one before, nicely done.  SkyMap Pro is just brilliant for browsing for targets, isn't it?  

19 hours ago, Adreneline said:

Yes I am sure I have the spacing correct. The focus position is within the foot of the 'L' mark. I am using the lens at f2 so I am not surprised star shapes in the corners are less than perfect. To be honest the fov with this camera is such that I tend to crop off the edges anyway.

In my opinion, being contenscious, the Samyang 135mm is not a lens suited to pixel peepers - it is more suited to imagers who want a large field of view without necessarily having to get into mosaics. I like the fact I can image all of IC1396 for example and the surrounding space and enjoy the majesty of the whole thing. I am not interested in looking at detail at the stars in the corners.

Let's not lose sight of the fact that this is not an astronomical telescope, it is a consumer photography lens, and a budget manual one at that. Sounds like you have a good one and maybe I don't.

 

l definitely agree with your comments above.  Using the Samyang with an Atik460 is hugely undersampling and stars are a bit blocky at the best of times.  That said, I usually use Starnet in wide-field image processing.  I give the star layer a bit of a Gaussian blur and then do a bit of reduction before pasting it back in to nebulae pics.  This tidies the stars up no end.

9 hours ago, Starflyer said:

I've found the moon useful when setting up an OAG too, big and lots of detail for focussing on.

...there's never a moon around when you want one...

The orange plug on the side of the power box allows for 12v input so you could run to that from your power supply.  Otherwise, drop the SX guys a line direct, they are usually pretty helpful.

From last year, 10 x 600s exposures each for LRGB, Esprit 100/Atik460

4 hours ago, michael8554 said:

Sorry, that makes no sense.

To be in focus, the guidecam sensor MUST be the same distance from the prism as the imaging camera.

And both are after the FR, so equally Reduced.

You must be measuring wrong.

Perhaps an image of your setup would clarify ?

Michael

No need to apologise - you are right, it makes no sense at all.  And it was really bugging me.  So this morning I decided to try it all out in the daylight.  As you asked, this is the set-up.  From the left, VC200L draw tube, focal reducer, OAG housing and guidecam, filter wheel and main camera (you can see the Vixen guide scope - Plan B - on the top of the scope...) 

Here's what the guide camera is seeing down the prism draw tube, so this shows that at least the prism is seeing some light...

The Lodestar is way too sensitive on an 8 inch aperture to be ran in the daylight, so I made up a crude aperture mask and stuck a couple of layers of neutral density film over the hole in the mask...

That done, I set the prism and the guidecam at about "half way" positions, fitted the guidecam, aimed the scope at a distant bridge, and set the guidecam running...

...and it works!!!  Yes, a grotty image, but taken through a window while it was raining.  Rotating the whole imaging train improved the vignetting which I think was being caused by one of the thick secondary supports...

The main camera was showing roughly the same view...

I think what had been happening was that in the dark, the guide cam was simply not seeing the street lights I could see in the field of the main camera.  The odd glimmer I did see in the guide cam was probably a reflection in the window.

So the moral of the story is .....   TEST IN THE DAYLIGHT!

Thanks to everyone who replied.  This may count as another Duuurrr moment...

39 minutes ago, kirkster501 said:

There is always a reason that the guidecam can't focus.  Always always it is because the distance between objective and imaging sensor that you get into focus on the main camera has to equal the same distance to the guidecam sensor as well.  Bullet camera sensors can get deep inside the OAG drawtube - so a lesser distance, whereas the "hockey-puck" ones sit outside the draw-tube and are further away.  Almost 100% certainly you have not got these distances correct and matching.  Play about in the day time with a remote roof or chimney and get them into focus that way.  Then, at night, a slight tweak and you are a-ok.

Seriously, once you crack it you'll wonder why you ever bothered with guidescopes.

Good luck.

I have always used an OAG for my refractors and indeed, prefer not to bother with guidescopes.  However, I decided to blow the dust of of my old VC200L.  I used an OAG with this many years ago, and had no problems as I recall.  However, I’ve thrown a focal reducer into the mix and this seems to be causing a problem, though I can’t work out why.  I can focus the guide cam or the main one, but not both. I have the rig set up pointing at some distant streetlights and that works quite well for testing purposes.  I have the SX OAG and its focussing is a bit primitive (and actually quite sloppy - not impressed really) and there is not a lot of it. The lodestar fits on a C mount rather than being pushed in to a socket.  The focal reducer ties me to a specific back focus for the main camera and it seems there just isn’t enough adjustment in the SX OAG to accommodate the guide cam.  

I’m not too bothered to be honest - I have a really nifty old Vixen guidescope of about 450mm fl with rock solid sweep adjustments.  It fits on the VC200L a treat and took about 30 seconds to set up! As I plan to be galaxy imaging, quite often in narrow and sparse star fields, the ability to easily shift the guide cam field might come in handy.  With the focal reducer bringing me down to 1278mm fl, I think any problems with guidescope flexure will be minimal.  There’s no mirror flop with the VC200L of course.

Guess I’ll see how it works out...

3 hours ago, Hallingskies said:

That's a good idea, thanks, I'll try that one.

And I did!  Sure enough, the guide cam comes into focus at a point well past where the main camera is in focus.  The focal reducer is obviously pulling the "light cone" in to a point outside of the range of the OAG focus adjustment.  Oh well, it's Plan B then (guidescope)... 

1 hour ago, Robindonne said:

Try getting in focus without having the maincam in focus.   You’ll probably find that the amount of play in the guidecam side of the oag is too short or too long. 

That's a good idea, thanks, I'll try that one.

Thanks for the replies.  The main camera comes to focus just fine and the prism of the OAG is most definitely in the light path (and facing the right way!).  I have a set of street lights and a brightly-lit bridge a couple of miles away and the area serves as a good target when I am trying to sort out focus on new kit.  Moving the guide camera in and out across the full range of its focus gives nothing at all, even though the main camera gives an in-focus image.  The guide camera is working - if I shine a torch down the scope the guide cam display goes from black to a fully saturated white.  Measurements from prism to guide cam tally up with prism to main cam distance - this is an SXV set-up and everything is supposedly engineered to be parfocal anyway.

It's not the first time I've set an OAG up (though the first for this equipment configuration) and it's normally straightforward - focus main cam, check prism isn't shadowing its chip, then focus guide cam, no problems.  I'm scratching my head on this one.  I'm assuming people must use OAGs with SCTs or newts, but when I slide the guide cam out of my set-up and look down its draw tube, the secondary mirror and a support vane fills most of the prism view - there's not a lot of sky to be seen. 

Will have another play when it's dark tonight (can't try the Lodestar in the day - it's too sensitive even at fastest exposure speed).  I do have a guide scope I can use and I might give up and use that instead! 

Am trying to use an OAG with my old Vixen VC200L fitted with a x 0.71 focal reducer.  The OAG is attached to the reducer, followed by the filter wheel, then camera.  I absolutely cannot find a focus point for the guidescope in this configuration.  Is the reducer putting me inside the focus point of the OAG?  When I take the guide camera off and look down at the prism, I can only see the shadow of the secondary mirror, no matter how far in or out I put the prism.

Anyone out there with experience of OAGs and SCTs with focal reducers?

I'm the same with BMs.  I find I get better results focussing on screen by looking at FHWM anyway.  Glad it's not just me.  So frustrating when you lose time due to your own mistakes.  It's why I try and test as much stuff in the daylight as I can.

Just trying to set up my Vixen Visac and a SX-694 combo to try a spot of galaxy hunting, not something I’ve attempted for years.   Got gear set up on mount, sorted power supplies, plugged mount, filter wheel and camera into laptop, everything worked fine, EQMOD talking to the mount, camera/wheel control software working fine.

Could not get the Lodestar guide cam to come up in PHD though.  Checked guide cam, no LED.  Connections looked solid, camera drivers OK.  Took it indoors, connected it direct to another lap-top via a USB a-type port, LED lit up and it worked fine.  Ah, dodgy wire, I thought.

Then it dawned on me.

I had used a mini usb to type B usb cable on the rig, and had plugged the type b end into the autoguider ST4 socket on the camera!

Connecting up with the right type of cable (mini usb both ends) between the main camera hub and the right socket on the lodestar solved the problem instantly.

Is it just me or does anyone else do dumb stuff like that?