teoria_del_big_bang

What flattener is it exactly, is it this one:

2019-all-new-adjustable-flat6aiii

15mm may be enough but I really cannot say for sure,

Steve

So long as there's some movement outwards then you may be able to focus on the stars but how much more movement you need I cannot say.

At the moment without the flattener the focal point is just dependent on the focuser position itself plus the length of the spacers. Hence the focuser could be almost all the way in with say 150 mm of spacers, or almost all the way out and only 50 mm of spacers (these figures just examples not necessarily for your scope and camera setup)

When it comes to fitting the flattener then it gets a bit more complicated. You need an exact amount of spacers between the flattener and the camera to give the desired "Back-Focus" as dictated by the flattener you have bought. The flattener is designed to give a flat field at a certain back focus, if this is not correct then the flattener will work to a certain extent but will not be perfectly flat.

Steve

How far out is the focusser itself ?

6 minutes ago, AndyThilo said:

Haha been quoted £1200 to make the base. What are these people smoking 😂

What !  That is crazy price. 

I am guessing but after material costs that must be at least £1000 for a days work.

Steve

If you can try it while still light, I am sure you will find it easier

Also you should be able to fit the flattener without tools, well on my WO 73 I can.

Steve

50 to 60 mm should be easily enough, try focussing on a land based object during daylight. I am sure you will need some spacers.

There is a manual here but even that does not tell you much.

GranTurismo_71_Owner_Manual

Again from the image of your setup it looks like you are not using a flattener.

Unfortunately I cannot find any info on spacers required without a flattener and I do not know how much that affects the back focus. But image below shows a setup with a flattener (ringed in red) and with a fair amount of spacers  (ringed in green) in between the focuser and camera. Looks to be nearly 50 mm of spacers.

Also without a flattener you will have a fair amount of distortion of your images so it may pay in the long run to get a flattener then you have all the info you need to determine what spacers are required.

There is 6.5mm between the front of the camera body and the image plane so with a flattener fitted you would need to measure to the front of the camera body and take into account it is another 6.5 mm to the image plane.

Steve

Oh @Tomatobro beat me to it whilst I was typing 🙂

Steve

I am no expert but looking at the image of your setu I would expect some spacers in between your focuser on the scope and the camera. So probably you cannot move the camera far enough back to get into focus.

You mentioned you have tried with sacers, but what size, I would need to check the specification of your scope but would be expecting something like 50 to 60 mm would be required.

Other possibilities are camera exposure settings.

It would be far easier for first attempts to use it (VERY carefully) in daylight and try to focus on a land based object. I say carefully because you must keep it well away from the sun, I know you are not looking with an EP but the sun could also damage your camera. Something like a tree as far away as possible.

Now when you can focus and get images of a tree (or whatever you choose) the focuser will need to be withdrawn a bit more to focus on stars or DSOs, which are at near infinity, but you have a start, just make sure you have a fair bit more travel outwards of the focusser.

So now for you next clear night you will know your camera can take images and that focus is outwards from the current position.

Steve

Basically as @Padraic M says above it is the field of view that will differ not any quality as such (until you start cropping smaller targets).

Unfortunately there is no real ideal do it all scope. Below are some examples and shows the FOV for the Esprit 80, 100 and 120 with the ASI1600.

For a large target, such as Andromeda as below , or something like the very popular Orion Nebula, the ED80 wins hands down as the others cannot get the whole image without cropping part of it.

But for smaller objects, such as the Dumbbell Nebula the 120 would be better.

Now of course you can always crop any image to make the target look larger but the more you crop then the quality of that image is reduced.

And you can always do a mosaic if your field of view means you cannot get all the target into your image, but that adds complexity and means you need much more data to complete your image.

It's a difficult one to give advice on because if you are relatively new to all this then some of the popular targets for beginners are Orion Nebula, Andromeda, North America Nebula really you are better with the ED80 but obviously the smaller targets the 120 (or even the much more expensive 150) come into their own.

Personally if it was a first scope I would get the 100ED (or even the 80ED) and put the extra money into the best mount I could afford making it as future-proof as I can. A HEQ5 is fine for the ED80 and 100ED (although with all the other equipment such as filter wheel, focusser, camera etc the 100ED is about the limit for the HEQ5). If later you get something like a 120 or 150 and you invested in a good sturdy mount with a good payload capacity then you will not need to upgrade your mount.

Steve

I certainly have seen much worse images so try not to get disillusioned for too long, I really think it still is an achievement.

I am by no means expert in any of this having only been doing this for just over 2 years have also had bad sessions and issues at times I do not know how to overcome at the time and often have looked at my data and think why do I bother. And I am sure everyone on this forum has been there at some stage and it will happen again from time to time.  But with great advice ( also often from @vlaiv ) I have always overcome these issues. Nobody on this forum has ever told me this hobby was easy though, but that is part of the challenge and definitely makes it all the better when something goes just right.

 Some great advice above and I am sure after a rest you will be back with improvements and you will be glad you persevered 🙂.

I look forward to your next images.

Steve

Francis,

I would be pretty happy with those readings. 103 ohms sounds reasonable for each coil and the 52 ohm is to the centre tap and hence half the coil resistance.

Obviously I cannot say 100% it is correct but would expect one coil at least to be almost short circuit or open circuit if any issues but they are look perfectly even. There could still be some issue that only shows up with the higher currents it would have when in use as opposed to the very minuscule current when checking with a meter but as said before these stepper motors are very robust and those checks would make me happy it is fine.

Steve

A real shot in the dark but:

I would really like to complete my set of Baader ultra narrowband filters which means I still need a Baader Ultra Narrowband SII 4.5nm CCD Filter 36mm Unmounted.

I think the chances of getting one this year is pretty slim to impossible but just wondered if anybody knew where I could source one ?

Steve

If you have a meter capable of checking resistance you should be able to check the stepper coils are not burnt out fairly easily.

Not sure what resistance they should be but if not open circuit or high resistance then usually will be okay. As @Richie092 the steppers are usually pretty robust and unlikely to be the cause.

Steve

20 hours ago, Starwiz said:

I've done a plate solve to find out.

Target position RA = 02 : 35 : 38, DEC = 61 : 30 : 51

New (unwanted) position after slew RA = 02 : 40 : 10, DEC = 62 : 39 : 38

So the unwanted position is still in the general direction of your target, but too far off for it to be in the frame.

What makes you think it slew to this position rather than having drifted to it over the imaging session since the cloud cover occurred ?

If you have some evidence it slew to that new position then we can stop talking about drift. 

Before the plateslove did the mount think it was in the correct position or the new unwanted position ?

Steve

To the best of my knowledge there are no mounts for ameteur use that have any motors on the adjustments needed to align to Polaris ( or more accurately to align the Centre of rotation of Ra to the rotation of the Earth).

The only motors are on the Ra and Dec axis themselves. The adjustments needed are mechanical movements with leveling the mount. then the angle of the tripod to the ground needs adjusting so this is placing the tripod at the correct approximate  angle then using some fine adjustment screws to get it correct and also using some fine adjustment to get the Declination angle correct (although this is dependent on where you are on the Earth Latitude wise usually some very small adjustments are needed each time you move the mount which again is a mechanical thing using some adjustment screws.

The only motors are on the rotation of Ra and DEC themselves which are not the adjustments needed to align the Ra axis correctly.

Now I am not saying this is not possible to make it automatic in theory but for one, the cost of putting motors on the adjustments will be expensive and for another how accurate is the GPS system currently ? Probably not as accurate as we can achieve currently using this manual alignment method.

After polar alignment the 2 or 3 star alignment again is just another very fine adjustment used to get it even better.

Steve

10 minutes ago, Realtimedoctor said:

A wild thought is sometime during the night/imaging session is APT does a meridian flip -> you wake up to the mount pointing in a different direction, assuming it has "slew" to a new target. 

That is actually a very good thought.

I too no longer use APT and thought if PHD2 lost the star it did not re-select a star when the clouds cleared , but it may well do especially if you have automatic star selection enabled in PHD2, in my case the cloud was usually still there in the morning anyway, the joys of living in the pennines 🙂 

But after a flip without  a successful platesolve then the mount could be a long way off target even if polar alignment was reasonable and tracking was working. Also it would definitely re-enabe PHD2 and select a new star whatever the settings (I think from memory).

Steve

From my short experience with PHD2 That is odd.

When I have used PHD2 with both APT/ASCOM and KStars /INDI acquisition software when this occurs PHD just stops delivering guide correction pulses to the mount, but the tracking is still enabled so the mount continues to track the object but without any corrections from PHD2. So I still continue to photograph the target (albeit now covered with cloud) but maybe not as accurately as with PHD2 working so the target may drift over time (but over hours it does not slew to a different position). So when this happens (as it does with everyone at sometime)  then if the cloud clears I will still be more or less on the target and will continue to take images of that target. It is just the target may have moved very sightly.

I have never seen PHD select another star when the cloud clears but depending on the acquisition software I am sure some can be setu to do so and in that case it would pick a guidestar and then continue to guide properly but the target will just have moved a very small amount from when it was guding before the cloud cover.

So it almost sounds like your tracking is the issue rather than PHD2 as you should be able to track a target well enough to take hours of images without losing the target altogether, it may slowly drift so the last image is in a different place on the image compared to the first but should still be there.

So As @Realtimedoctor suggests say what your whole setup consists of , what  acquisition software, are you using PHD2 with ASCOM or INDI or ST-4 etc ?

Steve

That is a very nice image indeed 🙂 

Steve

28 minutes ago, Chris Wright said:

Postie delivered my new guide scope. I hope somebody somewhere is enjoying said guide scope as this is not a picture of my front door!  

 

That is bad, I hope you get it sorted soon. Normally the driver at leasts asks my name before putting the parcel inside and taking a picture. So either they didn't this time or the wrong addressee has the same name which is highly unlikely.

Steve

Also that justifies me forking out for all new 36mm unmounted filters which I did when I bought the 1600 even though I could have used my existing 25 mm ones 🙂 

Steve

Just now, DaveS said:

Considerable improvements. Much larger sensor size, APS-C rather than 4/3 but still within the bounds of 36mm filters. But most of all, zero amp-glow and 16 bit ADC. Also it's BSI with a higher QE, reaching above 80%.

Thanks for that, looks Like I need to start saving then eh 🙂 

Steve

What are the improvements of the ASI 2600 over the ASI 1600 mono cameras ?

If priced similar to the OSC model then it is considerably more expensive than the ASI 1600.

Steve