Arran townsend

11 hours ago, Scorpius said:

You should check out this post: 

 

 

Thats very interesting, thankyou for sharing. I will have to take precautions to prevent dew from damaging my camera. I may use conformal coating on the cameras electronics aswell as a 3dprinted casing to extend the gap between the sensor and the screen (to house the peltier and fan) this will be ventilated ofcourse. Im also considering using mini fans to keep a constant airflow over the electronics to prevent dew from forming 

Hi all,

I'm working on a new diy-based astrophotography setup as I want to get back into this hobby. I have recently purchased a Canon 450d which its soul purpose is for staring at the night sky. 

I want to make modifications to it such as filter removal, mirror motor bypass to prevent the minute vibrations it causes. And more importantly to fit peltier cooling directly onto the back of the sensor. 

For inspiration ive been looking at cameras such as the ASI294MC PRO, which has a small form factor and is able to achieve -30°C on an average night. What I want to know is what type of peltier cooling chip does it have inside? I'm aware it is a 2 stage peltier cooler but I want to know if there are any other engineering trickery used to achieve such low temperatures with a very small fan cooling the hot side.

If anyone has taken apart a camera similar to this... I would like to know what the setup inside the camera looked like.

Thanks,

Arran

On 20/06/2019 at 18:57, vlaiv said:

Actually you can but it is not easy ...

For a good image you will need fast lens and a lot of total exposure, but it can be done even in very severe LP.

Processing will be a challenge as well.

Here is example:

This was taken from my balcony and I'm in bortle 7 skies (you can see evil street lights shining from below). This image is quite limited since I used short exposure (and not many of them, I think it was less than 20) because camera was mounted on alt-az mount without tracking (actually piggy backed on ST102 - it has appropriate thread to mount camera on one of its mounting rings).

Camera was Canon 760d and I used kit lens (18-55mm), so speed was F/4.5 max (I don't remember zoom and F/speed I actually used for this image).

I also wondered if I can capture it - so I gave it a go. At very best / very transparent nights you can actually start to distinguish MW near the zenith (you can tell that there is something there and you can even guess direction of it). I also managed M31 with averted vision on more than one occasion - but only when it is highest in the sky.

What shutter speed did you use for each frame?

Just now, Arran townsend said:

Hi, I agree with the fact about countering star trails, those 15 second shots were not very good due to poor judgment with polar alignment, I have fashioned together a polar scope using an old finderscope I had, using a calculator and some wire to make a polar scope, when I tested this I had good star tracking at 300seconds which dropped my jaw!

Which do you think I should get, a light pollution filter or a genuine polar scope?

2 hours ago, RolandKol said:

Hi Aaran,
I will agree with Vlaiv,

In your case even 15sec exposures have star trails @ 300mm FL. And light pollution has the minor impact... Star trails is the main battle you should fight. 
To get nice images, you will need to reduce your exposures drastically or upgrade tracker.

In the first case, @F7 and short exposures, - you will not get much data to produce nice images... Or it will take quite a few sessions... But, as I understand, you are limited to one target per session, as to re-target next night is quite difficult task with your set-up.

If you do not want to go small EQ tracker way, - reduce FL to 135 or 200mm and try imaging closer to F4 and with shorter exposures.

Once you get a nice round stars in the center of the images (you will have some coma/"egg shaped" stars in the corners, - you will not avoid it probably), try to get longer exposures by improving your barn door tracker..

And once you will notice, you reached the exposure time then images become too bright (or Histogram Peak falls into the right side), - you may start thinking about filters.

The image below, is only the example what you may get without filters, - it was done from London Bortle 8/9, ISO100, no filters, but @F2 135mm and 30sec exposures (45sec exposures, were too bright at F2..., 60sec almost white).

This one is not even close to the perfect image, just a usual not experienced image using EQ mount, - but I would start thinking about filters after I get result like this or even better one.

 

 

Hi, I agree with the fact about countering star trails, those 15 second shots were not very good due to poor judgment with polar alignment, I have fashioned together a polar scope using an old finderscope I had, using a calculator and some wire to make a polar scope, when I tested this I had good star tracking at 300seconds which dropped my jaw!

On 09/07/2019 at 13:34, vlaiv said:

After some thought we need to check if it is actually possible that said satellite could possibly caused such "flare". I have certain reservations about it so it is best to do "sanity check".

We would need to calculate angular speed of said satellite - we have basic info on that:

Orbital period: 124.3 minutes (semi major axis - 8252 km)

We would also need resolution of above shots in arc seconds per pixel. We can conclude that flaring object did not move more than one pixels for duration of flare. This will give us maximum total flare time. Next we need to calculate amount of reflected solar photons from flat surface of certain size (we can just make approximate there based on Sun magnitude in Earth orbit and some surface area of reflection common for satellites, or even find exact size of solar panels for that particular satellite). We can model reflection to be 100% without much impact on result.

Then we need to see how much photons will reach aperture on earth (given the distance and aperture size) and integrate for max duration of flare.

I have a feeling it will not be enough to saturate sensor for that brief moment - but it might be.

Hi Vlaiv, judging from my unfiltered photos, do you think that using a light pollution filter would benifit me?, I live in a bortal 7 area, but I can't see any light pollution in my images, perhaps I don't know what it looks like...

On 09/07/2019 at 13:17, The Admiral said:

I have no idea what might have caused it, but surely this wouldn't necessarily be true if the star(s) are bright enough to saturate the sensor?

I rather prefer the explanation being a transient movement of the mount. Is it a manually operated barn door tracker? Then again, it's suprising that there is no star streaking, which would mean it would have to move between exposures? Hmm!

Ian

It is a arduino driven barn door tracker

1 hour ago, vlaiv said:

Hm, need to retract above comment

Here is a screen shot from a paper in either Chinese or Japanese or some other oriental language that uses logograms - certainly one I can't speak or read, but graph is self explanatory I think:

From the graph it looks like GLOBALSTAR M006 is capable of producing brightness of Mag 2 star. That is about x8 brighter than 52 Cyg, so should be able to make same "footprint' in about 2 seconds.

However - that thing just zooms around at about 3'-4'/second, and at 300mm lens, with even large pixels, you still need it inside 5" to make above signature, and that would make flare last at most ~30ms. That is almost 100 fold lower than above 2 seconds - which means it should look like mag 7 star - certainly not saturating.

What do you think the probability of it being this satellite?

13 hours ago, Paul M said:

I think I've posted before about a number of "transient" naked eye stellar type objects I've seen over the years. Some I've put down to retinal "flashes", visual apparitions caused by the eye's vitreous humor dragging on the retina during sudden eye movements. They are related to floaters which I happen to be plagued with.

Other flashes have almost certainly been real events - that is not due to visual effects. They lasted maybe 5 seconds, then faded rapidly. No movement was visible. I've seen plenty of satellite flares and I'm something of a plane spotter and have been confident the flashes were not conventional satellites or aircraft.

Momentary bright, stationary phenomena all before the drone era, except the most recent one and I've put that down to possible drone activity as it was low over towards the seafront - popular with drones.

So what gives? Unlikely to be stellar in origin. Nothing could build and shed that kind of energy so rapidly that didn't make the news! Satellite laser ranging? Maybe? Very stellar in appearance though. Not a military grade red or green laser then.

A flare off a Molniya satellite at Apogee? Possible I suppose. And that's my final answer. Imperfect but the best I can do!

Your RIGHT!!, looking in stellarium at the exact time the photo was taken shows satellite GlobalStar M006, it matches the area perfectly, a reflection off of the sun is what happened. Well done to you!

4 hours ago, vlaiv said:

That would be possible explanation if there were significant mismatch between brightness of two stars.

I'm not sure, but it does seem that "ghost" image is actually brighter than 52Cyg - it features horizontal diffraction spike (very faint) as well - not present on 52Cyg. Even if this diffraction spike is caused by lens and star position in FOV rather than intensity - they do both look to be about the same in intensity (or near). This would mean that about equal time of exposure is needed for both - other less bright stars would also have identifiable double in this case.

Meteor down the line of sight is plausible but very low probability event - if star image was at least a bit out of shape - elongated in one direction - that would be much much more likely scenario.

A meteor could explain it, if this strange appearance was a meteor coming perfectly toward the lens, I'll feel pretty proud that I've captured perhaps a 1 in a few million event, but meteors usually would break up into small parts at it's peak burn in the atmosphere and this is not shown in the image, or the image after, unless it burned up and dissipated in the 5 second gap between exposures.

Plenty of food for thought!

6 hours ago, Roy Challen said:

Could this be a meteor moving along the axis of the lens? Explains why it's only in one frame, but alignment and magnitude could be just coincidence.

Very interesting point, I didn't think of that

1 hour ago, Ruud said:

The transient star is more yellow than its permanent neighbour.

We should call NASA.

Yeah we should :), i was thinking it might be a variable star of some sort

2 hours ago, DaveHKent said:

The red star on the right is 52 Cyg and the rogue star looks suspiciously the same, even down to the slight reddish flare. Could it be an imaging defect? Though, none of the other stars seem to have copied. Zooming in on Stellarium there is a faint dot of nebula right where this extra star appears. I'm not sure how accurate that is, as it seems to be a photo overlaid on genuine star coordinates.

I thought the same about the  reflection, but the star underneath the bright star on the right is not reflected under the star on the left, very strange...

Hi all, I have recently been out trying to take some images with my barn door tracker I have built, a few nights ago I thought I'll try and photo C34 Veil nebula, and while going through all of my frames I noticed somthing which I can not explain 1 of my images shows a bright star randomly appearing, I'll post the image below along with the image before and the image after, I imideantly ruled out a satellite and I thought it could be an optical reflection of some sorts,

Image details:

Exposure: 15 seconds

ISO: 3200

Sensor temperature 24°C 

300mm lens aperture around f/7

IMG_6891.CR2 IMG_6890.CR2 IMG_6892.CR2

Hi all, quick question, I live just outside birmingham, I have bortle 7 skies I can't see the milky way with my eyes or with long exposures, my question is if I take several exposures in the the milky way's direction, would I get be able to see the milky way?

On 07/06/2019 at 06:57, PeterCPC said:

A CLS filter will help to reduce light pollution from Sodium (Orange) lighting. It won't really help much if you have the more modern LED (White) lights. For those an IDAS D2 filter will help.

Peter

Hi peter, I'm wondering if a light pollution filter will still allow me to photograph celestrial objects like clusters and galaxies, I've heard that they are great for nebulae, but I can't find anything about galaxies and clusters. Could you help me out?

54 minutes ago, StarDodger said:

If you do decide to mod yourself.. Remember unless you shim the sensor you cant use autofocus with a lens after the mod..this is something the pros do when you send to them for the mod..

 

Do you know if light pollution filters fix small star deformities, I ask because I have a canon 75-300mm iii lens and using a bahtinov mask to focus, zooming all the way into my photos shows stars that almost look like an arch. Not to different the image below, I think it could be chromatic abberation, I'm unsure how to get around this or if it will affect my images.

54 minutes ago, StarDodger said:

Don’t bother with the Baader filter when having the mod, it causes star bloat, and you don’t want the colour balanced for daylight photography, that’s the whole point of the mod, you need the red shift, besides if you use a clip in CLS filter, they are designed to give really good colour balance with a modded camera, that’s how they were designed..if you have the Baader replacement filter too, you will get al sorts of odd star colours..

Ok, I'll bare that in mind for the future, for now I'm not going to modify my 1200d

On 03/06/2019 at 23:01, catburglar said:

Many nebulae shine in H-alpha, so you might struggle with some of them. But for galaxies, open clusters and globular cluster- you’re not missing out too much by not modding the camera. I’ve attached a couple of pics from when I started out with an unmodded 1300D- from Bortle 5-6 skies. They’re not world beaters, but I was quite chuffed at the time.

 One final point before the pics- the Baader modification keeps normal white balance so you can still use the camera for daytime shots.

 

Did you use a telescope or a lens for these images?

On 03/06/2019 at 22:56, Danjc said:

I have an unmodded 1100D with a Skytech CLS.

 

 

Class 6 sky’s. 

What telescope/lens did you use for this image?

3 minutes ago, PeterCPC said:

That certainly looks like Sodium to me. You can usually tell just by looking with the naked eye - does it have an orange glow. If LED lights are coming soon then I would not bother with a CLS.

Peter

I know the council have installed led lights on some of the main roads around my area, but not on the streets.

On 04/06/2019 at 08:49, StarDodger said:

Even with the normal astro mod on these cameras, there is still one filter left in the camera that does an excellent job of blocking the UV and IR, so no need for the CCD version at all, unless you go for the full spectrum astro mod, where both filters are removed, then for imaging you would need an IR / UV blocking filter, so the one you mention would be useful..

But not sure why you would want a full spectrum mod really....so get the cheaper non CCD version..

I was thinking that using my unmodified dslr won't be that good, because most online images I find are shot with an 'modified' DSLR. But seeing images of unmodified DSLR'S they look pretty good anyway.

On 04/06/2019 at 08:01, Nigella Bryant said:

I would look at the Idas D2 filter for your Dslr. I've been thinking of getting one. I use however a modded Canon 1000d. The D2 is a little bit more expensive but filters out led lighting which most of the UK will eventually be using so it's future proof too. 

 

I've been thinking of getting a filter that battles with the led lighting, but I think they are a bit pricey to start with. Here is a single test exposure to show the skies I'm dealing with, it looks like it's mostly sodium I'm dealing with, see what you think...

4 hours ago, PeterCPC said:

A CLS filter will help to reduce light pollution from Sodium (Orange) lighting. It won't really help much if you have the more modern LED (White) lights. For those an IDAS D2 filter will help.

Peter

Is there anyway I can find out what kind of lighting is in my area, maybe like an online map I cant find? 

Here is a test exposure of my skies, to me it looks like it's mostly sodium light causing the pollution, but I'm aware that LED lighting is on its way in 

Hi all, I am thinking of getting a light pollution filter, the Skytech CLS canon clip filter to be exact, and I have done some research into the capability's of this filter without finding much information about what can I photograph with this filter, and what can I not photograph?

I like the idea of being able to photograph most deep sky objects, galaxies, nebulae, clusters and so on...

Thanks, Arran.