Nikons and green stars

[MarkS]

You may or may not know that I've recently been testing a Canon 200D against a Nikon D5300 as entry level cameras for astrophotography.  I haven't previously used a Nikon and I was quite shocked to find a large number of green stars.

It seems that it's caused by the spatial filtering which can't be switched off.  Very similar to the problem(s) on Sony cameras.

Anyway, if you are interested, here is my ongoing thread over on Cloudy Nights

https://www.cloudynights.com/topic/635441-aa-filter-spatial-filter-and-star-colours/

What on earth have I started? 

Mark

[Carole]

You are so clever Mark, I can see the differences but would have no idea how to calculate all this stuff.

Carole

[ApophisAstros]

I know on some cameras the Bayer Matrix has more green than the R&B.
Roger

[NoelC]

Blimey; I can't even see them in the frame of Cygnus (until you enlarged it).
Some fascinating work there Mark.
I expect you are giving sleepless nights to the software teams at Nikon; it's a pity they aren't more engaged with astro-imagers, particularly since they appear to want to target this market.

Noel

[Mac]

To be honest, if any manufacturer wants to engage the astro market, they need to add an astro mode.

Which must include the following.

Manual selection of time from 10 to 900s.
Multiple images. 1 to 100.
True raw file saving with NO processing what so ever.
auto dark image/s at end of multiple image session, i.e. 10 light & 5 dark frames, (just dont open the shutter. Just take an image)
auto bias frames, same as above.

An option to program multiple images at different iso's
5 at 200, 5 at 800, 5 at 6400, ect with the above option of the darks.

An option to turn off all displays whilst taking astro photos to reduce thermal noise caused by the LCD displays.

Maybe a very very high iso setting so that you can quick focus, nothing worse then doing a 15 min shot to find out its blurred......

Thats an absolute minimum.

Mac.  (Still lurking,  )

[ApophisAstros]

You can do a lot of that with APT and any DSLR or CCD at the mo, basically you want a chip and a lens and spend all development and cost on that as most things can be done with capture software, and ultimately upgradable by us.
Roger

[Mac]

I agree that there is software around, I've even designed software control on a PIC chip for my D3

But at the end of the day software relies on a computer. which needs its own power, loads of leads ect.

Im talking about just dumping the mount, telescope and camera in a car, driving to a nice dark site and setting up, relatively quickly..

sticking the camera on the end of the scope setting the functions and off it goes. 25 shots at 300sec plus bias and darks. Point it at your headlights and there are your flats.

Most mounts will run off a car battery all night,  your cameras should last for a night session or two..

I understand that dedicated CCD systems need their own power but the things that bother me and still do

is setting up everything during the day, testing filter wheels, ccd's guiding software, ect ect, everything is working ok

Turn on at night and its as if the night demon has unpluged all the USB cables and swapped them around, filter wheel not working, CCD camera giving strange errors,
Laptop only booting into safe mode,  guiding wants to follow a fly on the camera ect we've all been there..

Sometimes its the simple things that we need. I used to hate setting everything up only to find out whilst ive been doing it the clouds have rolled in.

Waitied a couple of hours for it to clear and then given up, put everything away only for the sky to clear 5 mins later.

I now have the same problem except its with the observatory.

it would be nice to turn on the scope and camera and within 10 seconds im off.

Mac.

[MarkS]

I agree that there is software around

No.  Once the camera firmware has wrecked the data there is no possibility of ever recovering it.

Having said that, there is a fairly sophistaicated algorithm I have in mind that would work on a large number of dithered subs.  But it must stay under wraps for now 

Mark

[The Thing]

Algorithm sounds cool.

Mac, with ZWO usb3 cameras all you need is your phone to run it. Mine has a 9000mah battery so will run the ASI294 half the night and a USB power pack can fill in as well. I need to make a 5v dew heater strip for a lens and its all sorted. So things are improving on the portability front. I intend to take my StarAdventurer, camera and phone out for a wander some time this winter , probably to the dunes where there is a perfect south west horizon, and see what I can get.

[ApophisAstros]

Trying desperately to sell my StarAdventurer + kit, not being successful tho,
Roger

[RobertM]

Algorithm sounds cool.

Mac, with ZWO usb3 cameras all you need is your phone to run it. Mine has a 9000mah battery so will run the ASI294 half the night and a USB power pack can fill in as well. I need to make a 5v dew heater strip for a lens and its all sorted. So things are improving on the portability front. I intend to take my StarAdventurer, camera and phone out for a wander some time this winter , probably to the dunes where there is a perfect south west horizon, and see what I can get.

Likewise for the 183 I have that I plan to take to Cyprus a week Tuesday.  Bear in mind though that  9Ah 5v = 45W and at 12v it is just under 4Ah ( 45W/12v ).  My ASI183MM only draws more that one amp to reach temp then about 600-800mA to maintain a -30C differential.

I'll have about 180W of lithium packs when I go, enough for a whole night with the star adventurer and Asus ultra portable ... hopefully.

The star adventurer is a great piece of kit - are you selling to raise cash Roger ?

Robert

[The Thing]

I wasn't aiming to have the cooling operating, but its not beyond the realms of possibility, I would need another USB power slab and a 5to12v converter thingy like wot you've got Robert.

[Mac]

with regard to the software, i was just referring to timing software as opposed to processing anything..

So that with minimal equipment you can do a nights long exposure photography. No setting-up of laptops ect...

Processing would be at home in the warm. 

Mac.

[ApophisAstros]

The star adventurer is a great piece of kit - are you selling to raise cash Roger ?

Robert

Yes Robert I am going for a dual Rig with my new Altair Astro Lightwave 66ED-R refractor with my ASI183mm and my Canon 1000d with my Skywatcher 120ed, so need to get a few bits for that.
This is what i had in mind ;


Roger

[RobertM]

Looks good but I can see a few opportunities for sag and flexure - I would keep an eye on that if you start getting trailed stars.  Personally I would just bolt the 66ED straight on the tandem bar and adjust it using shims and the play in fixing bolts.

Crikey what a thread hijack !

Robert