To sell my 383L+ and buy the ASI1600 mono cool, or not too ?

[RuralBill]

Hi all,

Am reading lots of good things about the new ASI1600, and people comparing with the Kodak 8300 sensor, say it is better....

i have an Atik 383 mono, but is very heavy for my set up, so would swapping for the new ASK1600 be a good thing..??

i realise that the exposures would have to be a lot shorter, but people's opinion would be interesting.

any thoughts

cheers

Bill

[Adriano]

Hi. I would not do it. The Atik 383 is a 16-bit ADC camera and the ASI1600 is a 12-bit ADC camera.

[Gina]

As I have said in another thread, I plan to buy an ASI1600MM-Cool when I have the funds and see how well it performs for DSO imaging.  I currently have the Atik 460EX mono CCD - I don't know how it would compare with the 383 but doubt it would be as good.  The ZWO offering is new and many reports are coming in and will continue to do so - selling an already very good camera is a big step and I would wait until you're sure.

[RuralBill]

Thanks for the replies.....

And as I thought really, I will hang on a while me thinks...

Bill

[ChrisLX200]

I've kept an eye on the devlopment of the ASI1600-cool and there's nothing in there which would convince me to change from a standard CCD. It is an exciting development and offers much for the future but it's not there yet (IMHO).

ChrisH

[Ikonnikov]

1 hour ago, ChrisLX200 said:

I've kept an eye on the devlopment of the ASI1600-cool and there's nothing in there which would convince me to change from a standard CCD. It is an exciting development and offers much for the future but it's not there yet (IMHO).

ChrisH

What about this: http://www.cloudynights.com/topic/540439-asi-1600mm-cooled-post-your-images/?p=7293334 ?

The detail in the full sized image on flickr is quite something, especially considering the aperture of the scope used (102mm) even if it is a Tak.

On the flip side the sub-exposures are still 5 minutes which is too long to gain any real benefit from the lucky imaging-type approach (used by some with this camera for broadband imaging) and therefore implying superb seeing although to be able to get the detail of 30 minute subs in 5 minutes must still help keep image FWHM lower whatever your sky conditions.

 

Paul

 

 

[Ikonnikov]

Full res image I was referring to is here for convenience https://c2.staticflickr.com/8/7367/27902227685_5eb6127355_o.png

[Gina]

That is amazing - far better resolution than I get with my Atik 460EX mono CCD   But of course the ASI1600MM has a lot more pixels.

[iwols]

bill you know your gonna do it, so go for it just my opinion

[ChrisLX200]

M16 is fairly bright, I haven't seen any results on really dim objects (but I guess I may have missed them if such have been posted). There are still issues with amp glow as I understand it. The original question is 'should I sell my 383 in order to buy a 1600' and I still don't think that's a great idea, I would wait to see what other manufacturers come up with (QHY have something waiting in the wings) but then it's not my money :-) The Atik490 also has small pixels and does a similar job for me, difficult to compare on M16 because it's always very low near the horizon and so never shows its best to us here in the UK. I show it only to demonstrate you don't _need_ an ASI1600-cool to get something similar. This image was using 10min subs, taken 2 years ago.

Chris.

[iwols]

isnt the 490 nearly price the price though?

[trev27]

I've already ordered the 1600mm, but if I already had a 383, like the OP, I wouldn't have ordered it. The ASI is very new and the 8300 is tried and tested and known to work well with very dim objects. I don't really see the benefit of changing, unless one needs to use shorter subs for some reason, e.g. equipment issues.

Trev

[Gina]

Can't you use shorter exposures with the 383?  From what I've read it's a very good camera.  If I already had one I would think long and hard before selling it.  The Atik 490EX is much more expensive than the ASI1600MM-Cool.

[ChrisLX200]

38 minutes ago, iwols said:

isnt the 490 nearly price the price though?

Twice the price?   Indeed it is! 

To clarify: I think if I did not have any astro CCD camera at all then yes, I would certainly have the 1600MM-cool near the top of my shopping list. It is what all those who dream of converting their DSLRs into - perfectly debayered and cooled. However it is the suggestion that people abandon CCDs and jump onto the CMOS bandwagon in the hope of getting something that performs better which I'm arguing against. There's a lot of hype surrounding the 1600MM-cool at the moment, not least due to the threads on CloudyNights.

ChrisH

[ChrisLX200]

8 minutes ago, Gina said:

Can't you use shorter exposures with the 383?  From what I've read it's a very good camera.  If I already had one I would think long and hard before selling it.  The Atik 490EX is much more expensive than the ASI1600MM-Cool.

I think that is exactly where the main benefit of the 1600MM-cool lies - the low read noise means weak signals from short exposures are not swamped by noise. The 383 needs to be used in a different way and longer exposures are essential.

ChrisH

[Gina]

Ah - I see.

[ChrisLX200]

I can think of a few examples where the 1600MM-cool really shines and takes advantage of its ability to use short exposures - consider a portable setup, perhaps one that you take on holiday abroad (a lightweight astrotrack or SW StarAdventurer together with a long-ish telephoto lens or very short APO). You are wanting to push the focal length near the limits of the camera tracker - not wide field but 200-400mm f/l. Here you would have kit that is less dependant on the requirement for long exposures and it will work within the constraints of the lightweight mount. Perfect!

You do need to fiddle with the gain though, whack the 1600MM-cool up to max and you end up with a nasty posterised result. Instead what you aim to do is divvy up the signal nicely so it takes best advantage of the meagre 12-bit ADC, and that means optimising the gain setting. I know the guys on CloudyNights are working on that issue, calibrating what the best gain values are for a given exposure.

ChrisH

[RuralBill]

Well, thanks for all the input guys, and gals...really appreciate it

i think I am gonna hang onto my 383 at least for another winter anyway, and see what develops...

i know it s a very good camera, but the weight of it with the filter wheel, puts a bit of strain on my focuser, as it's not the best on my wide field rig, William optics ZS66 SD, but to be honest it would probably be cheaper to upgrade the focuser.....

Bill

[RuralBill]

Well another update,

Just been doing some testing with my 383 and my new SX USB filter wheel, and to my horror the 2" Feathertouch Crayford focuser I have fitted to the back of my SCT, which is rated to lift between 8 and 10 pounds, will not lift it without slipping..  Even with the adjustable brake almost fully on...am I doing something wrong here, as I have seen this set up hanging on the back of people's scopes without issue, the brake will not go on any more without locking the focuser altogether. My set up can't be more than half the rated lifting capacity

so if this focuser, which is supposed to be one of the best, will not lift it where do I go from here....??

now I am well miffed.  

Bill

[ChrisLX200]

Just now, RuralBill said:

Well another update,

Just been doing some testing with my 383 and my new SX USB filter wheel, and to my horror the 2" Feathertouch Crayford focuser I have fitted to the back of my SCT, which is rated to lift between 8 and 10 pounds, will not lift it without slipping..  Even with the adjustable brake almost fully on...am I doing something wrong here, as I have seen this set up hanging on the back of people's scopes without issue, the brake will not go on any more without locking the focuser altogether. My set up can't be more than half the rated lifting capacity

so if this focuser, which is supposed to be one of the best, will not lift it where do I go from here....??

now I am well miffed.  

Bill

Miffed - and I'm sure I would be too. Crayfords really have no place on an imaging rig and I junked a rather large and expensive one that came with my ODK12. It was replaced with a R&P and all such problems vanished. Having said that, I would have thought the modest weight of your own CCD setup would be within range of the FT focuser so certainly worth trying to adjust it. Use a de-greaser and ensure there is no trace of oil on the barrel and focusing spindle - even oil/sweat from your fingers can greatly reduce the essential friction needed to grip it. Make sure the pressure (governed by the tension on some small grubscrews) is even across both sides of the spindle so you get the largest contact 'footprint' - but don't over-tighten in an attempt to increase pressure against the focuser barrel or you will just bend the spindle slightly which again reduces the contact area. Making these adjustments is not intuitive and I struggled with mine - but then it was trying to lift 5Kg of kit (and failed...).

ChrisH

[RuralBill]

Hi,

thanks for the reply

the thing is with the Feathertouch focuser is that there are two screws, one sets the initial tension, (tension with no brake applied) and then that one is left untouched, then the second one which is off centre, is the brake system, so the more you tighten the more tension, but I think it is there own brake system design, so you can actually tighten it right up and it then locks the focuser, there is no separate lock screw. So it can't be overtightened, and I have it almost all the way up, and still slips, tighten is anymore and it is locked.

the shaft and friction plate are grease free, I did check that.

i am annoyed because on the Feathertouch website it states the lifting capacity as 8-10 pounds which is a lot more than my kit.

so I now have a half decent imaging set up, and can't use it .   grrrrrrrrrrrr

i have checked and it will work with just the camera, but that only weighs 0.9kg so it damn well should lift that, and is only 1.5kg with the filter wheel, which is around 3.5lb.

Bill

 

[RuralBill]

One other thing I forgot to mention, I have the Starizona stepper motor fitted also, and that has no problem turning the shaft, so it is the shaft that is slipping on the friction plate, the motor is not stalling or slowing at all, the focus knobs are turning as they should, just the drawtube not moving.

Bill

[ChrisLX200]

As I understood it the 'brake' only prevents rotation of the spindle so when pointed towards the zenith it won't unwind by itself, it has no effect on the 'gripping friction' between spindle and focus tube. However, if you have a stepper attached this would/should prevent unwanted rotation anyway so it's a bit redundant. The key adjustment is to the other screw(s) which governs the initial pressure. 

It's a bit late now but I usually recommend the Revelation R&P SCT focuser, inexpensive (comparitively) but it's well made, stiff and doesn't slip. Very pleased with mine.

ChrisH

[RuralBill]

2 hours ago, ChrisLX200 said:

As I understood it the 'brake' only prevents rotation of the spindle so when pointed towards the zenith it won't unwind by itself, it has no effect on the 'gripping friction' between spindle and focus tube. However, if you have a stepper attached this would/should prevent unwanted rotation anyway so it's a bit redundant. The key adjustment is to the other screw(s) which governs the initial pressure. 

It's a bit late now but I usually recommend the Revelation R&P SCT focuser, inexpensive (comparitively) but it's well made, stiff and doesn't slip. Very pleased with mine.

ChrisH

Hi,

not sure you have that correct regarding the brake system, I contacted Starlight a while back asking about this and they explained how it works, one screw sets the initial no brake pressure which should give a nice smooth feel, with very little tension, and then the brake screw should be tightened according to load, more load more brake, it puts pressure on spindle as does the tension screw on any other Crayford, this is the way I was led to believe it works anyway.

if I tighten the other screw more, it just means that the focuser is much stiffer to star with, and so the brake has less work to do, but I don't know exactly how is all works physically as I have never taken apart and don't really want to.....

Bill

[RuralBill]

Just been looking at the new Baader diamond steeltrack focuser, it states in the spec that it will lift 6kg straight up without slipping.....

any thoughts on this, looks like it has a slightly roughened surface of the friction plate, have I got that correct, as I would guess this would aid with the non slip design..

cheers

Bill