Which planetary cam, and why?

[Guest AstroOlly]

Hi all,

Am looking to get a colour camera for planetary imaging, I already have a mono, wanted colour for ease and when not got time for mono.

The two obvious choices are

QHY5L II

ASI120MC

But which one of them and why, I realise there is about £60 difference in price, but they look, spec wise, the same camera, what are the pros and cons of each camera besides price, as price is not an issue

Is it better software, electronics of the camera, drivers, physical size, cooling, or just after sales service?

Appreciate any advice

Olly

[dawson]

What about the cheaper colour zwo with a 640x480 sensor?

I only have experience of the ZWO 120MC. It does what it says on the tin. The new version (the version which is on sale now) has an ST4 guiding port, the IR cut filter (i've got the graph for its transmission at various wavelengths if you want that, else ask Sam at ZWO for it) is now fixed into the camera, so if you wanted to do IR let through imaging with it that would be difficult and I think you'd have to break the IR cut filter out; firecapture and sharpcap2 now love the ZWO, drivers are all online and not an issue, compact, cooling isn't an issue with planetary, but as Felix also noted, the capture software reports the sensor temperature and it's often close to ambient when outside when doing imaging runs (the body is metal), after sales service has been excellent for me, Sam in China replies to emails quickly and he has resolved an issue I had (my fault not a camera issue) very quickly and smoothly. If you wanted to send a ZWO back to Sam it would be more hassle/expense than sending the other back I suspect, but I'm not sure how that would work if you sent it back to 365Astronomy if you got it from there. So, no concerns about the ZWO design in principle.

Jd

Edited March 26, 2014 by dawson

[dawson]

Sorry it is 728x512:

http://www.365astronomy.com/zwo-asi034mc-colour-14-cmos-usb20-camera-p-3700.html

It seems this version has bigger pixels, the more conventional 5.6 microns; it is 8 bit rather than 12 for the 120MC, and ROI is still supported; longest exposure seems to be 60seconds rather than 1000seconds for the 120MC. It doesn't have the ST4 port.

If you don't intend to use it for guiding, or for exposures >60seconds, and the 5.6micron pixels match your kit (see footnote), I can't see why you'd spend more money on the ASI ZWO 120MC. Even with a 3x barlow, you would still fit Jupiter well within the frame at 640x480 (which is smaller than the maximum "resolution" of the 034MC (728x512).

I can't make any comments on the QHY.

Jd

Footnote: 8" LX90, focal length 2000, pixel size 5.6, binnin 1x1, gives you 0.58 arcseconds/pixel; add in a 2x Barlow/powermate gives you 0.29 arcseconds/pixel, a 3x barlow/powermate give 0.19 arcseconds/pixel. Using the smaller 3.75 micron pixels for the ASI120MC, a 2x barlow/powermate gives you 0.19arcseconds/pixels, and without a barlow/powermate 0.39 arcseconds/pixel. (Optimum arcseconds/pixel in the UK is probably around 0.25 according to Damian Peach; down to 0.15 arcseconds/pixel under exceptional UK seeing and with bigger scopes). All data calculated using: http://www.wilmslowastro.com/software/formulae.htm

Edited March 26, 2014 by dawson

[Guest AstroOlly]

What about the cheaper colour zwo with a 640x480 sensor?

 

I only have experience of the ZWO 120MC. It does what it says on the tin. The new version (the version which is on sale now) has an ST4 guiding port, the IR cut filter (i've got the graph for its transmission at various wavelengths if you want that, else ask Sam at ZWO for it) is not fixed into the camera, so if you wanted to do IR let through imaging with it that would be difficult and I think you'd have to break the IR cut filter out; firecapture and sharpcap2 now love the ZWO, drivers are all online and not an issue, compact, cooling isn't an issue with planetary, but as Felix also noted, the capture software reports the sensor temperature and it's often close to ambient when outside when doing imaging runs (the body is metal), after sales service has been excellent for me, Sam in China replies to emails quickly and he has resolved an issue I had (my fault not a camera issue) very quickly and smoothly. If you wanted to send a ZWO back to Sam it would be more hassle/expense than sending the other back I suspect, but I'm not sure how that would work if you sent it back to 365Astronomy if you got it from there. So, no concerns about the ZWO design in principle.

Jd

I am a little confused here, you say it would be difficult to do IR imaging as I would have to break the IR filter out, but before that you say the filter is NOT fixed in???

Olly

[catman161]

It was a typo olly-the IR filter is fixed therefore not allowing IR pass filter use to film in IR spectrum without removing the fixed IR block filter that comes with the camera as standard.

Bit if a design flaw really. They put it in the newer models as a dual function of being the filter but also to protect the sensor from dust. The older model 120MC just had an open space in from if sensor allowing dust to accumulate on sensor.

[dawson]

Yes typo. It is fixed in from my inspection of it but i've not tried to remove it. I'm sure sam would sell you the part/version of the camera body without the ir filter glued in, which would probably cost 25 or so i guess if you wanted to do ir imaging.

Edited March 26, 2014 by dawson

[Guest AstroOlly]

It was a typo olly-the IR filter is fixed therefore not allowing IR pass filter use to film in IR spectrum without removing the fixed IR block filter that comes with the camera as standard.

Bit if a design flaw really. They put it in the newer models as a dual function of being the filter but also to protect the sensor from dust. The older model 120MC just had an open space in from if sensor allowing dust to accumulate on sensor.

Thanks for clearing that up that Felix

So,it is fixed and unable to remove, that points me towards the QHY then as that one is removable

I have the IS DFK 21 that had the IR filter, I had to completely take that apart to remove the IR filter, but it was quite easy, once I got started

I assumed the ASI cameras had a removable IR filter, only I have a really good quality AStronomik one that I would want to use instead.

Cheers

Olly

[Guest AstroOlly]

So how good a quality is the IR filter that is fitted to the ASI cameras, could I live with it, or would my AStronomik IR/UV filter be better??

I am not bothered about imaging without an IR filter, but if it is fixed I want to know it is a good one unlike the IS cameras, the ones in those were not good at all.

Perhaps I will contact them and find out how easy it is to remove them

Olly

[dawson]

Email ZWO. He may be able to send you one with the new body with the st4 port, but the old style nose piece half (it's not just the nose piece, it one half of the camera casing) which has no filter fitted, then you could just use your own 1.25" filter in the nose piece.

I've no idea about the quality of this filter vs the one you've already got.

The ZWO is widely used by people on SGL so imd suggest asking there specifically about a) removing the ZWO filter, and how good is the ZWO filter.

Jd

[+Ibbo]

if you want to ir imaging get the monochip suffers from newtons rings

 

if you are wanting osc leave ir block in place

 

i now have a mono zwo

i am holding on to my imaging source cams untill i can try withthe sloar scope as i had heard with ha imaging the zwo cmos

 

 

i did not go with the qhy because i have had probs with the drivers on my old qhy5 which may now be have been cured

 

i am happy so far with the zwo120 mono

 

 

steve

[Guest AstroOlly]

I have had a reply back from Sam at ZWOptical, he says you can remove the IR filter by just unscrewing the case and taking it out from the back, he makes it sound easy.......

Olly

[dawson]

Fair enough; there's your answer then. I'm not trying it as it's all metal on metal screw connections and i'm sure it must generate fine dust everytime you unscrew and screw it back up, plus i'm happy with the zwo filter so have no need at present to take it out. Maybe ask sam for photos of it all, he must have display models in his office.

Jd

[Guest AstroOlly]

So the QHY IR filter screws out as far as I am told, so that might be the one for me

Also the QHY camera is only the size of an eyepiece, which means that with my Telvue Barlow I can sink it further into it and get different magnifications, by moving the camera up or down in the Barlow, which I think could be useful for me, I can get from 1.5x to 2.5x.

Still contemplating

Olly

[dawson]

What is against the QHY?

Is there not a stop inside the barlow to limit how deep you can go?

Jd

[dawson]

Sam has said the Ir filter comes out of his camera too...

[Guest AstroOlly]

Yes but to remove the IR filter from the ASI you have to take the camera apart

To take off QHY it just screws out of the front nosepiece, no taking camera apart

The QHY camera can go into the Barlow, as you just move the par focal ring up or down the camera, so it is possible to get the camera sensor around 25mm inside the Barlow and closer to the Barlow lens, to give less mag, or but a longer nosepiece on the camera to take further from the Barlow lens, obviously you can put a nosepiece extension on any camera, but you can't get the sensor inside the Barlow assembly, as you can with the QHY camera.

Hope that make sense

Olly

Edited March 27, 2014 by AstroOlly

[dawson]

Ah yes, i see.

When you say take the zwo apart, it is simply just unscrewing the body in two. The metal body consists of two halves, and they screw and unscrew by hand, it's no biggie and requires no tools and minimal force.

Jd

[Guest AstroOlly]

Yes I have just found that out too

Had another reply on ZWOPTICAL forum

This is what they said:

The front of the camera unscrews , it's not obvious as it's very neat / well made but it should unscrew

So that helps then, and you can confirm this James as to be true?

Olly

[dawson]

Very true; not that I like to name drop, but I showed it to "Damian" at the weekend and unscrew it for him. I can't think of an analogy, but it literally is very easy to take apart; as I say, I'm not sure I'd want to be screwing it on and off all the time as I suspect it would generate metal dust, which can't be good for the sensor. If you wanted to remove the ZWO IR cut filter, I'd be tempted to replace it with glass, so there is sensor protection, but no IR cut (though the glass may cut UV I'm not sure). Again, maybe Sam can supply you one with a different window in the camera.

 

JD