Should i buy the QHY 178 MM or the QHY 290?

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LEGV
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Should i buy the QHY 178 MM or the QHY 290?

Post by LEGV »

Hi, i have a Coronado PST double stacked and i use the camera Meade LPI-G monochrome

I was thinking about buy another planetary camera, but i have this questions?
1) my images will improve over my lpi-g camera?
2) thinking about pixel size, FPS and size sensor, should i buy the qhy (or zwo) 178 or 290?

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marktownley
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Re: Should i buy the QHY 178 MM or the QHY 290?

Post by marktownley »

Hi there,

I din't think there is anything to gain going for either of the cameras over what you have already. Why do you want to upgrade the camera?


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Re: Should i buy the QHY 178 MM or the QHY 290?

Post by SimonM »

LEGV wrote: Fri Feb 12, 2021 7:32 pm 2) thinking about pixel size, FPS and size sensor, should i buy the qhy (or zwo) 178 or 290?
The sensor and pixel size of the ARO130 is the same as IMX224. As a comparison, the 178 is 7.37mm x 5.63mm.

QHY5-III_Series.png
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The small sensor of the ARO130 is only 4.8mm x 3.6mm which means that with a 400mm scope it will not fit a full disc of the Sun.

The size of the sun's disk is roughly 1/100 the focal length = 4mm in the PST. 178 is big enough to show a full disc.

A big advantage of the QHY version of the 178 is that it is available in the guide camera MINI format and is USB3 and this means that it replaces a 1.25" EP and it can often be placed further into the focuser so has fewer demands on the back focus (BF) of the scope. With ZWO there is a choice between expensive (174) and cheaper (290) in a guide camera MINI format but no 178. 178 and 290 are similar prices and the QHY 178 is a much more interesting choice.

The QHY has a longer barrel (up to the first fin) compared to a ZWO and comes with an AR coverslip (can use the camera for normal or IR with the appropriate filter). It also has a 25mm extension, so finding focus is over a very wide range of positions. It also has a 1.25" parfocal ring that can be clamped so that it is parfocal with your favorite EP. One disadvantage of the 178, is that the thread for a 1.25" filter is on the 25mm extension and not on either the coverslip, the internal thread or a 5mm extension.

Simon


LEGV
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Re: Should i buy the QHY 178 MM or the QHY 290?

Post by LEGV »

Ok, excellent,
about why change the camera Is just because i was thinking i could have better pics. But if the difference Will be little then i can keep my actual camera.

Thanks a lot


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Re: Should i buy the QHY 178 MM or the QHY 290?

Post by MalVeauX »

Hi,

The IMX178 sensor would normally be ideal, with its 2.4um pixels for sampling at F10, however, it also has weird bayer matrix artifact problems with sub-angstrom HA wavelength. So it's hard to recommend it. It's a gamble. Otherwise, the pixel size and sensor size are ideal for your PST. The 290 sensor is too small for a full disc in your PST, so scratch that.

Look for this camera on ebay used:

Point Grey Research Camera FLIR Flea3 FL3-GE-28S4M-C (or any decent camera with the Sony ICX687 sensor).

It has larger pixels, but they're still an ok match for sampling at F10 and the sensor size is big enough for a full disc. I see these for $325 on Ebay.

Very best,


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Re: Should i buy the QHY 178 MM or the QHY 290?

Post by krakatoa1883 »

ASI178MM is a really good camera for full disc imaging. It works best from f/7 to f/11, depending on seeing conditions and the sampling formula. It may require taking a flat to avoid the fixed pattern in the final image, I never noticed it on full discs, however, only in hires imaging depending on the setup and the use of focal reducers.


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