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JamesAstro2002

183mm vs 1600mm

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Hi,

I'm considering taking my first step into the money pit of mono imaging, but I'm stuck between two options. The 183mm or the 1600mm. Currently I'm using a William Optics Z73. The 183mm is more appealing to me at the moment because of the price, I could buy it along with the filters and it would still cost less than the 1600mm alone. I like the FoV of the 183mm as well, as most objects fill the view with that sensor and my scope. But I heard somewhere that the 1600mm is more sensitive? Or Less noisy, can't remeber. Either way, is the 1600mm going to be that much better or not? Or is it just down to the size of the sensor?

Also, what models are best for either of these cameras? Considering the ZWO, QHY and Altair options I wouldn't know what's better. Or is it just down to price and availability?

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The 183 has smaller pixels, leading to a smaller dynamic range at full well depth. So in principle, the 1600MM will not saturate as soon as the 183MM, assuming the same quantum efficiency (I gather the 183MM has a peak quantum efficiency of 83%, so it is hard to beat). Stacking a sufficient number of images should however allow you to compensate for the lower dynamic range of 183MM. I have the ASI183MC, and my first attempt at deep sky wasn't too bad. Just one hour of data in 60s unguided shots with my 80mm F/6 triplet and 0.6x reducer.

M33-v3acrop.thumb.jpg.13587ca8996b50199cbab758310e1634.jpg

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1 hour ago, JamesAstro2002 said:

Hi,

I'm considering taking my first step into the money pit of mono imaging, but I'm stuck between two options. The 183mm or the 1600mm. Currently I'm using a William Optics Z73. The 183mm is more appealing to me at the moment because of the price, I could buy it along with the filters and it would still cost less than the 1600mm alone. I like the FoV of the 183mm as well, as most objects fill the view with that sensor and my scope. But I heard somewhere that the 1600mm is more sensitive? Or Less noisy, can't remeber. Either way, is the 1600mm going to be that much better or not? Or is it just down to the size of the sensor?

Also, what models are best for either of these cameras? Considering the ZWO, QHY and Altair options I wouldn't know what's better. Or is it just down to price and availability?

Look up micro lens diffraction pattern for the ASI1600mm pro before you make your final choice. However, don't agonise too much as either one will provide good results. 

Adam

Edited by Adam J

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58 minutes ago, Adam J said:

Look up micro lens diffraction pattern for the ASI1600mm pro before you make your final choice. However, don't agonise too much as either one will provide good results. 

Adam

Cheers Adam. I'm looking at the Altair astro 183m now. It's a little cheaper than the zwo and comes with a nice case. Seems all the same to me, are there any caveats you know of with the Altair counterparts? 

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I have no experience with the Altair offerings, but am very content with all the ZWO cameras I have had to date (ASI130MM, ASI120MC, ASI224MC, ASI174MM, ASI178MM, and ASI183MC (I still own the latter three)) and likewise for their electronic filter wheels (both the full size and the mini EFW)

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Nice, that's quite a range of different cameras! I'll try find some reviews on the Altair versions. If not, I'll probably go for the ZWO considering its great reputation.

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6 hours ago, JamesAstro2002 said:

Cheers Adam. I'm looking at the Altair astro 183m now. It's a little cheaper than the zwo and comes with a nice case. Seems all the same to me, are there any caveats you know of with the Altair counterparts? 

Yes, the Altair version of the ASI1600mm pro will need larger filters than the ASI model due to the longer sensor back focus, the ASI can use 1.25inch filters you will need at least 31mm filters with the Altair and possibly 36mm filters at faster f-ratios. Hence you may lose any cost benefit in the camera by having to purchase more expensive filters.

Don't make the mistake of thinking that 1.25 inch = 31mm either. One measurement is clear aperture the other to the actual thread on the filter holder, the 31mm are larger.

Adam

Edited by Adam J

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I have been going over the same decision back and forth for most of the summer.

Everything I read seems to point me towards the 1600, and it does seem the most popular by far but the 183 is a much more attractive price. Adam mentioning the filter sizes is reassuring to me as I went for 36mm just in case (I have the filters and ZWO wheel ready, just havent got the camera)

I could be wrong, but I think the imaging scale is slightly different, with the 183 being better suited to shorter focal lengths - but im tired and might have that backwards. This swayed me toward the 183 for some time as im shooting at 420mm but if I wanted to switch to a different scope I felt it would limit me.

Edit: To check suitability with various potential future scopes I used this tool - https://astronomy.tools/calculators/ccd_suitability

Edited by upahill

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10 hours ago, michael.h.f.wilkinson said:

The 183 has smaller pixels, leading to a smaller dynamic range at full well depth. So in principle, the 1600MM will not saturate as soon as the 183MM, assuming the same quantum efficiency (I gather the 183MM has a peak quantum efficiency of 83%, so it is hard to beat).

The 183 has 2.4um pixels, the 1600 has 3.8um, and the full well depths area 15,000 and 20,000 respectively.  Naively perhaps, that suggests to me that whilst the 1600 has the greater well depth, the factor of 2.5 increase in photosite area means the 1600 would saturate faster (almost twice as fast?) with the same optical train with the same QE.  But they don't have the same QE.  The 183 claims 84% whilst the 1600 claims 60%.  I think that means that the 1600 would actually saturate about a third faster than the 183 given the same optical train.

Or is my logic not logical?

James

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Re. Microlens artifacts with the ASI 1600, other than the example on CN I haven’t seen any issue with the multitude of images from this camera.....

Maybe I’m missing something???

I use the ASI 1600 ( a replacement for the rejected ASI 183 ) for solar imaging, with no issues.

 

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I never thought about filter sizes, thanks for bringing that up. I also came across the QHY 163m variant. Does this have the same, larger backfocus requirement?

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