Advice on ZWO ASI1600MM Cool Please

[Knight of Clear Skies]

Well, I've joined the 1600MM crowd. I think it's a good match for me, the small pixels make it suitable for use with my camera lenses and the low read noise makes guiding less important. I now need to accessorize up and would appreciate a quick sanity check on my next purchases.

Is there any reason not to go with the ZWO mini filter wheel please? It's quite thin, is this what I'd need to reach focus when using the ZWO EOS lens adapter? 5 positions should be fine I think, I could always swap out Lum for OIII as if I'm imaging in Ha/OIII I probably don't need any Lum, just RGB for a bit of star colour.

Looks like I want to use 31mm unmounted filters as I'd like to image at fast focal ratios (a Samyang 135mm F2 is quite tempting, but I have plenty of other lenses to use in the meantime). ZWO do a filter set but I notice that the OIII line is entirely within the green channel. I'm not too keen on that as I prefer blue OIII aesthetically but I'm wondering if colour balance might be easier with that set, as it's matched to the camera. I don't know how parfocal these filters are, but with fast lenses I suspect I would want to refocus for each channel anyway.

Finally, I also hope to use it with a borrowed ED120. The flattener has, I think, an M48 thread. Could anyone give me some guidance of what I'd need to connect everything up please? The world of spacing and sensor tilt is an alien one to me.

[Demonperformer]

The EOS adapter fits just between the camera and the lens and comes to focus. There is no extra room for the filter wheel. There should have been a filter adapter included with the camera, that screws into the nosepiece of the camera.

HTH

[Knight of Clear Skies]

2 minutes ago, Demonperformer said:

The EOS adapter fits just between the camera and the lens and comes to focus. There is no extra room for the filter wheel. There should have been a filter adapter included with the camera, that screws into the nosepiece of the camera.

HTH

Thanks, are the second and third images here incorrect then? They show a filter wheel in the train.

[Demonperformer]

I stand corrected.

Having taken images with just lens/adapter/camera (with filter in adapter) I assumed ... and you know what they say about "ass-u-me"-ing. Clearly FLO would not include pictures of a system that would not work.

[Knight of Clear Skies]

5 minutes ago, Demonperformer said:

I stand corrected.

Having taken images with just lens/adapter/camera (with filter in adapter) I assumed ... and you know what they say about "ass-u-me"-ing. Clearly FLO would not include pictures of a system that would not work.

I also found a user on Cloudy Nights who is using the EFW and adapter, so it looks like the FLO images are correct.

Interesting to hear I don't necessarily need the filter wheel though, to begin with I just want to get something working.

[Gina]

Looks like I should do a tutorial on using the ASI1600MM-Cool with EFW mini and camera lenses thought this information can be found in my thread.  I have used lenses as wide as f1.8 with 1.25" screw in filters without any significant vignetting.  The camera screws straight onto the filter wheel without the T2 gender changer ring keeping filter to camera as short as possible.  This is why 1.25" filter work alright.

I use vintage glass as supplied several decades ago for Pentax SLR cameras.  These are available second hand from ebay at low prices and are superb for astro imaging - particularly narrowband.  The 4/3" sensor of the ASI1600MM-Cool plus 16MPx resolution means high resolution images can be obtained without going for the very expensive larger filters.  The CMOS sensor with very low read noise means you can use very short exposures (around a minute) and lots of them and avoid the need for guiding.

I use a short T2 extension ring plus M42 Pentax thread (42mm x 1mm pitch thread) to T2 (42mm x 1.75mm pitch) adapter.  In most cases it is possible to "cheat" and screw the Pentax thread into a T2 thread - it goes in a few turns but not all the way due to the thread pitch mismatch.

[Gina]

To use Canon EOS lenses with ASI1600MM-Cool and ZWO EFW mini you want THIS ADAPTER which was designed for precisely that purpose.  I have one to expand my lens options as I have a couple of Canon zoom lenses to try out.

[Knight of Clear Skies]

I've now ordered my EFW, EOS adapter and holder ring but I still need to decide what filters to get. I'm hoping I can use M42 lenses as well using my M42-EOS adapter rings. Good to hear the vignetting isn't too bad with 1.25" filters but I might want to go for the 31mm unmounted ones to eliminate it, I'll price up the options. I also need to decide what Ha filter to get. A 6/7nm filter should be fine for when I'm imaging under dark Cornish skies but the 3nm could make quite a big difference if I also want to use the camera up here in Hertfordshire.