I am considering utilizing the Takahashi sale and getting the TOA-35 reducer for the TOA-130. I know that its performance is not as good as the 645 flattener, but I wanted to see how well it performs on a full frame sensor with small pixels like the IMX455. Can anyone post raw subs acquired with this combination on a full frame sensor or maybe a 3x3 square mosaic of unprocessed subs?
Thanks.
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I have this one https://takahashiamerica.com/products/takahashi-toa-35-reducer-for-toa-130 I call it the TOA-35. Is that what you meant? Camera is ASI6200MM. Filter is Antlia 2" 3nm Ha. I have never addressed tilt, it didn't seem like a problem. The scope is a TOA130-NFB, ZWO 7x2" EFW, ZWO OAG-L/.    |
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This was a single 900 second sub. Not calibrated, just ScreenTransferFunction and HistogramStretch so it was not all black.
Hmmm it might be been bad seeing. I will look for a pic from a different night.
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Warning! The TOA-35 reducer on a TOA-130 does NOT produce an image circle sufficiently large enough to cover the IMX 455 sensor. I have one, which was great when I had the CCD KAF-16200 camera, but when I upgraded to the Atik APX60, the vignetting was terrible! I've had to abandon using it, and reverted to my TAK 67 flattened instead, which is perfect.  CS Andy
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Ashraf AbuSara:
Here is a different night. FWHM is 2.146 pixels, better than the 3.591 in the above example.
Looks maybe like a mixup? Because these are the same frames you posted initially. Whoops. OK I edited my reply above with the second set of pics with the better FWHM.
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Andy 01:
Warning! The TOA-35 reducer on a TOA-130 does NOT produce an image circle sufficiently large enough to cover the IMX 455 sensor.
I have one, which was great when I had the CCD KAF-16200 camera, but when I upgraded to the Atik APX60, the vignetting was terrible!
I've had to abandon using it, and reverted to my TAK 67 flattened instead, which is perfect. 
CS
Andy Indeed. The corners of the FF sensor are quite dark. See the pic below. The spec from Takahashi says 44mm image circle, but if it is at only 20% illumination that isn't very good. There is still a place for this 0.7x flattener: I was trying to shoot the Squid Nebula (very very faint) at f/7.7 1,000mm and it was just way too dark unless I got tens of hours of data. At f/5.4 with this reducer I will get twice the photons per pixel per hour. I have the FLAT67 too, which is what I usually use. But when I try the Squid again next year I will use the reducer. I am not disappointed in this reducer. A lot of people think putting a chunk of glass at the camera end of a telescope will somehow make the front end grab a wider brighter cone of light. That isn't how it works.  |
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Andy 01:
Warning! The TOA-35 reducer on a TOA-130 does NOT produce an image circle sufficiently large enough to cover the IMX 455 sensor.
I have one, which was great when I had the CCD KAF-16200 camera, but when I upgraded to the Atik APX60, the vignetting was terrible!
I've had to abandon using it, and reverted to my TAK 67 flattened instead, which is perfect.
CS
Andy
Indeed. The corners of the FF sensor are quite dark. See the pic below.
The spec from Takahashi says 44mm image circle, but if it is at only 20% illumination that isn't very good.
There is still a place for this 0.7x flattener: I was trying to shoot the Squid Nebula (very very faint) at f/7.7 1,000mm and it was just way too dark unless I got tens of hours of data. At f/5.4 with this reducer I will get twice the photons per pixel per hour. I have the FLAT67 too, which is what I usually use. But when I try the Squid again next year I will use the reducer.
I am not disappointed in this reducer. A lot of people think putting a chunk of glass at the camera end of a telescope will somehow make the front end grab a wider brighter cone of light. That isn't how it works.
Ooof . That is a lot of vignetting. How does it look after applying flats?
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Andy 01:
Warning! The TOA-35 reducer on a TOA-130 does NOT produce an image circle sufficiently large enough to cover the IMX 455 sensor.
I have one, which was great when I had the CCD KAF-16200 camera, but when I upgraded to the Atik APX60, the vignetting was terrible!
I've had to abandon using it, and reverted to my TAK 67 flattened instead, which is perfect.
CS
Andy that's the same reason I bought and then sold the TOA-35 reducer. the illumination dropoff was steeper than I thought it would be. I moved back to the 645 flattener. (so sharp and no noticeable vignetting on the imx455). While I like the idea of the faster TOA-130, I like that 645 more.
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My experience is that what is left as useful is somewhere between a full frame and ASP-C format.
A lot of the vingetting can be removed by calibration frames but the stars in the corners are horrible.
For faster light gathering at ASP-C it is fine.
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Thank you all for the feedback. I will stick with the 645 0.99x flattner.
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 Here is a sub from my TOA-130 using the TOA-35 0.7 reducer, on my IMX45 camera, like t-ara-fan 's image above, the vignetting is terrible. On my former APS-H camera with the smaller KAF 16200 sensor, though, it wasn't noticeable.
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