ZWO ASI2600MM with Takahashi 120 TSA ZWO ASI2600MM Pro · Jeremy Phillips FRAS · ... · 6 · 357 · 0

I have the ZWO ASI2600MM Pro camera. I am looking to combine it with a Takahashi 120 TSA. But, using the TSA -35 0.7 focal reducer, won't the image circle be too small?  (Takahashi with reducer will be 40mm). Will my stars be distorted in the outer edges? Does anyone use this combination and could help me here please?

Dan Burns:
I use this exact combination frequently. I don't think the image circle is too small. You can see several images taken with this combination in my gallery. I had to adjust the distance between the camera and the focal reducer to get good stars out to the edges. I now have much better full frame images. There is some tilt causing stretched stars in one corner. I just ordered the ZWO M54 Sensor Plate Adjuster to make removing tilt easier.

Thanks Dan - much appreciated. In the end I picked up the ZWO ff107 which is giving me perfect stars to the corners, so I am sorted. Good luck with the sensor tilt. I had to deal with tilt also and found a combination of ASTAP and CCD Inspector (30 day trial before paying) really useful.

Antonio Parisi:
Hi I am currently using a Takahashi fc100dz with a Sony alpha IV looking for an astro camera...I'm interested to know why you Dan is talking about Full frame up there and Jeremy why did you get the 107?

I'm try to evaluate whether the apsc would be a good fit.
Many thanks to both.

I saw this video from Nico Carver and the ff107 looked great for an APS-C sensor...  https://www.youtube.com/watch?v=G1zM-lz7Fx4
I wasn't so convinced with his full frame sensor results, but I am using a smaller APS-C (ZWO2600MM). I have used it for one night so far, so no images to show yet, but the stars on my subs are perfect right to the corners and, being a quadruplet, there was no messing around with back focus, as you don't need to worry about it. Testing the images with PixInsight's Aberration Inspector is a very harsh test, but using this I can see the stars are perfect when pixel peeping. The optics seem great and it is nice and potable. I think the 749mm focal length is in the sweet spot for me also.  Good luck with your choice.

Jeremy Phillips FRAS:

Antonio Parisi:
Hi I am currently using a Takahashi fc100dz with a Sony alpha IV looking for an astro camera...I'm interested to know why you Dan is talking about Full frame up there and Jeremy why did you get the 107?

I'm try to evaluate whether the apsc would be a good fit.
Many thanks to both.

I saw this video from Nico Carver and the ff107 looked great for an APS-C sensor...  https://www.youtube.com/watch?v=G1zM-lz7Fx4
I wasn't so convinced with his full frame sensor results, but I am using a smaller APS-C (ZWO2600MM). I have used it for one night so far, so no images to show yet, but the stars on my subs are perfect right to the corners and, being a quadruplet, there was no messing around with back focus, as you don't need to worry about it. Testing the images with PixInsight's Aberration Inspector is a very harsh test, but using this I can see the stars are perfect when pixel peeping. The optics seem great and it is nice and potable. I think the 749mm focal length is in the sweet spot for me also.  Good luck with your choice.

*** many thanks, I think I will get a Player One Poseidon M Pro with their screwed in 2"x 7 FW (future proof and about 2400$  fo both) It has some little advanced tweaks compared to the ZWO, QHY,  Toptek  like USBC and  a bit better specs at least on paper  ***