Tak FSQ85EDX and ZWO 1600 MM Pro. Field flattener needed?

[Mikkel Kroman]

Hi all

Will I need to use the field flattener if I use my 1600MM Pro? It does not have a full frame sensor so I would think no.

Kind regards

Mikkel

[Stuart1971]

Hmmm, I have been having an ongoing issue with this scope and a modern small pixel camera…and have had to get the new flattener for it, as my corner stars were very bad with astigmatism, but I have the larger QHY268m sensor, so I would try yours first, but don’t be surprised if you need it, and when you do get it, the back space is critical at 56.2mm and even then you have to do your focusing around 2/3rds of the way across your image, to get rid of the full astigmatism…I have got there in the end with mine……. I think, but it’s been a real battle…and not what you would expect from a premium scope, this is what i was dealing with around the outside of my images before the flattener was added….😮

 

[johnturley]

5 hours ago, Mikkel Kroman said:

Hi all

Will I need to use the field flattener if I use my 1600MM Pro? It does not have a full frame sensor so I would think no.

Kind regards

Mikkel

I thought that the whole point of the Petzval based FSQ series is that they have a built in field flattener, and that you don't need to use an additional one.

John 

[Mikkel Kroman]

1 hour ago, johnturley said:

I thought that the whole point of the Petzval based FSQ series is that they have a built in field flattener, and that you don't need to use an additional one.

John 

It comes with a flattener. It says that it is to be used when using a full frame camera. 

[Stuart1971]

2 hours ago, johnturley said:

I thought that the whole point of the Petzval based FSQ series is that they have a built in field flattener, and that you don't need to use an additional one.

John 

Absolutely true, if you are using old CCD cameras with big pixels, they work great out of the box then, but with modern small pixel cameras this is not the case…as the optics were not designed for these, as I found out, so Tak bought out another flattener for this scope to combat the issue, and it’s now supplied as standard in the box with the scopes when new, so yes two flatteners are needed, to figure….🤔

[Stuart1971]

1 hour ago, Mikkel Kroman said:

It comes with a flattener. It says that it is to be used when using a full frame camera. 

Wrong, trust me you will need it with any sensor APC-S size and bigger, and maybe even with your camera too, they are very careful what they say about which sensor sizes suffer, but I have first hand experience of which do and which don’t…

[Stuart1971]

I used to use this scope without the new flattener out of the box with an older SXVR M35c APC-S sensor and it was superb, edge to edge, but the camera has 9 micron pixels, with my QHY268m with 3.76 micron pixels, it’s totally different it shows up every little bit of tilt and astigmatism….and the new flattener is needed without doubt, which I was not happy about at all, as I had to buy extra as was not supplied as standard when I bought mine…