Refractor for full frame DSLR imaging

[Photosbykev]

Hi folks, I normally photograph with a Canon 5D4 and Canon glassware but fancy a lightweight widefield refractor around 400mm fl that will produce a nice flat image circle large enough for a full frame sensor.

One scope I keep looking at is the William Optics Zenithstar 73 II Apo refractor and I'd like some advice on what else I would require for full frame imaging or maybe alternatives to the WO 73? The WO 61 Apo is also on the radar but I suspect I would regret not going slightly larger

I'll only be using it infrequently but it will be mounted on a SkyGuider Pro with ZWO guidescope system

regards

Kev

Edited August 17, 2019 by Photosbykev

[alan potts]

What ever Kev but I feel you would need a flattener with the WO offerings no matter which you go for. Same size chip but different scope My 1DS 2 was very poor at the edge of a similar 70mm ED.

Alan

 

[Photosbykev]

6 minutes ago, alan potts said:

What ever Kev but I feel you would need a flattener with the WO offerings no matter which you go for. Same size chip but different scope My 1DS 2 was very poor at the edge of a similar 70mm ED.

Alan

 

I agree the flattener will be necessary I'd hate to get annoyed by poor edge performance

Kev

[DaveS]

How about a Tecnosky 71 Quadruplet? The description says it will even cover a 36 x 36 mm frame. it looks to be a clone of the WO version that seems no longer available. Not cheap mind.

[GlenM]

Sharpstar 71 SDQ ?

 

Glen.

 

[DaveS]

Probably another clone, there are loads out there.

[alacant]

Hi. How about a lens designed to cover full frame? It may work out more economical and you also have the advantage of an already flat field.

HTH

[GlenM]

6 minutes ago, DaveS said:

Probably another clone, there are loads out there.

Large price difference though.

 

Glen.

 

[Photosbykev]

46 minutes ago, alacant said:

Hi. How about a lens designed to cover full frame? It may work out more economical and you also have the advantage of an already flat field.

HTH

I've got the 400mm f/5.6L lens and it's good and almost flat at f/8 but some vignetting at f/5.6 which flats can control, and I used to have the Canon 600mm f/4L which was superb, but I'd like to get away from variable apertures and the associated spikes. I could, and have in the past, fitted a fixed circular aperture disk on the Canon lens which does work. I'd expect a good dedicated telescope to produce better images.

Kev

Edited August 17, 2019 by Photosbykev
typos

[Photosbykev]

50 minutes ago, GlenM said:

Sharpstar 71 SDQ ?

 

Glen.

 

That's an interesting option and similar price of the WO 73+flattener

[Photosbykev]

1 hour ago, DaveS said:

How about a Tecnosky 71 Quadruplet? The description says it will even cover a 36 x 36 mm frame. it looks to be a clone of the WO version that seems no longer available. Not cheap mind.

Strange spec of image circle of 36x36mm but does cover full frame I guess. This would be at the very top end of any budget I'd consider for occasional use but one to consider

[DaveS]

The image circle *just about* covers the 37mm sq 16803 sensor.

[Photosbykev]

To close this out, I've ordered the WO Zenithstar 61 Apo with the Flat61A adjustable flattener.