Polar Alignment and live stacking with one DSLR (EOS R + 70-200mm lens)

Using SharpCap's Polar Alignment feature
Post Reply
james
Posts: 1
Joined: Thu Apr 01, 2021 6:12 am

Polar Alignment and live stacking with one DSLR (EOS R + 70-200mm lens)

#1

Post by james »

I am a novice in the astro-photography, so please consider it^^

Interested in planets, nebula

Is it possible to do both polar alignment and live stacking with one DSLR (EOS R + 70-200mm f/4 lens)

What do I have to do for the configuration or execution sequence?

My equipments:

- Smart EQ pro
- Canon EOS R
- Canon 70-200mm, 100-400mm f/4 L lenses
- SharpCap pro 3.2

ZWO ASI120MM-mimi + 30mm guide scope:
- During the test, CCD wasn't recognized suddenly in Camera tab of Sharpcap pro 3.2
As of now, I am working on it to solve the problem with ZWO. This is why I got this question.
After recent installation of ASCOM platform and DSLR driver, EOS R is successfully recognized.
But I am wondering,
-> EOS R (full frame) + 70-200mm combination gives a maximum 200mm focal length
-> ZWO ASI120MM-mimi (1/3" sensor size) + 30mm combination
gives about correspondingly 400mm focal length because of small sensor size which guider lens seems narrower than main photography lens
am I right?
Is it normal? I thought a guider scope will have wider scope which means shorter focal length.

Please advise me on anything to know^^
Thanks in adv.
User avatar
admin
Site Admin
Posts: 13175
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Polar Alignment and live stacking with one DSLR (EOS R + 70-200mm lens)

#2

Post by admin »

Hi,

your 30mm guide scope probably has a focal length of 120mm or so (~f/4). That's obviously shorter than your 70-200 lens at the 200mm focal length, but you also have to take into account the size of the sensor.

ZWO 120MM Sensor : 4.8 x 3.6mm
Full frame DSLR Sensor : 36 x 24 mm

The DSLR has a sensor that is about 7x bigger in each direction than the ZWO camera - that means it will show a wider field of view even with the 200mm lens. In fact you would have to put a lens of about 800mm focal length on the DSLR to get the same field of view as the ZWO with a 120mm focal length lens.

Hope that makes sense :)

On the subject of the ZWO problem - does the camera show up correctly in Windows Device Manager?

cheers,

Robin
Post Reply