FOV with DMK/DFK or WEB cams

[kris27]

I am experimenting with modified (in build lens are removed) WEB cams either CCD or CMOS - getting some impressive results.
The hard problem is FOV - when cam is inserted in place of eyepiece, the FOV is like 1.5 arcminutes on 114mm/F8 reflector. This makes shoot very difficult.
The telescopes in use: Newton 114mm/F8, Newton 250mm/F4.8, Maksutov 72mm/F8 and more.

1 - any ideas why so narrow FOV ? Is it due to microlenses on the imaging sensor ????
1a - Any formulae applicable to calculate FOV of the optical system - scope+cam ?
2 - what FOV can be expected with DMK/DFK??? cams, I am considering to buy DFK 31AU03.AS.
3 - is it possible to have live video with DMK/DFKs? I mean software grabs a few frames and overlays (addition) them so even objects that are not eye visible become almost visible via cam.
4 - Any software for Android devices ??? like PADs.

Thanks in advance ..... Kris

[Stefan Geissler]

Hi Kris,

I am not able to answer the questions regarding the optical problems, but maybe another astronomer can.


is it possible to have live video with DMK/DFKs? I mean software grabs a few frames and overlays (addition) them so even objects that are not eye visible become almost visible via cam.
Using IC Capture you have a live video, but no frame stacking. For doing so, you need some software, which I do not know, that can do this. Other software like Registax can do this, after the video has been recorded as Y800 uncompressed format.

4 - Any software for Android devices ??? like PADs.
I am afraid, there are no valid drivers available.

[donwaters]

I'm curious about the FOV as well. I'm sure there is an answer out there, and I imagine it relates to the physical dimensions of the eyepiece or baffles between the objective and camera since the camera is at the "prime focus".

[donwaters]

Try this site:

http://www.johnrcrilly.com/LX200-14/FOV.pdf

[donwaters]

One more link from Wikipedia
http://en.wikipedia.org/wiki/Digital_camera

Good discussion of how the small chip size limits FOV and shows what similar telephoto views would be with a 35MM camera. Uses the term "cropping ratio". It would nive to know the ratios for the chips in IMAGING SOURCE cameras and you should be able to calculate FOV. I imagine that info is availble soemwhere on web or from IMAGING SOURCE.

[Stefan Geissler]

Hello

I am not sure, what a crop ratio is, but the aspect ratio DFK 21AU04.AS sensor is 4:3.

[flyer]

This should do it! http://www.newastro.com/book_new/camera_app.php

You need pixel dimensions, and chip dimensions, telescope details. The software works great for larger CCD cameras but I don't see why it wouldn't work with small chips as well.

[Stefan Geissler]

The exact description of the sensor comes from Sony and can be downloaded at the camera specification on our webpage:
Mono : http://www.theimagingsource.com/downloads/icx098bl.en_US.pdf
Color : http://www.theimagingsource.com/downloads/icx098bq.en_US.pdf