Autoguiding camera questions

[ollypenrice]

On 31/05/2019 at 16:07, George Gearless said:

I just looked up the pixel size for my EOS 7D Mark 1. It's 4,1 µm. I realy have no idea if the difference between 3,75 µm and 4,1 µm is a lot or not. Numerically they look close, but in the AP universe that may be worlds apart.

The 7D has either 50 FPS or 60 FPS at HD resolution. I visited a few websites where there seems to be much discussion about this precise topic. Some say that only the Mark2 is capable of 60. Others say that it doesn't matter. In any case, 50 Fps seems to be a safe bet. The 224MC has 30 FPS at maximum resolution. But ofcourse, the FPS increases dramatically as the resolution decreases. 

It's difficult for a novice like myself to find out what these numbers translate into. But I do think that my EOS 7D deserves at least a few good runs before I rush out and buy myself even poorer on a new one.

 

41 dots:  .........................................

37 dots:  .....................................

That's the difference in planetary image size between the two cameras' outputs (exaggerated by half a dot since I can't type half a dot!)

Olly

 

[Stub Mandrel]

On 31/05/2019 at 15:07, George Gearless said:

The 7D has either 50 FPS or 60 FPS at HD resolution. I visited a few websites where there seems to be much discussion about this precise topic. Some say that only the Mark2 is capable of 60. Others say that it doesn't matter. In any case, 50 Fps seems to be a safe bet. The 224MC has 30 FPS at maximum resolution. But ofcourse, the FPS increases dramatically as the resolution decreases. 

It's difficult for a novice like myself to find out what these numbers translate into. But I do think that my EOS 7D deserves at least a few good runs before I rush out and buy myself even poorer on a new one.

The main difference is likely to be that the 7D is shooting 8-bit video and compressing it (" The Canon 7D records its movies as MOV files using AVC / H.264 compression ").  Even the humble 120MC will shoot 12-bit RAW uncompressed video. This is why it outperforms ordinary webcams.

Not to say the 7D won't do a decent job, but when you get a really clear, steady night you might wish you had a dedicated planetary cam.

 

 

[Stub Mandrel]

P.S. don't forget you need to use maximum digital zoom to get the most out of the 7D for planets - it shoudl not affect quality but you will only get maximum resolution this way.

[George Gearless]

42 minutes ago, Stub Mandrel said:

The main difference is likely to be that the 7D is shooting 8-bit video and compressing it (" The Canon 7D records its movies as MOV files using AVC / H.264 compression ").  Even the humble 120MC will shoot 12-bit RAW uncompressed video. This is why it outperforms ordinary webcams.

Not to say the 7D won't do a decent job, but when you get a really clear, steady night you might wish you had a dedicated planetary cam.

 

 

A perfect example why an amateurs amateur should take great care in reading technical data and thinking he understands them. I see 50 FPS and 30 FPS and go; "Oh, 50 must be better than 30". Numerically it is, but it's only half the story.

[George Gearless]

1 hour ago, Stub Mandrel said:

P.S. don't forget you need to use maximum digital zoom to get the most out of the 7D for planets - it shoudl not affect quality but you will only get maximum resolution this way.

I don't think the 7D has digital zoom. Besides, Helen is very subtly talking me into buing the AsiAir 'thingy' and a planetary camera. I suspect she may be on commission from FLO  😜

[Helen]

25 minutes ago, George Gearless said:

I don't think the 7D has digital zoom. Besides, Helen is very subtly talking me into buing the AsiAir 'thingy' and a planetary camera. I suspect she may be on commission from FLO  😜

😇😇

[Stub Mandrel]

1 hour ago, George Gearless said:

I don't think the 7D has digital zoom.

It does, I looked it up 🙂

[George Gearless]

5 minutes ago, Stub Mandrel said:

It does, I looked it up 🙂

Hmmm,  according to this specification it doesn't . https://www.imaging-resource.com/PRODS/E7D/E7DDAT.HTM see under "lens and optics".

Keep in mind that mine is a mark 1. Maybe the one you found is a mark 2?

[Stub Mandrel]

12 hours ago, George Gearless said:

Hmmm,  according to this specification it doesn't . https://www.imaging-resource.com/PRODS/E7D/E7DDAT.HTM see under "lens and optics".

Keep in mind that mine is a mark 1. Maybe the one you found is a mark 2?

You're right I shoudl have dug deeper.

That essentially makes it useless for planetary as :

16 hours ago, ollypenrice said:

41 dots:  .........................................

37 dots:  .....................................

That's the difference in planetary image size between the two cameras' outputs (exaggerated by half a dot since I can't type half a dot!)

Olly 

 

Becomes:

41 dots:  .........................................

13 dots: .............

 

 

 

 

[ollypenrice]

7 minutes ago, Stub Mandrel said:

You're right I shoudl have dug deeper.

That essentially makes it useless for planetary as :

Becomes:

41 dots:  .........................................

13 dots: .............

 

 

 

 

Because of the compression in video mode?

Olly

[Stub Mandrel]

47 minutes ago, ollypenrice said:

Because of the compression in video mode?

Olly

No, because it doesn't allow digital zoom - the HD video image is full sensor so the effective pixel size is apparently 2.87 times the actual pixel size.

[michael8554]

For planetary DSLR imaging, here's how you should do it for best quality:

http://www.astropix.com/html/i_astrop/eq_tests/canon_one_to_one_pixel_resolution.html

Michael

[George Gearless]

20 minutes ago, michael8554 said:

For planetary DSLR imaging, here's how you should do it for best quality:

http://www.astropix.com/html/i_astrop/eq_tests/canon_one_to_one_pixel_resolution.html

Michael

What a great link. Thanks, Michael.

As I'm writing this, I've only just perused the site. But it looks like there is a lot of information there which is directly relevant to my situation.

And here I was, doing great in convincing myself that getting a proper AP camera was my only option. And then you come and spoil everything. Dammit!  😁