Buffer on Alpha 7rII

[Helipilot]

I'm wishing to use this camera on a drone and wondered if any of you guys could help with a few questions. Firstly I want to shoot continuously as I will be doing 3d mapping of cell towers, I read from the specs the total no of shots per battery and the continuous rate but is this rate totally continuous or will it stop after so many to clear the buffer. I'm happy to use jpg only if that would help and would also need an external power supply to supplement the poor battery life. Ideally I'd like to be able to shoot around 1000 images at around 3 per sec. Is this do-able? Last question is there a zoom lens which doesn't change its physical size when zoomed as I don't want to have to re-balance the gimbal every time I change focal length....who knows maybe I'll just have to! Any help or advice would be greatly appreciated. Thanks

[adwb]

surely due to the battery life and th extra weight of a external power pack plus the buffering surly this is not the right tool for the job?

 

would not one of the GoPro type units not be of more use? or a small fixed lens zoom body?

[Helipilot]

The weight isn't an issue as the drone can carry 13lbs, the buffering is what I'm not sure about thus the question and to see if there was a zoom which didn't "expand" as it zoomed. The Go Pro isn't really an option for the type of work I'll be doing.

[jlat70]

Your buffer will certainly fill and require time to clear during the time aloft.  I can't tell you right now as my camera is not around me but you only get a few images shot in continuos mode before you have to pause for the buffer. JPG would give you more shots before the buffer hits than RAW obviously.  As for the zoom, I sold my 24-70 some time back and do not remember if it "expands" so to speak but certainly the weight would shift either way so for your gimble issue you would have to rebalance I would think.  If you don't mind me asking what flight platform will you be using?

John

[cws]

Just tested this on my A7RII with 2.8 24-70GM lens and yes, it does extend as you zoom.

If weight distribution on the gimble is your concern, then I would expect you'd have an issue with any zoom lens as the the glass inside would move to zoom the image, thereby shifting the balance point somewhat, even if the body of the lens doesn't extend.

A lighter-weight APS-C zoom lens might give you more leeway with this (and the frame buffering with smaller image).

 

Re the continuous shoot settings, tested as follows

i)   in jpg-fine (full 7952x5304px image), Auto exposure mode

ii)  using an Extreme Pro Class 10 U3 (95MB/s) SDXC 64Gb card

ii)  Continuous - low mode

iv)  shooting an on-screen analogue "clock" to track frames over time

v)   press and hold shutter.....  

vi)  create a 720p QT from the result to review

 

Result:  I started off getting 2-3 frames per second, but it varied slightly over the first few seconds as it was hitting the buffer... and after around 42 frames it dropped to 1 frame per second and then retained that rate until I stopped shooting at the 83rd frame as it seemed pretty consistent by then.

 

 

Test 2:  Same setup but using Metabones 4 & Canon EFS 18-55mm APS-C lens.

 

Image size 5168x3448px.

 

Cont-lo mode....  was only giving me 2fps

Cont-hi mode....  gave me 50 frames over 10 secs (5 fps) then it slowed to an average roughly 2fps.

 

The suggestion in the other thread to shoot 4k video has merit, if it gives you enough resolution.

[storyteller]

The only FE zoom that will do that (and not change it's size) is the 28-135mm but it is not a small lens. At the size and cost the 70-200 f4 might be a better option but I suspect too large for the gimbal! I wonder if an A6300 with a PZ18-105 isn't a better option? I believe the buffer is relatively better as well.

[Helipilot]

Jlat70 the platform is a DJI Matrice 600. CWS thank you so much for testing this for me. It's very disappointing as I was hoping for 3 or even 2 per second. It looks like I'll need to check the Canon to see how it performs. I take all the points about the weight shift even on "fixed" zoom lenses, it was just that it would minimise the shift. The gimbal can compensate for some shift so I was just trying to see what was available to keep this to a minimum. If the buffer isn't up to it then it's a no no anyway. Just wonder if there's anyway of boosting the buffer.

 

Thanks to all especially CWS for all advice.

[storyteller]

Jlat70 the platform is a DJI Matrice 600. CWS thank you so much for testing this for me. It's very disappointing as I was hoping for 3 or even 2 per second. It looks like I'll need to check the Canon to see how it performs. I take all the points about the weight shift even on "fixed" zoom lenses, it was just that it would minimise the shift. The gimbal can compensate for some shift so I was just trying to see what was available to keep this to a minimum. If the buffer isn't up to it then it's a no no anyway. Just wonder if there's anyway of boosting the buffer.

 

Thanks to all especially CWS for all advice.

 

I hope this doesn't come off as rude but why do you need a full-frame camera for this? 

[Helipilot]

Hi Storyteller, not rude at all. I'm trying to get the highest MP so that can get as much detail as possible. I might not be able to get as close as I would like and will have a limit on the lens size so thought if I can get 42mp then it will mean I can crop it a bit more. Does that make sense?