Sony A1 v A6700 4k 120

[twamers68]

Good morning gentlemen, a stupid question probably but here goes.



I’m trying to get max reach (focal length) for taking video of a distant Osprey nest close to where I live. These birds are still quite rare in the uk but are steadily making a comeback with some great re introduction programs.



I have a Sony A1 and would like to shoot 4k 120 fps so I have set up 600mm with 2 x tele and crop mode, I don’t think clear image zoom works in this configuration or at least I can’t get it to work ! So I think that is 1800mm focal length ?



If I was to buy a Sony A6700 and use the 600 mm with 2 x and shoot in 4k 120 I think that mode will crop the video by 1.58 ? I’m assuming being a crop sensor the 600 plus 2 x gets me to 1800mm (FF Equivalent) and the 1.58 crop extends the effective focal length to 2844mm ?



Or am I stupid ? Something that is quite possible I’m more than happy to admit !



Anyone with any input of firstly am I correct with the maths but also which set up would realistically give me the best output ? Is the FF sensor in crop on the A1 better than the sensor in A6700 with 1.58 crop for the 4k 120



I’ve only ever used the video side on the odd occasion and don’t really fully understand all the different settings and the various effects it may have on quality



Thanks Peter

 

[iamdlewis]

Before you go looking at any additional gear you might want to see what it is like recording at 1800mm. There is going to be a lot of air between you and the subject which can mean distortion and the slightest bit of motion is going to look jarring. Your field of view is also going to be the size of a pinhead.

 

[Angus Cameron]

Hi Peter,

I put the 1.4 + 200 to 600 on my A1 Set up with XAVC HS4K @ 60ps using the 35mm shooting to get crop sensor you can still use clear view zoom.

Hope that helps.

 

[Deleted Member 5003]

I can't comment on your video issues but certainly from the point of view of using your A1+ 200-600mm+ x2Tc+ crop mode you are
pushing the limits in terms of image sharpness/quality particularily in UK winter weather conditions at 1800mm and effectively f13.

Even if you were in a warmer climate even there, you would be challenged by heat shimmer at such long focal lengths but the focus speed
Would not be slowed down as much given the likely higher ambient light conditions

As has been discussed many times on the forum, out at 1800 mm(your Focal length calcs are correct), you need ideal light conditions
To get anything like usable quality images (I assume the same for video) and even then your focus speed will be much slower.

You will have many challenges with your anticipated lens/tc combo and whilst a x1.4 tc might lead to a better result my experience with the 200/600mm lens and a x1.4 tc and aps-c engaged, at f9 and 1260mm overall, in the high ambient light conditions of the middle east is just about manageable but you should not expect best quality images.

As suggested above take some test shots to test out your proposed set up before committing any funds...I am skeptical you will achieve what you
Want with these equipment combinations and I would investigate if you really need to be at 1800mm given the distance to the osprey nest site, etc.

Hope this adds value.....

 

[Angus Cameron]

Deleted Member 5003,

Peter is not using a 200 to 600 lens. He is starting from a 600 f4. I imagine this will improve the results.

I've a suspicion that given the quality of Peters images gallery and equipment he will be aware of the challenges of the project.

 

[Deleted Member 5003]

Deleted Member 5003,

Peter is not using a 200 to 600 lens. He is starting from a 600 f4. I imagine this will improve the results.

I've a suspicion that given the quality of Peters images gallery and equipment he will be aware of the challenges of the project.

Yes thanks for that I misread his lens designation but whilst the effective aperture will become lower at f8 the focal length will be the same at 1800mm. That said if he is asking if he has his focal length calculations correct to me that suggests he may not be as experienced as you suggest.... I may be wrong but that is what came across to me.
At 1800mm and f8 there will still be a reduction in focus speed and with lower light in the UK the image quality will reduced.

 

[FowlersFreeTime]

@twamers68 I can't comment on the A1, but regarding the A6700... you're right and would be at an effective 1800mm with that lens, 2X converter, and a crop sensor. According to the DPreview article, there is indeed a 1.58 crop on top of that when using 120p 4k.
However, if you want to record video at 120fps, I would not recommend the a6700. If you want the APSC crop, and to shoot at that speed WITHOUT OVERHEATING, you would be better served by an FX30. Same crop, but active cooling (internal fan) means no worries of overheating.

Do a little more research on ISO and noise levels (for FX30) though, just to make sure you'll be happy with the results before you commit.

 

[twamers68]

Hi everyone, firstly sorry for not replying directly to everyone who has taken the time and effort to reply but thank you for all the input.... I have taken a screen shot (can't post video???) of a bit of video to show how much reach I have been able to achieve with the A1, 2x converter in crop mode with clear image zoom ! its quite incredible (not award winning I grant you) but @FowlersFreeTime idea of the FX30 is interesting me. Just for reference the video was also cropped using Topaz video Ai, from camera to subject is about 1/4 of a mile (0.24 on a distance measure app)..... about 6/8 weeks before the Ospreys hopefully return from their winter break. again thanks to everyone who replied

 

[Angus Cameron]

Hi Peter,

That looks decent given the challenge. I've used the A1 for video many times. I've found if you tilt the rear screen away from the body this provides sufficient cooling to avoid high temperature problems.

Hope to see some posts of the birds when they have returned.

Angus.