lens to Sony nex 5 and Lumix GM1 and GM5

[hisky]

hello people !!
I want to know if one of you have used sony nex 5, lumix GM1 or GM5?
I'd like you recommend me which lens use for photogrammetry.
About the sony camera, i'm searching for a lighter lens that Voiglander 15mm, because I need charge two cameras simultaneously.
thank you very much
Hisky

[dtmcnamara]

I have a Sony Alpha a6000, A7R and a A7S, just newer NEX cameras. I use my Zeiss 55mm 99% of the time, link below:

http://www.bhphotovideo.com/c/product/1008124-REG/sony_sel55f18z_sonnar_t_fe_55mm.html

I also have a 24-70mm lens that I have used before. Only problem with this lens, or any lens with a zoom, is keeping it fixed at the same setting the entire shoot.

http://www.bhphotovideo.com/c/product/1008126-REG/sony_sel2470z_vario_tessar_t_fe_24_70mm.html

[hisky]

Hi!

Thank you for your reply, but I search a lens ligther.
The lens i'll show you in the link, can work fine to fotogrammetry between 150 at 300 m altitud?
http://store.sony.com/e-20mm-f2.8-e-mount-prime-lens-zid27-SEL20F28/cat-27-catid-All-E-Mount-Lenses

Thank you again, regards.

[Marcel]

This one is fairly light, and I think it would fit on your camera:

http://www.photographyblog.com/reviews/carl_zeiss_sonnar_t_fe_35mm_f2_8_za_review/

Not sure if that is the correct focal length for you, and it is fairly expensive.

It can be very sharp, but do purchase it at a store that has a good return policy. That way you can test it (shoot some test photos at the distance you will use it), and if the copy is slightly off you can return it for a different copy. I tested 3 of these, and one of them had a soft corner. The other two copies I tested were perfecly sharp. This was using a full frame A7R, so on your (cropped frame) Nex it's probably less of a problem.

It is a really good lens, especially considering the size and weight (120 grams).

[hisky]

I'm a bit confused about the focal distance that I need, because I don't have any experience with lens-inchangeable cameras. I've always used Lumix cameras with fixed lens. Your lens is good but it's very expensive for me because I have to make two equal cameras. How I know what focal distance I need to use if I fly at 150 to 300 metres height, with 16 megapixels? I really don't know how I can do that, there is some calculation to know that?

Thank you!! Regards

[Marcel]

Why do you need two cameras? If you fly with a drone, can't you just take photos at a faster interval?

I would also think that at 150 to 300m high, you will not have enough seperation between your cameras (unless they are not pointing straight down, but at an angle so they each cover a different area).

My own experience with a dual camera setup was not a happy time. It is a pain to setup (getting exact same settings  and correct focus on both cameras). I also had a camera specific problem (shutter slap causing blurred images, but this was with a dual A7R setup). Much money was wasted.

[hisky]

I need to fly with two cameras because one of them is RGB an the other is NIR. It's for count cups of small trees. We go to do two mosaics diferents, because of this we've to fly with two cameras.

[JMR]

For the Micro four thirds I'd recommend:
1. Oly12mm
2. Oly17mm (the expensive one)
2. Panaleica 20
3. Oly25mm

Take care with focus in the NIR camera, some lenses can't focus. it can vary from one camera model to another.
but more important. be aware of rolling shutter with GM's, you will have insane error if you use electronic shutter so you MUST use speeds under below 1/500
BTW why did you choose two diferent cameras?
To help you to understand calculation of the best focal lenght you should consider:
a) you should not fly over 120m because international air regulations say small civil UAVS are not allowed to fly higher than 400ft
b) having the flight height limited to 120m, you need to know the width of your sensor in mm and in pixels to obtain the actual pixel size (usually something about 5 microns). Finally you can say
Height_over_ground[m] * pix_size[mm]=GSD[m] * focal_lenght[mm]

[hisky]

oly= OLYMPUS?
are two identical cameras but one modified.
becomes very difficult to detect and count small trees with the spectrum rgb so we also need the nir band