Grass Hopper Express Review

Paul Haese · #1 24-07-2013, 11:40 AM

I have owned this camera for 12 months now and have used it a lot to achieve some great images of the Sun. I thought it prudent to let you guys know what I think of the camera and so I have written a review of the camera.

Feel free to let know what your thoughts of the review are, did I cover enough or are you interested in more.

Click here for link.

h0ughy (David) · #2 24-07-2013, 12:34 PM

nice review, i noted the temp issue, in my case i stopped direct sunlight hitting the camera with a foam board shield and a clamp. made a dramatic difference.

it would be interesting to compare a USB3 version with yours?

Poita (Peter) · #3 24-07-2013, 01:05 PM

I added heatsinks to mine and it does reduce the internal temp a bit.

One of the problems with this camera (and other Pt Grey cameras) is the gamma is calculated incorrectly, meaning shadow detail is sometimes lost.
The best way around this is to capture in 12 or 16bit modes and apply a correct gamma curve in software. In theory you can use the LUT to correct the curve in 8bit mode.

The main disadvantage with the FW800 model vs the USB3 model, is that the FW800 is slow in 12bit or 16bit modes whereas USB3 model can do the same framerates in 16bit as in 8bit, making it the one to get these days.

Other than that I agree with the review, great camera, low noise, good chip size and resolution for solar and lunar work. Adding a heatsink to the case and shielding it from the sun let me keep the temps well under 60 degrees, it got over 70 easily if exposed. The black case acts as the main heatsink, so fan cooling may also help keep temps down.

Poita (Peter) · #4 24-07-2013, 01:10 PM

The formula for using the LUT to correct the gamma curve is here:
http://www.ptgrey.com/support/kb/index.asp?a=4&q=391

naskies (Dave) · #5 24-07-2013, 01:29 PM

Thanks for sharing, Paul.

Quote:

Originally Posted by Poita

Adding a heatsink to the case and shielding it from the sun let me keep the temps well under 60 degrees, it got over 70 easily if exposed. The black case acts as the main heatsink, so fan cooling may also help keep temps down.

It sounds like adding a Peltier module for extra cooling might be quite effective?

Paul Haese · #6 24-07-2013, 01:59 PM

I never use gamma in any collection of data, either with the flea3 or the Grass Hopper Express, I cannot see its use valuable. I always have it off and that way I get the raw data I want. You can set this to off in fire capture and I agree the camera seems to have incorrect gamma but will operate fine without it operating.

The heat sink module I have considered many times but not really thought it absolutely necessary. The camera has performed easily without one but certainly worth looking at if you think it necessary. Anthony has stuck several onto his camera in the past and it helped keep temps down. Perhaps a peltier might produce lower noise levels but at present I cannot see it as a must.

Poita (Peter) · #7 24-07-2013, 03:14 PM

If running in 8bit I think a true gamma curve is often an advantage. It allows you to capture information that would be lost otherwise in 8bit RAW.

Heat wise, I think passive heatsinks work well enough, I don't like it running over 60 degrees and the passive sink is enough to keep it under that. The noise is pretty low, not sure if active cooling would reduce the noise any.

Lee · #8 24-07-2013, 06:19 PM

Nice review... and the camera sounds great.
Point Grey have annoyed me already though, with one line -

"Please login or register to view prices"

I loathe online suppliers who hide their prices...

icytailmark (Mark) · #9 24-07-2013, 07:19 PM

nice review paul. Can you tell me if there is a huge difference between point grey cameras and imaging source cameras besides the price.

asimov (John) · #10 24-07-2013, 07:21 PM

This camera won't run on just any laptop so be careful.

icytailmark (Mark) · #11 24-07-2013, 07:29 PM

would it run on a core i7? I am planning on buying a 4th gen i7 when they come out.

Paul Haese · #12 24-07-2013, 08:31 PM

It'll run on most laptops actually. You need RAM and an SSD on older machines. I was using it on a vista machine with dual core and 4 gig of RAM and it worked. I did need to have an 800mbit 34 express card and the slot to run it. With a i7 machine, so long as you have the slot in a laptop or don't mind using a desktop then this machine will work.

Peter I don't agree about the gamma, but each to their own.