Camera Test

[sil (Steve)]

I think key here is its vital to test for yourself the gear you have and understand what your tests tell you. Its also noy always essential to buy this years model cameras when last years are just as good and a quarter of the price second hand so just because its not state of the art do not automatically discount it.

Ryan's test is interesting to see and yes a good test of the red end of the spectrum the camera can grab. EtaC is difficult and faint for me to grab but that may be due to the filter i have permanently installed. I'd suggest you try plieidies (can never spell it) - seven sisters as it has so much faint blue structure. would be interesting if you find similar differing results especially if the same camera goes further into the blue as well as the red. Ideally you want the camera to go widest on the spectrum so you can be confident of good results on everything.

[RyanJones]

Originally Posted by sil

I think key here is its vital to test for yourself the gear you have and understand what your tests tell you. Its also noy always essential to buy this years model cameras when last years are just as good and a quarter of the price second hand so just because its not state of the art do not automatically discount it.

Ryan's test is interesting to see and yes a good test of the red end of the spectrum the camera can grab. EtaC is difficult and faint for me to grab but that may be due to the filter i have permanently installed. I'd suggest you try plieidies (can never spell it) - seven sisters as it has so much faint blue structure. would be interesting if you find similar differing results especially if the same camera goes further into the blue as well as the red. Ideally you want the camera to go widest on the spectrum so you can be confident of good results on everything.

Excellent points there Sil. I hadn't considered the blue end of the spectrum but you're 100% right. I will do the test on Subaru ( I'm a mechanic and also can never spell plieadies either lol ).

Thank you for your input Sil.

[JA]

If you want a way to easily test the Hydrogen Alpha line response of various cameras WITHOUT having to resort to imaging DSOs and the variability that that might provide with say light pollution etc... then you could use a RED light laser of the type typically employed in laser pointers. These typically have a wavelength of 650-660nm depending on model, but more usually 650nm. That wavelength (650nm) is very close to Hydrogen Alpha line wavelength of 656.3nm and has a very narrow bandwidth.

In addition to the red (650nm) laser you could even pimp your test rig to include a purple (405nm) laser pointer and a green (532nm) laser pointer as a reference. Then simply take an image of the laser/s illuminating a white diffuse surface like paper. Do not image the laser beam head-on in to the camera and take care with laser usage and safety and not look in to the beam.

In addition to visual comparison of the images from various cameras, you could easily quantify the image brightness in the coloured areas in terms of a pixel value in most photo editing suites and compare this with other cameras imaging the same scene at the same exposure and ISO sensitivity.

Best
JA

[RyanJones]

Another excellent suggestion there JA. Certainly a much more scientific way to carry out the tests. This however may be where the problem lies. A test on real DSOs is a real world test WITH the uncontrollable variables in place. Agreed that these variables will affect the quality if the data. If all 3 cameras are being tested under the same conditions ( as much as is practical as obviously time of the night can change sky glow etc ) then the results should have a greater applicability to the reason for testing which is creating images of DSOs. The other small consideration is the need for more equipment ( cheap as it may be )to carry out the test.

Thank you for your input JA. It's good to get other perspectives to validate the quality of the test.

[Cimitar (Evan)]

Hi Ryan,

When compared to the 350D, the difference between the 200D is significant. The red barely shows in the first image!
Thanks for sharing mate. I would have found this type of information very helpful when I started in astrophotography

Evan

[gb44 (Glenn)]

Hi,
IMHO the Pleiades would be an even more difficult test as DSLRs are even less sensitive to blue than to red.
Tarantula nebula is the most spectacular object in my book, so it must be an ideal test comparison. And its up early in the evening at the mo...

Cheers
GlennB

[RyanJones]

Originally Posted by Cimitar

Hi Ryan,

When compared to the 350D, the difference between the 200D is significant. The red barely shows in the first image!
Thanks for sharing mate. I would have found this type of information very helpful when I started in astrophotography

Evan

Thanks Evan

[RyanJones]

Originally Posted by gb44

Hi,
IMHO the Pleiades would be an even more difficult test as DSLRs are even less sensitive to blue than to red.
Tarantula nebula is the most spectacular object in my book, so it must be an ideal test comparison. And its up early in the evening at the mo...

Cheers
GlennB

I've got about 6.5 hrs of data on tarantula taken with the 5d and it seemed to love the blues. I do intend to get back to tarantula now I've got my new mount and can get some decent length subs. I don't think the target really matters as long as it's heavy in the blues so maybe I'll do the test on that instead.