[sbogar]

Hi folks,

 

RE:

Since speed seems to be important for your application: are you aware that the current Canon 200/2 IS replaced an even faster lens, the EF 200/1.8 L USM?

 

-- Markus

 

Yes, I know that there was this 200/1.8 lens. In fact, I have some of those, but they are getting impossible to

buy, and the used ones (by now, i.e. 2013) are often in mediocre condition.

 

 

The size of the entire displayed area should be a nominal 36mm x 24mm which is the sensor size used in the test cameras. I presume the inner box shows the nominal area of an APS-C sized sensor, but this will vary slightly between models and I don't know what value they may have used. It is in the range of 1.5x to 1.6x smaller on each axis than the overall area.



Also, I had one more thought. Again I don't know what the original application is, but would a hyperstar arrangement be any use?
https://starizona.com/acb/hyperstar/specs.aspx

 

Yep, know of it, and using this for a 40cm f/2 arrangement, but that is a whole different story.

Here I need roughly 200mm focal length, f/2 or better, compact design, and no central obstruction.

 

 

In short, you need to buy a compatible telescope and the matching hyperstar module. This can give you insane focal ratios at longer focal lengths. Want 675mm f/1.9? You can, if you can handle a physical aperture of 14" with a wallet to match! Smaller sizes are available too. However in terms of light gathering ability and overall contrast, there will be some reduction as the sensor needs to be placed in front of the optics. A DSLR would be at best inappropriate if it would even work at all in this scenario. To properly make use of this you would be looking at astronomical or industrial imaging cameras.

 

Thanks for the very creative ideas!

I will keep bombarding the list with lens-related questions, probably by opening a new thread for each topic.