From: Kevin in Fort Davis <fsm79734@gmail.com>

Date: May 22, 2015 11:46:56 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] IR Cut Filter Necessary?

Thanks for your suggestions so far, everyone!

Milton, I probably should have included more detailed information as to why I'm considering PGR USB3 cameras.  It's not for USB3 frame rate, but rather to get the to PGR cameras with larger physical chip sizes.  We need the image coming from the Lunt telescope to be full-disk, and it's not quite full-disk with the PGR USB2 Chameleon and Firefly 1/3" CCD cameras.  We need the chip size to be closer to 1/2".  We have two PGR FW800 2MP Flea3 cameras with which we've been quite happy, and we use those to show white light and hi-mag H-alpha views of the Sun.  However, because of the physical setup in the dome, our cable lengths are pretty long (4.5m from cameras to FW800 hub, then another meter to the computer), so it's sometimes a challenge for both cameras to be recognized at the same time - presumably because of the long cables.  Thus, I'm afraid of adding yet another FW800 camera and long cable on the same bus.  We could restructure the physical layout of the electronics in the dome, but with long focus 6" and 4" refractors, the cables by necessity have to be pretty long to allow for all slewing angles.

In my testing of the Lunt telescope along with the other two telescopes, we've been using a PGR USB2 Chameleon 1.3MP camera, and I've not had any issues with data transfer rates.  I can run the Chameleon at 3.75 fps and the two FW800 cameras at 7.5 fps consistently, and this is on a fairly old (mid-2010) Mac mini running Mac OS 10.6.8 on 8GB of RAM.

The thing is, we don't need fast frame rates - in general, anything faster than 7.5 fps - nor huge frame sizes (above 2MP).

So Milton, given that, and assuming that we're only running one of the PGR USB3 ~2MP cameras (in "USB2" mode since USB3 isn't implemented in Astro IIDC) on the bus with no other USB devices on the bus, in your experience do you think that would give us the ability to do 7.5 fps?

Use some other software?  No way!  We love Astro IIDC and would rather choose our cameras to fit the software than the other way around.  :)

-Kevin

On Thu, May 21, 2015 at 11:36 AM, fsm79734@gmail.com [Astro_IIDC] <Astro_IIDC@yahoogroups.com> wrote:

I do only solar imaging, and I'm about to purchase a PGR USB3 camera to use with my Lunt 60mm H-Alpha pressure-tuned solar telescope.  I have a few questions for those of you in the group who do this type of imaging.

First, is an IR-cut filter necessary?  Doesn't the filter in the Lunt already do this?  In my past discussions with vendors, they have recommend them - possibly with the intent of selling me a $73 filter - although I've never done a side-by-side comparison.

Secondly, any thoughts on the PGR Flea3/Chameleon3/Blackfly/Grasshopper3 relative advantages/disadvantages for solar imaging?  All of the above cameras I'm considering are the ~2 megapixel, monochrome variants.  In particular, I've never used a CMOS camera for imaging before, only CCD cameras.

Any suggestions are appreciated - thanks!

-Kevin