Target Framing, Imaging FOV

Astrophotography: share your photos & discuss techniques
User avatar
rjbokleman
Posts: 517
Joined: Fri Dec 19, 2014 11:09 pm

Re: Target Framing, Imaging FOV

Unread post by rjbokleman »

Pete,

Cool. What scope / camera combination are you running?
Ron B.
T5i/700D, ASI1600MM-C, ASI120MM, ASI174MM, XAGYL 7x36mm FW
Astronomik Deep-Sky(RGB), CLS, Ha, OIII, SII
SV60EDS 60mm f/5.5 APO
AT65EDQ 65mm f/6.5 ED Quadruplet
SW ProED 100mm f/9.0 Doublet APO
C8 EdgeHD, AT130EDT
AVX, iEQ45 Pro

http://www.astrobin.com/users/rjbokleman/
User avatar
Pete
Astro Day Coordinator
Posts: 3825
Joined: Fri Jun 13, 2003 9:03 pm

Re: Target Framing, Imaging FOV

Unread post by Pete »

rjbokleman wrote:Pete,

Cool. What scope / camera combination are you running?
It gets complicated Ron. It's a 14" f/10 Meade LX200GPS with a custom focal reducer bringing me down to around f/5.87 The camera's an SBIG ST-8XME with 9 um pixels binned 2X2. I've got a 2010 PowerPoint on the observatory reconfiguration that goes into this in depth.

Pete
Pete P.
User avatar
rjbokleman
Posts: 517
Joined: Fri Dec 19, 2014 11:09 pm

Re: Target Framing, Imaging FOV

Unread post by rjbokleman »

Hope you don’t mind, but just for fun, I thought I’d calculate this out as another example for others (learning) to review.

It looks like the scope is 3556mm since it's a 14" or 355.6mm. That would give us f/10 on the nose. :P

If your FR is at f/5.87, then that would put you at ~2087mm FL.

The SBIG looks to have a sensor of 1530px x 1020px and 9um or 13.8mm x 9.2mm, 1.6 megapixels.

So, BINning 1x1 is a Sampling Rate of: 0.889499281264974

BIN 2x2 would be 1.778998562529948

Right on the money! 8)

Now, for extra credit, does anyone want to calculate the FOV in degrees in both BIN 1x1 and 2x2?
Ron B.
T5i/700D, ASI1600MM-C, ASI120MM, ASI174MM, XAGYL 7x36mm FW
Astronomik Deep-Sky(RGB), CLS, Ha, OIII, SII
SV60EDS 60mm f/5.5 APO
AT65EDQ 65mm f/6.5 ED Quadruplet
SW ProED 100mm f/9.0 Doublet APO
C8 EdgeHD, AT130EDT
AVX, iEQ45 Pro

http://www.astrobin.com/users/rjbokleman/
User avatar
Stargrrl
Treasurer
Posts: 966
Joined: Mon May 01, 2006 5:51 pm

Re: Target Framing, Imaging FOV

Unread post by Stargrrl »

Note from Rebekah -- these are "catch up posts" that were added during the database transition to a new server. The date & poster are identified.

------------
Mar 3 menardre

Ron

Based on the equations my Nikon connected to my Stellarvue 90mm (F7) would be 1.96 pixels/arc second and my same camera connected to CPC1100 (with F7 focal reducer ) would be .631 pixels/arc sec.

Roger

---------------------------

Fri Mar 3 Pete

Is it possible to bin a DSLR setup?

---------------------------

Sat Mar 4 Pete

Here's an old S&T article that I used when reconfiguring my setup in 2006:
http://www.skyandtelescope.com/astronom ... -reducers/

One key factor that Dennis doesn't touch upon is sensitivity. A larger pixel will have more electron well depth, and will also capture more photons for a given exposure time. For me, this is an important factor as short exposures are required to "freeze" the motion of fast moving near Earth asteroids.

---------------------------

Sat Mar 4 rjbokleman

Pete,

BIN being defined as either hardware or software is a process where data from adjacent pixels is combined into a single pixel value.

If we limit the question to BIN @ acquisition as apposed to post-processing, then this is not possible or desirable for a DSLR. I believe the One-Shot-Color (OSC) nature of the DSLR and it's Bayer matrix would make this problematic.

Even if the ASCOM/INDI driver would let you, the pixels are filtered in an array placing some RGGB/GRBG or some pattern over the chip. If you could BIN 2X2 you would end up combining an arbitrary collection of those colored filters into one binned virtual pixel which might combine two reds, a green and a blue or some odd combination.

Therefore, when trying to de-Bayer the image later...it likely would create a mess.

Ron

---------------------------

Sat Mar 4 DonB

Yes my thoughts exactly !! WHOH !!Ron, baby, Your way over my head. Remember your generation started with computers and mine started with pencils. :lol: :lol: :lol: :lol: I found my mike and hope to be in on the teleconference. I also have my first auto guider coming so theirs another computer with a learning curve. But this is very interesting stuff even if I don't fully understand it.

Don
Post Reply