This image is an experiment and something of a homecoming. One of the first deep sky targets I ever tried was the Pleiades, back when I was just using a Canon point-and-shoot camera with terrible amp glow issues. I’ve come a long way since then. One of the challenges using a small-chip CCD camera like the Meade DSI IIc is trying to image larger objects; it’s just difficult the get them to fit on that little chip. About the only option is to use a shorter focal length. I’ve tried shooting through my finder scope with a focal reducer, but the optical flaws of that approach are formidable. So inspired by others like John Leader and Jammie Thouin I see using camera lenses, I decided to give that a try. I have an old Minolta autofocus SLR camera I never use any more, with an inexpensive Quantaray zoom lens we bought for use in a high school photography class. One of the challenges of using this lens is that it has a spring-loaded internal iris that is normally stopped way down. After messing with it a bit I noticed that the rear lens cover, used for capping the lens when it is not mounted on the camera, has a little plastic tab that pushes the iris open. So I cut a hole in the lens cover and glued that lens cover to a T-ring adapter of the right length to match the focal plane distance of the Minolta camera when mounted to my DSI IIc. I also have a filter mounting ring right next to the camera sensor, so I can use all my 1.25” filters. I got the distance close enough that I can get to focus at the 90 mm zoom setting (and down to about 65 mm currently; with another spacer inserted I think I could get all the way to 28 mm if I choose to try that). Mounting this chimera camera is currently very crude; I literally used a C clamp to hold the DSI camera body to one of the mounting rings on my ST-80 scope (which I used for guiding this image). This resulted in a lot of differential flexure and will need to be fixed with a better approach. Anyway, this is the first light image for this lens/DSI combination, and is also my first attempt following the “Sprinkler Disaster” of last week. I chose the Pleiades because I knew they would be easy to find and focus. Guiding failed a short way into the run, so most of this was unguided. I’ll have to look at the guiding logs to see if I can figure out what happened. Focusing this rig is difficult and very sensitive, but overall I’m happy with this as a first attempt.

Date: 10 Oct 2015

Subject: M45, The Pleiades

Scope: Quantaray 28-90 zoom lens at 90 mm setting

Filter: Baader Fringe Killer

Mount: CG-5 (Synta motors, PicGoto Simplificado)

Guiding: Orion ST-80 + DSI Ic + PHD 2.5.0.1 (Win 7 ASCOM)

Camera: DSI IIc, no chiller CCD 15 °C

Acquisition: Nebulosity 4.0.3, no dither

Exposure: 32x600 s

Stacking: Neb 4, bad pixel map, bias included, 33 flats, match histograms, deBayer & square, trans+rot align, DSS 2x drizzle 1.75 average κ-σ stack.

Processing: StarTools 1.4.305 Crop; Wipe 75%; Develop 81.77%; HDR optimize; Color: scientific, 275%; Deconvolute 4.8 pix; Life: heavy; Track 4.5 pix, Smoothness 88%; Magic: shrink 2 pixels. CS6 Astronomy Tools deep space noise reduction; increase star color; make stars smaller; levels & curves; Astroframe.