View Full Version : Problems imaging using a Coronado PST and Imaging Source DFK 21AU04.AS USB CCD color

Ed Hahnenberg
November 22, 2012, 20:58:56
I am new to imaging the sun using a Coronado PST with an Imaging Source DFK 21AU04.AS USB CCD color camera. My problems are twofold: First, I can't seem to get to focus by inserting the camera into the eyepiece holder of the PST. It would seem that I would have to get the camera closer, but cannot. Secondly, I get a ripple effect going live. How does one get rid of that. I have spent a few months imaging with a C1400 scope, Hyperstar lens, and Starlight Xpress M25C camera, but now I would like to do some planetary, lunar, and solar imaging with the PST and the DFK 21 camera. (You can see some of my prior work at www.hahnenberg.org.) My current attention is getting focus on the sun and solving the ripple effect. Any help would be appreciated. Thanks. You can also contact me at ejjhpiano@gmail.com.

Stefan Geissler
November 23, 2012, 09:36:06

First of all, I am not an astronomer, so I am lacking of telescope knowledge. Please accept my apologize for this.

The cameras a calibrated on C/CS mount, which is 17,5mm/12,5mm distance between sensor and lens. This is a norm. In case, it is not possible to focus, then there might is a problem with the telescope, so its plane of sharpness is not C or CS mount. Therefore, I would like you to ask your telescope service too.

The lens holder of the camera is a ring mounted in the housing. It is fixed by glue and two grub screws (or set screws, I am not sure for the correct translation of german "Madenschraube") on the sides of the black front frame. You may, on your own risc, loose this lens holding ring and calibrate it to your telescope. This has two issues:
- the grub scews drilled little hole in the ring, therefore, if you fix them again, the ring may switches back into the old position.
- the optical axis can be out of alignment

I had a similar problem with a very cheap telescope and changed something on the telescope (the screw, that fixed the mirror). The result was rather disapointing and I am glad, it was a very cheap telescope :-)

Regarding the ripple effect: I am not sure what this is. But if you do sun observation, you may use a H-Alpha filter. I had a case with a DMK 41, where there where interferences with the sensor protection glass of the sensor directly. The glass was not mounted correctly by SONY. So we got stripes on the image. However, the pixels of the DFK 21 are bigger than the ones of the DMK 41, so this interferences should not happen. But you may post an image, so we can see what happened.

Ed Hahnenberg
November 23, 2012, 17:02:07
Stefan...Thanks for answering my thread. I have to admit that I cannot show you the image with ripple effects. I snapped an image but didn't save it. I found an image in the The Imaging Source Europe GmbH\IC Capture.AS 2.0 folder called unis000 as a DAT image. I tried to rename it as an avi file, but I couldn't get it to come up. In NW lower Michigan, it looks like the sun will not appear because of all the cloud and cold fronts coming in for a few days before I can image again. I am not one to take cameras like the DFK apart to correct anything. I am sending pictures of how I have coupled the DFK to the Coronado and the folder of the DAT image.

I am pleased that I can at least view the prominences and flares on the sun with the Coronado and a 25mm eyepiece. I was hoping to get avi images with the DFK. Is there any other Imaging Source camera that will work with the Coronado that would avoid the ripple and focus problems?15341535

Ed Hahnenberg
November 24, 2012, 14:03:21
Stefan...I figured out that the DFK 21AU04 color always creates ripple effects with the Coronado PST. The monochrome 41 does not, so I ordered it and am selling the 21. Focus can be achieved by inserting a disk spacer. Thanks for your help anyway, you don't have to bother replying to the prior reply of mine.

Stefan Geissler
November 26, 2012, 12:43:11

"uninst.dat" contains the uninstallation information, in case you want to uninstall IC Capture.

DFK 21AU04 color always creates ripple effects with the Coronado PST
Do you know, why this is? From the image in your previous post, I conclude, you have a good telescope with fine lenses.

May 13, 2013, 01:27:17
Firstly, you need to cut off 8mm from the standard Imaging Source nosecone, as well as grind off the shoulder.

Secondly, you are wasting your time using a OSC camera for Solar work. You need a mono camera such as the DMK.