Quick assistance with PST & DMK imaging first time

[SteveT]

I am trying my first attempt to image the sun with my PST and DMK21 with short C adapter. Quick question, do I remove the lower spacer and just use the EP adapter or do I keep them both on as per visual operation to get focus?

Also Can someone give me a starting gain and exposure combination to get me roughly going please using the IS capture software as I can't seem to get to a starting point.

Also, do I need to use an IR blocking filter on the DMK?

Much appreictaed.

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[Merlin66]

If you have the short shoulderless nosepiece on the DMK this should just focus with the original PST.

For imaging the spacer between the eyepiece holder and the black box can be removed. (The filter fitted here is a "mini-ERF" just to give additional protection to the sensitive blocking filter) Leaving the IR filter on the nosepiece can sometimes help...

I use a DMK21, gain set around 300 and exposures down to <1/120 s

Registax has a good solar imaging processing tutorial on the website.

HTH

[SteveT]

Thanks, I will give that a try, how much disk should I expect with the 21, I know it won't be full disk.

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[Merlin66]

You'd need about 4 exposures to make up a full disk mosaic.

(The sun's diameter is close to 1/100 the focal length, so for the PST =4mm

the chip in the DMK is 2.8 x 3.7 mm - too small to cover the whole disk...)

[SteveT]

I'm not impressed with this camera, apart from the flickering, all the dust that I can't remove on the sensor despite using the proper fluid and pad, and the fact that it gives a very narrow optimum position ie all black or all white and almost nothing in between. This makes it almost impossible to even get an image that I can play around with trying to find the focus point with, not to mention the clouds..... I gave upon the end before the camera ended up over the hedge!

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[Merlin66]

Steve,

What ever the problem it can be resolved.

There are many solar observers using the DMK series all over the world very successfully.

One step at a time....

The "banding" is usually due to poor power/ usb connections....

What settings have you been using on IC capture?

Gain around 300, gamma 10 and exposures to give a reasonably bright image....

Let us know how we can help you move forward....

[SteveT]

Merlin, thanks for your support, I calmed down a bit today and tested it out on my equinox 80 in daylight and got used to the settings. Apart from the dreaded dust it worked fine.

I think my issues were that I hadn't enough familiarity with the settings before trying to use it in bright sunlight ( a challenge in itself ) and I wasn't convinced I could get focus with just the camera on a short nosepiece fully inserted into the PST eyepiece holder with the spacer as shipped, but I know I should be able to now.

I appreciate it is harder with a smaller sensor not seeing the whole disk but I believe I should get good high resolution close ups of whatever I see with the eyepiece after tuning the ring.

Does an IR filter in the nosepiece make any difference either way?

I use an active USB extension into a hub on the scope, I did think power to the camera may have been an issue so I plugged in a 5v power source into the hub to make sure the camera got what it needed but when I tried it today without the local hub powered it worked fine.

I did try to get an image with an SPC900 before I got the DMK but didn't get anywhere with that using SharpCap either so gave up and went for the DMK instead.

Thanks

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