Quick help with PST and DMK imaging for newbie

[SteveT]

Hi, I posted a quick help request in the beginners section, would be grateful if someone could take a look and give me a pointer to get me going.

Thanks

Sent from my iPad

[SteveT]

Anyone?

Sent from my iPad

[RikM]

Can't help I am afraid, but I am quite keen to hear any replies too. I am planning to add an Ha scope but can't decide whether to get a PST or something bigger. A PST is a great intro to solar observing, but they are not designed with imaging in mind.

I had heard that the back focus distance is very short so you may even need to use a cut down nose piece. The camera body needs to be butted right up to the top of the EP holder.

[SteveT]

I have a short nosepiece adapter so that should be fine. I don't know if I need to remove the lower spacer or not under the EP holder, or whether I need to use a IR filter ( don't think it should do anything). I just don't know what setting I need on the IS software to get an image, it is either totally white or black with sparkly edges. Trouble is I get just a few mins between clouds then have to go in for a while agin so it's very frustrating.

Sent from my iPad

[RikM]

I have a short nosepiece adapter so that should be fine. I don't know if I need to remove the lower spacer or not under the EP holder, or whether I need to use a IR filter ( don't think it should do anything). I just don't know what setting I need on the IS software to get an image, it is either totally white or black with sparkly edges. Trouble is I get just a few mins between clouds then have to go in for a while agin so it's very frustrating.

Sent from my iPad

I know what you mean about frustrating. I only managed a quick 30sec webcam shot in white light between the clouds this morning.

I don't think the IR filter will be necessary.

[Montana]

Steve, I can't find your question but if you need help I have a DMK41 and PST and image regularly with it. It is very easy, for full disc you need a shoulderless short nosepiece, and just use the nosepiece it came with if you wish to image with a 2x Barlow.

Remember to uncheck the Auto boxes in IC Capture in exposure and gain.

Regards

Alexandra

[SteveT]

Alexandra, thanks for you support, I tested the camera out today in daylight (rain) and got used to the settings of exposure, gain and gamma.

I do have 2 short nosepieces as well as the supplied one so that's not an issue. My problem was that I could either get a full bright blob or a black screen and nothing in between. I think I may have had the gamma down to minimum which may not have helped now I see it's effect in a daylight video stream.

I realise I have a smaller sensor in the 21 and to get full disk I would need 3 or 4 frames stitched together but I was expecting after researching quite a bit to get a good high resolution image on a sunspot or region of activity or proms etc like I have seen others produce, but I just could not get any focus.

So assuming apart from sensor size and higher frame rate from the 21AU618 version compared to your 41, I should get similar results as you but with higher resolution over a smaller FOV, correct?

I tried with the PST spacer and eyepiece holder and without the spacer but had no success with either but from what you say, if I leave the PST stock, ie with both bits fitted as shipped. I also tried with a 2.5 Barlow but that didn't help as it just made it more critical and I didn't really need the extra magnification.

Do you use an IR filter in the camera nosepiece, is there a benefit to this or not?

I will persevere when the sun come out again if you tell me that all I need is the camera and small nosepiece fully inserted into the PST eyepiece holder and focus with the PST focus knob (after tuning the view I want with the tuning ring) and using manual settings in the IS capture software. What settings do you find give a good starting place, I have been advised gain approx 300, exposure 1/60 ish and gamma 30 to 60 , does this sound about right?

Or maybe the 21 is not suited to solar but I can't see why it would be any different from the 41 apart from image size?

Thanks

Sent from my iPad

[Ibbo!]

To start leave gamma at 100

use exp and gain to alter the image

on my PST mod for surface I think I am at 300 gain and about 1/70 sec

for proms gain up a bit to 500ish and exp about 1/30

Steve

[Montana]

Hi,

Yes, I would leave the gamma at about 100, you can lift this this to 200 to get more prominence detail. I'll tell you what I used in my post later. Be careful of Gain as it will get more noisy the higher you go, stick low if you can. Remember that your frames per second are rate limited by exposure time.

You should be able to play with exposure and get it right, focus should come with a short nosepiece (make sure it is shoulderless and flat up to the socket.

No need to use an IR cut as the Ha band is very narrow at 656nm only otherwise it wouldn't work. Some have found a neodymium filter helps with contrast but no one has a clue why.

Regards

Alexandra