Jump to content

sgl_imaging_challenge_2021_2.thumb.jpg.72789c04780d7659f5b63ea05534a956.jpg

Need help with Solar CCD choices


Recommended Posts

Hi folks, I am a few days away from purchasing my Lunt LS60/ha scope and will be getting an imaging camera soon after. My camera budget is about £500 and have been looking at the DMK range but don't know which one will be better for use with my 60mm scope.

I know a few of you guys and gals have DMK's so could you share some thoughts on the various models. I mayl also be modding the Lunt to use with a 100 or 120 f/10 donor scope in the near future, so this may have to be considered as well.I tried using CCDCalc to try and see what FOV I would get with the DMK's and 60mm scope, but CCDCalc does not have the DMK's listed, so I cannot get an answer.

Any advice appreciated..

Link to post
Share on other sites

Can't specifically help with the Lunt, but if you divide 3437 by the focal length of your scope that should give you the image scale in arcminutes per mm of sensor. The Sun is at most 32 arcminutes wide, so divide your first result into 32 and you get the required minimum linear dimension of the camera sensor. Alternatively you could calculate the entire lot in one go as 32 x focal length / 3437.

For a PST (because I know the focal length), that would be 32 x 400 / 3437 = 3.72mm. Call it 4mm to give yourself a bit of wiggle room. The DFK31 sensor is only 3.57mm high so it's too small for a full disc on one frame. The DFK41 is 4.46mm high, so it fits nicely.

With a 120 f/10 the focal length will be 1200mm, so the minimum dimension works out as 32 x 1200 / 3437 = 11.2mm. I think you're getting into rather expensive CCD territory there.

James

Edited by JamesF
Link to post
Share on other sites

I gather that you would need a DMK41 to comfortably frame the Sun with a 60mm Lunt. The general advice is to use the DMK mono range for the best resolution and then colour to taste with post processing. :smiley:

Link to post
Share on other sites

Thanks James, the Lunt is 500mm f8.3 scope. So using the above calcs the result is 4.65mm so the DMK41 will be a tight fit, and just within my budget.

Thanks Peter, I have noticed some folks use the DMK41 but was not sure which scopes they used them with. I intend to get a mono CCD.

I want full discs with the Lunt LS60, but the bigger scope will be used mainly for closer inspection and imaging smaller portions of the disc. I know I will have to use mosaics to get the full disc with the bigger scope.

I'm not sure if there are any alternative CCD's that would fit the bill.

.

Edited by allcart
Link to post
Share on other sites

It would be sensible to check the genuine dimensions of the DFK41 (I meant DFK above, not DMK). Most places just seem to give the diagonal which is not helpful. I believe the figure I have is close, but when pixels are only a few thousands of a millimetre across even a small error can make a big difference.

James

Link to post
Share on other sites

Better with one which is ha sensitive like the 618s. Don't worry about getting it all in one go you can do a 4 pain mosaic easy and will need to merge surface and prom data anyway.

It appears that only the DMK21 has the 618 sensor chip but is the smallest chip size. Are you saying this would be the better option. I see you have the LS80, so I assume that you use 4 pics to get a full disc. Mosaics is something I have yet to try.

Link to post
Share on other sites

It appears that only the DMK21 has the 618 sensor chip but is the smallest chip size. Are you saying this would be the better option. I see you have the LS80, so I assume that you use 4 pics to get a full disc. Mosaics is something I have yet to try.

Yes that's what I use.

It's easy enough once you get used to it. Plus with the higher frame rate you should get better stacks.

There are some good workflow guides online for solar imaging.

You will probably also want to use a Barlow or powermate to get closer to the action anyway!!

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.