I use the Lunt 50mm together with the ZWO ASI174MM. I tend to use a 2x barlow for more image scale.
I'm having a hard time evenly illuminating the disc, sometimes it goes better than other times, like without a barlow it seemed to work fairly well, but then my last session it was very bad (see attached image), I tried to use the tuner to get it more evenly lit, but that just wasn't happening. Is there anything I can do to help it? Is it maybe because the ASI174MM's chip is so large? Or could it be slop in my optical path that's causing it?
Examples of the images I've taken with this setup can be seen on my AstroBin profile
Appreciate any insight you guys might have.
Some advice needed for my Lunt 50mm B600
- robert
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Re: Some advice needed for my Lunt 50mm B600
Tuning the etalon should move the bright area from one side to the other. You have to chose the best position. It helps to not have slop on the blocking filter too. Is the etalon square onto the scope axis? Or if it is pressure tuned is it sealing properly. Well lubricated o-ring and screw tight inside the adjuster.?
Robert
Robert
images and animations http://tinyurl.com/h5bgoso
2024 images https://www.flickr.com/photos/69734017@ ... 0313830045
2023 images https://www.flickr.com/photos/69734017@ ... 0304905278
ED80. ED100. Celestron-150mm-PST mod. C8 edge. ES127
LS60PT-LS60F-B1200. B600-Cak. PGR-Ch3-IMX265
2024 images https://www.flickr.com/photos/69734017@ ... 0313830045
2023 images https://www.flickr.com/photos/69734017@ ... 0304905278
ED80. ED100. Celestron-150mm-PST mod. C8 edge. ES127
LS60PT-LS60F-B1200. B600-Cak. PGR-Ch3-IMX265
Re: Some advice needed for my Lunt 50mm B600
Hey thanks for the reply.robert wrote:Tuning the etalon should move the bright area from one side to the other. You have to chose the best position. It helps to not have slop on the blocking filter too. Is the etalon square onto the scope axis? Or if it is pressure tuned is it sealing properly. Well lubricated o-ring and screw tight inside the adjuster.?
Robert
The pressure tuner is well lubricated and must be sealed well because it becomes noticeable harder to screw it further and further in. To minimize slop as much as possible I tighten the focuser but it's possible there's still a little bit of slop.
It seems that bright area which I can move around with the tuning is smaller than the disc 2x barlowed, when I was playing with exposures there as a small portion on the disc that got much brighter than the rest, but if you look at my AstroBin images, like this one below, it's not perfectly evenly exposed, but it's pretty close.
Maybe the 'tuned area' of the image circle is just so much smaller than the big ASI174MM chip? I'll research into it.
- robert
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Re: Some advice needed for my Lunt 50mm B600
That is probably it!
images and animations http://tinyurl.com/h5bgoso
2024 images https://www.flickr.com/photos/69734017@ ... 0313830045
2023 images https://www.flickr.com/photos/69734017@ ... 0304905278
ED80. ED100. Celestron-150mm-PST mod. C8 edge. ES127
LS60PT-LS60F-B1200. B600-Cak. PGR-Ch3-IMX265
2024 images https://www.flickr.com/photos/69734017@ ... 0313830045
2023 images https://www.flickr.com/photos/69734017@ ... 0304905278
ED80. ED100. Celestron-150mm-PST mod. C8 edge. ES127
LS60PT-LS60F-B1200. B600-Cak. PGR-Ch3-IMX265
- marktownley
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Re: Some advice needed for my Lunt 50mm B600
Maybe it is vignetting with the B600 and the barlow on the big chip? Do you have a full disk at native focal length without the barlow?
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
Re: Some advice needed for my Lunt 50mm B600
Yeah, here's an unsharpened shot of my very first image taken with the Lunt 50mm without any barlow.marktownley wrote:Maybe it is vignetting with the B600 and the barlow on the big chip? Do you have a full disk at native focal length without the barlow?
EDIT:
And here it is cropped & processed:
Seems nicely evenly exposed. I haven't taken many images with my Lunt 50 yet, so I'm still learning about it, I would certainly prefer to image with a barlow so I could make use of the nice big chip on the ASI174MM and get some more resolution, I have played with a 3x barlow as well, but I wasn't able to get it to focus.
Last edited by Amra on Tue Sep 06, 2016 6:06 am, edited 1 time in total.
- marktownley
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Re: Some advice needed for my Lunt 50mm B600
That looks fairly even to me.
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
Re: Some advice needed for my Lunt 50mm B600
Good news. Had plenty of sun today, so I actually had an opportunity to play with the tuner & focus a lot, and I discovered that my tuning was just way off the last time, I was able to find the sweet spot and it seems pretty evenly illuminated to me now. I also tried doing a timelapse of the sun disc for the first time successfully.
Here's the shot from today.
And the timelapse:
I intend to do a lot more of these to see the disc change over more time than 50 minutes. It was a fun experiment though.
Here's the shot from today.
And the timelapse:
I intend to do a lot more of these to see the disc change over more time than 50 minutes. It was a fun experiment though.
- marktownley
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Re: Some advice needed for my Lunt 50mm B600
It's all about practice!
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
- nickatnight
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Re: Some advice needed for my Lunt 50mm B600
Looks like you're on the right track to solaving your issue. I have the Lunt 50 with B600, and have the ASI174MM camera. I also have the ASI120MM-S which I prefer using with the Lunt 50, as the sun just about fills the chip at native focal length. However I think you'll have a bigger final disk going with the barlowed ASI174MM.