PST/TAL Mosaic Hell... Help!

[Notty]

Hello everyone.  I've got my cap in my hand again, and think this might be my last attempt at imaging with my PST TAL mod before giving up.   I've been out of commission solar wise this summer sue to my PGR Chameleon helpfully packing up at the start of the (best we've had in years) Summer, but I've just got it back from Canada repaired, and I've eagerly spent the afternoon taking some footage.  Now anyone else who has this mod might attest to the fact it has an awful hotspot problem, so bad that I've previously found mosaics impossible due to the gradients and apparent vignetting.  However looking at my captures, I just can't believe it is beyond the wit of Autostitch to do something with them?  I believe it may just be my complete lack of understanding of any of the settings (I'm using an old version as the latest one doesn't even let you alter most of them).  Try as I might, I get weird deformed shapes or "no match found".

I was advised last time I had a moan on here to try flats to see if they might even out the hotspot problem a bit.  I tried, by aiming at the centre of the disk, defocussing and trying to get the most even field, but even then it's dark on one side and light on the other.  I tried "flattening my flat" with curves in Paint.net but Autostakkert threw a "floating integer" wobbler at me.

Is anyone prepared to share with me what settings seem to work for them, and even better, allow me to run some of their subs through myself so I at least can see how they should look in order to process successfully?  As an example I've attached some of the raw stacked .jpgs I'm using.  I've cropped off the left extremes where the detail just goes flat due to the uneven tuning of the etalon but you can still see it, and it's obvious it will cause a problem thought I'm stumped as to how i can get around it.

Any advice deeply DEEPLY appreciated before the whole setup goes on ebay and I save up for a Quark.

Regards Andrew

fc2_save_2014-08-19-141948-0000_g3_b3_ap343.tif

fc2_save_2014-08-19-142237-0000_g3_b3_ap385.tif

fc2_save_2014-08-19-142324-0000_g3_b3_ap239.tif

fc2_save_2014-08-19-142415-0000_g3_b3_ap295.tif

fc2_save_2014-08-19-142805-0000_g3_b3_ap389.tif

[Notty]

Ok so I've attached the raw  .tifs instead of the partially sharpened .jpgs... these are the ones I meant to post.  Do they look that un-knittable?

[Pete Presland]

i have not had a lot of success with autostitch either. your images do seem to lack a great deal of contrast and are little "soft! at the edges maybe. have you tried cropping the edges off after stacking i am sure i read somewhere it can help.

i will watch this space, it will be interesting to see what others suggest.

[Davey-T]

Just stuck them together in P Shop and you only seem to have four sections one duplicated, if it's any consolation I haven't succeeded in making a Solar mosaic either

Don't think any software could auto stitch them

Dave

[Peter Drew]

Andrew. I strongly suggest you post your problem on Solarchat, this sort of thing crops up regularly and I'm sure the experts will be able to help you. 

[Steve Ward]

Couple of good PS tutorials here that may help ... 

https://www.youtube.com/watch?v=a5XxRHYD7Jk

[Notty]

Thanks guys, for the inputs all, just to clarify though, those were just a small selection of contiguous subs to illustrate my query, as to my eye they look like they should gel.

I'm not a PS user I've been using Paint.net, but maybe I'm going to have to bite the bullet!

[Steve Ward]

Try Microsoft ICE.

[Notty]

I tried ICE previously, but had less success than eith Autostitch, which a year ago I was able to force to knit at least a half a disk by playing with the settings... trouble is I can't remember what I set them to, but it was a case of randomly fiddling with each one.  Could anyone could maybe give me a screengrab of their Autostitch settings?  They are all absolute greek to me and I have no idea what any of them do!

[Davey-T]

Can you post a full disc of subs, P'Shop has a photomerge that works well on Solar mosaics but it couldn't do anything with your bits.

You can no longer buy Photo Shop and have to rent it monthly, not really worth it for dabbling, don't know what the licence position is with purchasing some ones old copy of PS4 or 5 which has all you need.

Dave

[Notty]

Why thanks Davey, here's the full set that is very kind.  I have applied a bit more sharpening, and cropped the areas to the upper left of each which are devoid of detail.  I really don't know how else I can set this rig up to capture them though; I've tuned for the most even disk I can but even when it looks nicely monotonal on the laptop at the time once it's stacked the gradient is clear.  It's possible I've maybe overcropped some bits out such that there might be a few holes but just to be able to get a basic circle would be enough to persuade me to have a rent of PS.

Sorry for the vast upload I don't know of a way of putting link in.

[Steve Ward]

PhotoshopElements has PhotoMerge included.

[JamesF]

Regarding the vignetting, I've been giving that some thought recently.  I have a modded PST using the original gold tube and objective, but I've replaced the "black box" with a modded SCT secondary focuser and a straight through adaptor for the eyepiece holder:

(Since that photo was taken I've also motorised the focuser.)

I'm now thinking about modding it to move the blocking filter to be as close as I can possibly manage to the camera sensor, perhaps also drilling out the filter retaining ring to 5.5mm at the same time.  I've posted about the idea here.  If I don't drill out the retaining ring then I think a small amount of vignetting is unavoidable.  If I do drill it out then I think I might well get rid of it pretty much entirely.  My next step is to work out how to remove the entire blocking filter unit from the upper half of the eyepiece holder.

If you're still using the BF5 with the Tal such a modification might help, but you're always going to suffer some vignetting because even at the sensor the image of the Sun is going to be in the region of 9.5mm across.  Ideally you need either a BF10 or even a BF15, at which point I can see the Quark starting to look quite appealing

James

[Montana]

I think the PST mod and Quark are both designed for high resolution imaging, they are not really for full discs. If you want full disc views you are better off buying a PST or a Lunt 60mm. It is horses for courses, trying to get something to do something it is not designed for will only cause you pain. Not that I am saying it won't work, you could spend hours zipping it together, but I can take a nice full disc with my PST in 1 minute

Alexandra

[DrRobin]

Hi Andrew,

Up until a few weeks ago, I could go out with my Lunt 60 and DMK41, shoot 9 or 12 panes across the sun, chuck them in to Autostitch (I use the new version now with blending bands set to 4) and it would just stitch them perfectly.  Since then I have removed my double stack filter and put it back, possibly in the wrong place and also been trying a new camera, an ASI120MM and I have been having problems getting any of my recent images to stitch more than 3 frames together, using any software.

The change in contrast or brightness across the frame doesn't help, but that isn't what is stopping my images from stitching.  I also thought it might be the [slight] Newton Rings with my ASI120MM which was causing the problem, but again I don't think it is that.  No, my problems seems to be not enough overlap in the images.  My DMK41 would give around 30 - 50% overlap, that is two adjacent images would show 30 - 50% of the same detail and there would be enough features in the overlap that hadn't changed for the stitching programs to work.

The ASI120MM has a slightly different aspect ratio leading to a slight narrowing of the frame and this coupled with a little delay in imaging (whilst cloud moved off) and some parts of the disc with few distinctive features has meant that my images won't stitch.

I have had a look at your images and I think I can see why they won't stitch as in most of them there isn't really enough sharp detail for the stitching program to work with.  The images look slightly off-band (incorrect tuning), could do with the contrast boosting and I would suggest need sharpening a little more to give enough features  for Autostitch to match.

I would therefore do the following:

- Try adjusting the tuning a bit more on your scope to pull out more detail in the image;

- Try different camera settings for gain/exposure to try and 'freeze' the detail.  Shorter exposures usually work best as long as the gain isn't too high;

- At long focal lengths and high F numbers you can easily loose contrast.  Try a focal reducer on your camera to reduce the F ratio.  This will help you get more of the disc and should improve contrast.  It will also help you reduce exposure time;

- Try to capture all your panes in as short a time as possible to avoid the features changing.  Taking 3 or 4 shots and then getting the rest an hour later is probably not going to work.  If it is clear I get 9 or 12 panes in about 15 minutes with a DMK41, taking 600 frames per pane.  I can get 1,000 frames per pane in less time with an ASI120MM-S;

- You can loose detail/contrast when you apply a flat, try processing without flats, I think you mentioned that AS! didn't like the flats?

- Sharpen and then crop the bits round the edge that don't contain good detail or have stacking artifacts.  If the source files don't contain some nice detail it isn't going to be able to stitch.

To give you an idea about how fussy the stitching programs are see this link of my last mosaic attempt.  The 'right hand side' view was three frames taken in very quick with some good prominent detail, it stitched those.  There was then a little bit of a gap due to cloud and the upper middle didn't contain all that much detail.  The lower middle did contain an AR and it stitched two panes together.  Another gap and then the right hand side partially stitched.  The whole lot wouldn't stitch together as one.

http://stargazerslounge.com/topic/223239-sun-in-ha-19814-back-to-my-lunt/

BTW the first image was taken in one go with a FR.

The main two reasons why the whole lot wouldn't stitch is probably due to the two gaps in imaging and not enough overlap in the vertical direction.  This was 9 panes and for my ASI120MM I will need to go back to 12 panes and/or use a lower powered barlow.

I hope that helps

Robin

[DrRobin]

Hi,

Sorry just looked at your panes again and compared them to mine.  Your panes have a much lower FoV than mine and I suspect that if you reduced the magnification to around a half of what you are currently using you would have a lot more success.  I would go for around 40% overlap and the ratio you need to use is the same aspect ratio of your camera.

If it is 4:3 camera then 12 panes (4 in the vertical and 3 in the horizontal) balances the image.  If it is a 16:9 (wide screen) then 5 in the vertical and 3 in the horizontal nearly works out right.  I would try to get it in 12 to 15 frames or less as it means you will get it captured faster with less chance of cloud interrupting the session.

Robin

[Davey-T]

Hi Notty, sorry for delay in replying been a bit busy.

Regards the upload could you not have done tifs as per your original post ? any way no matter, you now seem to have enough images to make two mosaics however as some of them only end up with a tiny bit showing and as you've cropped them to all different sizes P' Shop can't make head nor tail of them

As Alexandra says the images are a bit small for successful mosaicing, you need to have a plan of attack, work out how many subs you need for a full disc, make a drawing, number them and tick them off as you go, I find it's very easy to either duplicate one or miss one altogether , allow a reasonable overlap but not more than a quarterish of a frame and don't crop anything until after it's mosaiced.

Hope this helps, though I'm no expert as I still haven't actually succeeded in doing a full mosaic myself and I've really got no excuse with LS60 

Dave

[Notty]

Thank you so much for the detailed input Dave and Robin it is very much appreciated.  I'm a bit stumped I guess!

I think given the data all I can do is try some more aggressive sharpening and give it another go.  Tuning wise, I'm damed at either end, since the band that gives me the highest contrast and sharpest Ha also delivers me the most aggressive full-on hotspot, totally obliterating the lower right corner of the frame.  If I tune out the hotspot (or down as much as I can) then I get a darkening gradient towards the top left, with it almost blank there in terms of detail (hence why I needed to crop).  Regarding magnification, I thought that was fixed as a function of my focal length?  Or can I expand the FOV artificially somehow?  I had always thought the native F10 of the PST (and the TAL) had been altered by the size and position of the blocking filter (75mm I think about half way down the tube).  My images posted up here are after I'd cropped out the upper left blank bits... which unfortunately meant I lost the upper and left good parts of the crop (thinks... maybe CS will let me literally chop the corner off, thus preserving the rest?) 

I had a brief look at EQMOSAIC as a possible way to scan the panes more methodically, but it needs to know the exact FOV of the setup, and I have no idea how to calculate that as it's been modified (not by me!).  Has anyone had any luck with that program?

In the meantime I'll maybe go back to trying with the basic PST, and someone has pointed me at a good CS vignetting/gradient removal tool so once my CS skills are up to speed I'll have a go and report back for the benefit of anyone else having similar problems!  Sooo frustrating, as from a single pane I can get some absolutely lovely detail, but my full disk dreams continue to elude me.

Thanks again

Andrew

[DrRobin]

Hi,

I think I would be tempted to use the TAL mod for close ups only, it sounds like there are going to be too many issues to try and get good detail across the full frame.  Tune it to the best detail and crop the parts that are off band.  Mosaics require quite a lot of things to come together, good detail, reasonably flat images and plenty of overlap.  I took a 15 pane mosaic last night, the most I have ever done, but thanks to my USB3 camera, it captured all 15 panes in 5 minutes, including moving the mount.  The detail in the individual frames was great and as a result with lots of overlap Autostitch worked really well.  You can see the result here:

http://stargazerslounge.com/topic/223417-sun-in-ha-15-pane-mosaic-21814/

If you want to do full disc mosaics, try the PST in standard configuration, but put a 1.5x or may be 2x barlow on your camera to narrow the FoV and therefore make the best of the sweetspot.

You will probably find that most people using a PST will have to crop their images to remove the some sort of bright or dark patches.

Just another thought about flats, Firecapture will apply a flat to the video on the fly.  You take a flat, save it then use it as you capture.  I haven't tried it (I don't bother with flats), but that might be a partial solution.

Robin

[Ibbo!]

I managed to get 4 of the panes to stitch.

I do 20 pane FD with my Vixen mod PST

I do 500 frames /panel and stack 50 of each

I use The sky to control the scope I have done the size by trial and error and come up with a 13 x17 box

DMK31 and a 50% overlap to help with registration and the sweetspot problems but it does ot always work esp if there is cloud around

I also use a flat using a thin plastic bag to defocus the sun, the flats don't always work

They are not brilliant by the standards of the experts but OK

http://www.astrosphere.org.uk/astrophotography.htm

I must admit it was a lot easier with a 2 pane job I did with a visiting Lunt 60mm ss

might be easier with this link

http://www.astrobin.com/users/Ibbo/

[Davey-T]

Hi Notty, only had a quick play with your subs last night and will try to spend more time on it and produce some sort of disc.

Don't give up, suffering's good for the soul they say

Dave

[Notty]

Dave, if you can make a silk purse (or even a nylon one) from this sow's ear I'll be amazed, thrilled and very indebted!  I'm trying to upload all the post stacked files as .tifs to my photo bucket album... this is how they came out of AS! and have had no cropping or sharpening applied, I think this is what you were after?  I think the last 3 disasters were attempts at flats....

http://s935.photobucket.com/user/NottyReptile/embed/slideshow/

[Notty]

Oh dear!  Well at least it's a circle.  On the bright side I've just learned quite a lot about the abilities of Photoshop to manually achieve this.  If I can get some better data with larger overlaps then maybe I can hide those dreadful joins!  I'm determined to crack this; the PST mod does show some lovely detail.