Adding Longer Focal Length Data to Widefield Images

[Rodd]

I thought I would share this with those of you who have an interest in bringing out details n wider field shots.  I suppose if one has a 24" scope and a really big sensor, there would be no need fr this approach.  But if you are not fortunate enough to have something like that, this works quite well as a substitute.  One neddn't have 2 scopes--one scope and a reducer will work.  But I think having two scopes is better., specially if one is bigger aperture...otherwise, we may get bogged down in the quagmire of the focal reducer.....debate.  Heaven forbid.  To prevent that, use two scopes of different apertures.  It doesn't take much.  I used a 4" refractor and a 5" refractor.  The 4" refractor was reduced to a focal length of 318mm (and one at 432 mm) and the 5" refractor was native at 1,000mm.   I am not sure of the limits, i.e. how much of a difference in focal length can be tolerated by the software.  I think quite a big difference if you use the right approach.  I think the big issue is registration.  If the bsoftware can't register the two images, all bets are off.  Pixinsight has done pretty good--I'd say about an 80% success rate.  After registration, you use the higher focal length image as a mask and replace that portion of the data using pixel math--or a portion of it.  In actuality I think its a blend of datas unless you keep replacing several times.  Another important thing is to keep the two images similar in brightness.  Well--thats it.  I have wanted to do this for A LONG TIME and could not figure out how.  I finally was able to do it.  Here are two examples that I consider my best in terms of impact to the image and overall image quality.  Now, the proud folks at PI will tell you that this is blasphemey, for they regard it as "painting".   I don't see how rendering an image using this method can in the remotest be considered painting.--no more so than using a bit of moise contrl, or sharpening, or even a simple crop.   One stays true to the data.  The photons are going exactly where they belong.  There is no tricks with palette (`other than wnat is normally done to either image).  It is simply a chaoice of hardware.  Next they will say if you use a really big scope and a truly massive sensor with small pixels to achieve a wide field image with superior resolution, t'would be a capital ofense.  No sheffif in town, bubba, so I couldn't have shot one!

 

Sh2-132: The wide field was taken with a Televue np101is rduced my .8x to 432 mm (with STT-8300).  The head, or core, was taken with a TOA 130 native and the ASI 1600.  3nm filters were used for both.  First image is the before, and second image is the after.

 

 

IC-1396.  The widefield was taken with the FSQ 106 reduced by .6x to 318 mm and the Elephants Trunk column was taken with the TOA native--The ASI 1600 was used for both with 3nm filters.  First image is before, second image is after.  

 

[happy-kat]

To give this due attention I'll have to take a read and look from the PC, though can see the additional enhancement benefit from the combined images.

[Kinch]

Yes indeed, one can see the detail coming through. I wonder how much time is involved. Me being a lazy type....I am not too sure I would bother but then again if one wants to be 'Tops', one has to bother..... I guess.

On the other hand....the way I am set up....I just use one scope & one camera for months on end. I change camera only if I see a big change in field/resolution is required. Perhaps, whenever I get a duel system up & running....then this might method might provide some fun.

[Rodd]

4 hours ago, happy-kat said:

To give this due attention I'll have to take a read and look from the PC, though can see the additional enhancement benefit from the combined images.

That's it really--just that.  The images look so much better on a high resolution monitor.  The difference is very noticeable.  On my el-cheapo screen at work I have to say....eh.  then again, that goes for the whole image

[Rodd]

4 hours ago, Kinch said:

Yes indeed, one can see the detail coming through. I wonder how much time is involved. Me being a lazy type....I am not too sure I would bother but then again if one wants to be 'Tops', one has to bother..... I guess.

On the other hand....the way I am set up....I just use one scope & one camera for months on end. I change camera only if I see a big change in field/resolution is required. Perhaps, whenever I get a duel system up & running....then this might method might provide some fun.

No need.  With that FSQ 130 you can shoot a widefield at F3 if you have the .6x reducer--which is what I use with the FSQ 106, and then you can shoot with the 1.6x extender and if the seeing is good, you will get a benefit.  It might not be like Olly's addition of a 14" to a 140mm (Meade and TEC 140), but all it takes is an edge.  I am the same way--I shoot with a scope for a year or more.  These images represent data sets collected more than 1 year apart, and for sh2-132, almost 3 years apart.  You know, the C11EDdge is only $3,500...other scopes of similar size and price abound.--not a huge investment (I know, if the bus cost a dime and you only have a nickle...you'r walkin).   having a second longer focal length scope makes sense if you have an inclination to shoot galaxies at a longer focal length.  The TOA 130 does a fine job with larger to mid sized galaxies--but to get the smaller ones, more aperture is really needed.    I don't think I could stand only 1 scope--2 is perfect,   The fact that I have 4 is me losing control.

[Kinch]

4 minutes ago, Rodd said:

I don't think I could stand only 1 scope--2 is perfect

🤣....I actually have two....the FSQ130 and also my FSQ106. I hope to put them side by side when a new mount comes this way. Who knows, I may set up the 130 with the extender and the 106 with the reducer; I have not planned that far ahead yet. (I actually have a 3rd....an old Meade 8" SCT - bought 2nd hand. This is one I may pull out when I have visitors.....they always want/enjoy a look through a telescope and there is no way that I will disturb the my camera for that - no matter who the visitor is).

[Rodd]

BTW--here is the original sh2-132 after the longer focal length data was added.  I thought it a bit too garish.  But it does look better on my cheap screen, so who knows.

[Rodd]

2 minutes ago, Kinch said:

🤣....I actually have two....the FSQ130 and also my FSQ106. I hope to put them side by side when a new mount comes this way. Who knows, I may set up the 130 with the extender and the 106 with the reducer; I have not planned that far ahead yet. (I actually have a 3rd....an old Meade 8" SCT - bought 2nd hand. This is one I may pull out when I have visitors.....they always want/enjoy a look through a telescope and there is no way that I will disturb the my camera for that - no matter who the visitor is).

All you need is the .6x reducer--which will work on both FSQs.  That way you shoot at 318mm and 600 mm? (not sure what the FSQ 130 native is.  the TOA is 1,000, but the FSQ 130 is 600-800 I think

[Kinch]

41 minutes ago, Rodd said:

All you need is the .6x reducer--which will work on both FSQs.  That way you shoot at 318mm and 600 mm? (not sure what the FSQ 130 native is.  the TOA is 1,000, but the FSQ 130 is 600-800 I think

I have both Extender & Reducer....each works with either scope. I have lots of choices :-). (FSQ130 is 650).

[Rodd]

27 minutes ago, Kinch said:

I have both Extender & Reducer....each works with either scope. I have lots of choices :-). (FSQ130 is 650).

Then you are all set.  I don't advise trying to do it in one session, as that would entail a switch and we both hate switches.  But with a little planning, you are bound to image something at 800mm and the same region at 318...or even 500...at a later date.   That's what I did.  I went through my library and found images I shot long ago that I had revisited at a longer focal length.  There were 7 or 8.  Now I plan on planning for it.  I have been shooting with the TOA for over a year.  I plan on switching to the FSQ as soon as I finish the Helix.  I am sure I will have more overlapping datasets after the switch.  Unfortunately I shot a lot of galaxies so there might not be as many as I would like.  It is sort of a long game approach I suppose.   I am never satisfied with a result and tend to revisit data sets perpetually as I improve--this is just one more tool to amp image quality. 

[Rodd]

This was my last hoorah.  Only posted because I was asked not to leave.  I don't have anything better to offer than this--and I probably won't anytime soon.   What more do you want, a couple of pretty decent images and a pretty cool bit of acquisition and processing. 

If anyone needs me I am on Astrobin under RAD...always willing to share data and give CC when asked. 

I am no longer following this thread, so no need to respond for my sake.  I can't take the stress, SGL brings me down.  Life is hard enough.

CS to all.