Takahashi FSQ106ED - am I expecting too much?

[Steve 1962]

Thanks for your comments everyone (EDIT - some of which have crossed in the post) . Of course it's fine to resave it to your SmugMug Olly - I really appreciate your help.

PeteL and Earl - I will try your suggestion next time it's clear.

These are 400% zoomed crops of the first FIT file (030811) which I have just done a Pix insight Histogram Transform (Stretch and Black Clip) on:

Bottom Left

Bottom Right

Top Left

Top Right

Persoanlly, I definately see eggs in the TL and BR, the BL looks spot on and the bright star TR slightly less round to me.

This nicely sums up the reason for my post. I can see eggs, but Olly's view is that it's pure "Tak". 

Even though I can see eggs - should I be happy with the scope? I expected to be feeling  than   having spent so much on this.

Thanks again for everyone's help.

Steve

[Earl]

Are those corners from the image Olly posted as they look diffrenet

[Steve 1962]

Yes - I think they are from the same image (Frame 4) Earl - for some reason Olly version is vertically flipped from mine. Not sure how that's happened; it looks the same way up in SGP, Neb 3 and Maxim at my end!

[ollypenrice]

If you can consistently get images which will hold up at 100% in terms of noise, star reduction artefacts and a host of other challenges then you're doing really well in my view. You need a huge amount of data to do this. So if the stars look OK at 100% I feel they're more than good enough for any image you're likely to present. Just my view and perhaps I'm overly casual - but I think it's the whole picture that counts. I think you'll get cracking results from this.

Re the flip, I find that Artemis gives me the image in the true orientation of the sky whereas Nebulosity (in which the other camera runs) gives a horizontal flip. Beats me!

Olly

[Steve 1962]

Thanks again Olly - I think I just needed my feet planting firmly on realistic ground.

I think I'll stop worrying and tinkering until I've got a full image run done and see what happens.

All I can say about the flip is thank goodness for Registar and PI!!

Watch this space!

Steve

[Owmuchonomy]

Thanks again Olly - I think I just needed my feet planting firmly on realistic ground.

I think I'll stop worrying and tinkering until I've got a full image run done and see what happens.

All I can say about the flip is thank goodness for Registar and PI!!

Watch this space!

Steve

Mine are worse than yours so I think you are right. I can see eggs on your sub on my iPad though but Olly has to crop a lot so maybe it's my iPad, or worse its me!! :-0

[Gina]

A very slight eggyness perhaps but really that's very good   I can understand nit-picking when you buy something new but really your image is superb.  Few could stand that much zooming in.

[perfrej]

If you can consistently get images which will hold up at 100% in terms of noise, star reduction artefacts and a host of other challenges then you're doing really well in my view. You need a huge amount of data to do this. So if the stars look OK at 100% I feel they're more than good enough for any image you're likely to present. Just my view and perhaps I'm overly casual - but I think it's the whole picture that counts. I think you'll get cracking results from this.

Re the flip, I find that Artemis gives me the image in the true orientation of the sky whereas Nebulosity (in which the other camera runs) gives a horizontal flip. Beats me!

Olly

The flipped image situation comes from two different ways to interpret the FITS specification. Both are correct, and Pixinsight's version actually more "professionally" so (i.e. more common in professional observatories). PI has a setting for this so you can get them "flipped" if you like.

/per

[perfrej]

This is a long read right now, but if I back up to the opening post and study the CCD Inspector analysis, I'd be inclined to say: "Just adjust the focuser". The firrst step is to just add 1/8th of a turn or so to each of the four recessed (and glued) tinu grub screws offset 120 degrees from the top plate. Screw exactly the same amount on each and check the sag tendency with the focuser extended. It should become slightly harder to turn, but not too much.

If that adjustment doesn't make it straight and there is no sag you have to collimate it . an operation I wouldn't perform unneccessarily.

On a side note I think that your's is reasonably good and will probably improve a little

/per

[libraryman]

This is a long read right now, but if I back up to the opening post and study the CCD Inspector analysis, I'd be inclined to say: "Just adjust the focuser". The firrst step is to just add 1/8th of a turn or so to each of the four recessed (and glued) tinu grub screws offset 120 degrees from the top plate. Screw exactly the same amount on each and check the sag tendency with the focuser extended. It should become slightly harder to turn, but not too much.

If that adjustment doesn't make it straight and there is no sag you have to collimate it . an operation I wouldn't perform unneccessarily.

On a side note I think that your's is reasonably good and will probably improve a little

/per

Hi Per..is it your experience that the Tak 106ed focuser can be improved by a diligent adjustment? i need to get a Dial test indicator on mine just to check if there is indeed a little bit of sag.

i have read a number of threads that suggest the 106 focuser can exhibit some flex.

Ray

[perfrej]

Yes, it can sag. When I visited Houston I stopped by TNR and talked to Art himself, and he suggested the delicate adjustment. You do not need a dial test to see it, though, just extend the draw tube, place the scope on a solid work-bench and wrestle the draw tube with one hand while the other holds the scope put. You'll see it easily.

Put a drop of acetone in each of the four screws, wait two minutes and then tighten. Always the same amount on each screw and in very small steps. Tighten until the primary knob gets a little tight to move - just a little.

/per

[perfrej]

Oh, an NEVER touch the four hex screws in the plate on the top of the focuser!

[libraryman]

Cheers Per, I have shot a mail of to Ian King, just to check if my warranty remains in tact if I find that it needs a little adjustment

Ray

PS thanks for the warning on the top screws.

[ollypenrice]

Very good information from Per. Thanks mon brave.

Olly

[Steve 1962]

Thanks for the info Per. Do you know if the four 120 degree screws just adjust the focuser tension and adjust out any sag, or do they also "collimate" the focuser (I.e. Move it side to side or up and down) ?

Cheers

Steve

[perfrej]

They push the bearing holders up towards the tube. The actual collimation plate that determines where the draw tube then points is the one on top with four recessed screws.

None of these void the warranty, and TNR's Art says it takes some experience to get the collimation right. That's why I recommend you do not touch them

/per