Ovoids with Mesu and Tak FSQ 85

[gnomus]

I am no DSO imager, but I do now something of optics. My physics intuition would be that a slight tilt would result in a band of sharpness across the image, at right angles to the "slope". It almost looks like the optics have some cylindrical distortion, caused by some lack of collimation, perhaps.

Thanks Michael. I am no expert, but it was telling that when I asked why one-axis tilt would cause the radial elongation (or cylindrical distortion as you put it) he didn't really have an answer.

[gnomus]

Thanks Zakalwe. I had thought about the CC company (I did use a card). I've never done that before though. Do they recoup the dough from the retailer?

[Zakalwe]

Thanks Zakalwe. I had thought about the CC company (I did use a card). I've never done that before though. Do they recoup the dough from the retailer?

Under Section 75 of the 1974 Consumer Credit Act the card issuer jointly and severally liable for any breach of contract or misrepresentation by the company, as long as the item cost was more than  £100. So you can make a claim through the card issuer without even talking to the retailer, though in most cases you would normally (as you have done) speak to the retailer first. As the card issuer is jointly liable, they have an obligation to you regardless of the retailer's position.

More info here:

http://www.which.co.uk/consumer-rights/regulation/section-75-of-the-consumer-credit-act

http://www.moneysavingexpert.com/shopping/section75-protect-your-purchases

[DanL]

But - and just playing devils advocate here as I thoroughly sympathise - wouldn't that only apply if the item was faulty or misrepresented? What's the situation if Takahashi themselves say that it's within acceptable manufacturing tolerances?

[gnomus]

But - and just playing devils advocate here as I thoroughly sympathise - wouldn't that only apply if the item was faulty or misrepresented? What's the situation if Takahashi themselves say that it's within acceptable manufacturing tolerances?

Takahashi say that their scope will give 'pinpoints' out to 22 mm from optical centre. In the examples that I have posted do you see pinpoints at 12.5 mm from optical centre? Secondly, are you suggesting that if a company sells me a duff product, but then say that it is OK, I am just supposed to accept that?

Perhaps you are just teasing me, in which case I apologise for rising to the bait.

[ollypenrice]

Takahashi say that their scope will give 'pinpoints' out to 22 mm from optical centre. In the examples that I have posted do you see pinpoints at 12.5 mm from optical centre? Secondly, are you suggesting that if a company sells me a duff product, but then say that it is OK, I am just supposed to accept that?

Perhaps you are just teasing me, in which case I apologise for rising to the bait.

And there you have them.

Olly

[DanL]

Absolutely no intention to bait! Naturally your [removed word] as any one of us would be too. It was just meant as a curious question based on what your supplier was saying and the reluctance to replace it. Honest!

[DanL]

My [removed word] can be replace with "very annoyed"!

[Zakalwe]

The card issuer may try and reject the claim if the retailer has rejected it.

If one was to make a claim under S75 and declined to offer the information that the retailer has supplied, but rather showed the maker's specifications and your finding showing those specs to be in doubt, then I would suspect that such a  claim may be stronger.  You are under no obligation to tell the card issuer that the retailer has rejected a claim, as the card issuer is jointly and severally liable. You are free to pursue a claim with the retailer or the card issuer.

An independent optician's report would nail it, but that would incur costs which the claimant would then have to pursue. The mention that the  costs of such a test would be added to the S75 claim might also influence the card issuer to come to a sensible decision....

[gnomus]

The card issuer may try and reject the claim if the retailer has rejected it.

If one was to make a claim under S75 and declined to offer the information that the retailer has supplied, but rather showed the maker's specifications and your finding showing those specs to be in doubt, then I would suspect that such a claim may be stronger. You are under no obligation to tell the card issuer that the retailer has rejected a claim, as the card issuer is jointly and severally liable. You are free to pursue a claim with the retailer or the card issuer.

An independent optician's report would nail it, but that would incur costs which the claimant would then have to pursue. The mention that the costs of such a test would be added to the S75 claim might also influence the card issuer to come to a sensible decision....

I had understood that if you go to the CC company they will ask why I have not approached the retailer. I may go down the CC route but it does seem unfair to me that the supplier can get away with this shoddy service. I know that there are costs involved in going to the Court but these are not too bad and at least I do understand this system, having used it before. Furthermore, Court costs can (and should) be added to the claim. Edited November 10, 2015 by gnomus

[gnomus]

My [removed word] can be replace with "very annoyed"!

... or 'very drunk' perhaps?

[Zakalwe]

I had understood that if you go to the CC company they will ask why I have not approached the retailer.

They can ask all they want, but you have no obligation to go to the retailer first or even at all. The law is clear- they are jointly and severally liable. This means that they are as liable, no more or no less, than the retailer. There is no "first point of call"- you have complete freedom to claim from the card issuer first if you so wish. If the card issuer takes this approach, then you might want to point the at case 86/08 on the Financial Ombudsman's website:

http://www.financial-ombudsman.org.uk/publications/ombudsman-news/86/86-consumer-credit.htm

"card provider refuses to consider claim under section 75 until consumer has first pursued the matter direct with the supplier:

complaint upheld

We were satisfied, from the evidence Miss V had provided, that the dinner service was not a matching set. So she had not been given what she had paid for with her credit card. Under section 75, she could seek redress from the supplier of either the goods or the credit.

We thought Miss V had taken reasonable steps to try to resolve matters with the supplier. Despite what the card provider appeared to believe, however, she was not obliged to have done this - or indeed to have returned the dinner service - before she could make a claim to the card provider.

We told the card provider that Miss V was not obliged to exhaust all possible avenues with the supplier before claiming under section 75. And we said we could see no reason why it should not pay the claim. The card provider argued that if it gave Miss V a refund then she would still have the dinner set, as well as getting her money back. It did not think this was fair." (emphasis mine)

Of course, you will be asked to prove your claim.

 I know that there are costs involved in going to the Court but these are not too bad and at least I do understand this system, having used it before. Furthermore, Court costs can (and should) be added to the claim.

Yes, you could go down the Moneyclaim route. perhaps a written notification to the retailer might jog his/her conscience into action, especially if you remind them that the costs are claimable if you win. A S75 claim may be easier and faster.

[gnomus]

They can ask all they want, but you have no obligation to go to the retailer first or even at all. The law is clear- they are jointly and severally liable. This means that they are as liable, no more or no less, than the retailer. There is no "first point of call"- you have complete freedom to claim from the card issuer first if you so wish. If the card issuer takes this approach, then you might want to point the at case 86/08 on the Financial Ombudsman's website:

http://www.financial-ombudsman.org.uk/publications/ombudsman-news/86/86-consumer-credit.htm

"card provider refuses to consider claim under section 75 until consumer has first pursued the matter direct with the supplier:

complaint upheld

We were satisfied, from the evidence Miss V had provided, that the dinner service was not a matching set. So she had not been given what she had paid for with her credit card. Under section 75, she could seek redress from the supplier of either the goods or the credit.

We thought Miss V had taken reasonable steps to try to resolve matters with the supplier. Despite what the card provider appeared to believe, however, she was not obliged to have done this - or indeed to have returned the dinner service - before she could make a claim to the card provider.

We told the card provider that Miss V was not obliged to exhaust all possible avenues with the supplier before claiming under section 75. And we said we could see no reason why it should not pay the claim. The card provider argued that if it gave Miss V a refund then she would still have the dinner set, as well as getting her money back. It did not think this was fair." (emphasis mine)

Of course, you will be asked to prove your claim.

Yes, you could go down the Moneyclaim route. perhaps a written notification to the retailer might jog his/her conscience into action, especially if you remind them that the costs are claimable if you win. A S75 claim may be easier and faster.

OK Zakalwe I will think about that. If I go down the S75 route, does the scope go back to teh supplier or do the CC company own it?

[Zakalwe]

If successful the card issuer will advise what to do. The retailer won't come into it as the claim is handled by the card issuer.

[strutsinaction]

Hi John

If you decide to take your own issues further, then it would be interesting to hear what Mr King has to say. I use a different supplier.

Steve

I sent Ian King a few subs and he thinks this type of radial distortion at the corners is a collimation issue rather than mechanical tilt. He's sent my subs off to Takahashi Europe for further investigation. If they suspect a collimation issue then I'll have to return the scope to Ian for replacement or repair. In the meantime I still intend to do the zenith test when the skies clear.

Regards

John

Edited November 11, 2015 by strutsinaction

[ollypenrice]

Radial distortion cannot be tilt. Simple as that. Ian King's opinions need no endorsement from me but, FWIW, I do agree with him.

You might well find tilt in CCDI on Steve's images but that tilt cannot be the cause of the problem. (You might find a crack in your car's windscreen but that won't be why it doesn't start.)

Olly

[sharkmelley]

Radial distortion cannot be tilt. Simple as that.

I don't know how you can be so certain on that point.

Let's first clear up a question of terminology.  The elongation we are talking about does not take place in the direction of a radial line (i.e. towards the centre of the image) but perpendicular to it i.e. in the direction of the circumference.  For the purposes of this discussion I will refer to this as elongation in the tangential direction.

Forget about tilt for the moment and just consider a very slight defocusing of a star field on a perfectly orthogonal sensor on an optically perfect FSQ85 i.e. an FSQ85 exactly as designed.  In the centre of the image, a slightly defocused star will become larger but it will remain circular in shape.  However, it is not intuitive what will happen to the shape of a star at the edges of the image when defocused.  We already know from the spot diagrams that an in-focus star has various strange distortions in shape.  It would not be surprising if those distortions became more severe when defocused, leading to obvious elongation.  From experience on my Tak Epsilon (admittedly a scope with very different optics) a star at the edge of the image elongates in the tangential direction as it defocuses.  It would not be at all surprising to me if the same happens on the FSQ85.

Now let's consider the effect of tilt.  Tilt will cause part of the sensor to lie in the focal plane but most of the sensor will be out of the focal plane to varying degrees.  Typically the centre of the sensor will be in focus and most of the edges will be out of focus.  If these out of focus edge stars all exhibit tangential elongation then we end up with an effect very similar to the example images earlier in this thread, all caused by a simple tilt.

Furthermore, Takahashi appear to be saying that they think the effect is caused by tilt.  Not only that but they also provide an estimate of the amount of tilt. I see no reason to doubt that diagnosis - their engineers should understand the optics of the scope in great detail.  I struggled for weeks with tangential elongation on my Tak Epsilon which I finally realised was caused by tilt.  It's the main reason I ended up writing that PixInsight script illustrated earlier, because CCD Inspector really didn't provide a useful analysis of the problem.

Mark

Edited November 11, 2015 by sharkmelley

[ollypenrice]

Hmmm... I'm not sure it's Takahashi engineers who've been looking at this so much as the Tak importer who is essentially a retailer.

I've seen never seen tilt produce what looks like a spherical distortion and one limited almost entirely to the corners. The CCDI curvature test shows curvature on the extreme right hand side and at its worst in the two affected corners.

Of course I could be quite wrong but I cannot see tilt behaving like this.

Olly

[sharkmelley]

You're probably right then.  If you've never seen tilt cause those kind of distortions, I'm happy to stand corrected.  After all, you have experience with those Tak FSQ scopes which I don't have.

Mark

[strutsinaction]

If you decide to take your own issues further, then it would be interesting to hear what Mr King has to say. I use a different supplier.

If it's any consolation Steve I think my corner star elongation/distortion is worse than yours   See my latest image here:

http://stargazerslounge.com/topic/256830-ngc281-pacman-hoo/

Jury still out on this for me (at least, nothing from Mr King or Takahashi yet), although I have my suspicions that in my case it could be due to poor focussing.

Regards

John

[gnomus]

If it's any consolation Steve I think my corner star elongation/distortion is worse than yours   See my latest image here:

http://stargazerslounge.com/topic/256830-ngc281-pacman-hoo/

Jury still out on this for me (at least, nothing from Mr King or Takahashi yet), although I have my suspicions that in my case it could be due to poor focussing.

Regards

John

It doesn't look out of focus to me John, but it does, as you say have that radial elongation effect.  Once I saw it in my images I kept imagining 'join-the-dots' type circles around the image (if only they were dots, eh?)

I don't know if they are worse than mine from the size of image you posted.  I assume these are from your QSI 690 which has a physically smaller size, so will be looking at a smaller part of the 44mm 'flat' circle than my sensor.  But I don't know what effect your smaller pixels would have on ovoid-osity (I think I may have invented that word).

I downloaded an evaluation version of CCD-Inspector.  It is pretty easy to use and it might help you to put some 'numbers' to what you are seeing.  However, I'm not sure that I am happy that I now know about this software - it might turn me into even more of a measurebator than I already am.  (That word by the way is I believe copyrighted to a certain Ken Rockwell.  I hope it causes no offence - but it is a perfect term for what can happen to some of us).

[strutsinaction]

When I had the same issue with my Tak 85, it was suggested to me that I should try offset focusing. Now, I was prepared to consider this on a camera lens or cheaper telescope but not on an instrument at this price point - that was not what I bought in to!

I expected a flat field on an 8300 sensor but that's not what I got so it went back. Perhaps my expectations were too high (?) but then, so too was the promise!

Offset focusing might be worth a try for you and if you are happy with the results - and many owners must be - then you have the solution. At least you can now rule out focus slop leaving you with CAA adjustment, sensor tilt or the plain fact that the field is not perfectly flat for your sensor size.

I hope this turns out to be an adjustment for you because the potential FOV of the Tak 85 makes it a very desirable instrument.

FSQ85 offset focussing mentioned here (courtesy of sharkmelley):

https://groups.yahoo.com/neo/groups/UncensoredTakGroup/conversations/topics/59070

I'm going to try this next time I'm out imaging.

Regards

John

[Phillyo]

I've joined this thread late so please forgive me if this has already been suggested or the issue has been solved (I read first page then skipped to last one), but a very simple and easy way to check your images for Polar Misalignment is to do a no rejection stack in pixinsight. You will have something that looks like the image posted. This is basically an overlay of my subs and you can see that everything was revolving around a point just out of frame, which turns out to be the star my OAG was using to guide. So although my guide graph was lovely and level, the image was rotating around that star slightly due to not being accurately polar aligned.

If this is no use or I've just made a fool of my self then feel free to ignore/delete the post

Phil

[gnomus]

It's good to know of this PI feature, but if you had read the whole therad you would have seen that we eliminated polar misalignment a few pages back.

[gnomus]

FSQ85 offset focussing mentioned here (courtesy of sharkmelley):

https://groups.yahoo.com/neo/groups/UncensoredTakGroup/conversations/topics/59070

I'm going to try this next time I'm out imaging.

Regards

John

It will be good to know how you get on, but surely this should be unnecessary if we had a flat field, as promised.