Is it worth Re-Coating?

[FtDeSoto]

I am not what you would call an astronomer by any stretch of the imagination. I basically have a Meade ETX105EC that comes out to play every now and again when the planets are on view or if i fancy having a look at the sun "With Filter".

Recently i purchased a what i describe as a "Home Made" Russian Dobsonian, it is 6ft tall 12 inch tube and 10 inch mirror. When i bought it i knew the mirrors were filthy and now realise they are in need of replacing or re-coating. I only paid £85 for it and the mirrors will cost around £150 to re-coat.

I honestly have no clue whether it is worth it or not which is why i am asking on this forum. Any advice would be greatly appreciated. I mean i do not even know what the orange light thingy is.

I am quite excited to see if i could get some use out of it

[Carbon Brush]

From a single photo of the general assembly, it is difficult to know the general quality of the scope.
This does of course determine whether it worth effort, or how much effort.

It appears that the eyepiece holder is missing from the focusser.

Can you get a close up pic of the 'orange thingy'?

Have you had the mirrors out? They may have a name or serial number on the back that allows identification.

Have you tried cleaning the mirrors?
Last year I cleaned up a 10" mirror that was almost grey and is now almost like new.
Even 'mucky' mirrors often give really good results.

HTH, David.

[markse68]

Is it really Russian? Could have a Lomo mirror which I think are highly regarded if it is? What is the strange sight thing that looks like a baby’s bottle?

Edited December 12, 2019 by markse68

[FtDeSoto]

I thought that about the focuser but on putting an eyepiece in it was pretty tight, i think i will buy another though.

I have attached photo of "Orange Thingy"

I have taken the mirrors out and the secondary is pretty much fine but after i cleaned the primary i saw it has lots of spider like black marks on it see image. There are no numbers on either mirror.

[Peter Drew]

It appears to be a "Dark Star" brand Dobsonian.  Keith, the original proprietor used whatever mirrors were available or specified by the customer.  Some were very good so you could be lucky.   Worth the purchase price plus the recoating if necessary.    🙂

[FtDeSoto]

2 minutes ago, Peter Drew said:

It appears to be a "Dark Star" brand Dobsonian.  Keith, the original proprietor used whatever mirrors were available or specified by the customer.  Some were very good so you could be lucky.   Worth the purchase price plus the recoating if necessary.    🙂

It does yes, thanks for that

[Alan White]

10 minutes ago, Peter Drew said:

It appears to be a "Dark Star" brand Dobsonian.  Keith, the original proprietor used whatever mirrors were available or specified by the customer.  Some were very good so you could be lucky.   Worth the purchase price plus the recoating if necessary.    🙂

I thought the same Peter,
but not having owned one was using the old grey matter, which is a dangerous thing these days!

Looks worth a re-coat.
I think the Russian angle is being determined from the orange / red light fitted by a previous owner.
That light looks like something off a life belt or vest.
 

[John]

To give you an idea of whether it's worth investing in, an excellent condition 10 inch dobsonian by Skywatcher would cost around £280 on the used market.

 

[Chris]

Are there any markings on the back of the mirror which could indicate how well figured the mirror is e.g 1/4 wave is average diffraction limited, but 1/8 or 1/10 would have a very good quality figure. 

Having said the above, even with a 1/4 wave mirror you wouldn't be getting ripped off paying for a recoat considering what you paid. 

[FtDeSoto]

12 minutes ago, Lockie said:

Are there any markings on the back of the mirror which could indicate how well figured the mirror is e.g 1/4 wave is average diffraction limited, but 1/8 or 1/10 would have a very good quality figure. 

Having said the above, even with a 1/4 wave mirror you wouldn't be getting ripped off paying for a recoat considering what you paid. 

There are no numbers or anything else on the mirror. Sorry

[AdeKing]

1 hour ago, Peter Drew said:

It appears to be a "Dark Star" brand Dobsonian.  Keith, the original proprietor used whatever mirrors were available or specified by the customer.  Some were very good so you could be lucky.   Worth the purchase price plus the recoating if necessary.    🙂

Yes, it looks like a smaller version of the 12" that I've been told I must get rid of. 

[NGC 1502]

+1 for above.......regarding the focuser, zooming in on the first pic it appears nothing is missing. It’s a regular rack & pinion, but the eyepiece holder is friction fit - the split you can just see can be adjusted to suit.  You need to get it just right, not too tight or it’s hard to change eyepieces without moving the scope off target.   

Ed.

[FtDeSoto]

1 minute ago, NGC 1502 said:

+1 for above.......regarding the focuser, zooming in on the first pic it appears nothing is missing. It’s a regular rack & pinion, but the eyepiece holder is friction fit - the split you can just see can be adjusted to suit.  You need to get it just right, not too tight or it’s hard to change eyepieces without moving the scope off target.   

Ed.

I did wonder as my Meade Supers fit perfectly in.

[Paul M]

The primary mirror does look grotty and the fine scratches suggest to me that the coatings are absent or poor quality. But it might just be worth gently cleaning it (and the secondary) and then reassemble and collimate to see how it performs. You might be lucky and get some good views through it.

Search these forums for threads on mirror cleaning. It isn't rocket science, just needs some Fairy Liquid (other brands of washing up liquid are available) and a gentle touch.

Anyway, how much does it cost to re-aluminise a 10" mirror these days?

[FtDeSoto]

28 minutes ago, Paul M said:

The primary mirror does look grotty and the fine scratches suggest to me that the coatings are absent or poor quality. But it might just be worth gently cleaning it (and the secondary) and then reassemble and collimate to see how it performs. You might be lucky and get some good views through it.

Search these forums for threads on mirror cleaning. It isn't rocket science, just needs some Fairy Liquid (other brands of washing up liquid are available) and a gentle touch.

Anyway, how much does it cost to re-aluminise a 10" mirror these days?

Orion Optics have quoted me around the £150 mark plus shipping but i would probably take it an collect when ready.

[fozzybear]

you could have a chat with galvoptics UK based as well

https://www.galvoptics.co.uk/optical-components/telescope-products-andamp-services/telescope-mirror-coating---primary/

[wormix]

Vacuum Coatings seem to be very well priced and a quick forum search suggests they do good work;

 

http://www.scientificmirrors.co.uk

[Carbon Brush]

Perhaps someone with more experience of damaged mirrors might comment on this....

A well figured mirror will still give sharp stars - not ovals, not splodges. If you can get some decent shiny areas to show after cleaning.
They will be dimmer than 10" mirror expectations. But will help decide if i worth spending on a recoat.

If the coating is really bad and there aren't any decent flat shiny areas, you can't rely on the above.

Just a thought, awaiting comment from someone more knowledgable.

David.

[John]

I think you can get some sort of image from an uncoated mirror. Enough to see if the figure is decent anyway.

[Starflyer]

On 12/12/2019 at 18:12, FtDeSoto said:

Orion Optics have quoted me around the £150 mark plus shipping but i would probably take it an collect when ready.

Make sure this is including VAT, OO do not usually include VAT in their quoted prices.