Bresser Messier AR152s cracked objective lens collimation/retaining ring

[badhex]

Hi all

This might be a difficult question to answer without pictures, but I have chance of ownership of a Bresser Messier 152s frac which has some damage, and want to check whether repair will be at all feasible before make an offer.

I'm awaiting a picture but from the description it sounds like the objective lens retaining/collimation ring has one of the 'legs' cracked/broken off. I nicked a reference picture from SnakeyJ's thread on the same scope, hope you don't mind if you are reading Snakey... will post the proper one once I have it.

Anyone know if this kind of thing would be repairable or worth bothering with? Any owners of the scope who could let me know what the ring material is made of?

Spoke to Telescope House briefly but they said without picture they couldn't really help.

Thanks in advance...

[SnakeyJ]

No probs on the photo - I'll check on the material tonight for you.

[badhex]

Thanks Jake

[John]

It looks very similar to the Meade AR6 that I used to own. If it is the case, I seem to recall that the cell the objective lens is in is made of metal along with the 3 lugs projecting from it. There are 2 screws that go through each lug and these create a push-pull type lens collimation system with one screw of each pair resting on top of a high impact plastic section of whats called the counter cell (the part thats attached to the scope tube) and the other screw screwing into a metal lined threaded socket in the tops of the plastic section. This arrangement needs to be i) adjustable and ii) solid so that collimation of the objective lens can be adjusted and then held by the push-pull arrangement of the 3 pairs of screws.

I guess it all depends what has broken and what sort of break it is. If it's one of the metal lugs then it might be tricky because these support the objective lens.

I'd want to see a photo / photos of the actual damage before committing to be honest.

[badhex]

Thanks John. I do wonder now if the retaining ring might be replaceable with a Meade version (if they are the same, of course) which might give me a bit more scope for spares, if you excuse the pun

[John]

Thanks John. I do wonder now if the retaining ring might be replaceable with a Meade version (if they are the same, of course) which might give me a bit more scope for spares, if you excuse the pun

They are probably interchangeable as Meade and Bresser are part of the same company I believe. The trick will be to get the spare part which can be surprisingly difficult with mass produced scopes.

[badhex]

John, this was my understanding too - although I'm sure I read somewhere that Meade have sold Bresser. Either way, rebadged. It may help, or maybe I'm just looking too hard for a possible bargain which will become a nightmare...

[JamesF]

If the lug has cracked or is broken off and is metal you may be able to find someone who can weld it back together for you.  I might be a little concerned about how it managed to become damaged in the first place though.

James

[John]

If the lug has cracked or is broken off and is metal you may be able to find someone who can weld it back together for you.  I might be a little concerned about how it managed to become damaged in the first place though.

James

Thats a good point James. It's difficult to see how a blow to that area of the scope could not cause some optical mis-alignment as well.

Personally I'd tread very carefully with this one, request lots of detailed photos plus as much info as possible on the scopes history and, a rather low asking price !

[SnakeyJ]

Hi Joe,

Sorry for late reply but had to settle and get the kids off tonight.    Just removed the dew shield and taken a look and this appears to be cast resin on my scope.   Very tough and initially I thought it might be aluminium with a thick flocking, but scratching the ribs that help centre the dew shield and I can shave off the black material with no sign of any metallic shine underneath.

My hunch would be if this was simply cracked that it would glue very well and there is some space inside and out for some re-enforcement.

Mine is slightly out of collimation and I must admit that I have shied away from attempting this myself.     The scope is quite an unusual design with a 4 element near petzval design and there seems to be precious little information around on a collimating procedure.    I'm really not sure if any adjustment or checks would need to be done on the rear doublet, before tinkering with the objective.

Otherwise it's a nicely made scope and gives some great widefield views.    The RP focuser is solid up to around 80% extension, though I can achieve focus comfortably within this visually with a meade 5000 2" diagonal and all of my current EPs.     Worth noting that the design is not recommended for solar observing.   One other gripe is that the supplied dew shield is not really long enough for damp UK conditions, but can be easilly extended with neoprene.

[badhex]

Hi - you guys are awesome as always! Thanks so much for all the advice.

Jake - no worries, life first, hobbies second

James, John - absolutely right. This was a large concern of mine. Chap says he got it in a job lot and doesn't know much about scopes., but this whole thing started as a possible bargain for a fully working OTA, and seems to have gone downhill from there . I have asked the guy if he serious, he has responded to say He def. wants to sell but to be honest it's looking less than likely unless it's cheap, from my perspective.

I guess we will see...

[Peter Drew]

The lug could be pinned and superglued by drilling a couple of holes through the outer diameter and inserting steel pins through the two parts. It's OK to use a Petzval design for white light  solar provided that a front mounted solar film or glass type filter is used as they prevent any heat entering the tube. It is projection or Herschel Wedge use that is a no-no as the heat would pass through the rear elements. 

[badhex]

Well, the chap has finally sent me pictures although they don't let me know too much more than I already did. 

Looking at it, if he can confirm that there is definitely no damage to the lens itself maybe still tempted if the price is right as everything else appears to be in working order. What do you guys reckon? Maybe I'll offer him £50 for parts/as is...

    

[JamesF]

That looks like it might be tricky to repair reliably, though glue may well work if the break is clean and the material suitable.  It doesn't look like it needs to be hugely strong at least.  If the owner is willing to let it go cheaply then it could well be worth the gamble.

James

[philj]

I would strip the objective then cut the remaining lugs off. Spin the cell in the lathe to take the rough bits off. Then turn an ali ring on the lathe that slips over the cell. Drill and tap 3 new lots of screw holes. Then fix the ring to the cell with screws and loctite.

Any sticking the lug back on will not be reliable.

Go for it, theres alot of potential there for a little bit of work

[John]

Looks like it's a Petzval like SnakeyJ has, with a corrector lens set built into the focuser assembly. These can be complex to collimate and the scope will need it with the repairs to the objective cell and having been in pieces. 

If the price was very low I might take it on but it would have to be very low. I bought and sold my Meade AR6 F/8 for just £125 and that was in 100% perfect condition !

[NGC 1502]

Hi Joe, if you are a DIY type, and can buy it very cheaply indeed, could be worth a go, otherwise I'd pass myself.

Good luck, Ed.

[badhex]

Thanks all, I think I will offer him a low price as a project/parts, as discussed there will be some work and cost in getting it up and running, collimation, repairs, finderscope, diagonal etc. 

Hope it's not bad form to ask but what do you think the max you guys would pay for a project like this? He will almost certainly ask me to make him an offer and I really don't want to pay more than I should.

Thanks again for all your help and advice.

[philj]

Its going to take a few hours work and a bit of materials depending on which repair option you go for so take that into account. Collimation isnt complicated but you can use that for bargaining as well. I would start 50 to 60 but not go above the hundred.

If you dont want to take it on pass his details on to me, it looks like a nice little project :-) It would go nicely with my 150 f8 :-) :-)

[JamesF]

If you could potentially buy a similar used scope in very good condition for £125 as John suggests then I don't think I'd be willing to offer more than the £50 already suggested.  It's a gamble.  If there's no other damage to the OTA, the repair is possible and you can get it collimated then you might end up with a reasonable scope for not a huge amount of money.  If there's other damage or a repair isn't feasible then you've quite possibly got a pile of bits that probably isn't worth very much at all.

James

[badhex]

Thanks James, Phil, this is what I'm thinking. If we start with £125, then take off the cost of all the replacement parts and so on I can't see it being worth much more than £50 tops.

I'll let you know how it goes!

[badhex]

Well, I have taken the plunge, and I didn't go over my target price

I'll send some pictures once I've taken delivery.

Wish me luck...

[JamesF]

I look forward to seeing how it goes

James

[philj]

Well done, let us know how you get on Joe

[SnakeyJ]

Well done Joe - looks forward to hearing your repair and first light threads