Could anyone offer me their honest opinion on this dob mirror?
It is a replacement for a previous sub standard one supplied with my scope.
Should this be the norm with GS mirrors or is it lacking that new standard that i expect?
By all means i could be just way too fussy and particular, but without years of looking through an ep to accumulate the knowledge one needs to make this call, i am in need of advice from those that have.
Could anyone offer me their honest opinion on this dob mirror?
It is a replacement for a previous sub standard one supplied with my scope.
Should this be the norm with GS mirrors or is it lacking that new standard that i expect?
By all means i could be just way too fussy and particular, but without years of looking through an ep to accumulate the knowledge one needs to make this call, i am in need of advice from those that have.
All opinions greatly appreciated.
I doubt a photo of the mirror will help ascertain its quality mate.... I'm pretty sure the worst spherical el-cheapo and the finest zillionth wave parabolic would look the same in a photo.... I think you will need to gaze through it, hang on - its a mirror - gaze at it and see what you think.... maybe bring it to a group observing session for opinions....
For a new telescope and/or mirror, I would not expect to see so many "marks". They appear to be dust spots (scattered over the surface) and finger prints (around the edge).
These in themselves may not detract from the otpical quality, but if you paid for a new mirror you deserve to get a clean one with fewer surface markings.
I'd expect a new mirror to be in pristine condition with no marks at all.
The dust is not a problem, every open ended newt will collect dust on the mirror sooner or later.
In the first pic it looks like the mirror has been wiped with a contaminated rag as the smears have a direction to them. I'd be asking myself why the smears are there.
Did they send you a replacement OT or just the mirror or did they replace the mirror in the OT.
It looks like it might need a clean to get the dust etc. off...an open tube newt will always collect dust and such and will need an occasional clean...
Maybe I am not fussy enough and others may jump in and comment but I do not get too wound up or worried about a bit of dust or an occasional smudge...I don't think it makes much difference on the views...at least to my eyes...and that is why I have yet to clean any of my mirrors...
Remember that the relfectors of old used "shiny metal" as their mirrors and so even a "filthy, dusty, gunky" mirror will provide incredible views comparatively speaking...
I would only be concerned if there was a "gash" that cut through the coatings...I see a little dirt on the mirror but not big scratches...
I'd get that mirror out under the night shy and get some viewing time under your belt...
That is my 2 cents worth...
Last edited by wavelandscott; 25-09-2005 at 10:00 AM.
Reason: spelling
Thanks for the replies, the mirror was replaced in the returned ota, and fitted and collimated by the supplier.
My concern isn't really with the optical quality of the mirror as such, but the condition of it.
I know that dust is not a problem at all, even a fairly large amount, but the wipe marks and definately the fingerprints is what i am concerned about.
And as posted here, i would also expect a new mirror to be in pristine condition.
I am just wondering are all gs mirrors like this, and not noticed way down inside the tube, if looked through straight on the mirror looks immaculate, but move the tube around toward a light, theses marks appear from nowhere.
I would not be overly concerned myself.
I have had my mirror out & cleaned several times now.
Minor blemishes do not seem to greatly effect the performance of the scope.
I only clean my primary when it gets heavily coated in dust or salt spray (coastal viewing).
Dirty eyepieces will have far more effect on your viewing pleasure
Enjoy !
I would love to enjoy, but these things called clouds, (ooops dirty word), are hanging around this weekend, and oh that's right the courier sent my base on a country run, so i won't be able to set up till they send it next week
I would have thought, given the adverse comment generated in this forum, that the retailer would have made every effort to ensure that the replacement mirror was both spotless and flawless. Personally, I would be cleaning the mirror, (after researching the least invasive method) to ensure the dust and smears aren't disguising any defects. I have also read that fingerprints can leave permanent damage to coatings (at least the meade UHTC coatings) if left for more than a few days, although they may not affect the coatings on your particular mirror.
Just another thing to add. Fingerprints are not easy to clean off the mirror. It is expensive, because you need quite a lot of isopropyl alcohol which is not cheap, and time consuming because you likely need to repeat the soaking and wiping several times. And usually you can't tell if the marks are gone until the mirror is dry. It is a real PITA, and you'd want to dedicate most of a whole Sunday afternoon to the task.
Also on mirror cleaning, there are lots of howtos around, with lots of conflicting info re what to use; e.g., some say dishwashing detergent will ruin your mirror for ever others say its ok, same story for cleaning with wipes/cotton balls or never-ever wipe just soak-rinse-dry repeatedly, etc. Your best bet is to not listen to any specific advice on forums and info on other amateur sites, but get some official documentation from a reputable manufacturer.
Bintel are starting to look pretty good Eh !
They are prepared to send their Tech's to the USA for training, this shows a high degree of professionalism.
Warehouse direct is one thing (best price) a full service professional retailer (who gives discounts for club purchaces) is quite another.
I use both, but I know what to expect from each too !
IMHO
I reckon at this point you should accept that you got a good scope for a good price (with a lot of hassle). You can make good from here with the good advice from this forum, but yes, future purchacers might do well to peruse your tale. My mirror from Bintel was absolutely spotless and crystal clear...but I paid more.
But they do get a lot of forum members coming through, so it can't hurt to say g'day and mention you were recommended by the forum and i'm sure they'll look after you.
Some people have managed to get discounts at Bintel, but I think it depends what you're buying. Others may share their experiences.
Some people have managed to get discounts at Bintel, but I think it depends what you're buying. Others may share their experiences.
The Guys at Bintel have always looked after me.
Don and Michael C. are always great for advice and very helpful.
Mike Smith is great to have a yarn to, (could't get any answers out of him for the IIS competition though )
I've even managed to get a smile out of Lil' once or twice. I know she loves me deep down.
I always look forward to dropping in.
Mention my name and I'm sure they'll still look after you anyway.
the markings wont change noticably the view you get. If you decide to go back with your complaint, rather than asking for a new mirror ask them to clean your existing one. If you ask for a new mirror you may well get the same finger print problem again.
theres nothing wrong (as far as i can tell) with the mirror it's self so just get them to clean it.
and for cying out loud get rid of these clouds so i can get some viewing in!!!
, so i won't be able to set up till they send it next week
.
)
I know she loves me deep down.
