Eyepiece endcaps

[CSM]

Scott - that thread - Show me your eyepiece case - was precisely why I started this one, and because I don't generally use endcaps - well not on eyepieces.  Just because it is the general consensus doesn't mean that it is the right or necessary thing to do. The reasons given seem to be that a) because they were supplied like that and therefore that must be a reason to use them, and  because my eyepieces cost a lot of money and they might get scratched and dirty if I don't use them - though to be fair some are saying that they DO get scratched and dirty if they aren't used.  Am I convinced?  Not really but as long as everyone is happy....

[nightfisher]

Seems to me that 99.9% of astronomers like to replace end caps on telescopes and eyepiece`s, happy that they are doing all in their power to protect valuable equipment, and then we find 0.1% seem happy to leave caps of and let the equipment fend for itself, one ep that i bought on the used market arrived with no dust cap fitted, had a film of dust over the ocular, when cleaned it revealed a nice scratch in the glass, if this ep had kept its cap on, maybe it would be ok today, not sitting worthless in a draw 

[Stu]

I won't (with one exception) buy a used eyepiece without endcaps and generally they need to be boxed too. It shows a degree of care and so far has proved to be a wise way of operating.

My 'procedure' is generally, if there is no dew to cap them and put away in cases with a bag of desiccant to keep moisture away.

If there is any dew on the eyepieces, I bring them indoors to a cool room, prop them up uncapped in their case and leave them over night to dry off. Next day I normally check and clean them if needed then pop the caps on and back in the case they go.

When I sell eyepieces, I often get comments that the eyepiece looks unused, why am I selling it? The answer is normally that I have used the eyepiece plenty of times, I just look after them very well.

Anyway, this seems to be a case of each to their own. Personally I cannot see any valid reason not to use endcaps, provided you don't put them on when the eyepiece is wet. It takes seconds to do, why wouldn't you?

Stu

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[Digger1895]

I really don't want to cause any offence here but you've heard many reasonable arguments as to why people use end caps but if you don't want to that is your choice. Me, I would rather not take the risk of any damage to expensive glass for the sake of a few seconds of my time.

[John]

This is quite an interesting Sky & Telescope article on caring for optics:

http://www.skyandtelescope.com/astronomy-resources/caring-for-your-optics/

I think the point made there is that cleaning optics, although quite feasible if care is taken, should be done as infrequently as possible and therefore it makes sense to take reasonable precautions to prevent them from requiring cleaning and using dust caps to cover the optical elements when not in use is part of this.

It's a hobby though and folks are free to pursue it in whatever way they wish so and, as has been said "...as long as everyone is happy...."

[CSM]

My 'procedure' is generally, if there is no dew to cap them and put away in cases with a bag of desiccant to keep moisture away.

If there is any dew on the eyepieces, I bring them indoors to a cool room, prop them up uncapped in their case and leave them over night to dry off. Next day I normally check and clean them if needed then pop the caps on and back in the case they go.

Now that sounds sensible but possibly a little time-consuming.  If dew-free do you check around the rubber for any specks of dust, dandruff, etc., which always seem to collect?  Can be difficult to see in the dark?

Jules - I don't think anyone would be foolish enough NOT to end cap the scope.

[John]

......Jules - I don't think anyone would be foolish enough NOT to end cap the scope.

Dust on an objective lens or mirror does little or no harm to the view but a dusty or dirty eye lens on an eyepiece can make a big difference to light scatter, throughput, resolution and contrast.

The whole of the mirror or objective lens collects and focuses the light but the exit pupil at the eye lens might only be a couple of mm in diameter so passage though a dusty / dirty glass surface will impact much more.

[scarp15]

I once purchased an eyepiece off someone who had mislead the end caps, I happen to be collecting it and to make matters worse he accidental spilt cigarette ash onto it, which he then duly blowed off. The eyepiece was great, an old OVL 'grenade', it had plastic rather than rubber eye guards so was not so bad concerning attracting dust and I was able to source alternative caps off ebay. It got me started up and gave me my first wow experience of the Moon and Saturn.

Anyhow that was then, with my current collection of eyepieces I take great care, the caps are off when in use of course and after a session I often leave them off or partially off over night to dry out. The end caps as with the eyepieces are then treated to an air blower before being recapped and put back in the case. I will even go to the extent of ensuring my finger nails are cut short to prevent any chance of a clumsy accident occurring when handling during a session. The thought of leaving the caps off indefinitely with a collection of optical glass almost comparable to the cost of a mini mortgage would fill me with horror.

[Davey-T]

Don't know if it's been mentioned but I leave the outer cap on until I've inserted the eyepiece into the scope this hopefully stops me sticking my big fat finger on the glass while fitting it.

Dave

[scarp15]

Don't know if it's been mentioned but I leave the outer cap on until I've inserted the eyepiece into the scope this hopefully stops me sticking my big fat finger on the glass while fitting it.

Dave

Yep definitely good practice.

[Moonshane]

Jules - I don't think anyone would be foolish enough NOT to end cap the scope.

I have at least four scopes valued individually at less than a number of my eyepieces individually.

[scarp15]

I think that the main concern I have regarding eyepiece caps isn't so much whether they ought to be used or not, as that is clearly a no brainer, it is actually not loosing one. For example, when at a location away from home and a gust of wind happens to blow one away (acting like a mini frizby) off your camping table. Whilst most caps do remain in the case, I take great care over this aspect and will check the ground after the session with the torch switched to white light, even though I have double checked each cap in turn, quite paranoid perhaps.  Perhaps rather than black they ought to be made in fluorescent colours. 

[CSM]

I seem to have stirred up all the very experienced astronomers, judging by their post numbers.  So may I suggest, for newbies and ignoramuses like me, that a sticky - 'Eyepieces - How to take care of them' - might be useful.  Clearly, as far as eyepieces are concerned, what one does after finishing an observing session is as important as what you do when setting up.  And how you should store them to make sure they are in as pristine condition as when you bought them.

[swamp thing]

I thought the clue was in their name myself. Dust caps- one would think that with such a name that dust prevention would be high on the reasons for their use.

[scarp15]

I seem to have stirred up all the very experienced astronomers, judging by their post numbers.  So may I suggest, for newbies and ignoramuses like me, that a sticky - 'Eyepieces - How to take care of them' - might be useful.  Clearly, as far as eyepieces are concerned, what one does after finishing an observing session is as important as what you do when setting up.  And how you should store them to make sure they are in as pristine condition as when you bought them.

Spot on and then there is maintenance i.e occasional cleaning procedures, the required equipment and methodology of which is covered extensively if searching this forum. An air blower (such as Grottus Rocket air blower) would make a good and inexpensive investment for general maintenance.

[Stu]

You'd be hard pressed to better these off Astroboot....

Air blower for £2, and a couple of brushes which are very good for £2.95

Stu

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[sbooder]

This is my cleaning kit, and I never use anything else. Blower and top quality Chamois (never let the chamois get wet, if it does buy a new one).

[DRT]

My 'procedure' is generally, if there is no dew to cap them and put away in cases with a bag of desiccant to keep moisture away.

If there is any dew on the eyepieces, I bring them indoors to a cool room, prop them up uncapped in their case and leave them over night to dry off. Next day I normally check and clean them if needed then pop the caps on and back in the case they go.

That is exactly what I do.

I keep the diagonal for my CPC in the same case as some of my eyepieces. All of the eyepieces have caps but the SCT end of the diagonal is uncapped because I can't find anything to fit it. The mirror in the diagonal collects far lore dust than any of my eyepice lenses so I can only conclude that having the caps on helps avoid dust from inside the case collecting on the glass surfaces.

[YKSE]

I always put the caps on when not using an eyepiece, including switching eyepieces, even when I was out in dark site. It's fairly simple, caps off and in the eyepiece slot in the eyepiece case  when observing; when switching to a new eyepiece,  caps on first, eyepiece back in the slot, then the new eyepiece as before. Not much difficulty at all.

Even so, I've found that the scope-side the eyepieces collect some dust gradually, as mentioned by others, dust on an eyepice has much bigger negative impact than in telescope mirror or lens. I suspect that dust comes from diagonal, where I can clearly see quite layer of dust from time to time, even if I've always had it coverred (with a cap or an eyepiece).

I'd suspect that an eyepiece without caps will collect dust faster than with caps on, which means more frequent cleaning, or more often not optimum view of eyepieces.

[scarp15]

I always put the caps on when not using an eyepiece, including switching eyepieces, even when I was out in dark site. It's fairly simple, caps off and in the eyepiece slot in the eyepiece case  when observing; when switching to a new eyepiece,  caps on first, eyepiece back in the slot, then the new eyepiece as before. Not much difficulty at all.

Yes when switching between eyepieces, beside protecting the optic, recapping assists a little with preventing the build up of dew.

[CSM]

Even so, I've found that the scope-side the eyepieces collect some dust gradually,

Is this a result of static?  If so is there a way of preventing or minimising it?

[YKSE]

I'd not be surprised if static has something to do with it, since my dielectirc diagonal gets dusty much more easier than the prism diagonal. I have no idea how to prevent it, just clean the  dielectirc diagonal when dusty (rinse it with the running water).

[John]

I'd not be surprised if static has something to do with it, since my dielectirc diagonal gets dusty much more easier than the prism diagonal. I have no idea how to prevent it, just clean the  dielectirc diagonal when dusty (rinse it with the running water).

I've heard that Tele Vue are shortly to introduce a range of anti-static garments shortly to combat this problem. It includes gloves, socks, vests, special soles for observers shoes and high specification anti-static underwear made from specially treated polythene. Apparently the underwear rustles a bit as you move around but is otherwise very discreet.

I believe the colour scheme will be either black on green or green on black, they have still to finalise this.

[Spikey]

I've heard that Tele Vue are shortly to introduce a range of anti-static garments shortly to combat this problem. It includes gloves, socks, vests, special soles for observers shoes and high specification anti-static underwear made from specially treated polythene. Apparently the underwear rustles a bit as you move around but is otherwise very discreet.

I believe the colour scheme will be either black on green or green on black, they have still to finalise this.

Mine came yesterday 

[glowjet]

Why do manufacturers supply end caps with their products, so Astronomers like me can loose them in the dark