Is a Coma Corrector necessary for visual

[Rossco72]

TV's are great Eyepieces, there's no doubt. I am a big fan as you will see on my Sig Strip.

However, the difference is less noticeable in the Plossl design. Yes TV Plossl's are great but there are others just as good and often cheaper. The quality and difference starts to stand out as you look at the more exotic designs, Radians, Panoptics, Naglers and Ethos etc.

If you are really on a tight budget and really need 3 EP's you will struggle with Tele Vue. If all you can afford are plossls then you could save some money with the likes of Meade 4000 or 5000.

Otherwise, buy 1 really good TV, maybe a Nagler or Panoptic and then save for a bit for another one.

Cheers

[spaceboy]

:icon_salut:TV Panoptic 41mm, , TV Ethos 17mm, TV Nagler 12mm x2, TV Ethos 6mm, TV Nagler Zoom 6-3mm

TV Powermates 2x, 4x, 2.5x, 5x; 0.8 Reducer:icon_salut:

My word someones a MD of a Bank on loadz a £££££. This is what dreams are made of. Never mind I will have to keep dreaming.

I couldn't sleep last night at all the info on TV and the £££ they cost. I know from whats being said they goto be worth it in the long run but I would be waiting an awfull long time before I could get another ep at them prices. The panic I'm having about second hand TV's is if they are so good why would anyone want to sell them.... unless the one their selling has a flaw of some other issue.

Are there any threads reviewing the TBM cloans. I try not to be sucked into the brand name trap (mainly as I never have the funds too) so unbranded ep of a recommended quality sounds the winner to me but are they all OK for a fast telescope or would I still have to take care which I purchased?

[NGC 1502]

QUOTE: "The panic I'm having about second hand TV's is if they are so good why would anyone want to sell them.... unless the one their selling has a flaw of some other issue."

I can understand your worry here, but many TV EPs get sold

because people have upgraded from less expensive TVs to higher

end units, eg Plossls to Radians, Panoptic to Nagler, or Nagler to

Ethos.

Most TV EP owners look after their kit, so great savings can

be had.

Best regards, Ed.

[Rossco72]

It's rare to find a second hand TV which doesn't look exactly like a new one! they are usually treasured EP's.

And no, I am not a banker or in any way connected to banking, LOL

However, It soon became apparent that it costs more to keep upgrading than to just save and get the best quality you can, 1 at a time.

Cheers

[great_bear]

However, It soon became apparent that it costs more to keep upgrading than to just save and get the best quality you can, 1 at a time.

And live without a workable eyepiece collection in the meantime?

No thanks!

I don't think that's true at all. You lose no money (other than postage, which isn't significant) by trading within the second-hand market, and it means you can then relax and simply snap up those second-hand Tele Vue bargains as and when you spot them.

In that way, it's cheaper not more expensive - and you gain experience with a wide range of different eyepieces in the process.

Despite what you may read, Tele Vue are not the only supplier of quality eyepieces...

[great_bear]

Don't worry, loads of people have been in this quandary, and many still are.

I know from what's being said they got to be worth it in the long run, but I would be waiting an awful long time before I could get another ep at them prices.

Best not to get them then. It's all very well people saying "Only buy the best - buy Tele Vue" - but people all-too-often forget how the second-hand market works in astronomy. Provided that you take care of second-hand eyepieces, you can re-sell them at the price you've paid for them. If you treat your eyepiece collection like a bank account, then for the price of postage, you've got virtually free rental on an eyepiece collection for as many years as you like - and you can cash in at any time in order to upgrade to more expensive eyepieces or even to downgrade to free up cash for another purpose.

So (ignore what people say) you DON'T need to buy the "very best" right at the beginning, or take some snobbish pride in owning just one (megabucks) eyepiece, and end up living without a workable eyepiece collection until you can afford your next "show-off" eyepiece.

As has been pointed out before, people who genuinely have lots of money to spare normally don't have any hang-ups about having plenty of cheap eyepieces in their collection, because they have nothing to prove. They prefer to spend the serious money where it matters most. There's no point investing too much money on an eyepiece used only for high-power star-splitting or the lowest-power wide-field views.

It's also important to bear in mind that top-dollar prices only buy you edge-of-field sharpness and high-contrast image resolution in those WIDEFIELD eyepieces. Surprisingly, there is NOTHING significant in terms of image detail in those mega-expensive eyepieces that cannot be seen in a £50 second-hand Genuine Orthoscopic or Plossl - so please don't believe that you will miss out on view quality if you have a budget to stick to - you won't.

As for purchasing eyepieces second-hand, don't worry that people might only sell because of there being something "wrong" with what they've got. That's almost unheard of. It's always just to free up cash after buying something else. For example people sell Tele Vue Plossls to buy Panoptics, sell Panoptics to buy Naglers, sell Naglers to buy Ethos, and so on.

[Rossco72]

So (ignore what people say) you DON'T need to buy the "very best" right at the beginning, or take some snobbish pride in owning just one (megabucks) eyepiece, and end up living without a workable eyepiece collection until you can afford your next "show-off" eyepiece.

GB, I don't want to get into a debate, but I never said just have one EP and if you read the thread I actually advised Meade 4000 Plossls.

[great_bear]

OK - and although it probably looks otherwise - I actually wrote my post in Notepad earlier today, before you wrote yours, and so it's unfortunate that it looks like I'm taking a pop at you personally - that wasn't intended! I'm sorry.

[John]

I've been in the hobby for 30+ years. For most of that time I've had a lot of fun with a motley collection of kellners, old plossls and eyepieces made from old binoculars. It's only recently that I've been able to afford some really good quality eyepieces, most of which I've bought used.

I had just as much fun with my cheapo eyepieces, sometimes even getting a bigger kick from seeing a lovely astro object despite only spending a few £'s

Expensive gear is a "nice to have" but far from an essential ingredient to enjoying the hobby

[spaceboy]

Thank you both great_bear and Rossco72 both of your post have been very helpful.

My original concerns were the needing a coma corrector and would I need one even if I had better EP's. With all the imformation I don't think there should be any concerns for a corrector.

The edge of field is where I'm suffering and I can understand other SGL members posts regarding the different levels of quality available. I purchased my helios second hand and got a standard meade 26mm plossl thrown in with it. The Meade easily out performs my unbranded super P's at the edges. (although like said it made no difference in the center of the view) I wasn't sure what to do for the best as I didn't want to have to buy yet more plossl to replace the plossl I already have as it dosn't seem as though I would be making any advance in my ep collection. if there was a better alternative I would rather try SWA or UWA ETC and then just choose what plossl I have that work OK and get rid of the ones that are not so good.

To be honest I never had any issue with any of my eps when used in my old F/10 its only been since I changed to a F/5 and F/4.7 so I assumed this to be a matter of a couple of wider field eps, more so than the quality of the ep. I think this is where I can't sleep at night as now I have a telescope thats going to show up ep flaws in any thing other than ££££ eps should have stuck with the F/10 (

It makes sence what has been said about people looking after TV's and peoples reasons for sale so THANKS TO YOU ALL for the advice

ANYWAY I'VE POPPED ME 50 POST CHERRY SO NOW I CAN HAVE A HUNT ON SGL FOR SOME SECOND HAND EP'S YEAH!!!!

[Moonshane]

some great responses here since I last looked and they are all certainly valid views.

I totally agree with the 'buy used' philosophy. I don't own a new eyepiece but they are all in as new condition. As GB said there are ways to use eyepieces as a savings tool and I am one of the people who do just this. if you buy the gear you want used now (and this can be anything decent not always eg TV) then you can always save for better quality if you feel you need it and then sell the equivalents once you confirm the new one is better than the old one.

if not the only risk as stated is the postage - no real biggie.

I can honestly say I have never seen a dispute on here of people not getting what the ad said or it being broken etc so this is a relatively safe place to buy in my view. good luck with the hunt!

as you said yourself, the edge is where the problems lie and generally (but not always) the more you spend the less 'dodgy edge' you get. if you can ignore a little bit of distortion at the field edge then there really are hundreds of options.

[great_bear]

Well there's one other trick you can try by the way - and that's to gently barlow your eyepieces. If you screw on a 1.5x barlow onto an eyepiece when used in faster scopes, it can really help those edge abberations.

- you have to consider the side effect of the extra magnification naturally...

[matthewota]

I see coma in my SCT only when using wide angle eyepieces. It does not bother me.

[great_bear]

Indeed - it's no co-incidence that the Paracorr is made by Tele Vue

[spaceboy]

I planned to start my hunt for ep's on the SGL but can't find the used link? ( never mind found it! looks like my eyes are the problem not my EP's )

[John]

It's here:

Stargazers Lounge

It sometimes takes a while for the access to kick in once you have passed the 50 post mark.

If you don't see anthing interesting you can always try a "wanted" ad - that sometimes prompts some interesting offers.

Heres another tip: conduct negotiations using PM's (Private Mail's) rather than on the forum - it works better that way

[MartinB]

I have a 300mm Skyliner dob and use a Moonfish 30mm UWA, a 27mm panoptic, a 17mm type 4 Nagler, a 10mm Pentax XW and 7mm Pentax XL. The coma is quite pronounced with the relatively cheap moonfish but it is also the widest angle lense. Coma seems much less pronounced at higher mags with short focal length EPs. It is certainly present with the Nagler.

The coma does bother me a little but it depends how I'm viewing. If I'm just going for a "space walk" view the coma is in the periphery and doesn't bother me. However it does irritate when I scan around the view. I then tried using a Baader MPCC and found the improvement to be significant. In fact, with the right spacing correction is excellent with tight stars right out to the periphery with 82 deg apparent view EPs.

The corrector comes with a couple of spacers and these covered the spacing needed with my EPs.

My observing is often quite rushed and superficial I'm sorry to say. On these occasions I find the MPCC too much of a faff. When I have more time and wish to spend more time on a particular target or do some sketching the in goes the corrector.

[great_bear]

The coma is quite pronounced with the relatively cheap moonfish but it is also the widest angle lense. Coma seems much less pronounced at higher mags with short focal length EPs.

Then it's not coma you're looking at, but eyepiece astigmatism.

It's a characteristic of coma - as corrected by a Paracorr - that as the centre of the image is magnified, so is the coma around it - such that the amount of coma visually looks the same at all magnification levels, and with all eyepieces.

Eyepiece astigmatism is commonly mis-identified as coma.

[MartinB]

Then it's not coma you're looking at, but eyepiece astigmatism.

It's a characteristic of coma - as corrected by a Paracorr - that as the centre of the image is magnified, so is the coma around it - such that the amount of coma visually looks the same at all magnification levels, and with all eyepieces.

Eyepiece astigmatism is commonly mis-identified as coma.

You may well be right although it looks rather similar. I'd assumed it was a combination of inferior optics and the wider fov. The moonfish isn't a great performer with fast scopes, great with an SCT. The coma corrector seems to do a godd job strangely enough!

[spaceboy]

OMG my head is spinning too much info such little space.

I cannot believe how much a mine field astronomy could be. I started 6 years ago and I've not really made that much effort to look into improvements in fact I thought you buy the scope you buy the Box of EP's you point and there you go:bino2:

I cant believe how much more there is to it. I think I'm most shocked when you think how past masters in the field ( Messier Etc) managed with some what inferiour equipment compaired to modern day instruments.

I've spotted a Panoptic I'm trying to get my hands on but I'm not sure what prices I should pay for seconds. People always ask for more to allow for hageling but I don't want to insult people because I have a tight budget.

[John]

..I've spotted a Panoptic I'm trying to get my hands on but I'm not sure what prices I should pay for seconds. People always ask for more to allow for hageling but I don't want to insult people because I have a tight budget.

Good luck with it - TV eyepieces usually go for around 60-70% of the new price.

The problem is there is usually plenty of demand so the seller might not feel the need to shift much.

[Moonshane]

I am not sure that much of the quality astro stuff is put on at much more than the price they want. generally, demand is more than supply and therefore they sell quickly. people will often hold things for a while if you pay a deposit though.

[great_bear]

Indeed I've encountered very little haggling - it's not really that kind of culture.

[spaceboy]

Well I can officially say I am one step behind everyone else.

Not only do I miss out on eBay but I've now started the trend on Astronomy buy & sell now maybe I'm too aprehensive it being my first purchase of a £££ 2nd hand EP but I just can't get to the post in time.

Never mind I'm sure when I do get that EP I will be all the more appretiative that it took some work to get it

[Moonshane]

I know what you mean - we all feel a little bit twitchy when it comes to buying EPs for lots of cash from people we don't know but it's quite a small world. try googling the phoe number and email address of the person concerned. this often brings up a lot of appropriate references. I did this recently with someone I was buying from and there were lots of references to a local astro society etc which put my mind at rest, also a telephone conversation with a few questions helps with this too.

in the end you take a chance with all purchases re condition and whether you end up scammed but the latter is thankfully still extremely rare.

you might know this but on AB&S, there's a forum where people can report dodgy sellers and you can also search the archives for other sales etc.

don't worry too much, the right gear always comes along eventually and probably at the right price but you do need to be quick as you have found. just enjoy the hobby in the meantime (if the clouds ever clear)

I'll PM you back on the other thing shortly. hopefully this is a solution to one of your requirements