johninderby

That 3.7mm Ethos looks massive! Only five main eyepieces in that cast too and yet so many magnifications and exit pupils are catered for. Well thought out.

Ant

Yes that 3.7 is a bit of a beast isn't it

Just for interest I've weighed the eyepieces.

• Televue 3.7mm SX Ethos - 590 g.
  
• Televue 6mm Ethos - 440 g.
  
• Televue 13nn Ethos - 565 g.
  
• Televue 35mm Panoptic - 720 g.
  
• Penatx XF 6.5-19mm Zoom - 240 g.
  
• 1.5x APO (Japanese) Barlow element - 28 g.
  

John

My Eyepiece Case (latest)

The contents of my eyepiece case have been changed around a bit since getting the 3.7 SX Ethos but here's what's in it now.

• Televue 3.7mm SX Ethos
  
• Televue 6mm Ethos
  
• Televue 13nn Ethos
  
• Televue 35mm Panoptic
  
• Penatx XF 6.5-19mm Zoom
  
• 1.5x APO (Japanese) Barlow element
  

With the 1.5x Barlow element this gives me a 2.46mm, 3.7mm, 4.0mm, 8.6mm and 13mm Ethos line-up, although really the Barlow is only used with the 13mm to give 8.6mm. The Barlow element is the one that comes with the A&E Supreme Barlow and it's a Japanese made triplet APO that works extremely well, although at around £88.00 it's not cheap for a 1.25" Barlow. The Pentax zoom is a nice lightweight and compact zoom and is primarily used for solar viewing although it also performs well in regular night-time use.

All in all this gives me whatever mag I want in just one compact eyepiece case.

John

The Pyrex does cool down faster than plate glass. While it's true to say that there's no performance difference when they're both cooled down there is one very important additional factor to take into consideration. If the temperature is falling the Pyrex tracks the temperature change better than plate glass.

The bigger the mirror the bigger the problem with cooldown, which is why premium scopes with big mirrors use low expansion glass.

John

Now let me see........ They're both low cost entry level Ha scopes and the Lunt 35 and PST are about tied in overall performance, despite the PST having 14% more aperture, and the Lunt costs less than the PST. The biggest headache with the PST is that dammed small "sweet spot" which means that you can only see a small part of the surface in any detail at any one time. That's the reason I got rid of my PST.

John

If you get the Skywatcher Maksutov to SCT adapter http://www.firstlightoptics.com/proddetail.php?prod=synta_SCT_adapter then you could fit any SCT type Crayford focuser.

John

I had an 8" newt on an HEQ5 for a while, and while it gave great views, It was literally such a pain in the neck to observe with that I got rid of it. It may be a great setup for imaging, but for visual use no thanks.

My solution....an OO 14" dob (99 strehl mirror) with StellarCAT drive system. Sets up in 5 minutes and the eyepiece is always in a convenient place. Even if you don't bother taking the time to polar align accurately it still tracks well enough for visual use. The only downside is the cost, but as the old saying goes you get what you pay for.

John

Thanks for that link.

Telescope Service does indeed have the barrel end caps for 1.25" and 2" eyepieces, although not the caps for the other end of the eyepieces.

John

Please let us know what the result of your email is. If the shipping is reasonable I may order some myself. If shipping is too much I may try HandsonOptics as they do ship at actual cost, but not sure if they do supply the caps.

John

If an order is less than £18.00 in value then there is no tax or duty on it. You might email them and ask what the shipping would be. Some US dealers unfortunately have a minmum international rate no matter how smalll the order.

John

Unfortunately the only ones I have seen on eBay are the cheap dipped rubber ones, not the proper injection molded OEM type.

John

Hi

I've ben looking for a UK supplier of the proper ones as well but absolutely no luck at all. You can get them in the US from Otpcorp but I wonder what the shipping cost would be?

http://www.optcorp.com/productList.aspx?uid=30-82-779

John

Gel-cell batteries (as used in power tanks etc.) should always be charged after each use, as if one is put away flat it can actually be ruined after just a few weeks. When the charge in the battery gets too low some of the cells can reverse polarity and then there's no way to save it.

Cold also has a big effect on the battery. If the battery is fully charged and then kept indoors in the warm it can be stored for a year before it needs charging again. The worst thing you can do is to store the battery on a concrete floor in an unheated shed or garage, as even a fully charged battery can loose enough charge to permanently damage it in just a month or two.

Unlike ni-cad batteries gel-cells have no memory effect so you can give them a top up charge whenever you want. Preferably with an automatic charger, but even with a standard wall charger you would have to leave it on for several days to damage the battery.

John

I remember talking to an optics designer a little while ago and he said that the lens cell was as important as the lens itself in overall performance. He said I wouldn't believe just how difficult it was to design and make a really top quality one that would get the best out of a lens due to the often conflicting design parameters.

Apparently a temperature compensated lens cell built to the highest tolerances can cost as much as a good lens. Helps explain part of the reason why high end scopes cost more.

John