With a 17mm secondary eyepiece, the power is 1250/17 = 73.5. With a 4mm secondary eyepiece, the power is 1250/4 = 312.5.
Think of it like a lever. The objective is focusing the image in the air inside the telescope's tube. The longer the focal length, the larger this image (like a camera lens). The eyepiece is used like a magnifying glass to view this image "in the ether". The shorter the focal length of the magnifying glass, the larger the image to your eye.
Note: usually, the eyepiece is removed to attach the camera adapter. Focus will be in a markedly different place than with the eyepiece in place. In fact, the image must be moved from inside the telescope to outside it and onto your film or CCD. This is usually several inches. When *severely* out of focus, you'll see nothing but black.
Try focusing on a brighter object, such as a planet, first. Saturn is overhead now, and it's rings are tilted so as to be quite spectacular.
Regards, Bob...
----- Original Message ----- From: "Nick Clark" <[EMAIL PROTECTED]>
To: <pentax-discuss@pdml.net>
Sent: Wednesday, January 12, 2005 10:28 AM
Subject: Astrophotography (was Re: *istD EOL...)
I got a telescope for Christmas with a camera adaptor. I've not had much chance to play with it yet but was quite impressed with its power the first couple of times I used it. It's a Telstar 900x114 reflector, and fills the eyepiece with the moon with the 20mm objective. Strangely the moon is even larger when using the shorter focal length 4mm eyepiece, which I haven't quite worked out yet.
When looking at a group of stars (Seven Sisters) there are many more visible than with the naked eye, even here in light polluted London. Unfortunately when I put the camera adaptor on with the *istD I couldn't see anything - it was far too dark to focus. A bit disappointing. I haven't tried the camera with the moon yet, but will do next time it makes an appearance, and it's not raining, or cloudy.
Nick
-----Original Message----- From: "Tom C"<[EMAIL PROTECTED]> Sent: 11/01/05 23:45:05 To: "pentax-discuss@pdml.net"<pentax-discuss@pdml.net> Subject: Re: *istD EOL...
Bruce,
I'm curious why the shop people thought the Digital Rebel was junk. Was it
based on look and feel ? What about image quality?
I'm asking because right now the Rebel is the top selling DLSR for
astrophotography. I haven't had a chance to try the *ist D yet with my
telescope, but depending on results I get with the *ist D I wouldn't mind
trying the Rebel.
Tom C.
>From: Bruce Dayton <[EMAIL PROTECTED]> >Reply-To: pentax-discuss@pdml.net >To: Nick Clark <pentax-discuss@pdml.net> >Subject: Re: *istD EOL... >Date: Tue, 11 Jan 2005 15:33:08 -0800 > >I was in my local shop yesterday - mostly Nikon and Pentax, some >Canon. They are selling about five D70's everyday. People just keep >walking in a buying them. They think highly of the *istDS, but it >doesn't sell anywhere like the D70. Pretty much the word is out in >all media that photographers and would be photographers that the D70 >is THE camera to buy. Pop Photography proclaimed it Camera of the >Year. Size doesn't matter to most people at the time of purchase. >Later on, when having to carry the extra they might care, but it is >too late. The best Pentax can do with the *istDS is be respected. My >shop thinks the DRebel is junk next to the DS and they are very >willing to tell any potential customers. But they are really making >their money on the D70. It could well be the camera that saved >Nikon's hide. > >-- >Best regards, >Bruce > > >Tuesday, January 11, 2005, 3:18:50 PM, you wrote: > >NC> My local dedicated Camera shop says the *istDs isn't selling. >NC> They have it and the 300d and D70 (and the Minolta which is >NC> humungous) on display alongside each other. Even though the Pentax >NC> is smaller, they say the reasons people don't go for it are partly >NC> the SD card but mostly the difference in price. The 300d is >NC> something like GBP200 cheaper. > >NC> Nick > > >NC> -----Original Message----- >NC> From: "Pål Jensen"<[EMAIL PROTECTED]> > >NC> I think it will be more than enough. As high-end DSLR are >NC> larger than medium format cameras, and consequently suffers from >NC> the same lack of portability, the market niche is definitely >NC> there. Mind you, Pentax need to design cameras that look small, >NC> not only are small. The problem with the *istD(S) is that they >NC> look big. Products that are going to sell on their smallness need >NC> to comunicate their size through design. Small cars don't look >NC> like shrinked big ones. If they did they wouldn't sell. The small >NC> SLR's of the past looked small without any reference. Pentax M >NC> series and Olympus OM's had a slim smallish look whereas the >NC> *istD(S) look big and fat until you actually handle one or see a >NC> photo of it next to the competition. Since most people never see >NC> or handle a Pentax theres nothing telling them how small they are >NC> unless they do a lot of homework. >NC> The Pentax 40mm pancake lens is agreat idea. It is a pity >NC> though that Pentax haven't made a pancake camera. > > >NC> Pål > > > > > > > >
