Celestron 90° Angle Diagonal Mirror, 2″ with XLT Coating for Schmidt-Cassegrain Telescopes

30 Comments

1. Odeda says:

   February 13, 2010 at 1:13 am

   After using this high quality diagonal, I realize the 1.25″ star diagonal included with my Celestron C11 does not do the telescope’s optics justice.

   I did not know this, and for some months after I bought my C11 SCT last year, I kept experimenting with different 1.25″ eyepieces and filters, as I was unwilling to make the jump to a 2″ diagonal and eyepieces.

   Unfortunately, I kept coming up dissapointed on images, not seeing the brightness and clarity that I expected from such an expensive (and highly rated) telescope.

   I purchased this 2″ Diagonal mirror last weekend. Celestron includes a small locking aluminum case. This is a nice touch, and I feel it hints at the quality of the diagonal. At the least it is impressive for the new buyer, albeit maybe a little pretentious.

   I used this from my backyard for my first views. Even with the extreme light pollution from nearby Phoenix (you can’t see all of the Big Dipper with the naked eye many nights — it’s that bad!) I was seeing objects that I had never see even in deep space dark sky viewing sites before. I was surprised when I unexpectedly resolved the double star in Polaris. I admit to mixed feelings about this, as I wondered how much more I had been missing with the stock 1.25″ diagonal.

   Earlier attempts to see M31 from my backyard resulted in blurred and indistinct images, but with a F 6/6 focal reducer and this 2″ diagonal it was bright and well defined.

   Speaking of the focal reducer: I was concerned after I bought this diagonal that I would be unable to use the reducer, but the reducer screwed on the optical back threads as usual, and the diagonal screwed onto the reducer easily. I did find that I almost reached the end of the C11’s focus adjustment when I added a CCD camera onto this setup. However, I was still able to get a sharp focus with several turns left on the focusing knob.

   I used this combination with an Oxygen III filter and viewed M42. Again, previous attempts from my backyard resulted in a partial view of M42, with the outer edges fading rapidly. However, the addition of this 2″ diagonal (and a 10mm televue eyepiece) resulted in a full eyepiece image of M42, with the entire nebula clearly and brightly obvious across the field of view.

   I did not expect this dramatic of an improvement in the views, and feel I got more than I expected from this modest addition.

   I considered a high end diagonal claiming 99% reflectivity instead of the 96% reflectivity of this diagonal. The more than doubled expense might be worth it, but I did not think so at the time I bought this diagonal. I didn’t think I’d get this much more out of adding this diagonal, and I can’t comment on what an additional 3% of reflectivity might add.

   I have not compared this to other 2″ diagonals, but the incredible increase in quality compared to the stock 1.25″ diagonal is so spectacular that I feel as if I have a new (and far superior) telescope.

   You can continue to use your old 1.25″ eyepieces, as there is an adapter included. Now that I’ve seen the improvement in upgrading to a 2″ diagonal, I’m planning on upgrading to 2″ eyepieces as well. Anyone want to buy a few hundred bucks worth of 1.25″ eyepieces?

   I highly recommend this diagonal. If you’re using a 1.25 viewing system, consider upgrading to the 2″ diagonal and eyepieces before adding more aperture with a larger telescope.
2. comess kymbe says:

   February 15, 2010 at 5:01 pm

   Andy- it was about US$2100 for everything. Fortunately I found a seller (Adorama) that was offering free shipping, plus Celestron has been offering $300 off the CGEM models lately.
3. lingham carelandr says:

   February 20, 2010 at 3:46 am

   Best Deal HP Pavilion DV4-2140US 14.1-Inch Laptop. It’s powre by AMD Turion II Dual-Core Mobile Processor M520 (2.3 GHz, 1 MB L2 Cache), 4GB DDR2 System Memory (2 DIMM) (expandable to 8 GB), 320GB (7200RPM) Hard Drive (SATA) Genuine Windows 7 Home Premium 64-bit, Up to 3.25 Hours of Battery Life. 14.1″ Diagonal WXGA HD HP BrightView, ATI Mobility Radeon HD 4200 Graphics with 128MB Display Cache Memory with up to 1918MB total graphics memory
4. baeunin says:

   February 23, 2010 at 3:57 am

   #Earth 2? #scientists announced that they found #earthtype #planet useing household #telescope's: #space #astronomy
5. sylvernstl says:

   February 24, 2010 at 6:36 pm

   suckaz trynna figure my angle
6. oberariant says:

   March 5, 2010 at 11:32 pm

   Saturn is such a beautiful planet!
7. therre says:

   March 17, 2010 at 6:44 am

   [Periódico Diagonal] :: El PSOE regatea con el castigo a la manta
8. bosnier says:

   March 19, 2010 at 10:52 am

   Your best bet is to call your current mortgage company and try with them. If they say no—then wait a week and call again. I would even do it a third time if needed.

   I have found that maybe I say things in an odd way, The second time I called I got a different person and maybe I was more polished in my request.
9. jar says:

   March 24, 2010 at 5:56 pm

   Be careful.
   The Wattage can always be higher than the stated minimum for your laptop.
   The Voltage has to be the same.

   If your laptop needs a 65 Watt 19.5 Volt charger then you can use a 90 Watt 19.5 Volt charger

   Voltage has to be the same and wattage has to be the minimum or higher.

   If you have a Dell laptop, you should buy a replacement from Dell – or make sure it has the Dell ID chip in the charger
   Or it will not charge your battery.
10. calva says:

    April 4, 2010 at 10:23 pm

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