Celestron C8 XLT SCT vs Edge HD

[ninjageezer]

So I'm looking for another scope ,mainly for planetary but also for some of the smaller DSO that are a bit small for my widefield refractor. 

what i a would like to know ,is the large price difference worth it for my proposed use ?

i have not really found and good image comparisons with the Celestron C8 XLT SCT fitted with a Reducer/Corrector f/6.3

 

[OK Apricot]

Ed Ting on YouTube did a nice comparison video between the XLT and the Edge OTAs. There wasn't a lot in it. 

 

[newbie alert]

The difference between the XLT with reducer and edge with reducer are the focal reduction, 1280 at 6.3 with the XLT

1422 at .7 with the edge

With all mass production items performance relates to the accuracy of the manufacture of the optical tube and the reducer flattener.. slight machining inaccuracies will occur.. you may get slight off axis distortion that the flattener can't correct, or the flattener isn't made to a perfect tolerance.. 

Things to think about... Camera.. what are you going to use? To my mind with the edge you could use a camera sensor up to APS-C size, with the XLT it will need a sensor smaller than 4/3rds.. you will have vignette

How are you going to guide, I advocate using a oag with a SCT..  I know some use a separate guidescope system but I tried that and it just didn't work.. oag are fussy to setup but I'd you follow the guidelines once setup they work very well.. I use a qhy 290 and never had to search for stars by rotating as what James lamb ( if you've seen the u tube vids) does

I love imaging with the SCT, it's not been off the mount for about 18 months now...

[newbie alert]

[Cosmic Geoff]

The Edge version is sold as being more suitable for imaging (read the sales blurbs). 

According to some, the Edge also gives a sharper image when used visually, and there are unverified suggestions that this is because the Edge models are individually re-worked and the basic SCT is not.

Also bear in mind that  the focal reducer for the EDGE is eye-wateringly expensive (look it up!) 

I have used my CPC800 with the Celestron f6.3 focal reducer for imaging planetary nebulae and it worked pretty well.  f10 was just too much for most deep-space images.

For solar system planets, the field is small and  you are limited by the seeing, so the EDGE will offer no advantage IMHO.

Edited July 30, 2022 by Cosmic Geoff

[ninjageezer]

2 hours ago, newbie alert said:

The difference between the XLT with reducer and edge with reducer are the focal reduction, 1280 at 6.3 with the XLT

1422 at .7 with the edge

With all mass production items performance relates to the accuracy of the manufacture of the optical tube and the reducer flattener.. slight machining inaccuracies will occur.. you may get slight off axis distortion that the flattener can't correct, or the flattener isn't made to a perfect tolerance.. 

Things to think about... Camera.. what are you going to use? To my mind with the edge you could use a camera sensor up to APS-C size, with the XLT it will need a sensor smaller than 4/3rds.. you will have vignette

How are you going to guide, I advocate using a oag with a SCT..  I know some use a separate guidescope system but I tried that and it just didn't work.. oag are fussy to setup but I'd you follow the guidelines once setup they work very well.. I use a qhy 290 and never had to search for stars by rotating as what James lamb ( if you've seen the u tube vids) does

I love imaging with the SCT, it's not been off the mount for about 18 months now...

Great info thanks ,don't know a great deal about OAG,i have a APSC astro modified canon 60D.i use with my WO Z73 atm.

[ninjageezer]

2 hours ago, newbie alert said:

Great images are these with the edge hd ?

[newbie alert]

15 minutes ago, ninjageezer said:

Great images are these with the edge hd ?

Thanks, but no they're with the XLT version and 6.3 reducer

[newbie alert]

19 minutes ago, ninjageezer said:

Great info thanks ,don't know a great deal about OAG,i have a APSC astro modified canon 60D.i use with my WO Z73 atm.

The XLT image circle is too small for the APS-C sensor

[ninjageezer]

2 hours ago, newbie alert said:

The XLT image circle is too small for the APS-C sensor

This is what i found when i was looking if my camera was ok for it.

this is what made me look at getting one.

What is the optimized image circle for the EdgeHD OTAs and Reducers?
August 25, 2009

The EdgeHD optics are designed to optimize an image circle 21mm in radius from the center of the field of view. Doubling this figure gives an image circle 42mm in diameter. This is big enough to illuminate a 35mm sensor. The OTA's image circle extends well beyond the formats of popular APS-C sensors found on many DSLR cameras and many smaller chips used in specialized astrophotography CCD cameras.

If you are using one of the .7 reducer lenses for either the 1400 or 1100 Edge HD optical tubes, the diameter of the image circle will remain at 42mm. If you are using the .7 reducer lens for the 800 Edge HD the image circle will will shrink to 26.7mm in diameter. The shrunken image circle will fully illuminate a cropped DSLRs (APS-C) senor or smaller CCD.

 

 

 

Edited July 30, 2022 by Cornelius Varley
text size and colour corrected

[ninjageezer]

Also from the celestron website.

• The EdgeHD .7x Focal Reducer Lens makes your EdgeHD 800 one full f-stop faster than f/10, doubling the equivalent exposure at f/10
• 4-element lens design
• Maintains similar flat-field performance as native EdgeHD optical design
• Increases field of view by 43% (double by area) to better capture wide field images
• Optimized for APS-C sized sensors, including most DSLR cameras and Nightscape CCD cameras
• Provides generous 105mm back focus to accomodate additional accessories and a wide variety of cameras
• Compatible with EdgeHD 800 T-Adapter

[newbie alert]

Isn't that what I said?