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Old 10-08-2020, 07:45 AM
BobT (Bob)
Bob T

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Join Date: Aug 2020
Location: Grafton, Australia
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Camera help needed

This is my first post and I am a real beginner with a couple of camera questions. I have a Nexstar Evolution 8”. Hopefully someone here will have the answers.
I have only used it a little but since once was a professional photographer I really want to be able to cspture images of what I am viewing. Also my wife has trouble looking through an eyepiece and having the image visible on my laptop would allow her to be involved.
I looked at getting either a ZWO ASI178 MC or the ZWO ASI183 MC, both were recommended by a couple of Australian retailers. I then did a bit of research and discovered the “oversampling problem”
I wrote to Celestron and they suggested using a focal reducer and perhaps a ZWO ASI294MC-P with larger pixels than the two I had picked out. Unfortunately, this camera is too expensive for me.
Both the 183 and the 178 have 2.4um pixels, and the telescope has a 2032mm focal length. This combination gives a .25 result from the formula (pixel size x 206 / focal length) and from reading I believe this will give me a lot of oversampling.
My questions are: -
1. Is it worth buying a focal length reducer for imaging planets and the moon?
2. If so, is the .5 reducer available from a large online store for $29 worth buying?
3. Which camera would you prefer, the 178 (6.3mp) or the 183 (20.1mp)?
4. I also own an Olympus M5 mark 1 and would like to attach it to the telescope. Which adaptors and TMounts are required to mount it to the 1.25” eyepiece mount?
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  #2  
Old 10-08-2020, 08:17 AM
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Outcast (Carlton)
Always gonna be a NOOB...

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Location: Cairns, Qld
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Hi Bob,

Welcome to the forum, to answer some of your question in part, I highly recommend this site:

https://astronomy.tools/calculators/field_of_view/

It allows you to plug in various combinations & see what the results will be, including sampling rate.

You will not need a focal reducer for imaging planets, in fact, you might want to employ a 2 or 3x barlow. For the moon, reducer is handy if you want to capture more of the moon than just a small segment.

If you decide to purchase a focal reducer, don't buy the 0.5x they aren't particularly good & really aren't suited to an SCT. If anything, you want to get an f6.3 reducer designed specifically for your SCT, both Meade & Celestron have one, either one will work; make sure you don't get the Edge HD one if buying a Celestron one.. it's designed specifically for the Edge HD.

Depending on what you want to do, there are other options for a dedicated camera that are less expensive. I use a 224MC for planetary work & a DSLR for deep sky... The 224MC has a very small chip, works well for planets but, cannot capture a full disc moon, from memory, even with a reducer. Somne folk swear by the 290mc, slightly bigger chip but, not by much. Plugging in the different cameras in the link I sent you, the 178 & 183 will not get you full disc either, however they will get you more of it.

T-ring for your Olympus, I believe this is what you are after:

https://www.opticscentral.com.au/t-m...U#.XzCDU5MzZgc

Together with one of these from Sirius optics.. you can adjust the spacings with this rather than a fixed length one:

http://www.sirius-optics.com.au/siri...SABEgJjyPD_BwE

Hope this helps...
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Old 12-08-2020, 01:48 PM
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multiweb (Marc)
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Location: Sydney
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I started with a setup like that but my scope was an 5" newt F/5 not an SCT so much easier to image with. If you want to seriously go down the imaging path the first thing to do is get a proper mount.

Quote:
Originally Posted by BobT View Post
My questions are: -
1. Is it worth buying a focal length reducer for imaging planets and the moon?
Definitely not for planetary imaging. You'll fit about one quarter of the moon disc in your fov at prime focus with the 178 and nearly all of it with the 183.
Quote:
Originally Posted by BobT View Post
2. If so, is the .5 reducer available from a large online store for $29 worth buying?
Sounds a little on the cheap side for a reducer. Got a link?
Quote:
Originally Posted by BobT View Post
3. Which camera would you prefer, the 178 (6.3mp) or the 183 (20.1mp)?
The 183 is 16mm diagonal which is still good for your scope corrected imaging circle. The 178 is only 9mm diagonal. Seems to be a very small sensor. Maybe the 183 is easier to use. Either way it will require some skill to land anything on a sensor that small with that mount.
Quote:
Originally Posted by BobT View Post
4. I also own an Olympus M5 mark 1 and would like to attach it to the telescope. Which adaptors and TMounts are required to mount it to the 1.25” eyepiece mount?
You'll definitely fit the full moon on the Olympus without a reducer. You can shop for adaptors on eBay. There are stacks of them.
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