Planetary camera advice

[AstroMuni]

5 hours ago, Astro_Nic said:

Now you've got me worried I'll spend all of this and not be able to focus and it will all be a waste!  Is there a way to find out prior to I spend a small fortune?

Check how much travel is left on the scope (at the moment) when you reach focus. Then you can approximately work out how much extra distance you need to add/minus depending on equipment added. Thats the approach I took before I purchased my ASI224 for a scope that wasnt meant for AP (the Astromaster 130eq)

@FLO a wishlist to add a calculator for focuser travel distance please 🙂

Edited September 15, 2022 by AstroMuni

[sorrimen]

With camera + barlow you should be able to reach focus. I am just about able to with the 8” dob and asi224, but if you get a low profile 2” to 1.25” adapter there is no issue at all. It’s when you add ADCs or extension tubes etc that it’s starts to get tricky!

Edited September 15, 2022 by sorrimen

[Kon]

1 hour ago, Astro_Nic said:

Now you've got me worried I'll spend all of this and not be able to focus and it will all be a waste!  Is there a way to find out prior to I spend a small fortune?

Regarding focus with my asi462mc I cannot reach focus with the 1.25" adapter but if I move to the 2" one no problem at all. With the barlow or powermate, I can reach focus with the 1.25" if that helps. That was true for bot hthe asi120mc-s and 462mc that I have.

[Astro_Nic]

Excellent.  Thank you everyone for your help!

[catburglar]

On 14/09/2022 at 17:36, sorrimen said:

 

I would have to slightly disagree with catburglar above, as even though your level of detail would be the same with the 4x and 4um pixels, it would be virtually impossible to get the planet on the sensor, let alone on a shrunken ROI to get sufficient frames.

My point was that you could have the same RoI size (320x240 pixels say) in both configurations, and if the image scale is the same, then the FoV is the same also and hence - finding and tracking the planet will be just as easy/hard in both configurations…

But- I have never tried it and you have, so I’ll pipe down now and leave it to those with some practical experience…

 

Oops- this didn’t come through last night…andI can see you’ve moved past and it’s now irrelevant… just ignore me….walk on by…nothing to see here…

Edited September 15, 2022 by catburglar

[sorrimen]

1 hour ago, catburglar said:

My point was that you could have the same RoI size (320x240 pixels say) in both configurations, and if the image scale is the same, then the FoV is the same also and hence - finding and tracking the planet will be just as easy/hard in both configurations…

But- I have never tried it and you have, so I’ll pipe down now and leave it to those with some practical experience…

 

Oops- this didn’t come through last night…andI can see you’ve moved past and it’s now irrelevant… just ignore me….walk on by…nothing to see here…

Digressing a bit, I think you may be entirely correct logically, though I’ve had quite a think and I keep coming to different conclusions.

It would depend on the ROI being representative of different pixel sizes, and in practice I think an identical ROI (even with different pixel sizes) appears the same size on your screen, but with twice as much focal length the image is twice as large despite you getting the same amount of detail, so it’s much harder to track and get sufficient frames. I think this is more likely as your computer screen pixels can’t change size so it would simply reflect its own 320x240. I could certainly be wrong though, and if ROI on your screen does indeed reflect a different sized pixel then you would be 100% correct.

The caveat is also that your file sizes would be larger as you’d have to up your exposure to compensate for the dimmer image, also resulting in lower FPS. 

Sorry to Nic for hijacking the thread, but I’ve been racking my brain about this for the last 10 mins! 

[Cosmic Geoff]

On 14/09/2022 at 16:53, catburglar said:

1. Simple Tracking…you may not need or want GoTo, but could you get an equatorial platform for your dob?

Nic - I have no experience of these equatorial platforms, but it occurs to me that getting one might solve a lot of your problems.  For planetary imaging it only needs to work with the scope pointed S/SE/SW at the ecliptic. And it might prove useful for visual observing too. 

[Astro_Nic]

Thanks.  Excellent help.  I think I will stick with the 678.

 

In terms of filters, is there any benefit to a 2 inch one?  Or stick to 1.25"?  Money not an issue.

 

Thanks

 

Nic

[Astro_Nic]

Plus do I need any sort of T adapters to attach to the powermate?

Plus ADC or not?  Will be imaging at f10, so thinking not worth it?

Thanks

[johnturley]

17 minutes ago, Astro_Nic said:

Thanks.  Excellent help.  I think I will stick with the 678.

 

In terms of filters, is there any benefit to a 2 inch one?  Or stick to 1.25"?  Money not an issue.

 

Thanks

 

Nic

With the sensor size of the ASI 678 you don't need 2in filters, 1.25" is fine.

If you were to use a camera with a full frame sensor you would need 2 in filters. 

John 

[Astro_Nic]

6 minutes ago, johnturley said:

With the sensor size of the ASI 678 you don't need 2in filters, 1.25" is fine.

If you were to use a camera with a full frame sensor you would need 2 in filters. 

John 

Thanks.  Would 2" future proof me?  Just wondering if it will cause any issues in the image train.  Am getting a 2" powermate and have 2" focusers etc - no idea what thread is on the camera.

Thanks for your help.

 

Any brand worth getting or are they all about the same?  What's the difference between IR/UV and just an IR cut?

[johnturley]

1 hour ago, Astro_Nic said:

Thanks.  Would 2" future proof me?  Just wondering if it will cause any issues in the image train.  Am getting a 2" powermate and have 2" focusers etc - no idea what thread is on the camera.

Thanks for your help.

 

Any brand worth getting or are they all about the same?  What's the difference between IR/UV and just an IR cut?

1.25 in filters should be fine for up to 4/3" sized sensors, but 2 in for larger sizes.

If you are imaging planets you don't need a 2" Powermate, not only do these cost more, but they also add significant extra weight to the system which can result in balance issues.

Most ZWO Cameras (up to 4/3 " format) have a T thread, and come with a T thread to 1.25 in nosepiece, which is threaded for 1.25" filters.

Most observers recommend using an IR/UV cut filter for imaging planets such as the Baader one below, although cheaper brands are available. 

Baader CMOS Optimised UV/IR Cut and L Filter | First Light Optics

Hope this helps. 

Edited November 8, 2022 by johnturley

[Astro_Nic]

1 hour ago, johnturley said:

1.25 in filters should be fine for up to 4/3" sized sensors, but 2 in for larger sizes.

If you are imaging planets you don't need a 2" Powermate, not only do these cost more, but they also add significant extra weight to the system which can result in balance issues.

Most ZWO Cameras (up to 4/3 " format) have a T thread, and come with a T thread to 1.25 in nosepiece, which is threaded for 1.25" filters.

Most observers recommend using an IR/UV cut filter for imaging planets such as the Baader one below, although cheaper brands are available. 

Baader CMOS Optimised UV/IR Cut and L Filter | First Light Optics

Hope this helps. 

Thanks.  I was after getting a powermate as I am principally a visual user and therefore want a powermate - this will also allow me to attach my 2 inch eyepieces - not likely to need it for my 1.25" eyepieces.  Although not sure if I need a barlow for visual but it gives me flexibility.

The main reason though is that the powermate on FLO website only comes in 2" for the 2x.  The 1.25" is a 2.5x powermate........is that too powerful?

Thanks

[johnturley]

I generally use a 2.5x Powermate with my Esprit 150 (f7) and ZWO ASI 462 camera, which gives f17.5 and effective fl of 2650mm, I tried a 5x Powermate, but the results were not that great, although it might work ok on Mars under very good atmospheric conditions.  

With your f4.6 VX14 (fl 1600 mm), a 2.5x Powermate would give f11.5 (which incidentally is supposed to be close to the optimum for the ASI 462), and effective fl of 4,000 mm. I gather however that you were thinking of the ASI 678, which has a larger 1 /1.8 " format, so the image size would be similar to what I get with the Esprit 150 and ASI 462 with its smaller 1/2.8" format, so no a 2.5x Powermate would not be too powerful. 

John 

Edited November 8, 2022 by johnturley

[Astro_Nic]

39 minutes ago, johnturley said:

I generally use a 2.5x Powermate with my Esprit 150 (f7) and ZWO ASI 462 camera, which gives f17.5 and effective fl of 2650mm, I tried a 5x Powermate, but the results were not that great, although it might work ok on Mars under very good atmospheric conditions.  

With your f4.6 VX14 (fl 1600 mm), a 2.5x Powermate would give f11.5 (which incidentally is supposed to be close to the optimum for the ASI 462), and effective fl of 4,000 mm. I gather however that you were thinking of the ASI 678, which has a larger 1 /1.8 " format, so the image size would be similar to what I get with the Esprit 150 and ASI 462 with its smaller 1/2.8" format, so no a 2.5x Powermate would not be too powerful. 

John 

I was more meaning that it would be too much for manually tracking dob.  Don't want to make this anymore difficult!

[Astro_Nic]

so 2.5x 1.25" powermate or the 2x 2" powermate?

 

5 x 2um = 10 um optimum?  Although someone has mentioned that with the ADC it might be 2.2x barlow effect so 4.6 x 2.2 =  10.16......   That's a 3,500ish FL for a manual dob.  Looks perfect sampling

 

The 1.25" powermate is interesting as it's sp much cheaper.  But this gives a 4,000 FL or more with ADC and a 2.5x (2.8x?) x 4.6 = 12.9....too over-sampled? and harder to use?

 

Over-complicating it?  Maybe I just don't need a powermate and just get a 2x televue barlow and forget it for visual?  Have 22mm (2 inch), 13mm, 9mm, 6mm, 4.5mm eyepieces

Help!

Thanks! 

[Astro_Nic]

OK so last post but the powermate does not increase magnification with distance from camera, the barlow would.  Barlow more flexible then?  Or the constant of the powermate easier as I want 2x?!

[johnturley]

58 minutes ago, Astro_Nic said:

so 2.5x 1.25" powermate or the 2x 2" powermate?

 

5 x 2um = 10 um optimum?  Although someone has mentioned that with the ADC it might be 2.2x barlow effect so 4.6 x 2.2 =  10.16......   That's a 3,500ish FL for a manual dob.  Looks perfect sampling

 

The 1.25" powermate is interesting as it's sp much cheaper.  But this gives a 4,000 FL or more with ADC and a 2.5x (2.8x?) x 4.6 = 12.9....too over-sampled? and harder to use?

 

Over-complicating it?  Maybe I just don't need a powermate and just get a 2x televue barlow and forget it for visual?  Have 22mm (2 inch), 13mm, 9mm, 6mm, 4.5mm eyepieces

Help!

Thanks! 

Don't worry about possibly over-sampling with your proposed set up.

Geoff Lewis regularly uses f22 - f24 with his C14 and ASI 462, and gets good results.

John 

[Astro_Nic]

14 minutes ago, johnturley said:

Don't worry about possibly over-sampling with your proposed set up.

Geoff Lewis regularly uses f22 - f24 with his C14 and ASI 462, and gets good results.

John 

Yeah but he’s not using a manual dob! 

[johnturley]

18 hours ago, Astro_Nic said:

Yeah but he’s not using a manual dob! 

I understand that using a manual dob makes planetary imaging more difficult, but several observers such as Kon (see his recent Mars posting taken using a manual dob), produce some excellent results using these sort of set ups.

John 

Edited November 9, 2022 by johnturley