Barlows & Powermates - How to use them with Eyepieces and Cameras

[Chris]

Just a quick guide to the differences between Barlow's (Telenegatives) and Powermates (Telecentrics).

 

And for the beginners out there, I also cover how to use Barlow's and Powermates with both Eyepieces and cameras.

 

 

 

 

 

 

 

 

 

Edited August 22, 2021 by Chris

[John]

Nice piece Chris

I found the Explore Scientific Focal Extenders very, very nearly as good as the Tele Vue Powermates for observing use.

If the budget allows though, a Powermate is a superb piece of kit

Edited August 22, 2021 by John

[Chris]

25 minutes ago, John said:

Nice piece Chris

I found the Explore Scientific Focal Extenders very, very nearly as good as the Tele Vue Powermates for observing use.

If the budget allows though, a Powermate is a superb piece of kit

Thanks John, good to know. Similar situation to ES vs TV eyepieces then  

[JamesF]

Could someone take pity on a tired old pedant and remove the greengrocer's apostrophe from the topic title?

It's probably just me, but they make my brain do horrible things

James

[johnturley]

2 hours ago, Chris said:

Chris 

I noticed in your video that you have a ZWO ASI 462 Planetary Camera.

I have recently acquired an ASI 462 which I intend to use mainly for planetary photographs through my Esprit 150, I think that to get a decent image size with Saturn and Mars in particular, I will need something like a 4 or 5x Powermate, I already have a 2x Barlow but think that this will not give enough amplification. A 4x Powermate would give an effective focal length on the Esprit 150 of 4,200 mm, similar to that of a C14. 

I am also assuming that due to the small sensor size of the ASI 462, that there would be no advantage in having a 2 in Powermate over the 1.25 in, in fact the former would just add a lot of unnecessary weight to the system which is undesirable. Is this correct. 

John 

 

 

Edited August 22, 2021 by johnturley

[Chris]

50 minutes ago, JamesF said:

Could someone take pity on a tired old pedant and remove the greengrocer's apostrophe from the topic title?

It's probably just me, but they make my brain do horrible things

James

Done  Normal brain activity may now resume  

[CraigT82]

Nice video. Love the snazzy brick backdrop.  I echo John's comments on the ES focal extenders, I've had the 2x and 3x and both were excellent. 

Is that an amp on the bedside table... alarm clock not loud enough!? 

[Chris]

25 minutes ago, johnturley said:

 

 

Hi John, 

One planetary imaging rule of thumb says to aim for an f/ratio around 5x your pixel size. The ASI462 has 2.9um pixels, therefore 2.9 x 5= f/14-15, and this would be achieved with a 2x Powermate or Barlow and your Esprit 150.

Obeying the above rule of thumb leaves you at around 2100mm focal length.  

This is obviously a general rule of thumb and maybe the Esprit 150 can punch above it's weight. I'm not sure about using a 4 x Powermate at f/28 with 6" of aperture though? Maybe the hardcore planetary imagers can advice? I dabble with a bit of everything which makes me an expert on precisely nothing  

Yes, the ASI462mc has a very small sensor which wont vignette with it's supplied 1.25" nosepiece. You would only really want a 2" Barlow when imaging large objects like the Sun or Moon with a DLSR/Mirrorless camera with an APS-C or Full frame size sensor.   

 

 

 

 

 

 

[johnturley]

43 minutes ago, Chris said:

Hi John, 

One planetary imaging rule of thumb says to aim for an f/ratio around 5x your pixel size. The ASI462 has 2.9um pixels, therefore 2.9 x 5= f/14-15, and this would be achieved with a 2x Powermate or Barlow and your Esprit 150.

Obeying the above rule of thumb leaves you at around 2100mm focal length.  

This is obviously a general rule of thumb and maybe the Esprit 150 can punch above it's weight. I'm not sure about using a 4 x Powermate at f/28 with 6" of aperture though? Maybe the hardcore planetary imagers can advice? I dabble with a bit of everything which makes me an expert on precisely nothing  

Yes, the ASI462mc has a very small sensor which wont vignette with it's supplied 1.25" nosepiece. You would only really want a 2" Barlow when imaging large objects like the Sun or Moon with a DLSR/Mirrorless camera with an APS-C or Full frame size sensor.   

 

 

 

 

 

 

Thanks Chris

Will give it a go with my Meade 1.25 in 2x Barlow, and see what the results are like. 

John 

Edited August 22, 2021 by johnturley

[Chris]

40 minutes ago, CraigT82 said:

Nice video. Love the snazzy brick backdrop.  I echo John's comments on the ES focal extenders, I've had the 2x and 3x and both were excellent. 

Is that an amp on the bedside table... alarm clock not loud enough!? 

Thanks Craig, that's good to hear. I actually thought about mentioning the TS version in the video, but to keep things neat I decided to refer to all telecentrics as Powermates due to them being the original and probably best known example.

lol Yes it's my mini Marshal amp. Us night owls need some waking up sometimes  

 

[JamesF]

3 hours ago, Chris said:

Done  Normal brain activity may now resume  

Thank you, Chris.  Much appreciated

James

[wulfrun]

4 hours ago, JamesF said:

Could someone take pity on a tired old pedant and remove the greengrocer's apostrophe from the topic title?

It's probably just me, but they make my brain do horrible things

James

No it's not just you. However, I tend to just keep quiet...sometimes it's an innocent mistake (or, more annoyingly, an auto-correct induced thing).

[JamesF]

3 hours ago, wulfrun said:

No it's not just you. However, I tend to just keep quiet...sometimes it's an innocent mistake (or, more annoyingly, an auto-correct induced thing).

I tried, honestly I did.  But every time it appeared on the screen my brain just forced me to look at it.  I don't know why.

James

[JeremyS]

Another nice video job, Lockie 👍🏻