Optical train order

[zicklurky]

Hi!

I've been wondering, is there a difference between:

1) Telescope -> powermate -> filter wheel -> camera

2) Telescope -> filter wheel -> powermate -> camera

I ask because I can screw in my filter wheel to the back of my SCT via T-thread so it's nice and secure, whereas at the moment I'm using telescope to powermate etc via 1.25" sockets.

Cheers,

Chris

[GuillermoBarrancos]

I think the general rule is that you want to have the filter as close to the camera sensor as possible.

[Earl]

Having filters as close the the sensor is the normal practise as it reduces vignetting issues if present, however if for example you were going.

Light Pollution Filter > Flattener > Filterwheel > CCD

That also works.

From your setup i guess your doing planetary imaging? As the sensor is smal,l in most cases either option should work for you.

[zicklurky]

Yeah this is for planetary. Thanks for the replies. I have a manual filter wheel, so every now and then when I'm changing filters I can feel the 1.25" connection holding the filter wheel slipping a bit, even if I tighten it quite hard. Hmmmm..

[Merlin66]

Try the different configurations...if one works better for you then stick with it.

[teleskopjo]

I had read however that one could also have the sensor close to the powermate since the further away you are the magnification changes.

So it'd be focuser>filterwheel>powermate>camera.. but then how can you attach a powermate behind a filterwheel?

[D4N]

I thought powermates were unaffected by sensor distance, unlike barlows that as you say increase in magnification the further they are from the sensor.

Sent from my iPad using Tapatalk

[teleskopjo]

Have a look at http://www.televue.com/images/TV3_images/Images_in_articles/PowermatePowerIncrease.jpg

Only the 2x powermate is more or less unaffected by sensor distance

The 2.5x actually decreases magnification the further away you are

[teleskopjo]

I guess one would need a T2 'male' to 2" 'female' to attach the 2x powermate to a filter wheel

[SkySurfer]

Hi,

I was under the impression that none of the powermates suffered when moved away from the sensor,,that is the whole point of there design.

But I may be wrong....

SS

[Zakalwe]

Use a good quality centering 2" to 1.25" adapter in the SCTG. I use an Antares which does the job

Then pay a small fortune for yet another adapter doobrie that allows you to take off the compression clamp from the Powermate. Screw the filterwheel to the PM. The stick a T-thread to C-thread adapter at the back of the filterwheel and screw the camera on.

So that's nearly £100 for three bits of ally thread adapters to add to the growing collection of extensions tubes, T-threads, spacers and so on. Cheap this game certainly isn't!

[teleskopjo]

The TeleVue chart only shows the 2"2x Powermate doing that

Hi,
I was under the impression that none of the powermates suffered when moved away from the sensor,,that is the whole point of there design.
But I may be wrong....
SS

[SkySurfer]

The TeleVue chart only shows the 2"2x Powermate doing that

Ok, I must have been mistaken then.....sorry