x4 or x5 barlow?

[watulkuh]

Hi All

I've had a search through the beginners forum and couldn't find an answer so hopefully someone would be kind enough to reply.

I've been using a 2x barlow with an spc900 on my 8" reflector and I've been happy with the results but not ecstatic. I want to know if purchasing a 4x or 5x barlow would improve my images and allow me to either see more detail or view a larger image of say Jupiter?

Many Thanks

John

[Merlin66]

If your scope is an f5 system, then yes a x4 Barlow would give you fainter but larger images.

A effective f ratio of 20-30 would be good.

[watulkuh]

Thanks for reply Merlin66.

My scope is a fast F5 but I don't like the sound of a fainter image. SOunds like detail will suffer which is what I'm really after. I suppose I better go back to registax and work on my avi's.

Cheers

[Merlin66]

As you increase the focal length (by using a barlow) you're just spreading the same amount of light over a larger image, a x4 barlow will give a x16 fainter image...such is life...

[enigmacell]

Where can you get a 4x or 5x barlow with a t-adapter thread? I can only find 2x with a thread:icon_confused:

[steelfixer]

Hi John

I use an Antares 5x barlow with my 900 and the images are brilliant.

graham

[steelfixer]

Enigmacell scope and skies do a 5x barlow with the thread.

I cannot for the life of me think of the makers name but it is a british company.

I did try to get one before I purchased my Antares but had a lot of grief and waiting as it was not in stock.

So I would ring them up first to make sure they have one in.

Graham.

[enigmacell]

Thanx, I'll look into it now;)

[enigmacell]

If x5 makes images on an 8" too faint would x3 be the limit on a 6"?

[Merlin66]

No, There's usually enough light from the moon and planets ( the prime targets for the f 20 to f 30 images) for them to appear OK. A 6" at f20-30 would be as good, relatively, as any other scope....

[steelfixer]

To be honest I have never noticed any drop off in brightness when using my barlow.

I cannot dispute what Merlin is saying as I do not have the technical knowlage but as the chip in a 900 is so small I cannot see that it makes any difference.

You might notice it with a DSLR as it will have a larger chip.

With any luck someone who knows the ins and outs of this can put us both right.

Graham

[watulkuh]

Thanks for the replies peeps. I think I'm going to shell out for a nice x5 barlow i've seen on the tinternets so I will let you know how I get on. :-)