Improving contrast with barlows (1 Viewer)

[Paul Corfield]

Here's a simple solution to really boost the contrast with barlows. Barlows generally suffer from light scatter with varying degrees depending on the barlow make. This is easily eliminated by adding a baffle to the front of the barlow. Also insure that the internal walls of the T-mount are all matt black and if not then paint with matt black paint or line with black felt, black flock paper or something similar. Baffling the front will give any barlow an extra boost to contrast however.

With my 2" GSO I've added a piece of tube to the front and into that I've inserted a rubber eye cup from an old pair of binoculars. My T-mount is all matt black inside so this boost to contrast is coming purely from the light baffle on the front. See the before and after photos, both were shot at the same shutter speed and are not altered in any way.

Paul.

 

[bluedubius]

You're always one step ahead, Paul. I noticed that really shiny front on my GSO 2X when we were talking about baffling the t-mount, but never followed up on that observation. I can see from your modification that this will improve the system. I've found another material useful for baffling. It's just a thin, flat black craft foam that's sold in many stores. It's cheap, comes in a 8.5 x 11" sheet. I just cut it to the length I need, then roll it up and fit it inside the tube. I guess lot's of things one might have laying around would work for this. Anyway, thanks again for bringing these little details to our attention.

Rick

 

[Paul Corfield]

I can never understand why stuff like this has areas that are so shiny. I've read on some astronomy forums that even really expensive barlows in the $200 or more price range are improved with extra baffling to control stray light.

Paul.