GSO 2x (1 Viewer)

Musoman · Apr 7, 2010

Checking out the GSO 2x and still dont seem to have much luck with this..
I'm really happy with the quality of pics at the standard 600mm without any TC / Barlow, but they just seem to go AWOL when any TC or barlow is mounted. The DOI 2x i tried previously produced the same terrible results

Tripod was used, and no software was used at all other than to 100% crop all 3 pics

Ist pic is ISO 1600 @ 1/640th and figured the noise using ISO 1600 was the culprit.

2nd pic is ISO 800 @ 1/400th no difference really

3rd pic is ISO 800 @ 1/640th. no difference.

Its quite a dull day, overcast etc.

Musoman · Apr 7, 2010

And now the same TV aerial ( minus the pigeon cos it flew ) without Barlow, on a tripod, and zero post processing apart from 100% cropping. Still very dull out

1st pic ISO 800 @ 1/640th

2nd pic ISO 800 @ 1/1250th

The difference in quality is too much to simply be just the Barlow , surely ?

I fully expect to get less light and less IQ when adding any type of TC but the huge difference in quality between no GSO and GSO mounted is a mystery

Paul Corfield · Apr 7, 2010

I'd guess the range to be around 40m looking at the crops but you should be getting good quality at that sort of range or at any range come to think of it with the DOI and the GSO. For you there must be a manual focusing issue once you increase the magnification.

A 2X teleconverter for example will decrease the depth of field of the effective f stop by about 50% so focusing is more critical. The effective f stop is the new f stop created by adding the teleconverter. A 2X adds 2 stops and a 1.4X adds 1 stop. Also distance to subject will affect depth of field, the closer the subject then the lower the depth of field.

I remember you saying you had a cataract so do you think that changes in the depth of field is making it harder to focus.

Paul.

Musoman · Apr 7, 2010

Thanks for the info Paul. I didnt check the range, but i guess your experience will tell you the approx distance, bearing in mind that i have a 10mp sensor, so pics at 40 metres from my 40D will look a bit smaller than your 12mp 450D at 40 metres, i assume ?

Yes, i have a cataract but its in my right eye, but i use my left eye for focusing.

Anyway, if the cataract was the cause of the problem, i'd be getting issues of focusing at 600mm too, with out the Barlow or TC.

There is something else not right here, and it doesnt look like i'm ever going to get to the cause of it.
I think the best thing i can do is stop wasting my money on trying to get extra reach with TC's and Barlows, sell off the current 2x and 1.5x and simply only ever use the scope at its natural 600mm FL

Paul Corfield · Apr 7, 2010

I got my GSO 2X out earlier and did a selection from 12m out to 85m range and these are all around 50% crops. In theory focusing through it should be just the same as focusing with the scope at 600mm. The image either looks blurred or sharp in the viewfinder. The only out of focus shots I got today with the GSO were where the bird has moved too quickly so it's hard to suggest anything that could help. You can still get good photos though even at 600mm as you showed with your owl.

Paul.

Musoman · Apr 7, 2010

Paul Corfield said:
In theory focusing through it should be just the same as focusing with the scope at 600mm. The image either looks blurred or sharp in the viewfinder.

Paul.

Exactly.

I simply cannot get focus. I knew it before i took the shot. The pigeons posted today were motionless too.

Its a mystery, as the pics with and without Barlow or TC are so vastly different. I can focus ok without the Barlow / TC but i simply cannot get focus with one attached.
Thats a problem with the camera maybe.

The Owl was 190+ metres using 600mm, and the IQ isnt that good because of the huge distance, but its 10 times better than with any TC or Barlow i've used.

Paul Corfield · Apr 8, 2010

Musoman said:
Exactly.

I simply cannot get focus. I knew it before i took the shot. The pigeons posted today were motionless too.

So with a barlow or TC are you saying that the image in the viewfinder never appears sharp? It's a silly question but I need to check that you are taking the posted photos outside and not from behind glass or through an open window.

If you get some sun then try some stuff from close range and post maybe 50% crops rather than 100%. Closer distances will rule out any air disturbance ruining the IQ, especially if it's sunny as nearby buildings or rooftops etc give off so much heat that you can't photograph anything on them and get sharp results.

Beyond that I would need to see the scope to check it out myself.

Paul.

Musoman · Apr 8, 2010

Yes mate - they never appear sharp in the VF, unlike shooting without the Barlow or TC.

So i know the end result will be bad even before i've taken the shot.

I'll try your method of shorter distance, and in sunlight but away from heat emitting sources like rooftops, and 50% crops.
I'll post back asap

Musoman · Apr 8, 2010

More GSO 2x tests, and this time the shots were at 25 metres, google earthed.
Taken in sunlight ( at last ! ) on a tripod. The pigeons and top of the telegraph pole were the exact same distance. I merely took one of the pole when the pigeon flew.

Pigeons and top of pole are all 50% crops followed by their respective 100% crops. No processing what so ever

The last shot of the telegraph pole is a 33.3% reduction and processed

Both pigeons ISO 800 @ 1/500th

Both poles ISO 800 @ 1/800th

Musoman · Apr 8, 2010

......

Musoman · Apr 8, 2010

There was a mistake .. this is the proper 100% crop of the Pigeon No.2

Paul Corfield · Apr 8, 2010

The Pigeon ones don't look too bad but the main problem is the barlow is showing poor contrast and needs to be baffled. The photos I posted yesterday using the GSO haven't been altered and they show the contrast that can be achieved with a little bit of baffling. I made a simple ring out of the flock paper and made it a size that will sit in the front threaded part of the barlow. I cut a small 1" or 3/4" diameter approx hole in the flock paper. If you make the hole too big then the contrast gets worse. The smaller the better but not too tiny or you will get some vignetting so try about 3/4" first. The photos of just the pole show either some heat shimmer or maybe a slight movement but the processed one has been really overdone as it's covered in artefacts. With warm weather like today there will likely be annoying air currents even at this sort of range. Spring/summer is a terrible time of the year now for long range photography. I tend to get to my local places at the crack of dawn and leave by 10am or get to them near sunset.

Paul.

Musoman · Apr 8, 2010

Yes i noticed the bad contrast too. Also, I completely unscrewed the Barlow, and it sits in the MAX dslr. I flocked all the ext tubes & the MAX before taking the shots, so there's little to be done in that respect Paul.

The over processed shot has probably ended up like that trying to make a silk purse out of a sows ear :smoke:

I went to the local wildlife reserve this afternoon, avoiding the midday heat shimmer, and shot a complete 2 gig CF card full. Thats about 200 shots ( RAW )

I'll be lucky to get 5 good one's I reckon.

Paul Corfield · Apr 8, 2010

Flocking the sides of the tubes wont affect the contrast with barlows. Only making a ring for the front that covers a lot of the glass will alter it. If you've taken the barlow out of the lens cell then just stick it straight to the glass. I've stuck mine onto the glass with some blu-tac which works fine. Making a ring which cuts out at least 50% of the barlow glass will make a huge difference to the contrast and bring it up to the level of say a Kenko teleconverter as a comparison.

Were you shooting over water today or over land?

Paul.

Musoman · Apr 8, 2010

Well that was a waste of flock paper

Didnt realise flocking all the tubes was useless

When you say stick the Barlow to the glass, do you mean take the barlow out of the MAX and stick it to the flourite glass in the scope ? And also cut down the diameter of the front or rear of the barlow glass by 50% ?

I'm not sure if i've read you right there.

Today i was shooting over both land & water, though the water was quite still. Havent had time to process.

Paul Corfield · Apr 9, 2010

The ring that you make out of flock paper you stick to the barlow glass if you've taken the barlow glass out of the lens cell. Example below.

It was Fernando who said flocking the scope would improve contrast. This will improve contrast with the scope at 600mm and possibly to some degree with teleconverters but barlows are a different kettle of fish.

When shooting over water there is usually a fair difference in the temperature of the water and the air above it which can make it hard to photograph anything at distance. To some degree it's the same over land but after a while of photographing at high magnification you get to know when image quality is being affected by the conditions at any particular time of day.

Paul.

FernandoBatista · Apr 9, 2010

I don’t agree flocking all tubes will be useless, on the contrary.
The difference in flocking a Barlow internal tube maybe small, it probably is. But there will be a difference as tiny as it may be. And even you don’t notice that difference alone, if you get that tiny difference, added to all the other tiny differences it makes in flocking all the other parts on the scope setup, all put together will make a big difference. In that sense I really don’t agree it’s useless.

That said, I do agree with Paul, you’ll get a much better result if you baffle instead of flocking

IMHO every bit of part that can put a reflection in the optical path is worth "darkening", either by flocking or baffling.

Musoman · Apr 9, 2010

Thanks guys - now i've seen the Barlow with baffle it makes more sense.

I have more than enough flock left to do the scope tube too, but i figured this didnt need doing, as the scope tube is already matt black , where as all the ext tubes are gloss black

So, I'll get the scope tube done as well, and baffle that Barlow :t:

meanwhile, i'll have a look at the pics i took yesterday, and see what the temp / water has done

Paul Corfield · Apr 9, 2010

I think I read somewhere that even the best flat black paint reflects something like 5% light but it's probably a little more inside the 80ED.

Like Fernando said, all those little percentages add up.

I'm going on a trip out later this evening with the scope. Had a play mid morning but even 15m was a struggle to get razor sharp detail with the heat in the back garden.

Paul.

Musoman · Apr 10, 2010

Some Barn Owl shots just over 200 meters, so cant blame the scope / GSO for the poor quality.

Like you said Paul, shot across water into a neighbouring field so maybe some heat shimmer, and resting the scope on a window frame. The scope just didnt want to focus at that distance

GSO 2x (1 Viewer)

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