An Amusing Error

[jefrs]

I shot a time lapse series on the Sky-Watcher Star Adventurer EQ with the Panasonic GH4 to test the Samyang Reflex 500mm f/6.3 (8 seconds at ISO800)

In the middle of the series, this one shot stood out.

It's been post developed in Elements and cropped but not massaged (Elements doesn't actually convert the raw as well as the camera does: £45 software vs £1300 camera? go figure)

The lens is very difficult to focus, even with the manual focus assist x6 digital zoom on, and suffers badly from vibration (the optical image stabilised (OIS) Lumix G 100-300/F4.0-5.6 fares far better)

Tripod was the medium weight Manfrotto 055XPROB

The lens also seems to suffer from distortion/aberration but its sibling the Samyang Reflex 800mm f/8.0 fares worse. The stars appeared conical but could not be focussed circular; suggesting the focus mechanism needs finer movement at the infinity end of travel or it is just not man for the job.

Interestingly perhaps, the Panasonic GH4 and Lumix G 100-300/F4.0-5.6 combination later scored a perfect auto-focus lock using the pinpoint focus mode (confirmed by MF) on Sirius.

Sirius blew out the highlights impressively so I swung it over to the Pleiades where we acquired focus confirmation highlighting on the Pleiades cluster stars with manual focus (MF).

This was an equipment test on the patio where we have too much light pollution for decent viewing. Aligning on Polaris through the sodium yellow haze is particularly tiresome.

[RichM63]

"Its light Jef but not as we know it"

Coincidence but someone has dropped me an email offering one for sale (600mm f6.3) at about £90.

How does it perform during the day. I'm trying to decide if the time for the drive will be worth it.

Cheers,

Rich

[jefrs]

"Its light Jef but not as we know it"

Coincidence but someone has dropped me an email offering one for sale (600mm f6.3) at about £90.

How does it perform during the day. I'm trying to decide if the time for the drive will be worth it.

Cheers,

Rich

They're not that much more new, I think I paid £130 for the 800 f/8 and £120 for the 500 f/6.3

As with all reflex and indeed such long lenses you lose sharpness and contrast and they have a very shallow depth of field of something like 1/2-nch wide at 3 metres.

This deficit is easily boosted up by the camera or in post.

Image quality not the best but about the best you cant get at this length without selling body parts e.g. Nikkor 600mm f/4 £7,000

I say at this length because I'm using them on M43 (MFT) which has a x2 crop factor so the 800mm is equivalent to a 1600mm on full frame (and it has a x2 teleconverter)

I have used them for wildlife, some pics on my wall here https://www.flickr.com/photos/jefrs/ you'll have to sift but I always give description and exif: usually sooc jpeg unless I crop the rw2 raw: I refuse to photoshop every snap. The robin was taken at length of garden and filled the frame,  I adjusted sharpness and contrast at the camera. Not the best image quality by any means but it can be that of no image. I know Canon also do a reflex (500mm?) I've seen the results and not noticeably better.

The focus movement is little more than 1/4-turn and the infinity end is closed up (logarithmic scale) plus my arthritic fingers were numb with cold: I was disappointed not to resolve  circles but another nudge and I got doughnuts.

I shall try to focus astro again but on a stiffer mount where I'm not stretching; the moon may be a better target.

[RichM63]

Thanks for the extra info. Yes I have further checked and the new price rules out the offered S/H lens.

I can't afford or justify an L series telephoto at this length, even after selling body parts.

I'll be very interested to hear about your further 'Astro' focusing efforts although my main use will be daytime.

700D with 1.6x crop so 800mm. For Astro mounted on either EQ3-2 or EQ5, both motorized for tracking at slower shutter speeds. Worth getting the 2x convertor?? yes/no

Again, I'm more interested in using the lens at high shutter speeds during the day.

Currently using an ST80 as a prime lens, quite happy with the results, but it is a bit like aiming a Bazooker when everything is hooked up, and I really need to release the ST80 for its intended use.

I have an AF Confirm T2 adapter in the post, and would hope that this would work with this lens.

If it works on the Moon that would be a bonus.

Thanks again, I don't often see reviews on Catadioptric lenses.

[jefrs]

I've tried to use a "Dandelion" AF confirm chip/adaptor and it was about as much use as a chocolate teapot, fortunately it soon snapped itself in half.

All it ever did was fool the camera into thinking a lens was fitted but they don't need that, It was supposed to put the green focussed lamp on but never did.

M43 uses the "shoot without lens" setting for manual lenses.

Our M43 camera mostly all have focus highlight "peaking" which works with any lenses even manual ones. Only the older ones do not have this function.

Reflex lenses "doughnut" when out of focus and hence are reasonably easy to judge even without focus highlighting, but the long lens image dances about like mad when you touch the focus ring. And there's my problem, I can't make micro-movements with my fingers: I may drill and tap the alloy focus ring (there is more then enough metal thickness) to fit a focus-lock screw that would also serve as a long lever for micro adjustments, something like M3x80

Good sky tonight but freezing, my left hand is practically non-operational this evening, second and  third finger feel like someone stepped on them: I'll have to give my experiment a miss today :-(

[RichM63]

I have similar hand/finger problems, it is no fun.

Currently using ML and Focus Peaking with the ST80.

As for the dancing image, I cobbled together a mount for the camera + ST80 with a dovetail and tube ring, where everything bolts together and sits on the EQ3-2 this works great and only slightly less so with a cushion on the car roof. (see ST80 in the photography section).

I think I'll take a punt on the 500mm f6.3, from what you have said the 800mm f8 would be too much on my 700D. Slightly concerned that the lens hood is 1/3 of the price of the lens.

I'm certainly capable of adding a focus lever if required.

Thanks again. I hope you can continue the experiment soon, fingers permitting.

[jefrs]

What make/model reflex have you been offered on the 600mm f/6.3?

It may be better than the Samyang and second hand lenses are usually the best way to buy.

Samyang have a long and confusing list of names aka Walimex/Bower/Rokinon etc, at least half a dozen brand names which they are rationalising. Samyang use "Bower" for their filter line, so maybe hoods too but you can use a plastic flowerpot :-)

The vibration is not the rig as such but mainly that camera and lens are held on the one and only 1/4ANC20 screw under the camera body, no lens clamp ring mount possible.

I am/was using a Manfrotto 055XPROB, the Star Adventurer EQ motor, Manfrotto 410 Junior geared to Panasonic GH4 + reflex lens. A pretty solid rig.

Everything is fine until one touches the lens to focus it (or a big gust of wind, when I took the pic above we were on the tail of a major storm system, gusts over 100mph earlier, our house had minor damage)

"Cunning Plan" may not translate unless you are familiar with "Black Adder" :-

If an extension tube brings a lens focus point closer for macro then taking one out or using shorter should throw the focus longer giving me better fine adjustment at the infinity end: cunning plan.

[jefrs]

I have similar hand/finger problems, it is no fun.

Currently using ML and Focus Peaking with the ST80.

As for the dancing image, I cobbled together a mount for the camera + ST80 with a dovetail and tube ring, where everything bolts together and sits on the EQ3-2 this works great and only slightly less so with a cushion on the car roof. (see ST80 in the photography section).

I think I'll take a punt on the 500mm f6.3, from what you have said the 800mm f8 would be too much on my 700D. Slightly concerned that the lens hood is 1/3 of the price of the lens.

I'm certainly capable of adding a focus lever if required.

Thanks again. I hope you can continue the experiment soon, fingers permitting.

I cannot find "ST80 in the photography section" or rather I am spoilt for choice, too many hits for "ST80" that I cannot find the one you refer to.

Please show me a link to your pic?

[jefrs]

Down & dirty test with the adaptor tube.

With full length tube the 500/F6.3 focusses at some 15m down the front garden (the robin pics were here, the little robin filled the frame), that's according to its focus ring mark.

With the 2cm "extension tube" removed it now focusses at its 6m mark, which gives me more swing on the focus ring at this point, finer control. The focus length of the lens is slightly reduced, greater field of view

I think these lenses will be better at imaging the moon than stars. The best shots I have had of the moon so far have probably been with the Panasonic FZ200 bridge camera, now that has FoV equivalent to 35mm film of 24-600mm but also does a digital zoom without loss of resolution by pixel binning to 48X or about 1200mm (or to a barking mad 197X 4800mm by dropping resolution: all at max/widest aperture f/2.8 !!! ) Leica lens :-)

[RichM63]

LOL on the 'cunning plan' I pretty much had to do just that for the ST80, by adding an empty Barlow tube into the line to obtain sensible focus travel on the short end.

Here is the link to the thread. Woo hoo ST80 Works. Post 33 shows a picture.

Keeping the tube ring loose allows it to slide for focusing (can then be tightened if required). The whole thing can be hand held as effectively there are 2 fixing points, one at either end.

The lens offered was a badged Samyang, but as the new price is only about £25 more I'll go for new with 2yr guarantee. Good info on the Bower line. I'm hoping that there is a slim chance that I can use the ST80 hood as the internal diameter is 97.5mm if not then I'll make one out of pvc drain pipe by heat flaring a piece to match.

You may also find this article interesting about the 500mm f6.3.

As the ST80 has no focus marks at all I've marked a couple on the draw tube, 1 at approx 30 feet and one where I can hit pretty decent focus on the Moon. I'm guessing that I'll need to do the same here, as you seem to be reporting that the infinity mark is not at celestial infinity from your pic above. 

We'll see what happens when it arrives.

[jefrs]

Interesting.

The Pro Optics looks to be a Samyang, identical. Samyang do also make a 500mm f/8 which looks rather a lot like the Tamron 500mm f/8 mirror, and a smaller iris will be sharper but slower. The Samyang 500/f8.0 is cheaper than their 500/F6.3, I did wonder about that. The Canon comparison is a refractive lens, far better and no contest, it costs a lot.

Long story cut short but we visited T4 Cameras in Witney today (plus there's a really really nice tea house (posh cafe/restaurant) just across the road) then we went ostensibly looking for a simple p&s compact camera for my wife. Fortunately they convinced her to persevere with her GX7. They had sold us the 130SLT (&c) so we got talking about cameras and lenses. They reckon the best wildlife camera for me would be the new Canon 7Dii with a long Sigma or Tamron as the equivalent Canon lenses vary from £3,500 to £5,900. Body only the Canon is the best part of £1,600 and the Bigma is just under £1,500, nice but far too rich for me, but they did manage to sell us a nearly new unused s/h M43 (MFT) Leica 45mm f/1.4 Summilux, with discount. This is one of those few top world-class drop-dead lenses for not a lot of dosh. Thanks T4 :-)

Also interesting in the Pro Optic article regarding the old 1/focal.length "rule of thumb" telling us to multiply the speed by the crop factor so that for Canon's 1.6X 1/500 should become 1/800. Now I still have a 35mm film SLR with a 55-225mm zoom and that was never steady enough at 1/250, I'd have to double up to at least 1/500. I reckon the rule of thumb falls apart with extra-long lenses.

From talking to the chaps at T4, there is also another rule of thumb to determine maximum exposure for a given focal length, sensor format, and aperture size; it relates to the circle of confusion. Basically resolution: the longer the lens, the more the image moves about, and so the shorter the exposure has to be, even on a tripod. I wish I had written it down, but it does limit some long lenses to less than like 10 seconds. I shall have to phone them ;-)

I find the draw  of the 130SLT focusser varies with eyepiece, with lens; no fixed position for focus points.

I notice you fit bands around the scope to mount other stuff. I have acquired a Celestron camera mount but for large diameter than out 130SLT. To fit it I'll have to pop a couple of 4mm holes through the tube but I'm not certain I want to do that just yet (to catch swarf blob Blu-Tack and a good fridge magnet inside, and use a wheel brace with a sharp drill bit; hopefully wife can fit her hand through the spider 'cos I can't and I don't want to dismantle)

[jefrs]

typo correction :- "but for a larger diameter than our 130SLT"

Also not sure on naming of parts - by "spider" I mean the cross holding the secondary mirror.

[jefrs]

Thought re cameras. The chaps in T4 recommended the Canon 7Dii to me, showed me some lovely shots and enthused how good it is compared to everything especially M43.

So I pulled up the DXOmark comparison of GH4 vs 7D vs 7Dii and guess what? - the GH4 gets higher marks despite smaller sensor format, only just - but enough to convince me not to switch horses mid race.

But M43 lacks any extra-long OEM lenses and nothing better than the 100-300/F4.0-5.6 I have, no long long primes

[RichM63]

See Pyschobilly's shots with the new Canon 7D11 + Canon 600mm Lens and 1x4 convertor. Sensational.

Ordered a Samyang 500mm f6.3, apparently Samyang are the manufacturer but the lenses get badged in many forms. I understand the limitations, but can't spend any higher. Should be here by weekend.

Tube rings clamp to the tube, no drilling required and come in different diameters.

Playing with the ST80, and using the basic 500/fl to give max exposure time on a fixed mount. Celestial, and using matched ISO and shutter speeds for fixed aperture Terrestrial eg ISO1600 = 1/1600s. 

Hoping that I can modify my DIY mount to support the front end of the Samyang, thinking that a drain pipe hood that slide rotates within the tube ring to allow focus and give support with the camera bolted to the other end.

With the 400mm ST80 I can hand hold quite well because my front hand is a long way forward on the dovetail bar. Here's hoping.

[jefrs]

See Pyschobilly's shots with the new Canon 7D11 + Canon 600mm Lens and 1x4 convertor. Sensational.

Ordered a Samyang 500mm f6.3, apparently Samyang are the manufacturer but the lenses get badged in many forms. I understand the limitations, but can't spend any higher. Should be here by weekend.

Tube rings clamp to the tube, no drilling required and come in different diameters.

Playing with the ST80, and using the basic 500/fl to give max exposure time on a fixed mount. Celestial, and using matched ISO and shutter speeds for fixed aperture Terrestrial eg ISO1600 = 1/1600s. 

Hoping that I can modify my DIY mount to support the front end of the Samyang, thinking that a drain pipe hood that slide rotates within the tube ring to allow focus and give support with the camera bolted to the other end.

With the 400mm ST80 I can hand hold quite well because my front hand is a long way forward on the dovetail bar. Here's hoping.

I see a small problem. The focus ring is a metal cylinder, a tube the entire length of the lens, with a large rubber grip in the middle and a rim at the top. I cannot see how to make a sliding fit that provides enough grip for support

The Samyang 500/F6.3 is some 97mm diameter x approx 10cm L and weighs about 660g

[Daveb3650]

good ingfo here

[RichM63]

I've got that. My intention is to allow the whole cylinder inc hood to rotate within the felt padded tube ring in much the same way as the ST80 barrel slides in and out providing the ring is not too tight. Similar to a friction bearing. The hood will rotate with the lens but be in a fixed position in relation to the lens barrel.

So by sliding a DIY hood over the outside of the lens down towards the rubber grip I should I think be able to both rotate and the tube move forward/backward when focusing. If needs be, I'll cut a fine slot over part of the hood and jubilee clamp to the lens.

Remember the main strength of the support is at the camera end, this idea is just to provide some front end support for the lens similar to a snooker cue rest. All reports seem to indicate that this lens can be very shakey.

I've got one way to find out, it might not work at all, but it won't cost anything to find out. PS this is not on my photo tripod but an Astro EQ3-2 or EQ5 so much sturdier and will be balanced for the rig.

[jefrs]

Psycobilly's photos are nothing short of stunning, We do realise that is a £7,000 lens  (faints)

There is nothing in the M43 arsenal close to that lens; my 100-300/F4.0-5,6 is a "Mega.OIS" zoom and it is an "ordinary" Panasonic lens costing about £400 (I bought s/h)

But the GH4 with a decent lens -

test shot with Leica DG Summilux 25mm f/1.4 - Adobe Camera Raw auto (much as camera does) and Elements to crop from 4608x3456 to 3026x2198, little else

f/1.4 1/60 ISO200

[jefrs]

I've got that. My intention is to allow the whole cylinder inc hood to rotate within the felt padded tube ring in much the same way as the ST80 barrel slides in and out providing the ring is not too tight. Similar to a friction bearing. The hood will rotate with the lens but be in a fixed position in relation to the lens barrel.

So by sliding a DIY hood over the outside of the lens down towards the rubber grip I should I think be able to both rotate and the tube move forward/backward when focusing. If needs be, I'll cut a fine slot over part of the hood and jubilee clamp to the lens.

Remember the main strength of the support is at the camera end, this idea is just to provide some front end support for the lens similar to a snooker cue rest. All reports seem to indicate that this lens can be very shakey.

I've got one way to find out, it might not work at all, but it won't cost anything to find out. PS this is not on my photo tripod but an Astro EQ3-2 or EQ5 so much sturdier and will be balanced for the rig.

Very cunning.

I like simple because simple works: You have no idea how much important scientific equipment gets held together with sticky tape and string.

Perhaps get the hood onto the big rubber grip and secure with cable tie?

Can I get a tube ring around the 130SLT (130mm dia mirror, 158mm OD tube)?

What part/description would I be looking for?

[RichM63]

Tube rings are available from just about any supplier. FLO the forum sponsor do a 160mm set for £33 and I gather that people have also adapted the 130SLT to use with a conventional dovetail and rings to help remove wobble from tube flex. (no experience myself).

I suppose it depends on what you want to add to the telescope, a typical use is to 'piggy back' a camera or guide scope on top of the main OTA.

More weight will always be an issue.

The cat is thinking about something.;

[jefrs]

Thanks.

The 130SLT is a steel tube. I mounts to tripod with a long dovetail. I have not noticed any flex but then we have not had it long. However I am part mech/elec engineer and tend to notice stuff and fix it.

I am considering options for best engineering solution, I always do that; simple is best.

Our M43 camera system(s) are lighter that any DSLR, say 2kg tops. I am concerned that the alt/az motors can cope with the weight on the nose of the tube but it already copes with the 560g GH4 back on the eyepiece.

We also have the Sky-Watcher Star Adventurer EQ (I remember these things with a wind-up clockwork mechanism) which I'm using for AP. I can get it thrown together and aligned on Polaris in a just few minutes now despite the sodium street lamp. I needed to fabricate (bodge) a little hood for the finder from a 35mm film can. And tie it to a white find-me string. And find a plastic washer to insulate the battery so I can actually turn it off.

One of our cats is a Siamese, I'm pretty sure he can read ...

I have a Celestron camera piggyback mount intended for their larger scopes. It is supposed to fit under the finder but would foul the focuser on the 130SLT. It's screw holes are further apart too. I can drill and fit it opposite the eyepiece but the rings can be re-positioned. The rings are a good idea need a camera mounting bar, and all are additional expense: I shall probably drill the tube. Doing that I need to ensure the finder does not foul any lenses not the lenses protrude too far past the tube. I cannot fit my hand down past the mirror and do not want to dismantle that.

[jefrs]

By Jupiter!

This what I'm seeing with the GH4 1 second ISO3200 f/6.3 sooc jpeg

[RichM63]

Well, errr, ummm. Maybe a tad over exposed, slight Earth tremor, and hazy focus. The moons should be tiny bright uniform pin points, I reckon ISO3200 is too much.

The good news is that the 500mm f6.3 arrived this evening just 2 days after ordering, so maybe we could run some same target tests to compare settings etc.

[jefrs]

Well, errr, ummm. Maybe a tad over exposed, slight Earth tremor, and hazy focus. The moons should be tiny bright uniform pin points, I reckon ISO3200 is too much.

The good news is that the 500mm f6.3 arrived this evening just 2 days after ordering, so maybe we could run some same target tests to compare settings etc.

Yeah! :-  more like 3 tads and Richter 5 and a supernova

Btw native ISO on wunderkind Canon 7Dii is 100-12,800 and it has two processors giving it a dynamic range of 12EV, on GH4 it's 200-25,600 and it's got four processors, oh yeah and 13EV plus an effective heat sink on the LMOS (lower noise then CMOS) sensor, noise is low at ISO3200, noise is acceptable as ISO16,000 and still "publishable" at ISO25,600 (if you like grainy). Shooting at ISO10,000 or ISO12,000 is normal for dim indoor shots, no worries. The 16MP is same pixel density as 7Dii and equivalent to a full frame 62Mp. The GH4 is unbelievable, I've yet to find anything it can't do except maybe make coffee. The other M43 we have ain't too shabby neither: we do have access to a FF Nikki D600 which is awesome but cannot shoot in the dark at all.

An exposure of 1 second on static tripod with 500mm means slight star trail should'a been less then 1/2 second like you said 500/(500x2) incl drop factor and highlights blown way out at only ISO3200 and the Star Adventurer arrived the next day (birthday pressie to me from her)

I think that was the 500/F6.3 but could have been the 800/F8.0 which was on back order (I'm still waiting for the Sky Watcher counter-weight)

I'd have to check delivery dates, everything seemed to arrive at once over Christmas.

These lenses are tricky to focus due to sensitive focus ring (see earlier post re removing the tube), focus is off by a hair and a brace of rabbits. The 100-300 does an AF to infinity better than the reflex lenses on manual.

Seeing was good or exceptional.

I have seen the moons before through a scope. I do not know why the one on the right is bright blue? I think it was blue through the 130SLT as well. Shot on 07/01/2015 at 3 o'clock ...